Hypothalamus

Prenatal programming of human HPA axis development

gettingwell4 2-3 stars Required further work, Amygdala, Brain development, Brainstem, Cerebrum, Cortisol, Epigenetics, Hippocampus, Hypothalamus, Immune system, Limbic system, Locus coeruleus, Lower brain, Memory, Neurochemicals, Stress, Vasopressin , , , , , ,

This 2017 UC Irvine human review subject provided details of how fetal hypothalamic-pituitary-adrenal components and systems develop, and how they are epigenetically changed by the mother’s environment:

“The developmental origins of disease or fetal programming model predicts that intrauterine exposures have life-long consequences for physical and psychological health. Prenatal programming of the fetal hypothalamic-pituitary-adrenal (HPA) axis is proposed as a primary mechanism by which early experiences are linked to later disease risk.

Development of the fetal HPA axis is determined by an intricately timed cascade of endocrine events during gestation and is regulated by an integrated maternal-placental-fetal steroidogenic unit. Mechanisms by which stress-induced elevations in hormones of maternal, fetal, or placental origin influence the structure and function of the emerging fetal HPA axis are discussed.

Human gestational physiology and fetal HPA axis development differ even from that of closely related nonhuman primates, thereby limiting the generalizability of animal models. This review will focus solely on studies of prenatal stress and fetal HPA axis development in humans.”

1. Every time I read a prenatal study I’m in awe of all that has to go right – and at the appropriate times and sequences – for a fetus to be undamaged. Add in what needs to happen at birth, during infancy, and throughout early childhood, and it seems impossible for any human to escape epigenetic damage.

2. The reviewers referenced animal studies and human research performed with postnatal subjects, despite the disclaimer:

This review will focus solely on studies of prenatal stress and fetal HPA axis development in humans.”

This led to blurring of what had been studied or not with human fetuses regarding the subject.

3. These reviewers uncritically listed many dubious human studies that had both stated and undisclosed severe limitations on their findings. Other reviewers offer informed analysis of cited studies, as Sex-specific impacts of childhood trauma summarized with cortisol:

“Findings are dependent upon variance in extenuating factors, including but not limited to, different measurements of:

  • early adversity,
  • age of onset,
  • basal cortisol levels, as well as
  • trauma forms and subtypes, and
  • presence and severity of psychopathology symptomology.”

4. The paper would have been better had it stayed on topic with its title “Developmental origins of the human hypothalamic-pituitary-adrenal axis.” Let other reviews cover animals, post-natal humans, and questionable evidence.

5. I asked the reviewers to provide a searchable file to facilitate using their work as a reference.

https://www.researchgate.net/publication/318469661_Developmental_origins_of_the_human_hypothalamic-pituitary-adrenal_axis “Developmental origins of the human hypothalamic-pituitary-adrenal axis” (registration required)

A mid-year selection of epigenetic topics

gettingwell4 4-5 stars Advanced knowledge, Acetylcholine, Amygdala, Anterior cingulate cortex, Beliefs, Brain development, Brainstem, Cerebellum, Cerebrum, Cortisol, Dopamine, Epigenetics, Glutamate, Hippocampus, Hypothalamus, Immune system, Limbic system, Lower brain, Memory, Neurochemicals, Primal Therapy, Serotonin, Stress, Telomeres, Testosterone, Vasopressin , , , , , , , , , , , , , , , , , ,

Here are the most popular of the 65 posts I’ve made so far in 2018, starting from the earliest:

The pain societies instill into children

DNA methylation and childhood adversity

Epigenetic mechanisms of muscle memory

Sex-specific impacts of childhood trauma

Sleep and adult brain neurogenesis

This dietary supplement is better for depression symptoms than placebo

The epigenetic clock theory of aging

A flying human tethered to a monkey

Immune memory in the brain

The lack of oxygen’s epigenetic effects on a fetus

Melatonin and depression

gettingwell4 4-5 stars Advanced knowledge, Dopamine, Epigenetics, Hypothalamus, Limbic system, Neurochemicals, Serotonin , , ,

This 2018 Polish review subject was relationships between melatonin and depression:

“Although melatonin has been known about and referred to for almost 50 years, the relationship between melatonin and depression is still not clear. In this review, we summarize current knowledge about genetic and epigenetic regulation of enzymes involved in melatonin synthesis and metabolism as potential features of depression pathophysiology and treatment.

Melatonin has an antidepressant effect by:

  • Maintaining the body’s circadian rhythm;
  • Regulating the pattern of expression of clock genes in the suprachiasmatic nucleus (SCN); and
  • Modifying key genes of serotoninergic neurotransmission that are linked with a depressive mood.

Light input causes release of γ-aminobutyric acid (GABA) by the SCN, and the inhibitory signal is transmitted to the pineal gland to inhibit melatonin production.

Melatonin is produced via metabolism of serotonin in two steps which are catalyzed by serotonin N-acetyltransferase (SNAT) and acetylserotonin-O-methyltransferase (ASMT). Serotonin, SNAT, and ASMT are key melatonin level regulation factors.

Both melatonin and serotonin are synthesized from the same amino acid, tryptophan. People on a high tryptophan diet (>10 mg/kg body weight per day) have a significantly lower level of depressive symptoms, irritation, and anxiety than people on a low tryptophan diet (<5 mg/kg body weight per day).

To our knowledge, there are only 2 studies in the literature that characterize mRNA expression of ASMT in the peripheral blood of recurrent depressive disorders. They demonstrated reduced mRNA expression of ASMT in patients with depression and cognitive impairment. Surprisingly, these studies, despite promising results, have not been replicated. Moreover, no analysis of other melatonin related-genes as potential biomarkers of depression has been provided.

The main monoamine hypothesis of pathophysiology of depression indicates that depression is induced by a change in levels of ≥1 monoamines such as serotonin, noradrenaline, and dopamine. Evidence for the serotonergic theory is an observation that antidepressants such as tricyclic antidepressants, selective serotonin reuptake inhibitors, and noradrenaline reuptake inhibitors increase the level of serotonin in the brain.

We focus on serotonin as a neurotransmitter which is a precursor of melatonin synthesis. In a depressed patient, serotonin synthesis is impaired, and poor precursor availability may prevent formation of an adequate amount of melatonin. However, only a few studies have analyzed the relationship between serotonin and melatonin levels and the correlation with blood serum.”

At eight cents a day ($.04 for women), melatonin is a cheap and effective supplement.

I hadn’t considered possible antidepressant effects until reading this review. More human studies are needed.

https://www.karger.com/Article/Pdf/489470 “Pathophysiology of Depression: Molecular Regulation of Melatonin Homeostasis – Current Status” (not freely available)

The hypothalamus and aging

gettingwell4 2-3 stars Required further work, Brain development, Epigenetics, Hippocampus, Hypothalamus, Limbic system, Memory, Neurochemicals, Thalamus, Vasopressin , , , ,

This 2018 Korean review discussed aspects of the hypothalamus and aging:

“A majority of physiological functions that decline with aging are broadly governed by the hypothalamus, a brain region controlling development, metabolism, reproduction, circadian rhythm, and homeostasis. In addition, the hypothalamus is poised to connect the brain and the body so that the environmental information affecting aging can be transmitted through the hypothalamus to affect the systematic aging of the peripheral organs.

The hypothalamus is hypothesized to be a primary regulator of the process of aging of the entire body. This review aims to assess the contribution of hypothalamic aging to the age-related decline in body functions, particularly from the perspective of:

  • energy homeostasis,
  • hormonal balance,
  • circadian rhythm, and
  • reproduction,

and to highlight its underlying cellular mechanisms with a focus on:

  • nutrient sensing
  • inflammation,
  • loss of stem cell,
  • loss of proteostasis, and
  • epigenetic alterations.”

https://www.sciencedirect.com/science/article/pii/S0047637418300502 “Role of hypothalamus in aging and its underlying cellular mechanisms” (not freely available)

The reviewers didn’t consider aging to be an “unintended consequence” of development. This perspective was found in a reference to A study of DNA methylation and age:

“Aging is not programmed. Instead, aging is a continuation of developmental growth, driven by genetic pathways.

Genetic programs determine developmental growth and the onset of reproduction. When these programs are completed, they are not switched off.

Aging has no purpose (neither for individuals nor for group), no intention. Nature does not select for quasi-programs. It selects for robust developmental growth.”

The epigenetic clock theory of aging cited the same author, and modified his point to say:

“The proposed epigenetic clock theory of ageing views biological ageing as an unintended consequence of both developmental programmes and maintenance programmes.”

The current review’s opposite paradigm was:

“The hypothalamus is hypothesized to be a primary regulator of the process of aging.”

Almost all of the details discussed were from rodent studies.

As detailed in How to cure the ultimate causes of migraines? and its references, the hypothalamus is a brain structure that lacks feedback mechanisms for several of its activities. This structure develops shortly after conception and has an active prenatal role.

The hypothalamus plays its part in getting us developed and ready to reproduce, with certain feedback loops being evolutionarily unnecessary. The hypothalamus perfectly illustrates the point of:

“When these programs are completed, they are not switched off.”

Evolutionarily unnecessary feedback for aspects of hypothalamic activity may result in it not winding down when its developmental role is over. This activity shouldn’t be interpreted to construe a role that has some other meaning or purpose.

See Reevaluate findings in another paradigm for another view.

The lack of oxygen’s epigenetic effects on a fetus

gettingwell4 0-1 star Wasted resources, Acetylcholine, Amygdala, Brain development, Brainstem, Cerebellum, Cerebrum, Cortisol, Dopamine, Epigenetics, Glutamate, Hippocampus, Hypothalamus, Limbic system, Lower brain, Memory, Neurochemicals, Serotonin, Stress, Vasopressin , , , , , , , , ,

This 2018 Loma Linda review subject was gestational hypoxia:

“Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue.

An understanding of the specific hypoxia-induced environmental and epigenetic adaptations linked to specific organ systems will enhance the development of target-specific inhibition of DNA methylation, histone modifications, and noncoding RNAs that underlie hypoxia-induced phenotypic programming of disease vulnerability later in life.

A potential stumbling block to these efforts, however, relates to timing of the intervention. The greatest potential effect would be accomplished at the critical period in development for which the genomic plasticity is at its peak, thus ameliorating the influence of hypoxia or other stressors.

With future developments, it may even become possible to intervene before conception, before the genetic determinants of the risk of developing programmed disease are established.”

Table 3 “Antenatal hypoxia and developmental plasticity” column titles were Species | Offspring Phenotypes of Disorders and Diseases | Reference Nos.

Hypoxia phenotypes

This review was really an ebook, with 94 pages and 1,172 citations in the pdf file. As I did with Faith-tainted epigenetics, I read it with caution toward recognizing 1) the influence of the sponsor’s biases, 2) any directed narrative that ignored evidence contradicting the narrative, and 3) any storytelling.

Can you match the meaning of the review’s last sentence (“intervene before conception” quoted above) with the meaning of any sentence in its cited reference Developmental origins of noncommunicable disease: population and public health implications? I can’t.

One review topic that was misconstrued was transgenerational epigenetic inheritance of hypoxic effects. The “transgenerational” term was used inappropriately by several of the citations, and no cited study provided evidence for gestational hypoxic effects through the F3 great-grandchild generation.

One omitted topic was gestational hypoxic effects of caffeine. The first paper that came up for my PubMed search of “caffeine pregnancy hypoxia” was an outstanding 2017 Florida rodent review Long-term consequences of disrupting adenosine signaling during embryonic development that had this paragraph and figure:

“One substance that fetuses are frequently exposed to is caffeine, which is a non-selective adenosine receptor antagonist. We discovered that in utero alteration in adenosine action leads to adverse effects on embryonic and adult murine hearts. We find that cardiac A1ARs [a type of adenosine receptor] protect the embryo from in utero hypoxic stress, a condition that causes an increase in adenosine levels. 

After birth in mice, we observed that in utero caffeine exposure leads to abnormal cardiac function and morphology in adults, including an impaired response to β-adrenergic stimulation. Recently, we observed that in utero caffeine exposure induces transgenerational effects on cardiac morphology, function, and gene expression.”

The timing of in utero caffeine treatment leads to differences in adult cardiac function, gene expression, and phenotype. Exposure to caffeine from E6.5–9.5 leads the F1 generation to develop dilated cardiomyopathy with decrease % FS and increased Myh7 expression. In utero caffeine exposure from E10.5–13.5 leads to a hypertrophic cardiomyopathy in the F2 generation along with increased % FS and decreased Myh7 expression

Why was this review and its studies omitted? It was on target for both gestational hypoxia and transgenerational epigenetic inheritance of hypoxic effects!

It was alright to review smoking, cocaine, methamphetamine, etc., but the most prevalent drug addiction – caffeine – couldn’t be a review topic?

The Loma Linda review covered a lot, but I had a quick trigger due to the sponsor’s bias. I started to lose “faith” in the reviewers after reading the citation for the review’s last sentence that didn’t support the statement.

My “faith” disappeared after not understanding why a few topics were misconstrued and omitted. Why do researchers and sponsors ignore, misrepresent, and not continue experiments through the F3 generation to produce evidence for and against transgenerational epigenetic inheritance? Where was the will to follow evidence trails regardless of socially acceptable beverage norms?

The review acquired the taint of storytelling with the reviewers’ assertion:

“..timing of the intervention. The greatest potential effect would be accomplished at the critical period in development for which the genomic plasticity is at its peak, thus ameliorating the influence of hypoxia or other stressors.”

Contradictory evidence was in the omitted caffeine study’s graphic above which described two gestational critical periods where an “intervention” had opposite effects, all of which were harmful to the current fetus’ development and/or to following generations. Widening the PubMed link’s search parameters to “caffeine hypoxia” and “caffeine pregnancy” returned links to human early life studies that used caffeine in interventions, ignoring possible adverse effects on future generations.

This is my final curation of any paper sponsored by this institution.

https://www.physiology.org/doi/abs/10.1152/physrev.00043.2017 “Gestational Hypoxia and Developmental Plasticity” (not freely available) Thanks to coauthor Dr. Xiang-Qun Hu for providing a copy.

Resiliency in stress responses

gettingwell4 < 0 Detracted from science, Amygdala, Anterior cingulate cortex, Beliefs, Brain development, Brainstem, Cerebrum, Cortisol, Dopamine, Epigenetics, Glutamate, Hippocampus, Hypothalamus, Limbic system, Locus coeruleus, Lower brain, Memory, Neurochemicals, Oxytocin, Primal Therapy, Serotonin, Stress, Thalamus , , , , , , , , ,

This 2018 US Veterans Administration review subject was resiliency and stress responses:

“Neurobiological and behavioral responses to stress are highly variable. Exposure to a similar stressor can lead to heterogeneous outcomes — manifesting psychopathology in one individual, but having minimal effect, or even enhancing resilience, in another.

We highlight aspects of stress response modulation related to early life development and epigenetics, selected neurobiological and neurochemical systems, and a number of emotional, cognitive, psychosocial, and behavioral factors important in resilience.”

The review cited studies I’ve previously curated:

There were two things I didn’t understand about this review. The first was why the paper isn’t freely available. It’s completely paid for by the US taxpayer, and no copyright is claimed. I recommend contacting the authors for a copy.

The second was why the VA hasn’t participated in either animal or human follow-on studies to the 2015 Northwestern University GABAergic mechanisms regulated by miR-33 encode state-dependent fear. That study’s relevance to PTSD, this review’s subject, and the VA’s mission is too important to ignore. For example:

“Fear-inducing memories can be state dependent, meaning that they can best be retrieved if the brain states at encoding and retrieval are similar.

“It’s difficult for therapists to help these patients,” Radulovic said, “because the patients themselves can’t remember their traumatic experiences that are the root cause of their symptoms.”

The findings imply that in response to traumatic stress, some individuals, instead of activating the glutamate system to store memories, activate the extra-synaptic GABA system and form inaccessible traumatic memories.”

I curated the research in A study that provided evidence for basic principles of Primal Therapy. These researchers have published several papers since then. Here are the abstracts from three of them:

Experimental Methods for Functional Studies of microRNAs in Animal Models of Psychiatric Disorders

“Pharmacological treatments for psychiatric illnesses are often unsuccessful. This is largely due to the poor understanding of the molecular mechanisms underlying these disorders. We are particularly interested in elucidating the mechanism of affective disorders rooted in traumatic experiences.

To date, the research of mental disorders in general has focused on the causal role of individual genes and proteins, an approach that is inconsistent with the proposed polygenetic nature of these disorders. We recently took an alternative direction, by establishing the role of miRNAs in the coding of stress-related, fear-provoking memories.

Here we describe in detail our work on the role of miR-33 in state-dependent learning, a process implicated in dissociative amnesia, wherein memories formed in a certain brain state can best be retrieved if the brain is in the same state. We present the specific experimental approaches we apply to study the role of miRNAs in this model and demonstrate that miR-33 regulates the susceptibility to state-dependent learning induced by inhibitory neurotransmission.”

Neurobiological mechanisms of state-dependent learning

“State-dependent learning (SDL) is a phenomenon relating to information storage and retrieval restricted to discrete states. While extensively studied using psychopharmacological approaches, SDL has not been subjected to rigorous neuroscientific study.

Here we present an overview of approaches historically used to induce SDL, and highlight some of the known neurobiological mechanisms, in particular those related to inhibitory neurotransmission and its regulation by microRNAs (miR).

We also propose novel cellular and circuit mechanisms as contributing factors. Lastly, we discuss the implications of advancing our knowledge on SDL, both for most fundamental processes of learning and memory as well as for development and maintenance of psychopathology.”

Neurobiological correlates of state-dependent context fear

“Retrieval of fear memories can be state-dependent, meaning that they are best retrieved if the brain states at encoding and retrieval are similar. Such states can be induced by activating extrasynaptic γ-aminobutyric acid type A receptors (GABAAR) with the broad α-subunit activator gaboxadol. However, the circuit mechanisms and specific subunits underlying gaboxadol’s effects are not well understood.

Here we show that gaboxadol induces profound changes of local and network oscillatory activity, indicative of discoordinated hippocampal-cortical activity, that were accompanied by robust and long-lasting state-dependent conditioned fear. Episodic memories typically are hippocampus-dependent for a limited period after learning, but become cortex-dependent with the passage of time.

In contrast, state-dependent memories continued to rely on hippocampal GABAergic mechanisms for memory retrieval. Pharmacological approaches with α- subunit-specific agonists targeting the hippocampus implicated the prototypic extrasynaptic subunits (α4) as the mediator of state-dependent conditioned fear.

Together, our findings suggest that continued dependence on hippocampal rather than cortical mechanisms could be an important feature of state-dependent memories that contributes to their conditional retrieval.”

Here’s an independent 2017 Netherlands/UC San Diego review that should bring these researchers’ efforts to the VA’s attention:

MicroRNAs in Post-traumatic Stress Disorder

“Post-traumatic stress disorder (PTSD) is a psychiatric disorder that can develop following exposure to or witnessing of a (potentially) threatening event. A critical issue is to pinpoint the (neuro)biological mechanisms underlying the susceptibility to stress-related disorder such as PTSD, which develops in the minority of ~15% of individuals exposed to trauma.

Over the last few years, a first wave of epigenetic studies has been performed in an attempt to identify the molecular underpinnings of the long-lasting behavioral and mental effects of trauma exposure. The potential roles of non-coding RNAs (ncRNAs) such as microRNAs (miRNAs) in moderating or mediating the impact of severe stress and trauma are increasingly gaining attention. To date, most studies focusing on the roles of miRNAs in PTSD have, however, been completed in animals, using cross-sectional study designs and focusing almost exclusively on subjects with susceptible phenotypes.

Therefore, there is a strong need for new research comprising translational and cross-species approaches that use longitudinal designs for studying trajectories of change contrasting susceptible and resilient subjects. The present review offers a comprehensive overview of available studies of miRNAs in PTSD and discusses the current challenges, pitfalls, and future perspectives of this field.”

Here’s a 2017 Netherlands human study that similarly merits the US Veterans Administration’s attention:

Circulating miRNA associated with posttraumatic stress disorder in a cohort of military combat veterans

“Posttraumatic stress disorder (PTSD) affects many returning combat veterans, but underlying biological mechanisms remain unclear. In order to compare circulating micro RNA (miRNA) of combat veterans with and without PTSD, peripheral blood from 24 subjects was collected following deployment, and isolated miRNA was sequenced.

PTSD was associated with 8 differentially expressed miRNA. Pathway analysis shows that PTSD is related to the axon guidance and Wnt signaling pathways, which work together to support neuronal development through regulation of growth cones. PTSD is associated with miRNAs that regulate biological functions including neuronal activities, suggesting that they play a role in PTSD symptomatology.”

See the below comments for reasons why I downgraded this review’s rating.

https://link.springer.com/article/10.1007/s11920-018-0887-x “Stress Response Modulation Underlying the Psychobiology of Resilience” (not freely available)

The lifelong impact of maternal postpartum behavior

gettingwell4 4-5 stars Advanced knowledge, Amygdala, Brain development, Cerebrum, Cortisol, Epigenetics, Glutamate, Hippocampus, Hypothalamus, Limbic system, Neurochemicals, Oxytocin, Stress, Vasopressin , , , , , ,

This 2018 French/Italian/Swiss rodent study was an extension of the work done by the group of researchers who performed Prenatal stress produces offspring who as adults have cognitive, emotional, and memory deficiencies and Treating prenatal stress-related disorders with an oxytocin receptor agonist:

“Reduction of maternal behavior [nursing behavior, grooming, licking, carrying pups] was predictive of behavioral disturbances in PRS [prenatally restraint stressed] rats as well as of the impairment of the oxytocin and its receptor gene expression.

Postpartum carbetocin [an oxytocin receptor agonist unavailable in the US] corrected the reduction of maternal behavior induced by gestational stress as well as the impaired oxytocinergic system in the PRS progeny, which was associated with reduced risk-taking behavior.

Moreover, postpartum carbetocin had an anti-stress effect on HPA [hypothalamic-pituitary-adrenal] axis activity in the adult PRS progeny and increased hippocampal mGlu5 [type 5 metabotropic glutamate] receptor expression in aging.

Early postpartum carbetocin administration to the dam enhances maternal behavior and prevents all the pathological outcomes of PRS throughout the entire lifespan of the progeny..proves that the defect in maternal care induced by gestational stress programs the development of the offspring.“


This chart from Figure 4 summarized the behavioral performance of aged adult male progeny in relation to the experimental variables of:

  1. Stress administered to the mothers three times daily every day during the second half of pregnancy up until delivery; and
  2. The effects on the mothers’ behavior of daily carbetocin administration during postpartum days 1 through 7.

The symbols denote which of these relationships had statistically significant effects:

  • “* p [Pearson’s correlation coefficient] < 0.05 PRS-Saline vs. CONT-Saline;
  • # p < 0.05 PRS-Carbetocin vs. the PRS-Saline group.”

There are many interesting aspects to this study. Ask the corresponding coauthor Dr. Sara Morley-Fletcher at sara.morley-fletcher@univ-lille1.fr for a copy.

One place the paper referenced the researchers’ previous studies was in this context:

“Postpartum carbetocin administration reversed the same molecular and behavioral parameters in the hippocampus, as does adult chronic carbetocin treatment, i.e. it led to a correction of the HPA axis negative feedback mechanisms, stress and anti-stress gene expression, and synaptic glutamate release. The fact that postpartum carbetocin administration [to the stressed mothers in this study] had the same effect [on the PRS infants in this study] as adult carbetocin treatment [to the PRS offspring in the previous study] indicates a short-term effect of carbetocin when administered in adulthood and a reprogramming (long-term) effect lasting until an advanced age when administered in early development.”

This group’s research seems to be constrained to treatments of F0 and F1 generations. What intergenerational and transgenerational effects would they possibly find by extending research efforts to F2 and F3 generations?

As the study may apply to humans:

The study demonstrated that stresses during the second half of pregnancy had lifelong impacts on both the mothers’ and offsprings’ biology and behavior. Studies and reviews that attribute similar human biological and behavioral conditions to unknown causes, or shuffle them into the black box of individual differences, should be recognized as either disingenuous or insufficient etiological investigations.

The study showed that prevention of gestational stress was a viable strategy. The control group progeny’s biology and behavior wasn’t affected by carbetocin administration to their mothers because neither they nor their mothers had experience-dependent epigenetic deficiencies.

The study demonstrated a biological and behavioral cure for the PRS offspring by changing their stressed mothers’ behaviors during a critical period of their development. The above excerpt characterized improving the mothers’ behaviors as a long-term cure for the PRS descendants, as opposed to the short-term cure of administering carbetocin to the PRS children when they were adults.

What long-term therapies may be effective for humans who had their developmental trajectories altered by their mothers’ stresses during their gestation, or who didn’t get the parental care they needed when they needed it?

https://www.sciencedirect.com/science/article/pii/S0161813X18301062 “Reduced maternal behavior caused by gestational stress is predictive of life span changes in risk-taking behavior and gene expression due to altering of the stress/anti-stress balance” (not freely available)

Prenatal stress produces offspring who as adults have cognitive, emotional, and memory deficiencies

gettingwell4 4-5 stars Advanced knowledge, Brain development, Cerebrum, Epigenetics, Glutamate, Hippocampus, Hypothalamus, Limbic system, Memory, Neurochemicals, Oxytocin, Stress , , , , ,

This 2018 French/Italian/Swiss rodent study used a prenatally restraint stressed (PRS) model to create problems that could be resolved by various chemicals:

“S 47445 is a positive modulator of glutamate AMPA-type receptors, possessing neurotrophic and enhancing synaptic plasticity effects as well as pro-cognitive and anti-stress properties.

Most of studies examining the antidepressant effects of new molecules are carried out using behavioral tests performed in unstressed animals.

Corticosterone-treated mice and rats exposed to chronic stress are models that do not recapitulate the early programming of stress-related disorders, which likely originates in the perinatal period. The PRS rat model is characterized by a prolonged corticosterone response to stress and by abnormal behavior.

All the behavioral alterations induced by PRS were corrected by chronic S 47445 administration at both doses.”

The paper included a section comparing S 47445 to ketamine:

“Ketamine, however, causes severe cognitive impairment and psychotomimetic [mimics the symptoms of psychosis, reference not freely available] effects that are direct consequences of the prolonged inhibition of NMDA receptors in cortical and hippocampal interneurons, and seriously limit the chronic administration of the drug in the clinical setting. [reference not freely available]

S 47445 by inducing a direct activation of AMPARs displayed an antidepressant activity without the adverse effect of ketamine. Indeed, contrary to ketamine, S 47445 presented no psychotomimetic effects and induced no occurrence of spontaneous epileptic seizures. [reference freely available] Moreover, S 47445 also presented pro-cognitive properties.”

Compare the above with this April 2018 Chicago Tribune story that had opinions with no linked references:

“ketamine, an anesthetic used to sedate both people and animals before surgery. It’s also a notorious street drug, abused by clubgoers seeking a trancelike, hallucinatory high. But in recent years, numerous studies have found that ketamine can be an effective and speedy treatment for people with depression.”

Which coverage better informed us?

Treating prenatal stress-related disorders with an oxytocin receptor agonist was performed by several of this paper’s coauthors. One references to it was:

“We have already reported that depolarization-evoked glutamate release in the ventral hippocampus is negatively correlated with risk-taking behavior of PRS rats, and that such correlation can be corrected by chronic treatment with monoaminergic/ melatoninergic antidepressants or oxytocin receptor agonist. Thus, an impairment of glutamatergic transmission in the ventral hippocampus lies at the core of the pathological phenotype of PRS rats.”

Looking at the above graphic of the experimental design, I’m not sure why the term perinatal (occurring during or pertaining to the phase surrounding the time of birth) was used in the paper’s title and content to describe the stress period. The pregnant females were stressed three times every day during the second half of pregnancy up until delivery, so the prenatal (previous to birth) term was more applicable.

So, how does this study help humans?

One takeaway is to avoid stressing pregnant mothers-to-be if her children will be expected to become adults without cognitive, emotional, and behavioral problems.

The study demonstrated one way prenatal events cause lifelong effects. The PRS model provides another example of why it’s useless to ask adult humans to self-report causes of epigenetic problems in their lives when these originated before birth, during infancy, or in early childhood, well before humans develop sufficient cognitive capability to recognize such situations. It’s incomprehensible that this unreliable paradigm is still given significant weight in stress studies, especially when experimental designs:

“Do not recapitulate the early programming of stress-related disorders, which likely originates in the perinatal period.”

Also, a relevant difference between humans and PRS rats is that we can ourselves individually change our responses to experiential causes of ongoing adverse effects. Standard methodologies can only apply external treatments such as those mentioned above.

https://www.sciencedirect.com/science/article/pii/S0028390818301291 “The reduction in glutamate release is predictive of cognitive and emotional alterations that are corrected by the positive modulator of AMPA receptors S 47445 in perinatal stressed rats” (not freely available) Thanks to coauthors Stefania Maccari and Dr. Jerome Mairesse for providing a copy.

Manufacturing PTSD evidence with machine learning

gettingwell4 < 0 Detracted from science, Beliefs, Brain development, Cerebrum, Cortisol, Epigenetics, Hypothalamus, Limbic system, Memory, Neurochemicals, Stress

What would you do if you were a scientist who had strong beliefs that weren’t borne out by experimental evidence?

Would you be honest with yourself about the roots of the beliefs? Would you attempt to discover why the beliefs were necessary for you, and what feelings were associated with the beliefs?

Instead of the above, the researchers of this 2017 New York human study reworked negative findings of two of the coauthors’ 2008 study until it fit their beliefs:

“The neuroendocrine response contributes to an accurate predictive signal of PTSD trajectory of response to trauma. Further, cortisol provides a stable predictive signal when measured in conjunction with other related neuroendocrine and clinical sources of information.

Further, this work provides a methodology that is relevant across psychiatry and other behavioral sciences that transcend the limitations of commonly utilized data analytic tools to match the complexity of the current state of theory in these fields.”

1. The limitations section included:

“It is important to note that ML [machine learning]-based network models are an inherently exploratory data analytic method, and as such might be seen as ‘hypotheses generating’. While such an approach is informative in situations where complex relationships cannot be proposed and tested a priori, such an approach also presents with inherent limitations as a high number of relationships are estimated simultaneously introducing a non-trivial probability of false discovery.”

2. Sex-specific impacts of childhood trauma summarized why cortisol isn’t a reliable biological measurement:

“Findings are dependent upon variance in extenuating factors, including but not limited to, different measurements of:

  • early adversity,
  • age of onset,
  • basal cortisol levels, as well as
  • trauma forms and subtypes, and
  • presence and severity of psychopathology symptomology.”

Although this study’s authors knew or should have known that review’s information, cortisol was the study’s foundation, and beliefs in its use as a biomarker were defended.

3. What will it take for childhood trauma research to change paradigms? described why self-reports of childhood trauma can NEVER provide direct evidence for trauma during the top three periods when humans are most sensitive to and affected by trauma:

“The basic problem prohibiting the CTQ (Childhood Trauma Questionnaire) from discovering likely most of the subjects’ historical traumatic experiences that caused epigenetic changes is that these experiences predated the CTQ’s developmental starting point.

Self-reports were – at best – evidence of experiences after age three, distinct from the experience-dependent epigenetic changes since conception.”

Yet the researchers’ beliefs in the Trauma History Questionnaire’s capability to provide evidence for early childhood traumatic experiences allowed them to make such self-reports an important part of this study’s findings, for example:

“The reduced cortisol response in the ER [emergency room] was dependent on report of early childhood trauma exposure.”

https://www.nature.com/articles/tp201738 “Utilization of machine learning for prediction of post-traumatic stress: a re-examination of cortisol in the prediction and pathways to non-remitting PTSD”

Genomic imprinting and growth

gettingwell4 2-3 stars Required further work, Brain development, Epigenetics, Hypothalamus, Limbic system , , , , , ,

This 2018 UK paper reviewed genomic imprinting:

“Since their discovery nearly 30 years ago, imprinted genes have been a paradigm for exploring the epigenetic control of gene expression. Moreover, their roles in early life growth and placentation are undisputed.

However, it is becoming increasingly clear that imprinted gene function has a wider role in maternal physiology during reproduction – both by modulating fetal and placental endocrine products that signal to alter maternal energy homeostasis, and by altering maternal energetic set points, thus producing downstream actions on nutrient provisioning.”

“Imprinted genes in the conceptus produce products that alter maternal resource allocation by:

  1. altering the transport capacity of the placenta;
  2. increasing fetal demand for resources by their action on the intrinsic growth rate; and
  3. signalling to the mother by the production of fetal/placental hormones that modify maternal metabolism.”

Other studies/reviews I’ve curated that covered genomic imprinting are:

http://jeb.biologists.org/content/jexbio/221/Suppl_1/jeb164517.full.pdf “Genomic imprinting, growth and maternal-fetal interactions”

This post has somehow become a target for spammers, and I’ve disabled comments. Readers can comment on other posts and indicate that they want their comment to apply here, and I’ll re-enable comments.

How well do single-mother rodent studies inform us about human fathers?

gettingwell4 2-3 stars Required further work, Brain development, Cortisol, Epigenetics, Hippocampus, Hypothalamus, Limbic system, Neurochemicals, Serotonin, Stress , ,

Two items before getting to the review:

This 2018 Australian review subject was paternal intergenerational and transgenerational transmission of biological and behavioral phenotypes per this partial outline:

“Evidence for non-genetic inheritance of behavioral traits in human populations

  • Intergenerational inheritance modulating offspring phenotypes following paternal exposure to trauma
  • Epigenetic inheritance via the germline following paternal environmental exposures
  • Limitations of research on epigenetic inheritance in human populations

The transgenerational impact of stressful paternal environments

  • Impact of paternal stress on affective behaviors and HPA-axis regulation of progeny
  • Influence of paternal stress exposure on offspring cognition
  • Role of sperm-borne microRNAs in the epigenetic inheritance of stress

Sexually dimorphic aspects of paternal transgenerational epigenetic inheritance”

The review was comprehensive, and filled in the above outline with many details towards the goal of:

“This exciting new field of transgenerational epigenomics will facilitate the development of novel strategies to predict, prevent and treat negative epigenetic consequences on offspring health, and psychiatric disorders in particular.”

The reviewers also demonstrated that current intergenerational and transgenerational research paradigms exclude a father’s child care behavior.

The fact that studies use rat and mouse species where fathers don’t naturally provide care for their offspring has warped the translation of findings to humans. The underlying question every animal study must answer is: how can its information be used to help humans? I asked in A limited study of parental transmission of anxiety/stress-reactive traits:

“How did parental behavioral transmission of behavioral traits and epigenetic changes become a subject not worth investigating? These traits and effects can be seen everyday in real-life human interactions, and in every human’s physiology.”

Who among us doesn’t still have biological and behavioral consequences from our experiences of our father’s child care actions and inactions? Why can’t researchers and sponsors investigate these back to their sources that may include grandparents and great-grandparents?

Such efforts weren’t apparent in the review’s 116 cited references that included:

The reviewer in the latter has been instrumental in excluding behavioral inheritance mechanisms from these research paradigms, leading to my questions:

  1. “If the experimental subjects had no more control over their behavioral stress-response effects than they had over their DNA methylation, histone modification, or microRNA stress-response effects, then why was such behavior not included in the “epigenetic mechanisms” term?
  2. How do behavioral inheritance mechanisms fall outside the “true epigenetic inheritance” term when behavioral stress-response effects are shown to be reliably transmitted generation after generation?
  3. Wouldn’t the cessation of behavioral inheritance mechanisms confirm their status by falsifiability as was similarly done with studies such as the 1995 Adoption reverses the long-term impairment in glucocorticoid feedback induced by prenatal stress?”

Translating rodent studies into human mothers’ behavioral transmission of biological and behavioral phenotypes isn’t hampered by the studied species’ traits as it is for human fathers. But sponsors have to have the guts to support human research that may not produce politically-correct findings.

http://www.translatingtime.org provides an inter-species comparative timeline. For example, an input of:

  • Species 1: Human
  • Process: Lifespan
  • Location: Whole Organism
  • Days (post-conception): 270
  • Species 2: Mouse

produces a list of event predictions. Note how many significant events occur before humans are born at day 270, assuming everything goes right with our developmental processes! Also, the model predictions for humans end at post-conception day 979, three weeks short of when we celebrate our second birthday.

https://www.nature.com/articles/s41380-018-0039-z “Transgenerational epigenetic influences of paternal environmental exposures on brain function and predisposition to psychiatric disorders” (not freely available) Thanks to Dr. Shlomo Yeshurun for providing a full copy.

Sleep and adult brain neurogenesis

gettingwell4 < 0 Detracted from science, Amygdala, Anterior cingulate cortex, Brain development, Cerebrum, Epigenetics, Hippocampus, Hypothalamus, Limbic system, Memory, Stress , , , ,

This 2018 Japan/Detroit review subject was the impact of sleep and epigenetic modifications on adult dentate gyrus neurogenesis:

“We discuss the functions of adult‐born DG neurons, describe the epigenetic regulation of adult DG neurogenesis, identify overlaps in how sleep and epigenetic modifications impact adult DG neurogenesis and memory consolidation..

Whereas the rate of DG neurogenesis declines exponentially with age in most mammals, humans appear to exhibit a more modest age‐related reduction in DG neurogenesis. Evidence of adult neurogenesis has also been observed in other regions of the mammalian brain such as the subventricular zone, neocortex, hypothalamus, amygdala, and striatum.

Adult‐born DG neurons functionally integrate into hippocampal circuitry and play a special role in cognition during a period of heightened excitability and synaptic plasticity occurring 4–6 weeks after mitosis. Adult DG neurogenesis is regulated by a myriad of intrinsic and extrinsic factors, including:

  • drugs,
  • diet,
  • inflammation,
  • physical activity,
  • environmental enrichment,
  • stress, and
  • trauma.”

Some of what the review stated was contradicted by other evidence. For example, arguments for sleep were based on the memory consolidation paradigm, but evidence against memory consolidation wasn’t cited for balanced consideration.

It reminded me of A review that inadvertently showed how memory paradigms prevented relevant research. That review’s citations included a study led by one of those reviewers where:

“The researchers elected to pursue a workaround of the memory reconsolidation paradigm when the need for a new paradigm of enduring memories directly confronted them!”

Some of what this review stated was speculation. I didn’t quote any sections after:

 “We go one step further and propose..”

The review also had a narrative directed toward:

“Employing sleep interventions and epigenetic drugs..”

It’s storytelling rather than pursuing the scientific method when reviewers approach a topic as these reviewers did.

Instead of reading a directed narrative, read this informative blog post from a Canadian researcher. The post provided scientific contexts to summarize what was and wasn’t known in 2018 about human neurogenesis.

http://onlinelibrary.wiley.com/doi/10.1002/stem.2815/epdf “Regulatory Influence of Sleep and Epigenetics on Adult Hippocampal Neurogenesis and Cognitive and Emotional Function”

What will it take for childhood trauma research to change paradigms?

gettingwell4 0-1 star Wasted resources, Brain development, Cortisol, Epigenetics, Hippocampus, Hypothalamus, Limbic system, Memory, Neurochemicals, Serotonin, Stress , , ,

This 2018 German human study found:

“DNA methylation in a biologically relevant region of NR3C1-1F [glucocorticoid receptor gene] moderates the specific direction of HPA-axis dysregulation (hypo- vs. hyperreactivity) in adults exposed to moderate-severe CT [childhood trauma].

In contrast, unexposed and mildly-moderately exposed individuals displayed moderately sized cortisol stress responses irrespective of NR3C1-1F DNA methylation. Contrary to some prior work, however, our data provides no evidence for a direct association of CT and NR3C1-1F DNA methylation status.”

The study was an example of why researchers investigating the lasting impacts of human traumatic experiences won’t find causes, effects, and productive therapies until their paradigms change.

1. Limited subject histories

A. Why weren’t the subjects asked for historical information about their parents, grandparents, and great-grandparents?

The researchers had no problem using animal studies to guide the study design, EXCEPT for animal studies of the etiologic bases of intergenerational and transgenerational transmission of biological and behavioral phenotypes. Just the approximate places and dates of three generations of the German subjects’ ancestors’ births, childhoods, adolescences, and early adulthoods may have provided relevant trauma indicators.

B. Why are studies still using the extremely constrained Childhood Trauma Questionnaire? Only one CTQ aspect was acknowledged as a study design limitation:

“Our findings rely on retrospective self-report measures of CT, which could be subject to bias.”

But bias was among the lesser limiting factors of the CTQ.

The study correlated epigenetic changes with what the subjects selectively remembered, beginning when their brains developed sufficient cognitive functionalities to put together the types of memories that could provide CTQ answers – around age four. The basic problem that kept the CTQ from discovering likely most of the subjects’ traumatic experiences causing epigenetic changes was that these experiences predated the CTQ’s developmental starting point:

  1. A human’s conception through prenatal period is when both the largest and the largest number of epigenetic changes occur, and is when our susceptibility and sensitivity to our environment is greatest;
  2. Birth through infancy is the second-largest; and
  3. Early childhood through the age of three is the third largest.

CTQ self-reports were – at best – evidence of experiences after age three, distinct from the  experience-dependent epigenetic changes since conception. If links existed between the subjects’ early-life DNA methylation and later-life conditions, they weren’t necessarily evidenced by CTQ answers about later life that can’t self-report relevant early-life experiences that may have caused DNA methylation.

2. Limited subject selection

The researchers narrowed down the initial 622 potential subjects to the eventual 200 subjects aged 18 to 30. An exclusion criteria that was justified as eliminating confounders led to this limitation statement:

“Our results might be based on a generally more resilient sample as we had explicitly excluded individuals with current or past psychopathology.”

Was it okay for the researchers to assert:

“Exposure to environmental adversity such as childhood trauma (CT) affects over 10% of the Western population and ranges among the best predictors for psychopathology later in life.”

but not develop evidence for the statement by letting people who may have been already affected by age 30 and received treatment participate in the study?

Was the study design so fragile that it couldn’t adjust to the very people who may be helped by the research findings?

3. Limited consequential measurements

The current study design conformed to previous studies’ protocols. The researchers chose cortisol and specific DNA methylation measurements.

A. Here’s what Sex-specific impacts of childhood trauma had to say about cortisol:

“Findings are dependent upon variance in extenuating factors, including but not limited to, different measurements of:

  • early adversity,
  • age of onset,
  • basal cortisol levels, as well as
  • trauma forms and subtypes, and
  • presence and severity of psychopathology symptomology.”

The researchers knew or should have known all of the above since this quotation came from a review.

B. What other consequential evidence for prenatal, infancy, and early childhood experience-dependent epigenetic changes can be measured? One overlooked area was including human emotions as evidence.

There are many animal studies from which to draw inferences about human emotions. There are many animal models of creating measurable behavioral and biological phenotypes of human emotion correlates, with many methods, including manipulating environmental variables during prenatal, infancy, and early childhood periods.

Studies that take detailed histories may arrive at current emotional evidence for human subjects’ earliest experience-dependent changes. Researchers who correlate specific historical environments and events, stress measurements, and lasting human emotions expressed as “I’m all alone” and “No one can help me” will better understand causes and effects.

CTQ answers weren’t sufficiently detailed histories.

4. Limited effective treatments and therapies

The current study only addressed this area in the final sentence:

“Given their potential reversibility, uncovering epigenetic contributions to differential trajectories following childhood adversity may serve the long-term goal of delivering personalized prevention strategies.”

Researchers – if your paradigms demonstrate these characteristics:

  • Why are you spending your working life in efforts that can’t make a difference?
  • Aren’t your working efforts more valuable than that?
  • What else could you investigate that could make a difference in your field?

I hope that researchers will value their professions enough to make a difference with their expertise. And that sponsors won’t thwart researchers’ desires for difference-making science by putting them into endless funding queues.

http://www.psyneuen-journal.com/article/S0306-4530(17)31355-0/pdf “Glucocorticoid receptor gene methylation moderates the association of childhood trauma and cortisol stress reactivity” (not freely available)

Sex-specific impacts of childhood trauma

gettingwell4 4-5 stars Advanced knowledge, Amygdala, Anterior cingulate cortex, Cerebrum, Cortisol, Dopamine, Epigenetics, Hippocampus, Hypothalamus, Limbic system, Memory, Neurochemicals, Serotonin, Stress, Telomeres, Testosterone , , , , ,

This 2018 Canadian paper reviewed evidence for potential sex-specific differences in the lasting impacts of childhood trauma:

“This paper will provide a contextualized summary of neuroendocrine, neuroimaging, and behavioral epigenetic studies on biological sex differences contributing to internalizing psychopathology, specifically posttraumatic stress disorder and depression, among adults with a history of childhood abuse.

Given the breadth of this review, we limit our definition [of] trauma to intentional and interpersonal experiences (i.e., childhood abuse and neglect) in childhood. Psychopathological outcomes within this review will be limited to commonly explored internalizing disorders, specifically PTSD and depression.

Despite the inconsistent and limited findings in this review, a critical future consideration will be whether the biological effects of early life stress can be reversed in the face of evidence-based behavioral interventions, and furthermore, whether these changes may relate to potentially concurrent reductions in susceptibility to negative mental health outcomes.”

It was refreshing to read a paper where the reviewers often interrupted the reader’s train of thought to interject contradictory evidence, and display the scientific method. For example, immediately after citing a trio of well-respected studies that found:

“Psychobiological research on relationships linking impaired HPA axis functioning and adult internalizing disorders are suggestive of lower basal and afternoon levels of plasma cortisol in PTSD phenotype.”

the reviewers stated:

“However, a recent meta-analysis suggests no association between basal cortisol with PTSD.”

and effectively ended the cortisol discussion with:

“Findings are dependent upon variance in extenuating factors, including but not limited to, different measurements of:

  • early adversity,
  • age of onset,
  • basal cortisol levels, as well as
  • trauma forms and subtypes, and
  • presence and severity of psychopathology symptomology.”

The reviewers also provided good summaries of aspects of the reviewed subject. For example, the “Serotonergic system genetic research, childhood trauma and risk of psychopathology” subsection ended with:

“Going forward, studies must explore the longitudinal effects of early trauma on methylation as well as comparisons of multiple loci methylation patterns and interactions to determine the greatest factors contributing to health outcomes. Only then, can we start to consider the role of sex in moderating risk.”

I didn’t agree with the cause-ignoring approach of the behavior therapy mentioned in the review. Does it make sense to approach one category of symptoms:

“the biological effects of early life stress”

by treating another category of symptoms?

“can be reversed in the face of evidence-based behavioral interventions.”

But addressing symptoms instead of the sometimes-common causes that generate both biological and behavioral effects continues to be the direction.

After receiving short-term symptom relief, wouldn’t people prefer treatments of originating causes so that their various symptoms don’t keep bubbling up? Why wouldn’t research paradigms be aligned accordingly?

I was encouraged by the intergenerational and transgenerational focus of one of the reviewer’s research:

“Dr. Gonzalez’s current research focus is to understand the mechanisms by which early experiences are transmitted across generations and how preventive interventions may affect this transmission.”

This line of hypotheses requires detailed histories, and should uncover causes for many effects that researchers may otherwise shrug off as unexplainable individual differences. Its aims include the preconception through prenatal periods when both the largest and the largest number of epigenetic changes occur, and is when our susceptibility and sensitivity to our environment is greatest. There are fewer opportunities for effective “preventive interventions” in later life compared with these early periods.

Unlike lab rats, women and men can reach some degree of honesty about our early lives’ experiential causes of ongoing adverse effects. Experiential therapies that allow humans to potentially change their responses to these causes deserve more investigation than do therapies that apply external “interventions.”

https://www.sciencedirect.com/science/article/pii/S0272735817302647 “Biological alterations affecting risk of adult psychopathology following childhood trauma: A review of sex differences” (not freely available) Thanks to lead author Dr. Ashwini Tiwari for providing a copy.

DNA methylation and childhood adversity

gettingwell4 4-5 stars Advanced knowledge, Cortisol, Epigenetics, Hypothalamus, Immune system, Limbic system, Neurochemicals, Serotonin, Stress, Vasopressin , ,

This 2017 Georgia human review covered:

“Recent studies, primarily focused on the findings from human studies, to indicate the role of DNA methylation in the associations between childhood adversity and cardiometabolic disease in adulthood. In particular, we focused on DNA methylation modifications in genes regulating the hypothalamus-pituitary-adrenal axis as well as the immune system.”

Recommendations in the review’s Epigenetics inheritance and preadaptation theory section included:

“Twin studies offer another promising design to explore the mediation effect of DNA methylation between child adversity and cardiometabolic outcomes..which could rule out heterogeneity due to genetic and familia[l]r environmental confounding.”

As it so happened, the below 2018 study provided some evidence.

http://www.sciencedirect.com/science/article/pii/S0167527317352762 “The role of DNA methylation in the association between childhood adversity and cardiometabolic disease” (not freely available) Thanks to lead author Dr. Guang Hao for providing the full study.

This 2018 UK human study:

“Tested the hypothesis that victimization is associated with DNA methylation in the Environmental Risk (E-Risk) Longitudinal Study, a nationally representative 1994-1995 birth cohort of 2,232 twins born in England and Wales and assessed at ages 5, 7, 10, 12, and 18 years. Multiple forms of victimization were ascertained in childhood and adolescence (including physical, sexual, and emotional abuse; neglect; exposure to intimate-partner violence; bullying; cyber-victimization; and crime).

Hypothesis-driven analyses of six candidate genes in the stress response (

  1. NR3C1 [glucocorticoid receptor],
  2. FKBP5 [a regulator of the stress hormone system],
  3. BDNF [brain-derived neurotrophic factor],
  4. AVP [arginine vasopressin],
  5. CRHR1 [corticotropin-releasing hormone receptor 1],
  6. SLC6A4 [serotonin transporter]

) did not reveal predicted associations with DNA methylation.

Epigenetic epidemiology is not yet well matched to experimental, nonhuman models in uncovering the biological embedding of stress.”

One of the sad findings was that as the types of trauma inflicted by other people on the subjects increased, so did the percentage of subjects who hurt themselves by smoking. Two-thirds of teens who reported three or more of the seven adolescent trauma types also smoked by age 18:

Polyvictimization

Self-harming behaviors other than smoking weren’t considered.

Another somber finding was:

“Childhood sexual victimization is associated with stable DNA methylation differences in whole blood in young adulthood. These associations were not observed in relation to sexual victimization in adolescence.”

The researchers guided future studies regarding the proxy measurements of peripheral blood DNA methylation:

“The vast majority of subsequent human studies, including the present one, have relied on peripheral blood. This choice is expedient, but also scientifically reasonable given the aim of detecting effects on stress-related physical health systems that include peripheral circulating processes (immune, neuroendocrine).

But whole blood is heterogeneous, and although cell-type composition can be evaluated and controlled, as in the present study, it does raise the question of whether peripheral blood is a problematic surrogate tissue for research on the epigenetics of stress.

Comparisons of methylomic variation across blood and brain suggest that blood-based EWAS may yield limited information relating to underlying pathological processes for disorders where brain is the primary tissue of interest.”

1. The comment on “epigenetic epidemiology” overstated the study’s findings because the epigenetic analysis, although thorough, was limited to peripheral blood DNA methylation. Other consequential epigenetic effects weren’t investigated, such as histone modifications and microRNA expression.

2. An unstated limitation was that the DNA methylation analyses were constrained by budgets. Studies like The primary causes of individual differences in DNA methylation are environmental factors point out restrictions in the methodology:

“A main limitation with studies using the Illumina 450 K array is that the platform only covers ~1.5 % of overall genomic CpGs, which are biased towards promoters and strongly underrepresented in distal regulatory elements, i.e., enhancers.

WGBS [whole-genome bisulfite sequencing] offers single-site resolution CpG methylation interrogation at full genomic coverage.

Another advantage of WGBS is its ability to access patterns of non-CpG methylation.”

I’d expect that in the future, researchers with larger budgets would reanalyze the study samples using other techniques.

3. The researchers started and ended the study presenting their view of human “embedding of stress” as a fact rather than a paradigm. Epigenetic effects of early life stress exposure compared and contrasted this with another substantiated view.

4. The study focused on the children’s intergenerational epigenetic effects. An outstanding opportunity to advance science was missed regarding transgenerational epigenetic inheritance:

  • Wouldn’t the parents’ blood samples and histories – derived from administering the same questionnaires their twins answered at age 18 – likely provide distant causal evidence for some of the children’s observed effects?
  • And lay the groundwork for hypotheses about aspects of future generations’ physiologies and behaviors?

https://ajp.psychiatryonline.org/doi/full/10.1176/appi.ajp.2017.17060693 “Analysis of DNA Methylation in Young People: Limited Evidence for an Association Between Victimization Stress and Epigenetic Variation in Blood” (not freely available) Thanks to coauthor Dr. Helen Fisher for providing the full study.