Non-emotional memories

This 2019 US review covered memory mechanisms:

“With memory encoding reliant on persistent changes in the properties of synapses, a key question is how can memories be maintained from days to months or a lifetime given molecular turnover? It is likely that positive feedback loops are necessary to persistently maintain the strength of synapses that participate in encoding.

These levels are not isolated, but linked by shared components of feedback loops.”

Despite the review’s exhaustive discussion, the reviewers never came to the point. The word cloud I made of the review’s most frequent thirty words had little to do with why memory occurs.

Why do some stimuli evoke a memory in response? Why are almost all of the stimuli an organism receives not remembered?

Much of the discussion was baseless because it excluded emotion. Many of the citations’ memory findings relied on emotion, though. For example, in the subsection Roles of persistent epigenetic modifications for maintaining LTF [long-term facilitation], LTP [long-term potentiation], and LTM [long-term memory]:

  • Histone acetylation is increased after fear conditioning in the hippocampus and amygdala.
  • Correspondingly, inhibition of histone deacetylase enhances fear conditioning and LTP.
  • Following fear conditioning, histone phosphorylation is also increased.
  • DNA methylation is also up-regulated in the hippocampus and amygdala after fear conditioning, and inhibition of DNA methylation blocks fear LTM.” “How can memories last for days, years, or a lifetime? Proposed mechanisms for maintaining synaptic potentiation and memory”


Our brains are shaped by our early environments

This 2019 McGill paper reviewed human and animal studies on brain-shaping influences from the fetal period through childhood:

“In neonates, regions of the methylome that are highly variable across individuals are explained by the genotype alone in 25 percent of cases. The best explanation for 75 percent of variably methylated regions is the interaction of genotype with different in utero environments.

A meta-analysis including 45,821 individuals with attention-deficit/hyperactivity disorder and 9,207,363 controls suggests that conditions such as preeclampsia, Apgar score lower than 7 at 5 minutes, breech/transverse presentations, and prolapsed/nuchal cord – all of which involve some sort of poor oxygenation during delivery – are significantly associated with attention-deficit/hyperactivity disorder. The dopaminergic system seems to be one of the brain systems most affected by perinatal hypoxia-ischemia.

Exposure to childhood trauma activates the stress response systems and dysregulates serotonin transmission that can adversely impact brain development. Smaller cerebral, cerebellar, prefrontal cortex, and corpus callosum volumes were reported in maltreated young people as well as reduced hippocampal activity.

Environmental enrichment has a series of beneficial effects associated with neuroplasticity mechanisms, increasing hippocampal volume, and enhancing dorsal dentate gyrus-specific differences in gene expression. Environmental enrichment after prenatal stress decreases depressive-like behaviors and fear, and improves cognitive deficits.”

The reviewers presented strong evidence until the Possible Factors for Reversibility section, which ended with the assertion:

“All these positive environmental experiences mentioned in this section could counterbalance the detrimental effects of early life adversities, making individuals resilient to brain alterations and development of later psychopathology.”

The review’s penultimate sentence recognized that research is seldom done on direct treatments of causes:

“The cross-sectional nature of most epigenetic studies and the tissue specificity of the epigenetic changes are still challenges.”

Cross-sectional studies won’t provide definitive data on cause-and-effect relationships.

The question that remains to be examined is: How can humans best address these early-life causes to ameliorate their lifelong effects? “Early environmental influences on the development of children’s brain structure and function” (not freely available)

A therapy to reverse cognitive decline

This 2018 human study presented the results of 100 patients’ personalized therapies for cognitive decline:

“The first examples of reversal of cognitive decline in Alzheimer’s disease and the pre-Alzheimer’s disease conditions MCI (Mild Cognitive Impairment) and SCI (Subjective Cognitive Impairment) have recently been published..showing sustained subjective and objective improvement in cognition, using a comprehensive, precision medicine approach that involves determining the potential contributors to the cognitive decline (e.g., activation of the innate immune system by pathogens or intestinal permeability, reduction in trophic or hormonal support, specific toxin exposure, or other contributors), using a computer-based algorithm to determine subtype and then addressing each contributor using a personalized, targeted, multi-factorial approach dubbed ReCODE for reversal of cognitive decline.

An obvious criticism of the initial studies is the small number of patients reported. Therefore, we report here 100 patients, treated by several different physicians, with documented improvement in cognition, in some cases with documentation of improvement in electrophysiology or imaging, as well.” “Reversal of Cognitive Decline: 100 Patients”

The lead author commented on Josh Mitteldorf’s informative post A cure for Alzheimer’s? Yes, a cure for Alzheimer’s!:

  1. “We have a paper in press, due to appear 10.22.18 (open access, JADP, I’ll send a copy as soon as available), showing 100 patients with documented improvement – some with MRI volumetrics improved, others with quantitative EEG improvements, others with evoked response improvements, and all with quantitative cognitive assessment improvement. Some are very striking – 12 point improvements in MoCA, for example – others less so, but all also have subjective improvement. Hopefully this will address some of the criticisms that we haven’t documented improvement in enough people.
  2. We were just turned down again for a randomized, controlled clinical trial, so on the one hand, we are told repeatedly that no one will believe that this approach works until we publish a randomized, controlled study, and on the other hand, we’ve been turned down (first in 2011/12, and now in 2018), with the complaint that we are trying to address more than one variable in the trial (as if AD is a single-variable disease!). Something of a catch-22. We are now resubmitting (unfortunately, the IRBs are not populated by functional medicine physicians, so they are used to seeing old-fashioned drug studies), and we’ll see what happens.
  3. I’ve been extending the studies to other neurodegenerative diseases, and it has been impressive how much of a programmatic response there seems to be in these “diseases.”
  4. I agree with you that there are many features in common with aging itself.
  5. You made a good point that APP is a dependence receptor, and in fact it functions as an integrating dependence receptor, responding to numerous inputs (Kurakin and Bredesen, 2015).
  6. In the book and the publications, we don’t claim it is a “cure” since we don’t have pathological evidence that the disease process is gone. What we claim is “reversal of cognitive decline” since that is what we document.
  7. As I mentioned in the book, AD is turning out to be a protective response to multiple insults, and this fits well with the finding that Abeta has an antimicrobial effect (Moir and Tanzi’s work). It is a network-downsizing, protective response, which is quite effective – some people live with the ongoing degenerative process for decades.
  8. We have seen several cases now in which a clinical trial of an anti-amyloid antibody made the person much worse in a time-dependent manner (each time there was an injection, the person would get much worse for 5-10 days, then begin to improve back toward where he/she was, but over time, marked decline occurred), and this makes sense for the idea that the amyloid is actually protecting against pathogens or toxins or some other insult.
  9. It is important to note that we’ve never claimed that all people get better – this is not what we’ve seen. People very late in the process, or who don’t follow the protocol, or who don’t address the various insults, do not improve. It is also turning out to be practitioner dependent – some are getting the vast majority of people to improve, others very few, so this is more like surgery than old-fashioned prescriptive medicine – you have to do a somewhat complicated therapeutic algorithm and get it right for best results.
  10. I’m very interested in what is needed to take the next step in people who have shown improvement but who started late in the course. For example, we have people now who have increased MoCA from 0 to 9 (or 0 to 3, etc.), with marked subjective improvement but plateauing at less than normal. These people had extensive synaptic and cellular loss prior to the program. So what do we need to raise the plateau? Stem cells? Intranasal trophic support? Something else?
  11. I haven’t yet seen a mono-etiologic theory of AD or a mono-therapeutic approach that has repeatedly positive results, so although I understand that there are many theories and treatments, there doesn’t seem to be one etiology to the disease, nor does there seem to be one simple treatment that works for most. It is much more like a network failure.”

At a specific level:

  • “There doesn’t seem to be one etiology to the disease,
  • nor does there seem to be one simple treatment that works for most.
  • We don’t have pathological evidence that the disease process is gone.”

For general concepts, however:

  • “AD is turning out to be a protective response to multiple insults,
  • It is a network-downsizing, protective response, which is quite effective.
  • The amyloid is actually protecting against pathogens or toxins or some other insult.”

For a framework of an AD cure to be valid, each source of each insult that evoked each “protective response” should be traced.

Longitudinal studies would be preferred inside this framework. These study designs would investigate evidence of each insult’s potential modifying effect on each “protective response” that could affect the cumulative disease trajectory of each individual.

In many cases, existing study designs would be adequate if they extended their periods to the end of the subjects’ natural lifetimes. One AD-relevant example would be extending the prenatally-restraint-stressed model used in:

The framework would also encourage extending studies to at least three generations to investigate evidence for transgenerational effects, as were found in:

Adverse epigenetic effects of prenatal and perinatal anesthesia

This 2018 Chinese animal review subject was prenatal and perinatal anesthesia’s adverse epigenetic effects on a fetus/neonate:

“Accumulating evidence from rodent and primate studies has demonstrated that in utero or neonatal exposure to commonly used inhaled and intravenous general anesthetics is associated with neural degeneration and subsequent neurocognitive impairments, manifested in learning and memory disabilities.

So far, conflicting data exist about the effect of anesthetic agents on neurodevelopment in humans and no definite conclusion has been given yet.”

The inhibitors in the above graphic counter anesthesia’s effects on the fetus/neonate, summarized as:

“Epigenetic targeting of DNA methyltransferases and/or histone deacetylases may have some therapeutic value.”

Are there any physicians who take into consideration possible epigenetic alterations of a newborn’s chromatin structure and gene expression when they administer anesthesia to a human mother during childbirth? “Epigenetic Alterations in Anesthesia-Induced Neurotoxicity in the Developing Brain”

The epigenetic clock now includes skin

The originator of the 2013 epigenetic clock improved its coverage with this 2018 UCLA human study:

“We present a new DNA methylation-based biomarker (based on 391 CpGs) that was developed to accurately measure the age of human fibroblasts, keratinocytes, buccal cells, endothelial cells, skin and blood samples. We also observe strong age correlations in sorted neurons, glia, brain, liver, and bone samples.

The skin & blood clock outperforms widely used existing biomarkers when it comes to accurately measuring the age of an individual based on DNA extracted from skin, dermis, epidermis, blood, saliva, buccal swabs, and endothelial cells. Thus, the biomarker can also be used for forensic and biomedical applications involving human specimens.

The biomarker applies to the entire age span starting from newborns, e.g. DNAm of cord blood samples correlates with gestational week.

Furthermore, the skin & blood clock confirms the effect of lifestyle and demographic variables on epigenetic aging. Essentially it highlights a significant trend of accelerated epigenetic aging with sub-clinical indicators of poor health.

Conversely, reduced aging rate is correlated with known health-improving features such as physical exercise, fish consumption, high carotenoid levels. As with the other age predictors, the skin & blood clock is also able to predict time to death.

Collectively, these features show that while the skin & blood clock is clearly superior in its performance on skin cells, it crucially retained all the other features that are common to other existing age estimators.” “Epigenetic clock for skin and blood cells applied to Hutchinson Gilford Progeria Syndrome and ex vivo studies”

An introduction to the study highlighted several items:

“Although the skin-blood clock was derived from significantly less samples (~900) than Horvath’s clock (~8000 samples), it was found to more accurately predict chronological age, not only across fibroblasts and skin, but also across blood, buccal and saliva tissue. A potential factor driving this improved accuracy in blood could be related to the approximate 18-fold increase in genomic coverage afforded by using Illumina 450k/850k beadarrays.

It serves as a roadmap for future clock studies, pointing towards the importance of constructing tissue or cell-type specific epigenetic clocks, to more accurately measure biological aging in the given tissue/cell-type, and therefore with the potential to be more informative of disease-risk or the success of disease interventions in the tissue or cell-type of interest.” “Epigenetic clocks galore: a new improved clock predicts age-acceleration in Hutchinson Gilford Progeria Syndrome patients”

The role of recall neurons in traumatic memories

This 2018 Swiss rodent study found:

“Our data show that:

  • A subset of memory recall–induced neurons in the DG [dentate gyrus] becomes reactivated after memory attenuation,
  • The degree of fear reduction positively correlates with this reactivation, and
  • The continued activity of memory recall–induced neurons is critical for remote fear memory attenuation.

Although other brain areas such as the prefrontal cortex and the amygdala are likely to be implicated in remote fear memories and remain to be investigated, these results suggest that fear attenuation at least partially occurs in memory recall–induced ensembles through updating or unlearning of the original memory trace of fear.

These data thereby provide the first evidence at an engram-specific level that fear attenuation may not be driven only by extinction learning, that is, by an inhibitory memory trace different from the original fear trace.

Rather, our findings indicate that during remote fear memory attenuation both mechanisms likely coexist, albeit with the importance of the continued activity of memory recall–induced neurons experimentally documented herein. Such activity may not only represent the capacity for a valence change in DG engram cells but also be a prerequisite for memory reconsolidation, namely, an opportunity for learning inside the original memory trace.

As such, this activity likely constitutes a physiological correlate sine qua non for effective exposure therapies against traumatic memories in humans: the engagement, rather than the suppression, of the original trauma.”

The researchers also provided examples of human trauma:

“We dedicate this work to O.K.’s father, Mohamed Salah El-Dien, and J.G.’s mother, Wilma, who both sadly passed away during its completion.”

So, how can this study help humans? The study had disclosed and undisclosed limitations:

1. Humans aren’t lab rats. We can ourselves individually change our responses to experiential causes of ongoing adverse effects. Standard methodologies can only apply external treatments.

2. It’s a bridge too far to go from neural activity in transgenic mice to expressing unfounded opinions on:

“A physiological correlate sine qua non for effective exposure therapies against traumatic memories in humans.”

Human exposure therapies have many drawbacks, in addition to being applied externally to the patient on someone else’s schedule. A few others were discussed in The role of DNMT3a in fear memories:

  • “Inability to generalize its efficacy over time,
  • Potential return of adverse memory in the new/novel contexts,
  • Context-dependent nature of extinction which is widely viewed as the biological basis of exposure therapy.”

3. Rodent neural activity also doesn’t elevate recall to become an important goal of effective human therapies. Clearly, what the rodents experienced should be translated into human reliving/re-experiencing, not recall. Terminology used in animal studies preferentially has the same meaning with humans, since the purpose of animal studies is to help humans.

4. The researchers acknowledged that:

“Other brain areas such as the prefrontal cortex and the amygdala are likely to be implicated in remote fear memories and remain to be investigated.”

A study that provided evidence for basic principles of Primal Therapy determined another brain area:

“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.”

The study I curated yesterday, Organ epigenetic memory, demonstrated organ memory storage. It’s hard to completely rule out that other body areas may also store traumatic memories.

The wide range of epigenetic memory storage vehicles is one reason why effective human therapies need to address the whole person, the whole body, and each individual’s entire history. “Reactivation of recall-induced neurons contributes to remote fear memory attenuation” (not freely available)

Here’s one of the researchers’ outline:

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.

Flawed epigenetic measurements of behavioral experiences

This 2018 New York rodent study not only wasted resources but also speciously attempted to extrapolate animal study findings to humans:

“While it is clear that behavioral experience modulates epigenetic profiles, it is less evident how the nature of that experience influences outcomes and whether epigenetic/genetic “biomarkers” could be extracted to classify different types of behavioral experience.

Male and female mice were subjected to either:

  • a Fixed Interval (FI) schedule of food reward, or
  • a single episode of forced swim followed by restraint stress, or
  • no explicit behavioral experience

after which global expression levels of two activating (H3K9ac and H3K4me3) and two repressive (H3K9me2 and H3k27me3) post-translational histone modifications (PTHMs), were measured in hippocampus (HIPP) and frontal cortex (FC).

A random subset of 5 of the 12 animals from each sex/behavioral experience group were used for these analyses. FC and HIPP were dissected from each of those 5 brains and homogenized for subsequent analyses. Thus, sample size for PTHM expression levels was n = 5 for each region/sex/behavioral treatment group and all PTHM expression level analyses utilized the homogenized tissue.

The specific nature of the behavioral experience differentiated profiles of PTHMs in a sex- and brain region-dependent manner, with all 4 PTHMs changing in parallel in response to different behavioral experiences. Global PTHMs may provide a higher-order pattern recognition function.”

The researchers knew or should have known that measuring “global expression levels” in “homogenized tissue” of “n = 5” subjects was flawed, and they did it anyway. They acknowledged some of the numerous study design defects with qualifiers such as:

“Even though these were global levels of histone modifications (and thus not indicative of changes at specific genes or sites on genes)..

As FS-RS behavioral experience was completed before FI behavioral experience, a longer overall post-behavior experience time (approximately 1 week) elapsed for this group, resulting in some differences in overall timing between these experiences and global PTHM assessment. However, extending the duration of the FS-RS experience (i.e., repeated exposures) would also have led to habituation..”

Did they purposely make these mistakes because of the “biomarkers” paradigm?

What would they have found if they had followed their judgments and training to design a better study? Experience-dependent histone modifications that differed by gender and brain region was certainly a promising research opportunity.

As for extrapolating the cited animal study findings to humans? Ummm..NO! “Different Behavioral Experiences Produce Distinctive Parallel Changes in, and Correlate With, Frontal Cortex and Hippocampal Global Post-translational Histone Levels”