Why drugs aren’t ultimately therapeutic

This 2016 Oregon review’s concept was the inadequacy of drug-based therapies, explored with the specific subject of epilepsy:

“Currently used antiepileptic drugs:

  • [aren’t] effective in over 30% of patients
  • [don’t] affect the comorbidities of epilepsy
  • [don’t] prevent the development and progression of epilepsy (epileptogenesis).

Prevention of epilepsy and its progression [requires] novel conceptual advances.”

The overall concept that current drug-based therapies poorly address evolutionary biological realities was illustrated by a pyramid, with the comment that:

“If the basis of the pyramid depicted in Figure 1 is overlooked, it becomes obvious that a traditional pharmacological top-down treatment approach has limitations.”

Why drug ultimately aren't therapeutic

I would have liked the reviewer to further address the “therapeutic reconstruction of the epigenome” point he made in the Abstract:

“New findings based on biochemical manipulation of the DNA methylome suggest that:

  1. Epigenetic mechanisms play a functional role in epileptogenesis; and
  2. Therapeutic reconstruction of the epigenome is an effective antiepileptogenic therapy.”

As it was, the reviewer lapsed into the prevalent belief that the causes of and cures for human diseases will always be found on the molecular level – for example, the base of the above pyramid – and never in human experiences. This preconception leads to discounting human elements – notably absent in the above pyramid – that generate epigenetic changes.

A consequence of ignoring experiential causes of diseases is that the potential of experiential therapies to effect “therapeutic reconstruction of the epigenome” isn’t investigated.

http://journal.frontiersin.org/article/10.3389/fnmol.2016.00026/full “The Biochemistry and Epigenetics of Epilepsy: Focus on Adenosine and Glycine”

A one-sided review of stress

The subject of this 2016 Italian/New York review was the stress response:

“The stress response, involving the activation of the hypothalamic-pituitary-adrenocortical axis and the consequent release of corticosteroid hormones, is indeed aimed at promoting metabolic, functional, and behavioral adaptations. However, behavioral stress is also associated with fast and long-lasting neurochemical, structural, and behavioral changes, leading to long-term remodeling of glutamate transmission, and increased susceptibility to neuropsychiatric disorders. Of note, early-life events, both in utero and during the early postnatal life, trigger reprogramming of the stress response, which is often associated with loss of stress resilience and ensuing neurobehavioral (mal)adaptations.”

A key point in the review was the intentional dismissal of the role of GABA in favor of the role of glutamate:

“The changes in neuronal excitability and synaptic plasticity induced by stress are the result of an imbalance of excitatory (glutamatergic) and inhibitory (GABAergic) transmission, leading to long-lasting (mal)adaptive functional modifications. Although both glutamate and GABA transmission are critically associated with stress-induced alteration of neuronal excitability, the present review will focus on the modulation of glutamate release and transmission induced by stress and glucocorticoids.”

No particular reason was given for this bias. I inferred from the review’s final sentence that the review’s sponsors and funding prompted this decision:

“In-depth studies of changes in glutamate transmission and dendrite remodeling induced by stress in early and late life will help to elucidate the biological underpinnings of the (mal)adaptive strategies the brain adopts to cope with environmental challenges in one’s life.”

The bias led to ignoring evidence for areas the reviewers posed as needing further research. An example of relevant research the reviewers failed to consider was the 2015 Northwestern University study I curated in A study that provided evidence for basic principles of Primal Therapy that found:

“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.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4812483/ “Stress Response and Perinatal Reprogramming: Unraveling (Mal)adaptive Strategies”

A review that inadvertently showed how memory paradigms prevented relevant research

This 2016 Swiss review of enduring memories demonstrated what happens when scientists’ reputations and paychecks interfered with them recognizing new research and evidence in their area but outside their paradigm: “A framework containing the basic assumptions, ways of thinking, and methodology that are commonly accepted by members of a scientific community.”

1. Most of the cited references were from decades ago that established these paradigms of enduring memories. Fine, but the research these paradigms precluded was also significant.

2. All of the newer references were continuations of established paradigms. For example, a 2014 study led by one of the reviewers found:

“Successful reconsolidation-updating paradigms for recent memories fail to attenuate remote (i.e., month-old) ones.

Recalling remote memories fails to induce histone acetylation-mediated plasticity.”

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

3. None of the reviewers’ calls for further investigations challenged existing paradigms. For example, when the reviewers suggested research into epigenetic regulation of enduring memories, they somehow found it best to return to 1984, a time when dedicated epigenetics research had barely begun:

“Whether memories might indeed be ‘coded in particular stretches of chromosomal DNA’ as originally proposed by Crick [in 1984] and if so what the enzymatic machinery behind such changes might be remain unclear. In this regard, cell population-specific studies are highly warranted.”

As an example of relevant research the review failed to consider, the 2015 Northwestern University study I curated in A study that provided evidence for basic principles of Primal Therapy went outside existing paradigms to research state-dependent memories:

“If a traumatic event occurs when these extra-synaptic GABA receptors are activated, the memory of this event cannot be accessed unless these receptors are activated once again.

It’s an entirely different system even at the genetic and molecular level than the one that encodes normal memories.”

What impressed me about the study was the obvious nature of its straightforward experimental methods. Why hadn’t other researchers used the same methods decades ago? Doing so could have resulted in dozens of informative follow-on study variations by now, which is my point in item 1 above.

The 2015 French What can cause memories that are accessible only when returning to the original brain state? was another relevant but ignored study that supported state-dependent memories:

“Posttraining/postreactivation treatments induce an internal state, which becomes encoded with the memory, and should be present at the time of testing to ensure a successful retrieval.”

The review also showed the extent to which historical memory paradigms depended on the subjects’ emotional memories. When it comes to human studies, though, designs almost always avoid studying emotional memories.

It’s clearly past time to Advance science by including emotion in research.

http://www.hindawi.com/journals/np/2016/3425908/ “Structural, Synaptic, and Epigenetic Dynamics of Enduring Memories”

What’s the underlying question for every brain study to answer?

Is it:

  • How do our brains internally represent the external world?

Is it:

  • How did we learn what we know?
  • How do we forget or disregard what we’ve learned?
  • What keeps us from acquiring and learning newer or better information?

How about:

  • What affects how we pay attention to our environments?
  • How do our various biochemical states affect our perceptions, learning, experiences, and behavior?
  • How do these factors in turn affect our biology?

Or maybe:

  • Why do we do what we do?
  • How is our behavior affected by our experiences?
  • How did we become attracted and motivated toward what we like?
  • How do we develop expectations?
  • Why do we avoid certain situations?

Not to lose sight of:

  • How do the contexts affect all of the above?
  • What happens over time to affect all of the above?

This 2015 UCLA paper reviewed the above questions from the perspective of Pavlovian conditioning:

“The common definition of Pavlovian conditioning, that via repeated pairings of a neutral stimulus with a stimulus that elicits a reflex the neutral stimulus acquires the ability to elicit that the reflex, is neither accurate nor reflective of the richness of Pavlovian conditioning. Rather, Pavlovian conditioning is the way we learn about dependent relationships between stimuli.

Pavlovian conditioning is one of the few areas in biology in which there is direct experimental evidence of biological fitness.”

The most important question unanswered by the review is:

  • How can its information be used to help humans?

How does Pavlov conditioning answer:

  • What can a human do about the thoughts, feelings, behavior, epigenetic effects – the person – that they’ve been shaped into?

One relevant hypothesis of Dr. Arthur Janov’s Primal Therapy is that a person will continue to be their conditioned self until they address the sources of their pain. A corollary is that addressing symptoms will seldom address causes.

How could it be otherwise? A problem isn’t cured by ameliorating its effects.

As an example, the review pointed out in a section about fear extinction that it doesn’t involve unlearning. Fear extinction instead inhibits the symptoms of fear response. The fear memory is still intact, awaiting some other context to be reactivated and expressed.

How can that information be used to help humans?

  • Is inhibiting the symptoms and leaving the fear memory in place costless with humans?
  • Or does this practice have both potential and realized adverse effects?
  • Where’s the human research on methods that may directly address a painful emotional memory?

http://cshperspectives.cshlp.org/content/8/1/a021717.full “The Origins and Organization of Vertebrate Pavlovian Conditioning”

Use it or lose it: the interplay of new brain cells, age, and activity

This 2015 German review was of aging and activity in the context of adult neurogenesis:

“Adult neurogenesis might be of profound functional significance because it occurs at a strategic bottleneck location in the hippocampus.

Age-dependent changes essentially reflect a unidirectional development in that everything builds on what has occurred before. In this sense, aging can also be seen as continued or lifelong development. This idea has limitations but is instructive with regard to adult neurogenesis, because adult neurogenesis is neuronal development under the conditions of the adult brain.

The age-related alterations of adult neurogenesis themselves have quantitative and qualitative components. So far, most research has focused on the quantitative aspects. But there can be little doubt that qualitative changes do not simply follow quantitative changes (e.g., in cell or synapse numbers), but emerge on a systems level and above when an organism ages. With respect to adult neurogenesis, only one multilevel experiment including morphology and behavior has been conducted, and, even in that study, only three time points were investigated.

In old age, adult neurogenesis occurs at only a small fraction of the level in early adulthood. The decline does not seem to be ‘regulated’ but rather the by-product of many age-related changes of other sorts.

From a behavioral level down to a synaptic level, activity increases adult neurogenesis. This regulation does not seem to occur in an all-or-nothing fashion but rather influences different stages of neuronal development differently. Both cell proliferation and survival are influenced by or even depend on activity.

The effects of exercise and environmental enrichment are additive, which indicates that increasing the potential for neurogenesis is sufficient to increase the actual use of the recruitable cells in the case of cognitive stimulation. Physical activity would not by itself provide specific hippocampus-relevant stimuli that induce net neurogenesis but be associated with a greater chance to encounter specific relevant stimuli.

Adult hippocampal neurogenesis might contribute to a structural or neural reserve that if appropriately trained early in life might provide a compensatory buffer of brain plasticity in the face of increasing neurodegeneration or nonpathological age-related functional losses. There is still only limited information on the activity-dependent parameters that help to prevent the age-dependent decrease in adult neurogenesis and maintain cellular plasticity.

The big question is what the functional contribution of so few new neurons over so long periods can be. Any comprehensive concept has to bring together the acute functional contributions of newly generated, highly plastic neurons and the more-or-less lasting changes they introduce to the network.”

I’ve quoted quite a lot, but there are more details that await your reading. A few items from the study referenced in the first paragraph above:

“The hippocampus represents a bottleneck in processing..adult hippocampal neurogenesis occurs at exactly the narrowest spot.

We have derived the theory that the function of adult hippocampal neurogenesis is to enable the brain to accommodate continued bouts of novelty..a mechanism for preparing the hippocampus for processing greater levels of complexity.”

The role of the hippocampus in emotion was ignored as it so often is. It seems to me that the way to address many of the gaps mentioned by the author may be to Advance science by including emotion in research.

For example, from the author’s The mystery of humans’ evolved capability for adults to grow new brain cells:

“Adult neurogenesis is already effective early in life, actually very well before true adulthood, and is at very high levels when sexual maturity has been reached. Behavioral advantages associated with adult neurogenesis must be relevant during the reproductive period.”

When human studies are designed to research how “behavioral advantages associated with adult neurogenesis must be relevant” what purpose does it serve to exclude emotional content?

http://cshperspectives.cshlp.org/content/7/11/a018929.full “Activity Dependency and Aging in the Regulation of Adult Neurogenesis”

Chronic pain causes epigenetic changes in the brain and immune system

This 2015 Canadian rodent study by McGill researchers found:

“The critical involvement of DNA methylation in chronic pain. We show that in the PFC [prefrontal cortex], a brain region strongly implicated in chronic pain, a stunning number of promoters [control gene expression] are differentially methylated 9 months after injury. These changes are distant both in time and space from the original injury.

The changes in DNA methylation are highly organized in functional pathways that have been implicated in pain such as dysregulation of dopaminergic, glutamatergic, opioid and serotoninergic systems and important signaling and inflammatory pathways.

Genome-wide DNA methylation modifications of T cells [circulating white blood cells that control immune response] are also associated with nerve injury.

Most of the promoters (72%) identified as differentially methylated in T cells after nerve injury were also affected in the brain. While the methylation profiles in some of these modules were affected in the same direction in the brain and the T cells, others went in opposite direction. This is consistent with the idea that the brain and the immune system play different roles in chronic pain.

These data suggest that persistent pain is associated with broad and highly organized organism-wide changes in DNA methylation, including two critical biological systems: the central nervous and immune systems. This work also provides a possible mechanistic explanation for commonly observed comorbidities observed in chronic pain (i.e anxiety, depression). Finally, the sheer magnitude of the impact of chronic pain, particularly in the prefrontal cortex, illustrates the profound impact that living with chronic pain exerts on an individual.”

The news coverage focused on how the study’s findings may lead to non-invasive DNA methylation measurements of chronic pain as well as treatments of the effects. I’d argue that the researchers’ concluding statement of the Discussion section deserved the most focus:

“Beyond the example of chronic pain, the robust and highly organized DNA methylation changes seen here in response to nerve injury provides some of the strongest evidence to date that experience effects DNA methylation landscapes at large distances in time and space.”

The study provided “some of the strongest evidence to date” that experiences caused widespread, long-lasting epigenetic changes. Given experiences’ etiologic functions, research with working hypotheses that experiences may potentially reverse epigenetic changes should be green-lighted.

“DNA methylation landscapes at large distances in time and space” warrant systematic examination of how experiential epigenetic changes during early life may be reversed by experiential therapies later in life. In 2016, there’s sufficient evidence for modifying research goals to primarily address causes, not just effects.

http://www.nature.com/articles/srep19615 “Overlapping signatures of chronic pain in the DNA methylation landscape of prefrontal cortex and peripheral T cells”

Treating prenatal stress-related disorders with an oxytocin receptor agonist

This 2015 French/Italian rodent study found:

“Chronic systemic treatment with carbetocin [unavailable in the US] in PRS rats corrected:

  • the defect in glutamate release,
  • anxiety- and depressive-like behavior,

and abnormalities:

  • in social behavior,
  • in the HPA response to stress, and
  • in the expression of stress-related genes in the hippocampus and amygdala.

These findings disclose a novel function of oxytocin receptors in the hippocampus, and encourage the use of oxytocin receptor agonists in the treatment of stress-related psychiatric disorders in adult life.”

The adult male subjects were:

“Prenatally restraint stressed (PRS) rats..the offspring of dams exposed to repeated episodes of restraint stress during pregnancy.

These rats display anxiety- and depressive-like behaviors and show an excessive glucocorticoid response to acute stress, which is indicative of a dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis caused by an impaired hippocampal glucocorticoid negative feedback.

PRS rats show a selective reduction in glutamate release in the ventral hippocampus.”

The researchers cited several other studies they have performed with the PRS phenotype. In the current study:

“Carbetocin treatment had no effect on these behavioral and neuroendocrine parameters in prenatally unstressed (control) rats, with the exception of a reduced expression of the oxytocin receptor gene in the amygdala.

Carbetocin displayed a robust therapeutic activity in PRS rats, but had no effect in unstressed rats, therefore discriminating between physiological and pathological conditions.”

The phenotype showed the ease with which a child can be epigenetically changed – even before they’re born – to be less capable over their entire lifetime. Just stress the pregnant mother-to-be.

http://www.psyneuen-journal.com/article/S0306-4530%2815%2900239-5/abstract “Activation of presynaptic oxytocin receptors enhances glutamate release in the ventral hippocampus of prenatally restraint stressed rats” Thanks to one of the authors, Eleonora Gatta, for providing the full study