The epigenetic clock theory of aging

My 400th blog post curates a 2018 US/UK paper by two of the coauthors of Using an epigenetic clock to distinguish cellular aging from senescence. The authors reviewed the current state of epigenetic clock research, and proposed a new theory of aging:

“The proposed epigenetic clock theory of ageing views biological ageing as an unintended consequence of both developmental programmes and maintenance programmes, the molecular footprints of which give rise to DNAm [DNA methylation] age estimators.

It is best to interpret epigenetic age estimates as a higher-order property of a large number of CpGs much in the same way that the temperature of a gas is a higher-order property that reflects the average kinetic energy of the underlying molecules. This interpretation does not imply that DNAm age simply measures entropy across the entire genome.

To date, the most effective in vitro intervention against epigenetic ageing is achieved through expression of Yamanaka factors, which convert somatic cells into pluripotent stem cells, thereby completely resetting the epigenetic clock. In vivo, haematopoietic stem cell therapy resets the epigenetic age of blood of the recipient to that of the donor.

Future epidemiological studies should consider other sources of DNA (for example, buccal cells), because more powerful estimates of organismal age can be obtained by evaluating multiple tissues..other types of epigenetic modifications such as adenine methylation or histone modifications may lend themselves for developing epigenetic age estimators.”


I’ve previously curated four other papers which were referenced in this review:


The challenge is: do you want your quality of life to be under or over this curve?

What are you doing to reverse epigenetic processes and realize what you want? Do you have ideas and/or behaviors that interfere with taking constructive actions to change your phenotype?

If you aren’t doing anything, are you honest with yourself about the personal roots of beliefs in fate/feelings of helplessness? Do beliefs in technological or divine interventions provide justifications for inactions?

https://www.nature.com/articles/s41576-018-0004-3 “DNA methylation-based biomarkers and the epigenetic clock theory of ageing” (not freely available)

Advertisements

Manufacturing PTSD evidence with machine learning

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.”


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.”


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.

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.”

An interview with Dr. Rachel Yehuda on biological and conscious responses to stress was the perspective of one of the study’s coauthors.

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”

What are the chances?

This 2018 UC Davis anthropology study was on dice changes over two centuries:

“In Roman times, many dice were visibly lopsided..It did not matter what the objects were made of (metal, clay, bone, antler and ivory), or whether they were precisely symmetrical or consistent in size or shape, because, like the weather, rolls were predetermined by gods or other supernatural elements.

Dice, like many material objects, reflect a lot about people’s changing worldviews, Eerkens said. In this case, we believe it follows changing ideas about chance and fate.”


Think of a significant event in your life. Was it brought about by:

  • Fate?
  • Karma, divine intervention?
  • A prayer, belief, placebo-effect process?
  • Randomness?
  • A coin-flip, card-draw, dice-roll decision process?
  • A weighted-probability decision process?
  • Chosen behavior, thoughts, and feelings?
  • Unconscious behavior, thoughts, and feelings?
  • Culturally-guided motivations?
  • Non-arbitrary influences of other parties?

Which one or more of these factors would you now prefer to have been involved?

https://www.ucdavis.edu/news/it-not-how-you-play-game-how-dice-were-made “It’s Not How You Play the Game, but How the Dice Were Made”

The impact of the last snowflake

Was the recent Swiss avalanche’s cause the last, triggering snowflake, or the billions of snowflakes before it?

There’s been a slight increase in the number of PNAS studies that included the “catastrophic” search word from October 2016 to mid-January 2018 compared to the January 2014 to mid-April 2015 period referenced in How well can catastrophes be predicted?.

What are the drivers?

Or is the main driver something else?

Science and technology hijacked by woo

I’m an avid reader of science articles, abstracts, studies, and reviews. I tried a free subscription to Singularity Hub for a few weeks last month because it seemed to be a suitable source of articles on both science and technology.

I unsubscribed after being disappointed by aspects of science and technology hijacked almost on a daily basis into the realm of woo. Discovering scientific truths and realizing technologies is inspiring enough to stand on its own. It’s sufficiently interesting to publish well-written articles on the process and results.

I was dismayed that the website didn’t host a feedback mechanism for the authors’ articles. We shield ourselves from information incongruent with our beliefs. It’s a problem when a publisher of science and technology articles similarly disallows non-confirming evidence as a matter of policy.

An article may or may not advance knowledge of the subject, and Singularity Hub enables author hubris in presenting their views as the final word on the subject. Directing readers elsewhere for discussion is self-defeating in that every publisher’s goals include keeping visitors on their website as long as possible.

Here’s my feedback on two articles that inappropriately bent reality.


Regarding What Is It That Makes Humans Unique?:

“This trait [symbolic abstract thinking] not only gives us the ability to communicate symbolically, it also allows us to think symbolically, by allowing us to represent all kinds of symbols (including physical and social relationships) in our minds, independent of their presence in the physical world. As a result, internal associations of novel kinds become possible.”

Why limit discussion of our capability for symbolic representations? Other features to explore are:

  • Isn’t a belief a product of symbolic abstract thinking?
  • What attributes of human behavior provide evidence for hopes and beliefs as symbolic representations?
  • What’s the evolved functional significance that benefits humans of using symbolic abstract thinking to develop hopes and beliefs?

“Our revolutionary traits stand out even more when we take a cosmic perspective..We are not only in the universe, but the universe is also within us..Our brains, as an extension of the universe, are now being used to understand themselves.”

This article should be written well enough to inspire without resorting to unevidenced assertions about revolutions, the cosmos, and the timing of brain functionality.

“Some of us possess higher consciousness than others. The question that we now have to ask ourselves is, how do we cultivate higher consciousness, structural building, and symbolic abstract thinking among the masses?”

What’s the purpose of steering an evolution topic into elitism?


How a Machine That Can Make Anything Would Change Everything received >53,000 views compared with <5,000 views of the above article. This was an indicator that readers of Singularity Hub are relatively more interested in the possible implications of future technology than those of our past biological evolution. Why?

“If nanofabricators are ever built, the systems and structure of the world as we know them were built to solve a problem that will no longer exist.”

We are to believe that we’ll soon have the worldwide solution to problems in food supply, energy supply, medicine availability, income, knowledge – all that’s needed for survival? Should we develop hopes that technology will be our all-providing savior? Hope sells, without a doubt, but why would Singularity Hub mix that in with science?

This article reminded of the chip-in-the-brain article referenced in Differing approaches to a life wasted on beliefs. Both articles seemingly appealed to future prospects, but the hope aspect showed that the appeals were actually reactions to the past.

If we individually address the impacts of past threats to survival – that include beliefs about future survival – each of us can break out of these self-reinforcing, life-wasting loops. Otherwise, an individual’s thoughts, feelings, and behavior are stuck in reacting to their history, with hopes and beliefs being among the many symptoms.

“Human history will be forever divided in two. We may well be living in the Dark Age before this great dawn. Or it may never happen. But James Burke, just as he did over forty years ago, has faith.”

Is it inspiring that the person mentioned has had a forty-year career of selling beliefs in technology?

Yes, future technologies have promise. Authors can write articles that provide developments without soiling the promise with woo.


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.

The pain societies instill into children

The human subjects of this 2017 Swiss study had previously been intentionally traumatized by Swiss society:

“Swiss former indentured child laborers (Verdingkinder) were removed as children from their families by the authorities due to different reasons (poverty, being born out of wedlock) and were placed to live and work on farms. This was a practice applied until the 1950s and many of the Verdingkinder were subjected to childhood trauma and neglect during the indentured labor.

DNA methylation modifications indicated experiment-wide significant associations with the following complex posttraumatic symptom domains: dissociation, tension reduction behavior and dysfunctional sexual behavior.”


Imagine being taken away from your family during early childhood for no other reason than your parents weren’t married.

Imagine just a few of the painful feelings such a child had to deal with then and ever since:

  • I’m unloved.
  • Alone.
  • No one can help me.

Imagine some of the ways a child had to adapt during their formative years because of this undeserved punishment:

  • How fulfilling it would be to believe that they were loved, even by someone they couldn’t see, touch, or hear.
  • How fulfilling it would be to get attention from someone, anyone.
  • How a child became conditioned to do things by themself without asking for help.

The study described a minute set of measurements of the subjects’ traumatic experiences and their consequential symptoms. The researchers tried to group this tiny sample of the subjects’ symptoms into a new invented category.

https://bmcresnotes.biomedcentral.com/articles/10.1186/s13104-017-3082-y “A pilot investigation on DNA methylation modifications associated with complex posttraumatic symptoms in elderly traumatized in childhood”


Another example was provided in Is IQ an adequate measure of the quality of a young man’s life?:

“During this time period [between 1955 and 1990], because private adoptions were prohibited by Swedish law, children were taken into institutional care by the municipalities shortly after birth and adopted at a median age of 6 mo, with very few children adopted after 12 mo of age.”

Swedish society deemed local institutional care the initial destination for disenfranchised infants, regardless of whether suitable families were willing and able to adopt the infants. What happened to infants who weren’t adopted by age 1?

Did Swedish society really need any further research to know that an adoptive family’s care would be better for a child than living in an institution?


A third example of the pain instilled into children by societies was related to me last year by two sisters. During the Chinese Cultural Revolution, 1966-1976, among other things, parents were required to be out of their households from dawn to late night, leaving the children to fend for themselves.

One of the daily chores for the sisters at ages 6 and 7, after attending school, was to buy food for dinner and the next day’s breakfast and lunch with ration coupons, and prepare the family’s evening meal. They never met their four grandparents, who had died in ways the sisters either didn’t know or weren’t willing to express to me.

It wasn’t difficult to infer that traumatic childhood events still impacted the women’s lives 50 years later. My empathetic understanding of their histories, though, didn’t improve their current situations.


It’s a challenge for each of us to recognize when our own thoughts, feelings, and behavior provide evidence of childhood pain that’s still with us.

Let’s not develop hopes and beliefs that the societies we live in will resolve these or other adverse effects of childhood trauma its members caused. Other people may guide us, but each of us has to individually get our life back.

Europe, Asia, Africa, Australia, North and South America: every society has its horror stories, and there are people still living who can document last century’s events and circumstances. Have traumatic effects on children from societal policies ceased?

Epigenetic study methodologies improved in 2017

Let’s start out 2018 paying more attention to advancements in science that provide sound empirical data and methodology. Let’s ignore and de-emphasize studies and reviews that aren’t much more than beliefs couched in models and memes, whatever their presumed authority.

Let sponsors direct researchers to focus on ultimate causes of diseases. Let’s put research of treatments affecting causes ahead of those that only address symptoms.

Here are two areas of epigenetic research that improved in 2017.


Improved methodologies enabled DNA methylation studies of adenine, one of the four bases of DNA, to advance, such as this 2017 Wisconsin/Minnesota study N6-methyladenine is an epigenetic marker of mammalian early life stress:

“6 mA is present in the mammalian brain, is altered within the Htr2a gene promoter by early life stress and biological sex, and increased 6 mA is associated with gene repression. These data suggest that methylation of adenosine within mammalian DNA may be used as an additional epigenetic biomarker for investigating the development of stress-induced neuropathology.”

Most DNA methylation research is performed on the cytosine and guanine bases.


Other examples of improved methodologies were discussed in this 2017 Japanese study Genome-wide identification of inter-individually variable DNA methylation sites improves the efficacy of epigenetic association studies:

“A strategy focusing on CpG sites with high DNA methylation level variability may attain an improved efficacy..estimated to be 3.7-fold higher than that of the most frequently used strategy.

With ~90% coverage of human CpGs, whole-genome bisulfite sequencing (WGBS) provides the highest coverage among the currently available DNAm [DNA methylation] profiling technologies. However, because of its high cost, it is presently infeasible to apply WGBS to large-scale EWASs [epigenome-wide association studies], which require DNAm profiling of hundreds or thousands of subjects. Therefore, microarrays and targeted bisulfite sequencing are currently practicable for large-scale EWASs and thus, effective strategies to select target regions are essentially needed to improve the efficacy of epigenetic association studies.

DNAm levels measured with microarrays are invariable for most CpG sites in the study populations. As invariable DNAm signatures cannot be associated with exposures, intermediate phenotypes, or diseases, current designs of probe sets are inefficient for blood-based EWASs.”