Monday, April 22, 2019

Evolutionary Psychiatry (Reading Group) Part 1

Over the coming months I am participating in a reading group on Nesse's latest book Good Reasons for Bad Feelings. The members of our reading group are pretty diverse, with a few people who have educational backgrounds and professional experience in the field of mental health and those who, like myself, are interested in the way evolutionary biology can be applied to help us better understand some of the societal predicaments we find ourselves grappling with.

So on this blog I want to post my thoughts, and summary of notes on the chapters, so I have a resource it is easy for me to go back to when I, eventually, write something more substantial on these issues.

I will begin with why I am interested in this topic, and this book in particular. About 6 years ago I came across Why We Get Sick and was really impressed by the importance of applying insights from evolution to the study of disease. For nearly 15 years I have been following the field of biogerontology which studies the biology of aging and so I was fascinated with the question "why do we age?" Given the reality that aging is the major risk factor for the chronic diseases of late life I felt it was imperative to consider the significance of science that could lead to the alteration of the aging process if this could delay disease and disability, and possibly compress the period of morbidity at the end of life. The crux of the story on aging, from what I have learned over the past decade and a half, is that primary aging is the result of evolutionary neglect (the disposable soma theory of the tradeoff between reproduction and longevity) and that secondary aging is the result of a mismatch between our biology and the environments we have created for ourselves in developed countries (e.g. high caloric diets and sedentary lifestyles). My hunch is that a similar story could be told about our emotional lives, especially personality disorders, mental illness, anxiety and depression. And it is with those expectations that I decided to get some friends together to read through Good Reasons for Bad Feelings.

It is worth starting this summary of the book by noting the central tenet of evolutionary biology: "selection shapes organisms to behave in ways that maximize their reproductive success" (11). Nesse notes that, when he and George Williams began working on evolutionary medicine they tried to find en evolutionary explanation for disease. Nesse refers to this as VDAA- Viewing Diseases as Adaptations. But he notes this is a mistake. Diseases are not adaptations. The diseases themselves were not selected for by evolution, but rather "aspects of the body that makes us vulnerable to diseases do have evolutionary explanations" (14).

In Chapter 3 "Why Are Minds So Vulnerable?" Nesse provides the following 6 reasons why evolution by natural selection has left us so vulnerable:

1. Mismatch: our bodies are unprepared to cope with modern environments
2. Infection: bacteria and viruses evolve faster than we do.
3. Constraints: there are some things that natural selection can't do.
4. Trade-offs: everything in the body has advantages and disadvantages.
5. Reproduction: natural selection makes reproduction, not health.
6. Defensive responses: responses such as pain and anxiety are useful in the face of threats. (34-35)

Details on Part 2 of the book to follow in a few weeks.


Friday, April 05, 2019

Changing the Definition of Ageing

Wired has a great article by Sinclair and Barzilai on treating aging as a disease. A sample:

In June 2018, the World Health Organization (WHO) released the 11th edition of its International Classification of Diseases. It contained an important addition: “Code MG2A: Old age.”

This tiny line of text could be one of the most important documents in human history, potentially leading to medicines designed to tackle the world’s most common ailment – ageing itself – and one that causes almost all others. It could lead to a new regulatory attitude to ageing (currently the United States Food and Drug Administration does not see ageing as a legitimate target for healthcare), and to doctors being able to prescribe medicines to slow the condition.

That change in regulatory attitude may still be far off, but in the meantime, research is pressing ahead, and in 2019 we will see significant breakthroughs in the sector.