Thursday, February 12, 2009

Darwin and the Psychiatric Advantage

Happy birthday, Charles! You're looking great at 200.

Also happy anniversary of "On the Origin of the Species," which was published 150 years ago today.

Here's an interesting fact: Peacock tails drove Darwin crazy. The sight of one "makes me sick," he wrote. These feathered accessories played havoc with his work-in-progress theory of natural selection. Surely, any bird stupid enough to flaunt their colors in the wild wouldn't live long enough to mate.

Darwin's solution seems obvious enough today, but back in the nineteenth century it was a scientific breakthrough, a work of genius. The showy tails, he figured out, were chick magnets. The flashier, the better. The well-endowed cock, so to speak, won the right to make a deposit. The bird's genes would live on, even if its owners' days were numbered.

Evolutionary biologists refer to this as a trade-off. The sickle cell gene, for instance, helps confer immunity against malaria.

Fine. But how does Darwin apply to mental illness? According to evolutionary biologist Randolph Nesse MD of the University of Michigan: "Psychiatrists still act as if all anxiety, sadness, and jealousy is abnormal and they don't yet look for the selective advantages of genes that predispose to schizophrenia and bipolar disorder."

I heard Dr Nesse at the American Psychiatric Association annual meeting a few years back talk about the selective advantage in anxiety. Obviously, sufficiently anxious cave men were able to steer clear of saber toothed tigers long enough to find an opportunity to pass on their genes to the next generation.

Anxiety traits are no mere artifacts of an earlier age. It is crucial to marshaling our wits. We could never survive one day in traffic without it, let alone the full range of personal interactions.

Dr Nesse compared the brain's limbic system to a smoke detector that is programmed to deliver 100 false alarms for every genuine alert. The false alarms are the price of survival. Better to be too anxious. The seriously anxious, it turns out, have hyper-sensitive smoke detectors. The false alarms and the hyper-sensitive in our midst tend to blind us to the fact that a certain degree of anxiety is good, that we would fail to exist as a species without it.

Similarly, you can make a Darwinian case for bipolar. Highly energetic and productive and creative types certainly had a selective advantage over their more mundane kinfolk. Think of mania lite. Passing on the risk of more serious manifestations was an acceptable trade-off.

But what is the advantage to depression? For one, depression is when the rose-colored glasses come off, when reality sets in. If mania is all about daring, depression is about caution. The daring have an advantage in life's ultimate prize, the opportunity to mate. So do the cautious.

Depression also provides an opportunity for regrouping and recouping, not to mention a time of introspection and reflection. Think of depression as an enforced time-out. In its own perverse way, depression may set the stage for needed psychic healing.

As with anxiety and mania, we are talking more benign manifestations. The more virulent versions of depression, it seems, are part of the price we have to pay.

For the longest time, I could see no selective advantage to schizophrenia. There are those who claim that those with schizophrenia would have made perfect shamans and seers back in the old days - a romantic notion of serious mental illness totally without merit, as I see it.

Then I picked up "A Beautiful Mind" by Silvia Nasar. The book chronicles the life of John Nash, the Nobel Laureate who lost some 25 years of his life to schizophrenia. As the book makes clear, John Nash was a social and intellectual oddball well before his schizophrenia erupted. We tend to think of mental illness as a complete break with reality or rationality, but these breaks don't just happen overnight. Subtle symptoms may manifest many years earlier, what the experts describe as "prodromal" states.

And there may be certain advantages. Nancy Andreasen MD, PhD of the University of Iowa mentions that Newton, Einstein, and Watson all had schizotypal tendencies or schizophrenia running in the family. Newton, in fact, had a full-blown psychotic episode later in life.

John Nash confided to a friend that he took his psychotic delusions seriously because they came to him the same way his mathematical ideas did. As the title says, "A Beautiful Mind."

Darwin made no attempt to reconcile his discoveries with religion, but that doesn't mean the two are mutually exclusive. Nevertheless, because one cannot witness evolution in action the way one can observe gravity or thermodynamics in action, Darwin is still a hard sell for most of the population. For many of us, evolution is an act of faith, even though science is virtually unanimous on its general points.

Evolutionary psychiatry, though, is still a speculative endeavor. A legitimate argument can be made that we are retrofitting psychiatry to conform to evolutionary precepts. Then again, a very strong case can be made that our behavior makes no sense without taking evolution into account. Instead of viewing all mental illness as solely destructive, we are forced to consider its advantages. And in looking at the advantages, we find potential in our own worth.

Happy birthday, Darwin, from a big fan of yours.


Randolph Nesse said...

Thanks for your post! It is great you are letting more people know that the basic science of evolutionary biology is useful for understanding mental disorders.

I do think, however, that it is important to distinguish disorders that are from dysregulation of a useful emotion (such as panic disorder) from other disorders that arise from abnormalities unrelated to any normal response (such as schizophrenia). I don't see anything useful about schizophrenia, and the evidence that schizophrenia genes foster creativity is questionable. That such creativity could give a selective advantage to compensate for the huge fitness costs of schizophrenia seems even more unlikely. It seems much more likely that it arises from new mutations that are steadily selected out. There remains a very good evolutionary question--Why does the mind fail in this particular way so often? But this is very different from looking for an advantage from genes associated with schizophrenia.
Randy Nesse

John McManamy said...

Hi, Dr Nesse. I'm very honored that you responded to my blog post.

I'm very interested in getting the word out via my other outreaches such as my Newsletter, so please - let's keep in touch.

misere said...

As a child, I believed that I was more evolved than those around me. Of course, I didn't have the words to explain this feeling, but my experience was that I "knew" things and had a superior spiritual perception of the world around me (which was very negative and frightening). I believed that I had something very important to say and no way to be heard.

At the same time- the trade-off I suppose- I believed myself to be "evil" in the sense that I had the psychic ability to cause terrible things to happen. I felt deep guilt from a very young age.

Since entering the world of psychiatry as a patient diagnosed with Bipolar II Disorder and multiple trauma from childhood emotional abuse, I have been told that my genetic predisposition to the disorder along with acute emotional sensitivity and intelligence were the cause of these distorted beliefs or delusional thinking.

But your blog post got me thinking. Looking back, I don't see the genetic predisposition as a helpful thing. I felt superior, but so what? I felt so ashamed of the human race that I believed myself to be an Alien. I felt compelled to hide all of these feelings and beliefs, although some leaked through enough to earn me a reputation for being very creative and eccentric. The pain I was able to conceal.

I haven't yet found a way to turn an illness (albeit with much potential) into something that could allow me a quality of life that would soothe the raging conflicts and calm the inevitable self loathing. My creative accomplishments have not been enough, because depression will suck the life out of everything worthwhile.

John McManamy said...

Hi, Misere. It sounds like you have been leading a very parallel existence to mine, so I strongly resonate with your comments. Think of us as conflicts in search of a resolution. We are struggling, thinking, asking questions. As for those who are not - they better be enlightened, that's the only excuse for standing still.

I would contend your psychic pain and self-doubts are positive forces. Often extremely difficult to bear, but also signs of a very vital force pushing back the darkness.

misere said...

thanks John, that's an awesome viewpoint. If I could print this, I'd take it to my therapist. I know she would approve!