Thursday, March 4, 2010

Rerun - Darwin and the Psychiatric Advantage

My most recent blog post, Ruminating Depressions, queried whether there is a purpose to our suffering. The reason we are able to ask questions like this in the first place is due to Charles Darwin. Following is a piece I published last February in honor of the 200th birthday of the man who changed the way we think. Enjoy ...

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.


Tony said...

I could see the possibility that excessive manifestations of advantageous mental traits leads to illness. There is a PNAS paper on how an overactive default mode in the brain is seen in people with schizophrenia and their healthy immediate relatives, though not so in healthy controls. Maybe an overactive default mode may sharpen cognition, as long as it doesn't go to extremes as in schizophrenia. But tying schizophrenia to a potentially good trait shouldn't deny the fact that it is a terrible disease.

In physical health, there are conditions where some positive trait is carried too far. Take allergies: the IgE part of our immune systems is tuned for bacterial and parasitic infections. Having a strong IgE component clearly has it's advantages. But take it too far, and the IgE goes berserk reacting to innocuous pollen and foods. (The reason for this is that bacteria and parasitic worms clothe themselves in proteins very similar to foods and pollen to avoid detection by IgE. Human immune system adapted, but for too many of us, the IgE attacks both the parasites and the pollen.) And IgE can go so out of whack that anaphylaxis can occur, leading to death. Hence, allergies are a disease. So what is true for the physical body, is probably true for the mind. Hopefully knowing which traits have gone too far resulting in disease will give doctors insights into how to treat them.

Anonymous said...

I kinda have a crazy thought... Since I am convinced that there are other dimensions in this world that we can't see or prove, I wonder if rumination is our subconscience mind (who is aware of other dimensions) working with our conscience mind (who is not) to solve the problem we are ruminating. Our subconscience mind thinks the answers are in that other dimension (maybe going back in time and acting differently) and that since we can't see or prove other dimensions, we can't get the answer. The missing piece is in another dimension.

eazyeazy said...

Hi reviewed many elements of your site and did a 5% fact check: see if 5% or more of what you say is supported by the documents you site. Sadly you do not pass that minimal test for credibility. You are a striver for factual basis but only if it fits comfortably in your presumption. This is reverse science and totally acceptable if the practitioner declares their methods. Quoting an NIH study on fish oil effects on post-partum depression that disclaims its own findings as inconclusive unfortunately damns your entire site because it is evident that you are willing to selectively delete credible evidence there and thus anywhere.

The shotgun approach to mental health issues from the world of para-professionals results in information that is wrong being used to treat people who are ill with products that don't work. If flaxseeds were as effective as stated, or eating fish were so beneficial, the world would be populated with people who always ate flaxseed and fish (you may keep substituting if you will all the other substances and reasons we have had a hundred-fold increase in depression since we stopped eating fish). That number is preposterous no matter how its interpreted unless it means just adding 100 patients more than we used to whereas fold implies multiply. 100 times more cases of bipolar disorder diagnosed today since when?

Get a grip on scientific method currently your charming ineptness is masking dangerous diagnosis and treatment.

John McManamy said...

Hi, Anonymous. I think you speak for a lot of people (myself included) concerning other dimensions. Sometimes it's as if my brain is in another dimension trying to get along in this one. Certainly, I long for the day when I can return to the planet of my birth. Keep posting ...

John McManamy said...

To readers: Every once in a while someone like eazyeazy comes along and posts an insulting comment, which I typically reject rather than post. But every once in a while I need to post one of these insults just to keep you posted, in a manner of speaking.

Eazyeazy for some reason took exception to an article about omega-3 on mcmanweb but decided to post here, for some reason. It seems Eazyeazy takes objection to the studies I cited in the article, as if I'm using them to support my position. Actually, in the article, I take no position on omega-3. In fact, I note that:

"Finally, keep in mind that although omega-3 looks like a promising way to treat depression and bipolar disorder, there are no major clinical trials to guide us. We are barely aware of its putative efficacy, much less its optimal dosage, much less how it actually works on the brain."

Apparently, unless the science is 100 percent nailed down, I shouldn't publish. By that criteria, there would be no writing on mental health - period. In physical illness, we know a certain med will knock out a certain virus. We can pinpoint the fracture to a broken bone. That kind of certainty doesn't exist in mental illness. Even the most rigorous scientific studies have a highly-speculative element and are open to many many interpretations.

Anyway, you are smart enough to make up your own minds.

On second thought, I should have hit the "reject" button.

John McManamy said...

Hey, Tony. You took the words right out of my mouth. I definitely think there is a strong case that a slightly overactive default mode can sharpen cognition. But then the circuits overload, so to speak. Too much input, no way to regulate it. Complete system breakdown. An advantage morphs into a terrible illness.

There is no advantage to the illness. But there are obvious advantages to the supernormal or hypernormal states that occupy that middle ground between normal and abnormal.

It's easier to argue an advantage to bipolar, as we tend to cycle in and out from normal to supernormal to normal in very short time spans. If we don't manage to wreck our lives in the process, we can accomplish unbelievable things.

For many with schizophrenia, on the other hand, there is no coming back (or it may take decades). They just don't cycle back to normal.

This is a fascinating discussion. People do not have to believe there is an advantage to anything. But by simply asking the question, we gain amazing insights.