Monday, September 28, 2009

Jerry Coyne FUD, part I

Two posts by the evolutionary biologist Jerry Coyne, in which he paints Paul Andrews and Andy Thomson, friends and colleagues of mine, as reckless, just-so-story-telling kooks, inspired me to write my first blog posts.

Andrews and Thomson (A&T) argue, contrary to almost everyone, that major (clinical) depression is not a disorder but is instead an adaptation whose function, in part, is to direct one's thoughts towards solving a major life problem. A&T refer to this as the "analytical rumination hypothesis" (ARH).

Were A&T "unwise"? Are they kooks? Or was Coyne just spreading FUD about evolutionary approaches to human behavior? I tackle those questions in this post and the substance of Coyne's critique in my next two posts.

First, some background

Physics' Standard Model has faced, and continues to face, exhaustive empirical tests. Any physicist can name the classic empirical papers supporting the standard model. In contrast, the "illness model" of depression -- the idea that depression is a brain dysfunction -- has never been empirically tested. Ever. It has simply been assumed and asserted by countless mental health researchers. (Pop quiz: what are the classic empirical papers supporting the illness model over alternatives? Answer: there aren't any.)

Yes, depression has numerous costs, including suicidality, and yes, the brains of depressed people differ from the brains of non-depressed people in numerous ways (for a materialist, how could they not?). But those costs and those differences are assumed, a priori, to be evidence that depression is a brain dysfunction. The possibility that many of those costs and differences are functional has never been seriously considered. In principle, the truly destructive differences, which probably include reduced hippocampal volume in depressed individuals, could be unavoidable consequences of activating depression, much as damage to healthy tissue is probably an unavoidable consequence of activating the innate immune system.

Despite the intuitive appeal of the illness model of depression, by the most important measure it has clearly failed. More than 50 years of research inspired by the illness model has not improved the treatment of depression. Newer antidepressants, such as Prozac, though generally causing fewer side effects, are no more effective at treating depression than the older antidepressants introduced in the 1950's, nor are they more effective than talk therapy. And although antidepressants are effective, this generally means that they reduce the severity of depression but often do not "cure" it.

Given this poor showing -- no improvement in treatment of depression after more than half a century of research costing billions of dollars -- it's time to rethink the illness model. Maybe it will ultimately be vindicated and maybe it won't, but this model can tolerate, indeed desperately needs, a few scientific critics (it already has social critics).

The motivation for Coyne's critique

Let me now turn to the motivation for Coyne's critique of Andrews and Thomson:
Well, ideas like [the ARH] have been floated before. What is new is the authors’ prescription that because depressive rumination is good, and because drugs that alleviate depression also alleviate the adaptive rumination, the best way to treat depression is not through drugs but through psychotherapy that helps the patient solve problems. Drugs only make things worse — they may alleviate the symptoms of depression, but they don’t alleviate the cause (life problems).

I’m not taking either a pro- or anti-drug stand here. What I am saying is that it seems unwise, especially in light of the insubstantial evidence that Andrews and Thomson offer for their evolutionary theory, to tell doctors to back off from a therapy that seems to help people.
I'm not sure which is more amusing, Coyne's paternalism or his naiveté. Readers of Psychological Review, the journal in which Andrews and Thomson's paper was published, are professional psychologists and psychiatrists who are well-qualified to evaluate the ARH. They don't need Coyne warn them about the ARH or its implications. Furthermore, because almost all mental health folks researching and treating depression have based their careers on the illness model, the likelihood that they would "back off" drug therapy for depression based on a single theoretical paper is nil.

Was it nevertheless "unwise" of A&T to argue that the use of antidepressants might have negative consequences? Hardly. It is standard practice in theoretical psychiatric papers to discuss the clinical implications of the theory. I can even imagine that the reviewers insisted on it. If the ARH is correct, then Andrews and Thomson are correct that antidepressants might interfere with the evolved function of depression, just as pain killers like morphine interfere with the evolved function of physical pain. If the ARH is not correct, then, of course, the clinical implications do not follow. The two professionals who wrote this paper, and all professionals reading it, understand that the clinical implications are contingent on the hypothesis being true. And the truth of the hypothesis can only be determined by rigorous empirical tests that have yet to be done (that's why Andrews and Thomson refer to their idea as an hypothesis).

Finally, various forms of talk therapy, the alternative treatment advocated by Andrews and Thomson, are just as effective in treating depression as are antidepressants. Hence, Andrews and Thomson are recommending one effective form of treatment over another equally effective form of treatment. This is scarcely cause for hand wringing (except by insurance companies, which might have to pay more for talk therapy).

Andrews and Thomson recommend some form of talk therapy because these therapies typically include a component that emphasizes solving life problems, thereby treating what the ARH posits is the cause of the depression. Antidepressants, in contrast, would (under the ARH) merely treat depression symptoms. There is also some empirical evidence that talk therapies have more lasting effects than do antidepressants.

Because Coyne must know that psychiatrists aren't looking to him for guidance on patient treatment, and because he must also know that spelling out the clinical implications of a new psychiatric theory is standard practice, my guess is that he isn't really worried that doctors will "back off" using antidepressants. His hand-wringing and snide tone are just means to sow FUD about evolutionary psychology in general and evolutionary psychiatry in particular, something he, his adviser Richard Lewontin, and Lewontin's late colleague SJ Gould, have done for years.

For some reason, these folks worry that it is dangerous to even ask certain scientific questions, and Coyne admits he sees "evolutionary psychology as dangerous." Because these questions scare them, they often try and scare other scientists away from these questions too.

Footnote 1: sociobiology, the original target of this FUD in the 1970's, has become an extremely successful mainstream science of human and especially non-human animal behavior, with sociobiological articles regularly appearing in Science, Nature, and PNAS. To escape the FUD, however, the term sociobiology was quickly dropped, and this work now occurs in the field of behavioral ecology, which also explores non-social aspects of animal behavior.

Footnote 2: In case the above link goes away, here is the Coyne quote on ev psych:
So, why do I see evolutionary psychology as dangerous? I think it is because I am afraid to see myself and my fellow humans as mere marionettes dancing on genetic strings. I would like to think that we have immense freedom to better ourselves as individuals and to create a just and egalitarian society. Granted, genetics is not destiny, but neither are we completely free of our evolutionary baggage. Might genetics really hold a leash on our capacity to change? If so, then some claims of evolutionary psychology give us convenient but dangerous excuses for behaviors that seem unacceptable. It is all too easy, for example, for philandering males to excuse their behavior as evolutionarily justified. Evolutionary psychologists argue that it is possible to overcome our evolutionary heritage. But what if it is not so easy to take the Dawkinsian road and "rebel against the tyranny of the selfish replicators"?

1 comment:

  1. Dear Dr.

    You wrote that antidepressants like "Prozac ... are no more effective than talk therapy". That is incorrect and unsubstantiated. An argument that conrolled clinical studies showed equal effect with placebo or psychotherapy only demonstrate inadequacies of the research.

    As an anecdotal statistical evidence of antidepressant effectiveness observe reverse correlation between suicide rates in the USA and SSRI prescription rates.

    Depression is a heterogeneous, cyclical disorder. That fact must be taken into consideration when critically reviewing clinical studies. Something that psychiatric establishment is reluctant to do for multitude of different but converging reasons.



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I am a biological anthropologist at Washington State University. Here is my faculty page.