by DANIEL LENDE
Marcia Angell has a wonderful review, The Epidemic of Mental Illness: Why?, up at the New York Review of Books. I want to highlight two things: (1) the fall of the “chemical imbalances” theory of the brain, cloaked in the language of neurotransmitters and synapses; and (2) that healing matters, in particular signs people can interpret that drugs they are getting must be making a difference.
Chemical imbalances is our most recent folk theory of mental illness in the Western world. A focus on doctors and therapists doing, rather than on how healing happens, is the corollary – the imbalance, whether chemical or psychoanalytic, needs to be corrected. Both of these are rich arenas for medical anthropology, and I particularly hope people will dig into work on how healing and placebos work.
But for those also interested in the brain, Angell’s piece gives some great overview of how our understanding of brain function and treatment is progressing. Here she is on the chemical imbalance approach:
Because certain antidepressants increase levels of the neurotransmitter serotonin in the brain, it was postulated that depression is caused by too little serotonin. (These antidepressants, like Prozac or Celexa, are called selective serotonin reuptake inhibitors (SSRIs) because they prevent the reabsorption of serotonin by the neurons that release it, so that more remains in the synapses to activate other neurons.) Thus, instead of developing a drug to treat an abnormality, an abnormality was postulated to fit a drug.
That was a great leap in logic, as all three authors point out. It was entirely possible that drugs that affected neurotransmitter levels could relieve symptoms even if neurotransmitters had nothing to do with the illness in the first place (and even possible that they relieved symptoms through some other mode of action entirely). As Carlat puts it, “By this same logic one could argue that the cause of all pain conditions is a deficiency of opiates, since narcotic pain medications activate opiate receptors in the brain.” Or similarly, one could argue that fevers are caused by too little aspirin.
But the main problem with the theory is that after decades of trying to prove it, researchers have still come up empty-handed. All three authors document the failure of scientists to find good evidence in its favor. Neurotransmitter function seems to be normal in people with mental illness before treatment. In Whitaker’s words:
Prior to treatment, patients diagnosed with schizophrenia, depression, and other psychiatric disorders do not suffer from any known “chemical imbalance.” However, once a person is put on a psychiatric medication, which, in one manner or another, throws a wrench into the usual mechanics of a neuronal pathway, his or her brain begins to function…abnormally.
Carlat refers to the chemical imbalance theory as a “myth” (which he calls “convenient” because it destigmatizes mental illness), and Kirsch, whose book focuses on depression, sums up this way: “It now seems beyond question that the traditional account of depression as a chemical imbalance in the brain is simply wrong.”
And here is the relevant piece on anti-depressants, placebos, and really getting at the science of what is going on.
Kirsch was also struck by another unexpected finding. In his earlier study and in work by others, he observed that even treatments that were not considered to be antidepressants—such as synthetic thyroid hormone, opiates, sedatives, stimulants, and some herbal remedies—were as effective as antidepressants in alleviating the symptoms of depression. Kirsch writes, “When administered as antidepressants, drugs that increase, decrease or have no effect on serotonin all relieve depression to about the same degree.” What all these “effective” drugs had in common was that they produced side effects, which participating patients had been told they might experience.
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