If you’ve read Marcia Angell on antidepressants, you’re unlikely to be surprised by a recent study suggesting that “individuals who use antidepressants are much more likely to suffer relapses of major depression than those who use no medication at all… [P]eople who have not been taking any medication are at a 25 per cent risk of relapse, compared to 42 per cent or higher for those who have taken and gone off an antidepressant.” Paul Andrews, of McMaster University, argues that “antidepressants interfere with the brain’s natural self-regulation of serotonin and other neurotransmitters, and… the brain can overcorrect once medication is suspended, triggering new depression.”

In her much-discussed New York Review of Books essay, Angell reviews the similar arguments of Robert Whitaker:

If psychoactive drugs do cause harm, as Whitaker contends, what is the mechanism? The answer, he believes, lies in their effects on neurotransmitters. It is well understood that psychoactive drugs disturb neurotransmitter function, even if that was not the cause of the illness in the first place. Whitaker describes a chain of effects. When, for example, an SSRI antidepressant like Celexa increases serotonin levels in synapses, it stimulates compensatory changes through a process called negative feedback. In response to the high levels of serotonin, the neurons that secrete it (presynaptic neurons) release less of it, and the postsynaptic neurons become desensitized to it. In effect, the brain is trying to nullify the drug’s effects.

… With long-term use of psychoactive drugs, the result is, in the words of Steve Hyman, a former director of the NIMH and until recently provost of Harvard University, “substantial and long-lasting alterations in neural function.” As quoted by Whitaker, the brain, Hyman wrote, begins to function in a manner “qualitatively as well as quantitatively different from the normal state.” After several weeks on psychoactive drugs, the brain’s compensatory efforts begin to fail, and side effects emerge that reflect the mechanism of action of the drugs. For example, the SSRIs may cause episodes of mania, because of the excess of serotonin. Antipsychotics cause side effects that resemble Parkinson’s disease, because of the depletion of dopamine (which is also depleted in Parkinson’s disease). As side effects emerge, they are often treated by other drugs, and many patients end up on a cocktail of psychoactive drugs prescribed for a cocktail of diagnoses. The episodes of mania caused by antidepressants may lead to a new diagnosis of “bipolar disorder” and treatment with a “mood stabilizer,” such as Depokote (an anticonvulsant) plus one of the newer antipsychotic drugs. And so on.

Some patients take as many as six psychoactive drugs daily. One well- respected researcher, Nancy Andreasen, and her colleagues published evidence that the use of antipsychotic drugs is associated with shrinkage of the brain, and that the effect is directly related to the dose and duration of treatment. As Andreasen explained to The New York Times, “The prefrontal cortex doesn’t get the input it needs and is being shut down by drugs. That reduces the psychotic symptoms. It also causes the prefrontal cortex to slowly atrophy.”*

Getting off the drugs is exceedingly difficult, according to Whitaker, because when they are withdrawn the compensatory mechanisms are left unopposed. When Celexa is withdrawn, serotonin levels fall precipitously because the presynaptic neurons are not releasing normal amounts and the postsynaptic neurons no longer have enough receptors for it. Similarly, when an antipsychotic is withdrawn, dopamine levels may skyrocket. The symptoms produced by withdrawing psychoactive drugs are often confused with relapses of the original disorder, which can lead psychiatrists to resume drug treatment, perhaps at higher doses.