There’s a lot of sloppy thinking in my field. This troubles me. While psychiatry inevitably deals with the speculative and poorly understood, this surely cannot excuse faulty logic and intellectual laziness. Worse yet, this laxity of thought extends across the field, from biological psychiatry to psychotherapy, and from the general to the specific. My next few posts will address what I see as major areas of psychiatric sloppiness.
“Chemical imbalance” is a phrase used by psychiatrists and laypeople alike. When a mental problem seems to arise from within instead of without, it is said to be due to a chemical imbalance. In truth, however, no chemical imbalance, nor any structural abnormality in the brain, has ever been found to account for anything we currently consider a psychiatric disorder. Historically, whenever chemical or structural abnormalities were found to account for abnormal mental functioning, those conditions were no longer considered psychiatric and were adopted by another branch of medicine. If this trend continues, psychiatry will never include pathophysiology in the usual medical sense. It certainly does not at present.
Like many paving stones on the road to hell, the phrase “chemical imbalance” was sincere and well-intended at first. It originally referred to the biogenic amine model of depression, i.e., the hypothesis that a lack of excitatory neurotransmitters such as norepinephrine and serotonin underlies depression. While it’s a fairly compelling concept, it suffers from a lack of solid evidence. People who are depressed do not have “decreased serotonin in the brain,” and taking an SSRI does not “correct” the serotonin level. Such drugs may offer benefits as a result of boosting serotonin, but that’s not because serotonin levels were low to begin with. Moreover, the fact that SSRIs increase the amount of serotonin in brain synapses says nothing about the ultimate cause of depression. A cascade of downstream effects follows from tinkering with serotonin, including receptor down-regulation and probably new protein synthesis. If there’s any inherent chemical imbalance being remedied, we don’t know a thing about it.
Population studies show subtle changes on average in the brains of patients with certain psychiatric disorders. However, the findings in subjects with psychiatric diagnoses overlap so much with those of normal subjects that no blood test or brain study can diagnose mental illness in an individual. (Dr. Daniel Amen claims otherwise regarding SPECT scanning of the brain, but many critics are skeptical. Likewise, a putative new blood test for depression raises many questions.) At best, “chemical imbalance” is shorthand for a presumed brain abnormality that no one has yet proven. At worst, it is disingenuous hand-waving aimed to add medical legitimacy to the field of psychiatry.
Why is “chemical imbalance” so often advanced as a pseudo-explanation for mental illness? Many psychiatrists confidently proclaim that psychiatric disorders “are medical conditions just like diabetes and hypertension” to justify chronic ongoing management and the need for medication even when the patient feels subjectively well. Suffering a “chemical imbalance” implies that proper medication will correct a pre-existing, permanent organic abnormality. The problem here is that the end (patient cooperation) does not justify the means (lying). The honest answer is that we psychiatrists believe our medications help relieve psychiatric symptoms and distress — although even that is hotly debated — including maintenance treatment to forestall relapse. This belief is based on outcomes research and clinical, aka anecdotal, experience, not on knowledge of biological mechanisms.
Psychiatry has long been the red-headed stepchild of medicine. In medical centers we’re often in a separate building across the street from the main hospital. Other physicians sometimes don’t understand what we do and make nervous jokes. Critics accurately note that psychiatric disorders are never found in standard pathology textbooks, and some claim the field is baseless and harmful. “Chemical imbalance” gives some psychiatrists the medical bona fides they crave, but at the price of intellectual laziness and sloppy thinking. This serves no one. Psychiatry must embrace uncertainty, and not seek false security in empty phrases. Physicians prescribed aspirin for pain and fever long before we understood the intricacies of these conditions, or the mechanism by which aspirin affected them. We simply knew it worked — no one claimed that a subtle “aspirin imbalance” was being corrected. Like it or not, psychiatry is in much the same place now.
I’m hardly the first to critique “chemical imbalance,” although some still defend it. I started with this as the prime example of sloppy thinking in psychiatry. But as we shall see, there are many others.
Photo courtesy of Petr Kratochvil.