In a recent NPR story, there was a discussion of the serotonin theory of depression. It was acknowledged by the scientists who were interviewed that there is no evidence of a serotonin deficiency in the brains of people who are depressed. In this piece and in related commentaries this notion is referred to as a “chemical imbalance” and psychiatry was criticized for not being honest about the lack of evidence to support this notion.
I share the criticism of those who argue that psychiatry has had an overly cozy relationship with the pharmaceutical companies. I also agree that the efficacy of a wide variety of agents has been overstated. However, there is a component of the current round of criticism with which I disagree: specifically, the assumption that if there is no evidence of neurotransmitter abnormalities then conditions such as schizophrenia do not involve alterations of brain function. This idea is often linked to a related assumption that, therefore, medications could not be effective treatments.
Are the symptoms of schizophrenia a reflection of brain function?
I approach this argument from the philosophical perspective of a monist. That is, I take as a given that cognition, emotion, and perception are brain functions. If someone reading this is a dualist (i.e., believes that there is something other than the material world from which these experience airs) then we have deeper disagreements that I will not address here.
When someone hears a voice, parts of the brain have been activated to create the experience of that voice. That is true regardless of whether or not that experience was a response to a set of sounds produced by another person’s vocal chords. Similarly, people who have lost limbs often experience pain and other sensations in them, despite the fact that they have been amputated. The experience of the limb is as it would be if the extremity were still present.
The experience of hearing a voice that no one around you can hear is reflective of a set of brain processes. It may not be due to “excess dopamine” but it nevertheless is due to the way the brain is working. Something has happened in that brain to create the experience of that voice despite the fact that there is no external stimulus that caused it. It is a reasonable, interesting, and valid question for research to understand what happens in such a person’s brain when that voice is heard.
Can medications, in theory, be effective for problems of thought, mood or cognition?
Even if there is no dopamine excess in the brain, that does not mean that medications that alter dopamine function in the brain cannot a priori be effective. The effective treatment of a condition is not necessarily linked to its cause. If a condition is thought to be due to a genetic or structural abnormality then it is commonly thought to be “biological” and therefore more amenable to treatment with a “biological” treatment such as a medication. If something is due to environmental effects such as trauma, then it is thought to be more responsive to “environmental” treatments such as psychotherapy. But these are false distinctions. ALL treatments are biological. Psychotherapy is as “biological” a treatment as medications. If someone, for instance, learns meditation and is able to feel less anxious, that change is mediated by changes in the brain.
If someone participates in Open Dialogue because he is hearing voices and over time the voices go away or the person is less bothered by them, then some change has occurred in his brain to which that change is attributable. If someone takes a medication that blocks dopamine receptors and he no longer hears voices, a change has occurred in his brain. Maybe it is the same change. Maybe it is different. Maybe the changes effected by Open Dialogue are safer or more long-lasting. Maybe the efficacy of our currently available medications have been exaggerated. The point is that there is nothing inherent to the symptom or its the hypothesized etiology that in itself allows one to know what sort of treatment will be most effective. That is always an empiric question and all potentially effective treatments deserve the same critical scrutiny.