One of the most astonishing things in the history of the brain is the seesawing between mentalism (focus on the mind as separate from the brain) and physicalism (emphasis on the primacy of the physical brain). As early as 400 BC, Hippocrates acknowledged the brain as the center of human emotions and thinking. During the ensuing centuries this viewpoint moved like a pendulum from that position to one espousing the dynamics of mental processes. Now, it appears, we are returning to a belief in the primacy of the brain.

When I began my practice in the late 1970s, psychiatry was in transition. A different model was replacing psychoanalytical explanations for mental and emotional illnesses, which had focused on the impact of infant and childhood development, particularly interactions with parents and siblings, for creating adult neuroses and psychoses. Research on behavioral genetics and brain neurotransmitters was bearing fruit, so that by the 1990s there was increasing acceptance of the notion that serious mental illness had its origins in biological dysfunction.