Close to one-in-six American adults is currently prescribed an antidepressant. A serotonin, or “chemical,” imbalance hypothesis remains one of the key justifications for antidepressant use. But many are now questioning whether the term chemical imbalance is sufficiently explanatory, asking whether antidepressants resolve a chemical imbalance or risk creating one. I recently spoke to Joanna Moncrieff, author of Chemically Imbalanced, about avoiding neuro-reductionism and thinking about mental states in ways that aren’t disempowering.

Chris Lane: Recent surveys you’ve quoted indicate that 85-90 percent of the American public believes low serotonin or a chemical imbalance causes depression and other mental states; the percentages are strikingly similar in Australia and the United Kingdom. Not unrelated, though spiked by the pandemic, antidepressant prescribing in the United States increased by 34.8 percent over six years, reaching 83.4 million in 2021-22. Why do you think the chemical imbalance metaphor has been so popular and resilient, even as its supporting evidence was always quite flimsy?

Joanna Moncrieff: I would credit the massive marketing campaigns of the 1990s and 2000s, undertaken by the pharmaceutical industry, and aided and abetted by the psychiatric profession. The chemical imbalance message is particularly useful because it suggests that people with depression need a chemical intervention. So it helped overcome people’s natural caution about using drugs to manage emotional problems. The message also had intrinsic appeal........

© Psychology Today