We all know that depression is caused by – or at least linked to – low serotonin levels. Even in popular culture, as the singer-songwriter Girl in Red sings in her song “Serotonin” (2021)

I'm running low on serotonin
Chemical imbalance got me twisting things

But is there really a scientific basis for this view?

The British psychiatrist and author Joanna Moncrieff put together at team that rigorously reviewed decades of research, and they conclude that it actually lacks support in the data.

Moncrieffs latest book, Chemically Imbalanced – The Making and Unmaking of the Serotonin Myth (2025), is a rather unsettling account of how this highly debatable theory became so mainstream that few even question it.

She argues that the old way of looking at psychiatric drugs – that they altered your mental states (amphetamines made you active, valium made you calm), gradually gave way to a model that says that psychiatric drugs correct an underlying abnormality (e.g. serotonin deficiency).

This shift did not come about because of new evidence, she argues, but because this model made antidepressants much easier to justify and market. After all, who doesn’t want a treatment that make your brain and nervous system function as normal again?

And this strategy seems to have worked. The use of anti-depressants has sky-rocketed since the nineties, in England almost one in five (!) take them, and almost one in four women. And the serotonin-deficiency model has become mainstream.

Moncrieff opens up for big, often uncomfortable questions about what depression is and what antidepressants and psychiatric drugs actually do. It questions the biological roots of depression and other psychiatric disorders, and medication as a convenient and cheap quick fix.

Last, but not least, it shows how relatively unsupported scientific narratives can become cultural truths.

World renowned physician and author Gabor Maté says about Chemically Imbalanced :

This essential book debunks one of the greatest misperceptions besetting current medical practice: that what we call mental illness is reducible to biological causes, divorced from people’s life experiences and traumas. Dr. Moncrieff explains both the scientific flaws and the deliberate manipulations underlying much of today’s psychiatric ideology and treatment.

Joanna Moncrieff is a British psychiatrist and author, and a leading voice in the Critical Psychiatry Network. She has also written The Myth of the Chemical Cure (2007) and The Bitterest Pills (2013), and is an active public commentator in the United Kingdom, with articles and interviews in outlets such as The Guardian and The Spectator.

In conversation with Johanne Pontoppidan Tuxen, science journalist in Information