The Daily Mail published an article last month with the headline

Depression is NOT caused by low serotonin levels and most drugs used to treat it are based on a myth, psychiatrist claims

DavidHealysmall1The story was based on an editorial in the British Medical Journal (BMJ) by psychiatrist David Healy (pictured), who argued that the popularity of SSRI antidepressants such as Prozac is based on a myth, grown from the notion that ‘SSRIs restored serotonin levels to normal, a notion that later transmuted into the idea that they remedied a chemical imbalance’.

In fact, whilst levels of serotonin may be linked to depression, it is not known exactly how, and nor is it understood how SSRI antidepressants really work.

According to Healy, the strength of the chemical imbalance myth means that SSRIs are often prescribed at the expense of more effective treatment, and with no regard to individual characteristics of a patient’s depression. But he says:

Serotonin is not irrelevant. Just as with noradrenaline, dopamine, and other neurotransmitters, we can expect it to vary among individuals and expect some correlation with temperament and personality.


Is the ‘depression is a chemical imbalance’ idea really incorrect?

prozacThe academics and medics who commented on the BMJ piece seem to be clear that the science has moved on a long way since SSRIs were introduced, and that the causation of depression is much more complicated than too much or too little of one neurotransmitter in the brain. So it is way too simplistic to say that SSRIs correct a chemical imbalance.

An article on the website io9 gives some background into how the chemical imbalance ‘myth’ took root and grew. It also summarises where the scientific thinking on depression is now:

Depression’s wide range of symptoms can be linked to myriad overlapping factors, from genetic vulnerability, to deficiency of certain neurotransmitters, to disruptions in circadian rhythms, to factors that can alter the survival and growth of neurons.

The birth of new neurons, for example, is a hallmark of a healthy brain; a prominent new theory about how SSRIs work has connected elevated serotonin levels to the elevated birth of neurons.

But the science still has a ways to go.  It is also obvious that psychological stress and so-called early lifetime stress can cause depression.

Poul Videbach, professor of psychiatry at Aarhus University Hospital in Denmark (Levi Gayde, io9)


So it’s a myth, so what?

The many comments on the Daily Mail and io9 articles illustrate the two main issues arising from all this: 1. SSRIs are overprescribed because patients and doctors have bought into the myth; 2. SSRIs really do help a lot of depressed people

If Prozac, or any of the SSRIs (Cipramil, Cipralex, Faverin, Seroxat, Lustral are the others used in the UK) improve your symptoms and side effects aren’t a problem, does it matter if we don’t really know how they work? No. Keep taking the tablets.

But if sorting out serotonin levels isn’t the answer, or not the whole answer anyway, to managing depression, it makes sense to keep doing the other things that help: healthy sleep, good diet, social contact, exercise, mindfulness, anti-ruminatory activity, exposure to sunshine.


References and further reading

Daily Mail 22.4.15  Depression is NOT caused by low serotonin levels and most drugs used to treat it are based on a myth, psychiatrist claims

David Healy Serotonin and depression: The marketing of a myth British Medical Journal, April 2015 (comments via BMJ 2015;350:h1771)

Levi Gayde The Most Popular Antidepressants Are Based On An Outdated Theory [UPDATED] io9 website

Jonathan Leo and Jeffrey Lacasse  A Reply to Peter Kramer: Do Serotonin Imbalances Cause Depression? April 2015

NHS Choices Selective serotonin reuptake inhibitors (SSRIs) 

‘depression is a chemical imbalance’ a myth: so what?

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