Are antidepressant pills really effective?

by Marc Wilson / 23 March, 2018
RelatedArticlesModule - Anti-depressant pills

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Johann Hari is right about some things, but effective depression treatment means casting a wide net. 

“Prediction is not explanation,” I was once told. Women are more likely to vote for Labour, study for PhDs in art history and get depressed, but that doesn’t mean it is because they’re women.

About 10% of us will experience depression, and Johann Hari’s new book is a personal account of a journalist’s search for insight into his own experience.

Hari makes several headline-worthy claims. He urges us, for example, not to accept uncritically that depression is caused by lopsided brain chemistry, specifically levels of the neurotransmitter serotonin, and that routine drug treatment is the only option. He writes that depression has multiple “causes” that have nothing to do with our brains, including life experience, in the past and present.

Most controversially, he argues that prescriptions for medication to treat depression aren’t worth the paper they’re written on, and we should throw our therapeutic nets wider.

The science of prediction is relevant here. We know that depression is about 50% heritable, or genetic: if you have a close family member with major depression, you’re two to three times as likely to develop major depression as someone who does not. This is true of most psychiatric conditions: family history is a predictor of risk.

But not everyone with this genetic risk goes on to develop the disorder. Think of it as having a switch that doesn’t get flipped unless the conditions – such as life experience, for example – are right. Having that genetic risk and bad stuff going down makes Jack (or Jill) much more likely to become a sad boy (or girl).

If antidepressants increase the levels in the brain of such chemicals as serotonin, do serotonin levels predict depressed mood? We can’t directly delve into brains to see, but what we can do is deplete these brain chemicals by interfering with or blocking the process that produces them and seeing if mood changes. And that’s exactly what happens, particularly for men with a family history of depression.

If lowering levels of these brain chemicals lowers mood, does putting them in make you happier? Is it true, as Hari suggests and the Verve song insists, that “the drugs don’t work”? And if they do work, is it only because they have a placebo effect? The way to test this is to treat two groups of depressed people, one with a placebo, the other with an antidepressant, and see what happens.

Hari reports, accurately, that 20-40% of 10 people given a sugar pill will report feeling better. But 40-60% of those 10 who get an antidepressant feel better. The evidence is unequivocal that antidepressants do work and they work better than a sugar pill. But not everyone will feel better, whether they got the real or the pretend pill.

As good as a pill, though – and better if you consider side effects – is talk therapy. The prevailing view is that talk therapy is as effective as medication. An important thing these reviews obscure is that therapy may help people for whom the drugs don’t work, and maybe vice versa. We’re not very good at working out what works best for whom.

Regardless, if Hari was never asked what else might be going on for him, he never spoke to a good health professional. I defy anyone who’s been to see a clinical psychologist for more than a couple of sessions to swear they weren’t asked about their lives.

In short, Hari is right about some things, but his central claims that people treat depression as if it’s all about brains and that drugs are used as the only treatment even though they don’t work are wrong. Prediction isn’t explanation: I don’t feel confident that we’ve explained depression, but that doesn’t mean we don’t know how to help most people who experience it.

Marc Wilson is a Victoria University psychology professor and Listener columnist.

This article was first published in the March 3, 2018 issue of the New Zealand Listener.

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