Do The Drugs Work? It's Complicated

Over at Comment is Free a week ago, Ed Halliwell proclaimed that "The Drugs Don't Work". The drugs being antidepressants. On this blog I've often written about antidepressants and the evidence that they work, or don't, so I was interested to see what he had to say.

Halliwell begins by noting that antidepressant prescriptions are rising. This, he declares, is a bad thing because antidepressants just don't work very well - "....A recent review found the SSRIs barely more effective than a placebo pill. Still, the NHS bill for prescribing them runs into hundreds of millions of pounds a year. It's a crazy situation, and the tide may be turning..."

This invokes the famous Kirsch et al 2008 PLoS review of antidepressants. This analysis concluded that 6 weeks treatment with antidepressants was only slightly better than placebos for depression. But slightly is better than nothing. Kirsch et al is evidence that the drugs do, in fact work.

This despite the fact that the analysis included "suppressed" unpublished drug company data unfavorable to antidepressants. So almost uniquely in medicine, there can be none of the publication bias which plagues all clinical trials. In other words, an exceptionally high standard of evidence shows that the drugs do work. A bit. And in fact they probably work better than that, because Kirsch et al's paper was biased against antidepressants as a series of classic posts by P J Leonard and Robert Waldmann pointed out.

Halliwell then says that instead of popping pills to ease our troubled minds, we should turn to "...simple, socially based steps everyone can take to improve their wellbeing. These include building good relationships, lifelong learning, being kind to others and exercise – not rocket science, but somehow we seem to have forgotten them."

Now I don't know what drugs you would need to take to think that "building good relationships" is "simple" - Ecstasy washed down with alcopops might do it. But once you sobered up and read a novel, or watched a play, or just remembered your last breakup, you would realize that relationships can actually be quite complicated. Not to mention being kind to others and lifelong learning, which are so simple that everyone is has a PhD in Being Nice.

But such nonsense aside, the actual hard evidence that these kinds of things can treat clinical depression as opposed to just "improving wellbeing" is weak. There is some evidence that exercise can treat depression, for example, but it's often of poor quality, with no placebo, and publication bias could be rampant.

Indeed as luck would have it, today, two Cochrane Reviews were published. One was about antidepressants for the treatment of depression in primary care. The other was about exercise for depression.

Respectively, they concluded that - "Both tricyclic antidepressants and SSRIs are effective for depression treated in primary care" (not massively effective I hasten to add, but it's something) while the exercise one concluded that "Exercise seems to improve depressive symptoms in people with a diagnosis of depression, but when only methodologically robust trials are included, the effect sizes are only moderate and not statistically significant..."

I'm not endorsing these conclusions. Neuroskeptic readers know that I've long been critical of antidepressant trials and sometimes even Cochrane Reviews. I study antidepressants for a living, and I honestly don't know if they work for the millions of people who take them. (I'm fairly sure that they work in severe depression, but this isn't a very common disease.) But I do know that it's a really complicated issue. And I know that simplistic pro- or anti- medication rhetoric helps no-one and insults the intelligence of all.

But there's more here. Ed Halliwell has a history. He was the lead author of "In The Face of Fear", a deeply flawed Mental Health Foundation report from a couple of months back. The main message of the report was that anxiety is currently on the rise in Britain. We're getting more scared and anxious. There is an epidemic of fear - right now.

This claim was supported by two things - a completely unscientific opinion poll (which didn't really show much of an increase at all), and a reference to government mental health survey data from 1993 and 2007. These indeed show an increase in reported prevalence of anxiety disorders.

Now whether surveys such as these give meaningful data is questionable, but quite apart from that, the MHF report was guilty of a much more glaring error. As I said at the time, it simply failed to mention that we also have data from 2000. And in 2000, rates of anxiety disorders were almost exactly the same as in 2007, higher in some cases.

Now, the 1993, 2000 and 2007 figures are right next to each other in the government report (page 41 of this publicly accessible pdf): unless Halliwell has some kind of visual defect rendering him unable to see the middle of three columns of numbers, he must have seen this. The best available scientific data is that rates of anxiety have been stable for the last 10 years.

Stable, but very high. And the irony - and the tragedy - is that these massive reported rates of depressive and anxiety disorders in the British population (17.6%, at any one time and this is only for some disorders), are why antidepressants are so widely prescribed. Not these figures alone, but rather the more general belief that mental illness is very common - a belief promoted, inter alia, by organisations such as the MHF.

This belief - the "one in four" myth - is music to the ears of the very drug companies that Halliwell and others lambasts for pushing pills. When tens of millions of people are told that they are ill and need treatment, can you blame them for turning first to pills instead of a wholescale reconstriction of human life and society?