A new paper has added to the growing ranks of studies finding that antidepressant drugs don't work in people with milder forms of depression: Efficacy of antidepressants and benzodiazepines in minor depression.
It's in the British Journal of Psychiatry and it's a meta-analysis of 6 randomized controlled trials on three different drugs. Antidepressants were no better than placebo in patients with "minor depressive disorder", which is like the better-known Major Depressive Disorder but... well, not as major, because you only need to have 2 symptoms instead of 5 from this list.
They also wanted to find out whether benzodiazepines (like Valium) worked in these people, but there just weren't any good studies out there.
The results look solid, and they fit with the fact that antidepressants don't work in people diagnosed with "major" depression, but who fall at the "milder" end of that range, something which several recent studies have shown. Neuroskeptic readers will, if they've been paying attention, find this entirely unsurprising.
But in fact, it's not just not news, it's positively ancient. 50 years ago, at the dawn of the antidepressant era, it was commonly said that most antidepressants don't work in everyone with "depression", they work best in people with endogenous depression, and less well, or not at all, in those with "neurotic" or "reactive" depressions (see, e.g. 1, 2, 3, but the literature goes back even further).
"Endogenous" is not strictly the same as "severe", however, in practice, these two concepts have never really been clearly seperated, and they're largely equivalent today, because the leading measure of "severity", the Hamilton Scale, measures symptoms, and arguably these symptoms are mostly (though not entirely) the symptoms of the old concept of endogenous depression. The Hamilton Scale was formulated in 1960 when modern concepts of "minor depressive disorder" and "major depressive disorder" were unknown.
Why then are we only now working out that antidepressants only work in some people? There's one obvious answer: Prozac, which arrived in 1987. Before Prozac, antidepressants were serious stuff. They could easily kill you in overdose, and they had a lot of side effects. Many of them even meant that you couldn't eat cheese. As a result, they weren't used lightly.
Prozac and the other SSRIs changed the game completely. They're much less toxic, the side effects are milder, and you can eat as much cheese as you want. So it's very easy to prescribe an SSRI - maybe it won't work, but it can't hurt, so why not try it...?
As a result, I think, the concept of "depression" broadened. Before Prozac, depression was inherently serious, because the treatments were serious. After Prozac, it didn't have to be. Drug company marketing no doubt helped this process along, but marketing has to have something to work with. Over the past 25 years, terms like "endogenous", "neurotic" etc. largely disappeared from the literature, replaced by the single construct of "Major Depression".
For nearly 1,000 years, the great scientific and philosophical work of the ancient Greeks and Romans were lost to Europeans. Only when Christian scholars rediscovered them in the libraries of the Islamic world did Europe begin to remember what it had forgotten. We call those the Dark Ages. Will the past 25 years be remembered as psychiatry's Dark Age?
Barbui, C., Cipriani, A., Patel, V., Ayuso-Mateos, J., & van Ommeren, M. (2011). Efficacy of antidepressants and benzodiazepines in minor depression: systematic review and meta-analysis The British Journal of Psychiatry, 198 (1), 11-16 DOI: 10.1192/bjp.bp.109.076448