When my American friend Bill, who’d been on SSRI antidepressants for 22 years (Prozac, followed by Paxil, Lexapro, then Celexa), read a two-part article by Dr Marcia Angell in The New York Review of Books recently about the crisis in psychiatry and the inefficacy of antidepressants, he stopped taking his meds (tapering off gradually, monitored by his doctor). "The article brought on enough doubt to push me over," he said. Since then, his moods have become more volatile – more anger, more emotion, such as crying at the end of the last Harry Potter film (he’s in his 50s). But he’s got his libido back after years of "muffled response" and that seems a worthwhile trade-off.
Instead of listening to Prozac, have we been listening to placebo all along? Research repeatedly appears to show that: antidepressants are little more than placebos, with very little therapeutic benefit but serious side-effects (70 per cent of people on Celexa and Paxil report sexual dysfunction, and in some, it carries on even when they stop taking the pills). The theory of chemical imbalance as a cause of depression is an unproven hypothesis; and doctors are prescribing the drugs mainly because of the "juggernaut of pharmaceutical promotion", as the US psychiatrist Dr Daniel Carlat calls it.
It’s not surprising there’s a US media furore – about 10 per cent of Americans over the age of six take antidepressants. In the UK, prescriptions for the drugs went up 43 per cent in the last four years to 23 million a year.
Professor Irving Kirsch, associate director of the programme in placebo studies at Harvard Medical School and author of The Emperor’s New Drugs: Exploding the Antidepressant Myth, says the theory of chemical imbalance – that there is not enough serotonin, norepinephrine and/or dopamine in the brain synapses of depressed people – doesn’t fit the data (lowering serotonin levels in healthy patients has no impact on their moods). Chemical imbalance is a myth, he says. It follows that the idea that "antidepressants can cure depression chemically is simply wrong". His meta-analysis of 38 clinical studies – 40 per cent of which had been withheld from publication because drug companies didn’t like the results – involving more than 3,000 depressed patients, shows that only 25 per cent of the benefit of antidepressant treatment was due to the drugs and that 50 per cent was a placebo effect. "In other words, the placebo effect was twice as large as the drug effect," though the placebo response was lower in the severely depressed.
This is not quite as damning as it sounds: placebos are extraordinarily powerful and can be "as strong as potent medications". Placebo response is specific: placebo morphine eases pain, placebo antidepressants relieve depression. It’s a question of expectancy and conditioning: if you expect to feel better, you will, even if you’re getting negative side effects, because side effects, Kirsch says, convince people that they’ve been given a potent drug.
Psychotherapy boosts the placebo effect and is "significantly more effective than medication" for all levels of depression, he says. Antidepressants should only be used "as a last resort and only for the most severely depressed".
Of course, not everyone agrees. Ian Anderson, Professor at psychiatry at the University of Manchester, who is to debate whether "antidepressants are useful in the treatment of depression" with Kirsch at a conference in Turkey next month, thinks we’re in danger of throwing the baby out with the bathwater when we say antidepressants are rubbish. Antidepressants are part of a doctor’s toolbox, though probably most useful for the most depressed; some people don’t take to talking therapies; it’s not an either/or situation, he says.
Professor Allan Young, chair of psychiatry at Imperial College London, agrees. "Depression is such a huge category of illness – there are multiple types, and each type responds differently." Of course, the brain and the body are inextricably linked, he says, and placebo effects are greater in the less-severely ill.