Patients who use antidepressants are more prone to relapsing than those who struggle through melancholy without drugs, a McMaster University study suggests.

In fact, those patients who take drugs can be nearly twice as susceptible to future episodes of major depression after they go off the medication.

Paul Andrews, an evolutionary psychologist, and his colleagues reviewed dozens of published studies to compare outcomes of patients who used antidepressants to those who used placebos. Their findings suggest that those who do not take medication are at a 25 per cent risk of relapse compared to 42 per cent or higher for those who take and then go off drugs.

Andrews believes antidepressants interfere with the brain’s natural self-regulation of serotonin and other neurotransmitters. The brain can overcorrect once medication is suspended, triggering a new and even stronger depression, he says.

The findings will no doubt fuel the debate about the effectiveness of antidepressants.

Asked if antidepressants should never be used, Andrews said: “I am sort of on the anti-medication spectrum. I personally would avoid it if at all possible. Having said that, I can imagine there are certain instances where it can be useful.”