Use of isotretinoin for acne vulgaris apparently more than doubles the risk of depression, according to the results of a case-crossover study. Still, the absolute risk is probably very small.

The study is the first controlled investigation to find a statistically significant link between isotretinoin and depression, senior author Dr Anick Berard, from CHU Sainte-Justine Research Centre in Montreal, and colleagues note in the Journal of Clinical Psychiatry for April.

The study involved 30,496 subjects in Quebec, Canada who received at least one isotretinoin prescription from 1984 through 2003.

During the study period, 126 of these subjects had a depression-related diagnosis, hospitalization, or treatment during follow-up.

Based on previous research, the researchers focused on isotretinoin use in the five months prior to depression diagnosis or hospitalisation (risk period) compared with a five-month period a year before the diagnosis (control period).

Case subjects were 28 years of age, on average, and nearly 40 per cent were male. Most of them were urban dwellers.

Forty-one cases were exposed to isotretinoin in the risk period and 28 in the control period. "Twenty-six cases were exposed in the risk and not the control period, versus 13 exposed in the control and not the risk period (crude relative risk =26/13 = 2.0)," the researchers report.

After accounting for potential time-related confounders, isotretinoin exposure was associated with a relative risk of depression of 2.68.

"Depression is likely to be a rare side effect of isotretinoin therapy," Dr Berard and colleagues state.

Nonetheless, "current guidelines should possibly be modified to include psychiatric assessments of patients prior to and during isotretinoin therapy."

Reuters