The relationship between depression and interferon beta-1a therapy in patients with multiple sclerosis

It has been suggested that interferons (IFN) may cause depression de novo or worsen pre-existing depression. Depression data collected using validated instruments from individual clinical trials in multiple sclerosis, however, have consistently failed to identify an association. In this study, pooled data from 6 controlled studies and 17 noncontrolled clinical trials of subcutaneous IFN beta-1a were assessed to determine the relationship between IFN therapy with physician reports of depression and suicide. In distinction to the negative findings for depressive symptom ratings, pooling of physician-reported side effect data from these clinical trials identified a statistically significant association between depression and IFN use during the first six months of treatment. There was an association between these reported episodes of depression and discontinuation of IFN therapy, but IFN treatment was not associated with suicide attempts. IFN beta-1a may induce a constellation of symptoms, particularly early in therapy, that may be labelled as depression by physicians. However, the lack of an increase in depression-rating scale scores and the lack of association with suicide risk suggests that the syndrome may be an atypical one.