Interferon Beta 1b and Depression

The Journal of Neurology has a rather oddly reported Canadian prospective study on the relationship between depression and interferon beta-1b treatment in MS. The study's objectives were twofold: to explore a possible association between major depression and treatment with interferon beta-1b in patients with multiple sclerosis; and to investigate whether putative antecedent risk factors such as a previous psychiatric history and a family history of affective illness influence the prevalence of major depression post-treatment with interferon beta-1b.

Forty-two patients with relapsing-remitting MS underwent neurological examination and were interviewed with the Structured Clinical Interview for Axis 1 DSM-IV Disorders prior to starting interferon beta-1b and thereafter at 3, 6 and 12 months. At index assessment, 21.4 % of the sample were diagnosed with a major depression, the figures falling to 17.5 %, 11.4 % and 6.3 % at 3, 6 and 12 months respectively (the study's authors note that ethical considerations required them to start all patients diagnosed with major depression on antidepressants prior to starting therapy. The majority of subjects with a major depression had a history of psychiatric illness prior to treatment with interferon beta-1b, they say -- which begs not only the question of why they weren't already on treatment, but what role MS, MS relapses or MS deficits might be playing in their depression.

The study design addressed "previous psychiatric history," yet the reporting makes it appear as though many of these patients were first diagnosed at intake.) The study's authors claim that their data demonstrate that major depression post-treatment with interferon beta-1b is linked to a history of psychiatric illness prior to starting treatment. They claim that the threefold decline in prevalence rates for major depression over the course of a year demonstrates a good response to antidepressant medication and -- without any substantiation -- possible beneficial effects of interferon beta-1b on mood. This is a tiny study, and I believe, a poorly designed one. A more interesting study would be to look at a cohort, non of whom were judged to have major depression prior to initiating therapy, and see how they fared. Ongoing sub-clinical depression of the sort that has been associated with interferon therapy can also be quite debilitating, and assessment of the frequency and impact of that would also be of interest.