Interferon beta-1a-induced depression and suicidal ideation in multiple sclerosis.

Depression and suicide have been reported in association with multiple sclerosis (MS). Some studies show that interferon beta may increase the depression rate. We report a case of depression and suicidal ideation in coincidence with the start of increased doses of interferon beta-1a and their complete reversal following the drug withdrawal. The patient was a 21-year-old man with MS and no past history of affective disorders who was given interferon beta-1a in the dose of 11 microgram three times per week. As a new relapse occurred the dose of interferon beta-1a was increased to 22 microgram three times a week. The patient then observed increased worry, irritability and a sense of discouragement as well as recurring suicidal thoughts. His mood was rapidly restored following interferon beta-1a withdrawal. This case suggests that patients with MS may develop depression and suicidal thoughts when treated with high doses of interferon beta-1a.