Depression is the most frequent psychiatric disorder encountered in patients with Multiple Sclerosis (MS), with a life-time prevalence of approximately 50%. INF-beta (INF-β) shows beneficial effect on the course of MS. Although it has been suggested that interferons may be associated to depression, the validity and the nature of this relationship remain unclear regarding INF-β. The objective of this study is to review the scientific literature in order to elucidate the relationship between depression and INF-β therapy.

This systematic review was based on Medline, Embase and, PsycLIT literature searches (through January 2005), supplemented by bibliographical citations in identified papers.

The majority of studies ruled out a correlation between INF-β_1a/1b and depression in MS patients. However, patients with a recent history of depression may be at higher risk for depression particularly in the early phase of treatment (first 6 months), even if they are not depressed at the initiation of medication. There is an association between depressive symptoms and discontinuation of INF therapy but INF-β does not seem to be associated with suicide attempts. Treating patient-reported depression increases adherence to treatment.

Clinicians should not refrain from including patients with MS in INF-β treatment programs, even those with depression in the past or at the present time. Screening, monitoring, and early antidepressant treatment is necessary to optimize IFN therapy for the majority of patients with MS.