Depression is highly common in MS with a lifetime risk for major depressive disorder (MDD) as high as 25-50% and a 12-month prevalence of up to 25%, particularly in younger patients. Depression in MS has been linked to biological as well as psychological factors and substantially impacts psychosocial function. Importantly, depressive symptoms correlate with decreased quality of life, absence from work, and lower social support and are among the strongest predictors for suicidal ideation in MS patients.