Multiple sclerosis, depression, and the risk of suicide

The articles by Feinstein1 and Patten and Metz2 in this issue of Neurology advance our understanding of depression and suicidal thoughts and behaviors in patients with MS. They have fundamental implications about the mechanisms of depression and suicide, as well as practical implications that are immediately important for clinical care. At the fundamental level, Feinstein’s work adds to the literature3,4⇓ regarding physical illnesses, particularly CNS diseases, as risk factors for suicidal ideas, behavior, and completed suicide. As noted by Feinstein, CNS diseases do not produce this effect uniformly. Rather, those illnesses that cause or contribute to depressive disorders increase suicidal risk. Depression is extremely common in MS, with a point prevalence of major depression in MS clinic patients of 15 to 30%, and a lifetime prevalence of 40 to 60%.5 Feinstein6 and others have reported that subsyndromal symptoms are also common in patients who do not meet formal criteria for major depression. More than three decades ago, researchers reported that suicide can be associated with milder forms of mood disorders,7 so the absence of a major depressive diagnosis should not be viewed as the absence of suicidal risk. Proposed reasons for the association between MS and depression include the psychosocial effects of disability8 and direct effects of brain lesions,9 but the complex interplay of these factors remains unclear. Within …