Depression and multiple sclerosis

Multiple sclerosis (MS) is one of the most common neurologic disorders affecting young adults. The suggestion of a possible relationship between depression and MS has existed for many years. ^[1-4] The historical explanation for observed ``depression'' in persons with MS is a reaction to a stressful illness with potential consequent impact on all aspects (e.g., family, social, work, independent self-care, and so on) of daily living. Other studies suggest that depressive symptoms in MS patients may be correlated with progressive neurologic disability. ^[2,5] However, more recent work suggests that it is the increasing and specific CNS involvement that results in depressive symptoms. ^[6,7]

To date, studies on MS and depression have been problematic for several reasons. It is crucial in such studies to differentiate between ``depressive symptoms'' and a ``major depressive illness,'' which are very different entities. Major depressive illness is a discrete, operationally defined psychiatric disorder involving a constellation of mental and physical symptoms, only one of which may be a depressed mood. ^[8] However, few of the studies on MS and depression have used standardized objective diagnostic criteria for depression, thus lacking the diagnostic rigor necessary to differentiate depressive symptoms from a major depressive illness. Further, there has been little attempt to control for possible confounding factors such as the degree of MS disability and bias in case ascertainment.

Our interest in the relationship between MS and depression arose because of the results of a Canadian study on causes of death among 3,125 MS patients attending two MS clinics (Vancouver, British Columbia, and London, Ontario). ^[9] The suicide rate among these individuals was 7.5 times the rate for the age-matched general population. ^[9]

The possible relationship between MS and depression is of importance in both the understanding of the etiologies of these two common conditions and the potential …