The association between multiple sclerosis (MS) and depression has been well established but prevalence estimates have varied widely. The aims of this study were to assess the point prevalence of previously unrecognised symptoms of depression in a community–based population with MS and examine their relationship to other disease characteristics.

Three hundred and seventy six patients with clinically definite or probable MS (Poser criteria) were ascertained during the course of an epidemiological study on two counties in Ireland. Of these 211 agreed to participate in the study. Subjects were examined and a Kurtzke Expanded Disability Status Scale Score and Multiple Sclerosis Functional Composite score rated. Participants also completed a Beck's Depression Inventory–II and a Multiple Sclerosis Impact Scale.

In total 60 (28%) patients had moderate or severe symptoms of depression. Only thirty–five of the 211 patients had a history of depression as defined by a medical diagnosis of depression or prescription of an anti–depressant medication at any time prior to enrolment in the present study, of the remaining 176 patients, 41 (23.3%) had moderate or severe symptoms of depression as assessed by Beck's Depression Inventory–II. The only significant clinical difference between the 41 patients with pronounced depressive symptoms and the 135 less affected was shorter disease duration in the former.

In this study one in four patients with MS had unrecognised and therefore untreated symptoms of depression. Disability alone is not a good indicator of the likelihood of coexistent depressive symptoms.