Multiple sclerosis presenting as major depression: a diagnosis suggested by MRI scan but not CT scan.

A 43-year-old woman had melancholic major depression and mild incoordination. A magnetic resonance imaging (MRI) scan showed extensive lesions of the cerebral white matter that were not detected on a computed tomography (CT) scan. Since multiple sclerosis may initially present as depression, the differential sensitivities of MRI and CT scanning should be considered in deciding which neurodiagnostic studies should be conducted in depressed patients.