Relationship of cognitive impairment to psychiatric symptoms in multiple sclerosis.

Psychiatric and cognitive changes are common in patients with multiple sclerosis (MS), but their relationship has not received much attention. We studied the relationship between psychiatric symptoms and verbal memory, working memory, and mental speed in 78 patients with MS and 40 healthy control subjects using linear regression analyses. The MS group exhibited impaired performance on all cognitive tests. Apathy was associated with intrusions and depression with impaired memory and mental speed. The association between apathy and intrusions supports the hypothesis that lesions in frontal areas or frontal connections contribute to a specific neuropsychiatric syndrome in patients with MS.