Platelet monoamine oxidase and plasma dopamine-beta-hydroxylase activities in patients with multiple sclerosis.

Platelet monoamine oxidase (MAO) and plasma dopamine-beta-hydroxylase (DBH) activities were determined in a large group of multiple sclerose patients in relapse (49 patients) and in remission (28 patients), and compared with an age- and sex-matched control group (52 normal subjects). The activities of both enzymes did not differ from normal in both patient groups. Women had higher MAO activities both in normal and in patient groups. Multiple linear regression analysis revealed an association of low platelet MAO to the score in the mental subscale in the Kurtzke Disability Status Scale. Both male and female patients with mental symptomatology had significantly (p = 0.02) lower platelet MAO activities compared to the patients without. The possibility of a relationship between MAO activity and psychiatric vulnerability in MS is considered.