CHANGES IN PLATELET MONOAMINE-OXIDASE AND PLASMA DOPAMINE-BETA-HYDROXYLASE ACTIVITIES IN LITHIUM-TREATED BIPOLAR PATIENTS

The activity of monoamine oxidase (MAO) and dopamine-beta-hydroxylase (DBH), enzymes involved in monoamine metabolism, were studied in 29 bi polar patients (mean age = 33.12 years, SD = 7.27) who were treated wi th lithium carbonate and in 20 healthy volunteers (mean age = 30.05 ye ars, SD = 6.04). Platelet MAO activity was higher after lithium withdr awal, whereas plasma DBH activity was lower in remitted euthymic bipol ar patients compared with normal volunteers. During lithium treatment, platelet MAO activity decreased and plasma DBH activity increased com pared with the lithium-withdrawal values. It was also observed that th e activities of these enzymes in the bipolar patients during lithium t reatment did not differ from those in the volunteers. Thus, platelet M AO and plasma DBH activities differed in unmedicated patients with bip olar affective disorder from those of healthy subjects. Treatment with lithium appeared to have a normalizing effect on MAO and DBH activity levels.