Regional cerebral blood flow changes following chronic administration of antidepressant drugs.

1. Twenty-six patients with major unipolar depression were rated clinically and regional cerebral blood flow (rCBF) determined prior to and after six months of treatment with 75-100 mg/day amitriptyline (n. 16) or 200 mg/day amineptine (n. 10). 2. rCBF was measured in 16 regions over each hemisphere by the Xenon 133 inhalation method and was computed as the initial slope index (ISI). The severity of depression was quantified by the Hamilton rating scale for depression. 3. Baseline rCBF values of depressed patients tended to be lower than those of normal subjects. Significant reductions were observed for all probes exploring the frontal region of the left hemisphere and for some probes exploring the frontal region of the right hemisphere. Chronic treatment with amitriptyline induced a significant increase in rCBF in the left frontal region. Similar results were obtained after treatment with amineptine. 4. Besides confirming frontal lobe dysfunction in depressed patients which is reversed by treatment with classic tricyclic antidepressants, the present results show that this dysfunction may also be reversed by treatment with dopaminergic drugs.