Dopamine and depression - Striatal dopamine D-2 receptor SPECT before and after antidepressant therapy

Ten unmedicated and ten medicated patients with major depression and ten controls were investigated with IBZM-SPECT. The ten unmedicated patients were reinvestigated after treatment with tricyclic antidepressants. Dopamine D-2 receptor occupancy was not different between patients and controls, or medicated and unmedicated patients. IBZM binding was increased in four patients with psychomotor retardation, Antidepressant therapy led to a decrease in IBZM binding in the five improved patients. Dopamine D-2 receptor binding remained unchanged in nonresponders. It is concluded that striatal dopamine D-2 receptor binding is not changed in depression or by tricyclic antidepressants; however, it is affected by psychomotor activity. The changes observed might be the result of increased tonic dopamine release in the basal ganglia, but several other explanations exist.