Decreased presynaptic dopamine function in the left caudate of depressed patients with affective flattening and psychomotor retardation.

The study assessed striatal presynaptic dopamine function in patients with different subtypes of depression. Magnetic resonance imaging and positron emission tomography with [(18)F]fluorodopa ([(18)F]DOPA) were used to compare six depressed patients with marked affective flattening and psychomotor retardation, six depressed patients with marked impulsivity and anxiety, and 10 healthy comparison subjects. Depressed patient groups were matched for severity of depression. [(18)F]DOPA uptake K(i) values in the left caudate were significantly lower in patients with psychomotor retardation than in patients with high impulsivity and in comparison subjects. These results suggest that left caudate dopamine function differs between depressed patients with psychomotor retardation and those with impulsivity and provide direct evidence of a link between dopamine hypofunction and psychomotor retardation in depression.