Dopaminergic function in depressed patients with affective flattening or with impulsivity: [18F]fluoro-L-dopa positron emission tomography study with voxel-based analysis.

A decreased striatal presynaptic dopaminergic function has been reported in depressed patients with affective flattening and psychomotor retardation, using (18)F-fluorodopa positron emission tomography and regions-of-interest. The present study aimed to investigate regional ;[(18)F]dopa uptake in mesolimbic and mesocortical dopaminergic projections with the hypothesis that there should be a decrease in mesolimbic [(18)F]dopa uptake associated with affective flattening and psychomotor retardation. [(18)F]Dopa-positron emission tomography and anatomical magnetic resonance imaging datasets from 12 screened depressed patients with either marked affective flattening and psychomotor retardation (n=6) or with marked impulsivity (n=6), and from eight healthy subjects, were analyzed using a voxel-based approach. Regional differences in [(18)F]dopa uptake rate constant (K(i)) values between the healthy group and the two depression subgroups were compared using both statistical parametric mapping and cluster-based regions-of-interest. Patients with affective flattening and psychomotor retardation had [(18)F]dopa K(i) decreases in the left caudate, bilateral putamen and nucleus accumbens, left parahippocampus and dorsal brainstem. Impulsive depressives had [(18)F]dopa K(i) decreases in the anterior cingulate and hypothalamus, and an increase in the right parahippocampal gyrus. These findings support distinct regional dysfunctions of monoamines depending on the depressive symptomatology.