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 18F-fluorodopa positron emission tomography and regions-of-interest. The present study aimed to investigate regional `[18F]dopa uptake in mesolimbic and mesocortical dopaminergic projections with the hypothesis that there should be a decrease in mesolimbic [18F]dopa uptake associated with affective flattening and psychomotor retardation. [18F]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 [18F]dopa uptake rate constant (Ki) 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 [18F]dopa Ki decreases in the left caudate, bilateral putamen and nucleus accumbens, left parahippocampus and dorsal brainstem. Impulsive depressives had [18F]dopa Ki 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.