Platelet 3H-imipramine binding distinguishes depression from Alzheimer dementia.

Platelet 3H-imipramine binding and serotonin uptake were studied simultaneously in normal subjects and in depressed, parkinsonian and Alzheimer's disease patients to investigate the usefulness of these variables in the diagnosis of depression in the elderly. Whereas Vmax of platelet serotonin uptake was significantly reduced in all patient groups compared to age matched normal subjects, the density of 3H-imipramine binding was reduced in depressed patients only. The lower Bmax values in depressed patients was independent of patient age. These data suggest that platelet 3H-imipramine binding may be a useful laboratory index which discriminates depression from dementia in the elderly.