Background: Psychotic depression has been proposed as a distinct subtype of major depression. There is considerable evidence for this in younger patients, although the neuroimaging has been rudimentary. Volumetric imaging studies are required of consecutive cohorts of patients with depression.
Methods: Ninety-nine consecutive elderly patients were diagnosed with DSM-III-R major depression. Eighteen were psychotic, and 81 were not. Sixty-six patients were given a neuropsychological test battery, and 44 had a magnetic resonance imaging brain scan. A model integrating clinical, psychological, and neuroimaging findings for the explanation of delusion formation during depression is proposed.
Results: Psychotic depression was characterized by worse physical health, more family history of depression, a poorer response to antidepressant drugs, and more severe lowering of mood; however, the strongest predictors of the presence of delusions were diencephalic atrophy, reticular activating system lesions, brain stem atrophy, and left-sided frontotemporal atrophy. The psychotic patients had poorer performance on tests of frontal lobe function and mental processing speed.
Conclusions: In the elderly, psychotic depression is etiologically, clinically, and neuroradiologically distinct, and has different treatment requirements, from nonpsychotic major depression.