A VOXEL-BASED ANALYSIS OF CEREBRAL PERFUSION IN DEMENTIA AND DEPRESSION OF OLD-AGE

Thirty-nine elderly depressed patients as well as 15 demented patients with Alzheimer's disease and 11 healthy volunteers were imaged at res t with a high resolution single-slice 12-detector head scanner (SME-Ne uro 900) and the cerebral perfusion marker Tc-99m-Exametazime (HM-PAO) . Statistical parametric maps were computed to compare early-and late- onset depressed, Alzheimer patients and healthy volunteers and to exam ine associations between regional perfusion and clinical and MRI varia bles. Patients with late-onset depression showed reductions in tempora l lobe perfusion compared with early-onset depression and controls. Al zheimer patients had the expected reduced perfusion in temporoparietal and prefontal cortex, as well as basal ganglia, compared with healthy controls. Compared with depressed patients, they showed a relative re duction in temporoparietal cortex, only. This difference was more pron ounced between Alzheimer patients and early onset, compared to late-on set patients with depression. Periventricular white matter changes on MRI were associated with temporal lobe reductions of tracer uptake in depression. In the Alzheimer group, deep white matter MRI changes were associated with frontal perfusion deficits. Our results support a vul nerability hypothesis, which predicts that patients with late-onset de pression will. show more brain changes than patients with an early ons et of their illness. Statistical parametric mapping in patients with o rganic psychiatric brain syndromes is feasible and promising as a clin ical and research method. (C) 1998 Academic Press.