A SPECT STUDY OF DEPRESSION IN ALZHEIMERS-DISEASE

While dysthymia and major depression are frequent findings among patie nts with Alzheimer's disease (AD) the mechanism of these affective dis orders in AD is not well known. We examined the presence of significan t regional cerebral blood flow (rCBF) correlates of dysthymia and majo r depression in a consecutive series of patients with AD. Ten AD patie nts with major depression, 18 AD patients with dysthymia, 21 AD patien ts with no depression, and 10 normal controls were studied with 99m-Tc HMPAO-single photon emission tomography (SPECT). AD patients with majo r depression showed a significantly lower rCBF in the left temporal su perior and parietal regions as compared to nondepressed AD patients. A D patients with major depression had a significantly lower rCBF over t he left hemisphere (mainly involving the frontal dorsal, temporal, and parietal cortices), and the right temporal cortex and basal ganglia a s compared to AD patients with dysthymia. On the other hand, no signif icant rCBF differences were found between AD patients with dysthymia a nd no depression. While major depression in AD may result from metabol ic deficits in specific brain regions, dysthymia may have a different mechanism.