THE DIFFERENTIATION OF DEPRESSION FROM DEMENTIA BY TEMPORAL-LOBE MAGNETIC-RESONANCE-IMAGING

Temporal lobe Magnetic Resonance Imaging (MRI) was performed in 43 pat ients with NINCDS/ADRDA Alzheimer's disease (AD) (33 probable, 7 possi ble, 3 definite) and 32 subjects with DSM-III-R Major Depression (DEP) matched for age, sex and level of education. Hippocampus (anterior an d posterior, right and left), amygdala, entorhinal cortex, parahippoca mpal gyrus and cerebral cortex were rated for atrophy on a 4-point sca le. Good discrimination between groups could be achieved using a cut-o ff of 2 or more on anterior hippocampal atrophy rating (sensitivity 93 %; specificity 84%; 89% cases correctly grouped overall). Even among a subgroup of 9 mild AD subjects and 10 cognitively impaired DEP subjec ts (matched on mini-mental state score), the same cut-off correctly gr ouped 84% (16/19) cases. Hippocampal atrophy increased with age in bot h AD and DEP subjects leading to a reduction in specificity (but not s ensitivity) for those aged over 75. Within the AD group a significant correlation was observed between length of history and atrophy of the entorhinal cortex (r = 0.39, P = 0.009). We conclude that temporal lob e atrophy on MRI can provide good discrimination between AD and DEP su bjects, including those DEP patients with cognitive impairment apparen t on screening tests of cognitive function.