The differentiation of depression from dementia by temporal lobe magnetic resonance imaging

Abstract

SynopsisTemporal lobe Magnetic Resonance Imaging (MRI) was performed in 43 patients with NINCDS/ADRDA Alzheimer's disease (AD) (33 probable, 7 possible, 3 definite) and 32 subjects with DSM-III-R Major Depression (DEP) matched for age, sex and level of education. Hippocampus (anterior and posterior, right and left), amygdala, entorhinal cortex, para-hippocampal gyrus and cerebral cortex were rated for atrophy on a 4-point scale. Good discrimination between groups could be achieved using a cut-off 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 subjects (matched on mini-mental state score), the same cut-off correctly grouped 84% (16/19) cases. Hippocampal atrophy increased with age in both AD and DEP subjects leading to a reduction in specificity (but not sensitivity) 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 lobe atrophy on MRI can provide good discrimination between AD and DEP subjects, including those DEP patients with cognitive impairment apparent on screening tests of cognitive function.