Different MRI findings for normal elderly and very mild Alzheimer's disease in a community: implications for clinical practice the Tajiri Project.

To investigate magnetic resonance imaging (MRI) findings of very mild dementia, 485 participants were randomly selected in a community. Three hundred and forty participants were of Clinical Dementia Rating (CDR) 0 (healthy), 113 were of CDR 0.5 (questionable dementia), and 32 were of CDR 1 and 2 (including 20 Alzheimer's disease, AD). Cortical atrophy, white matter lesion, etc., were visually assessed. We found that each part of the brain showed atrophy in older adults for CDR 0. For CDR 0.5, the relationships between MRI findings and age were weaker, and for AD, there were no such relationship. Atrophy related with dementia severity was found to be limited to the lateral and medial temporal lobes. For CDR 0.5, amygdala atrophy was the only finding indicating CDR effect but no age effect. The amygdala or anterior entorhinal atrophy is important for discriminating very mild dementia from normal elderly.