Brain volumes discriminate clinical dementia rating scale categories

Brain atrophy is well documented in various kinds of dementia, particularly in Alzheimer's disease. Here, we evaluated gray matter volume of 87 cortical and subcortical areas in 460 individuals characterized according to the Clinical Dementia Rating (CDR) as cognitively unimpaired (n = 352), undetermined (n = 72), or mild dementia (n = 36). We found a highly significant correspondence between increased dementia severity and reduced brain volume, particularly for the amygdala and temporal cortical areas, including the hippocampus, middle temporal gyrus, and inferior temporal gyrus. The negative correlation between brain volumes and dementia severity was significantly stronger in men than women, and in apolipoprotein E4 carriers than non-carriers. Brain volumes discriminated between cognitively unimpaired and mild dementia cases with high accuracy; application of those classification functions to the undetermined group resulted in two distinct groups, one resembling the cognitively unimpaired Control group and another resembling the Dementia group. These findings highlight the correspondence between clinical dementia stages and objective brain volume measures, and point to the potential clinical utility of adjunctive structural brain measures to identify individuals with memory complaints who may be at risk of dementia.