Researchers at Massachusetts General Hospital and the National University of Singapore evaluated data from 378 participants in the Alzheimer's Disease Neuroimaging Initiative (ADNI). Of this group, 188 individuals had been diagnosed with Alzheimer's disease, 147 had mild cognitive impairment, and 43 were cognitively normal (PNAS, October 4, 2016).
Thomas Yeo, PhD, and colleagues then used a mathematical model that estimated the probability that each MR image was associated with atrophy in a specific location within the brain. They found three atrophy factor patterns:
- Cortical, which represented atrophy in most of the cerebral cortex
- Temporal, which indicated atrophy in the temporal cortex, hippocampus, and amygdala
- Subcortical, which indicated atrophy in the cerebellum, striatum, and thalamus, all structures at the base of the brain
Individuals with predominant temporal atrophy had greater problems with memory, while cortical atrophy was associated with difficulties in executive function.
Additional study is needed to determine if and how the atrophy patterns may relate to the distribution of amyloid and tau and the mechanisms by which they affect specific cognitive abilities, according to Yeo.
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