Can hippocampal subfield measures supply information that could be used to improve the diagnosis of Alzheimer's disease?

The diagnosis of Alzheimer's disease (AD) needs to be improved. We investigated if hippocampal subfield volume measured by structural imaging, could supply information, so that the diagnosis of AD could be improved. In this study, subjects were classified based on clinical, neuropsychological, and amyloid positivity or negativity using PET scans. Data from 478 elderly Korean subjects grouped as cognitively unimpaired beta-amyloid-negative (NC), cognitively unimpaired beta-amyloid-positive (aAD), mild cognitively impaired beta-amyloid-positive (pAD), mild cognitively impaired-specific variations not due to dementia beta-amyloid-negative (CIND), severe cognitive impairment beta-amyloid-positive (ADD+) and severe cognitive impairment beta-amyloid-negative (ADD-) were used. NC and aAD groups did not show significant volume differences in any subfields. The CIND did not show significant volume differences when compared with either the NC or the aAD (except L-HATA). However, pAD showed significant volume differences in Sub, PrS, ML, Tail, GCMLDG, CA1, CA4, HATA, and CA3 when compared with the NC and aAD. The pAD group also showed significant differences in the hippocampal tail, CA1, CA4, molecular layer, granule cells/molecular layer/dentate gyrus, and CA3 when compared with the CIND group. The ADD- group had significantly larger volumes than the ADD+ group in the bilateral tail, SUB, PrS, and left ML. The results suggest that early amyloid depositions in cognitive normal stages are not accompanied by significant bilateral subfield volume atrophy. There might be intense and accelerated subfield volume atrophy in the later stages associated with the cognitive impairment in the pAD stage, which subsequently could drive the progression to AD dementia. Early subfield volume atrophy associated with the beta-amyloid burden may be characterized by more symmetrical atrophy in CA regions than in other subfields. We conclude that the hippocampal subfield volumetric differences from structural imaging show promise for improving the diagnosis of Alzheimer's disease.

Automated summary

This study investigated the relationship between hippocampal subfield volume measured by structural imaging and the diagnosis of Alzheimer's disease (AD). The results suggest that early amyloid depositions in cognitive normal stages do not result in significant bilateral subfield volume atrophy, while intense and accelerated subfield volume atrophy may be associated with cognitive impairment in the later stages of AD. The volumetric differences in hippocampal subfields, particularly in the CA regions, show promise for improving the diagnosis of AD.