Comparing hippocampal atrophy in Alzheimer's dementia and dementia with lewy bodies.

BACKGROUND/AIMS: Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) are the two most common neurodegenerative dementias. During the early stages, clinical distinction between them is often challenging. Our objective is to compare hippocampal atrophy patterns in mild AD and mild DLB. We hypothesized that DLB subjects have milder hippocampal atrophy relative to AD subjects.

METHODS

We analyzed the T1-weighted magnetic resonance imaging data from 113 subjects: 55 AD, 16 DLB and 42 cognitively normal elderly (normal controls, NC). Using the hippocampal radial distance technique and multiple linear regression, we analyzed the effect of clinical diagnosis on hippocampal radial distance, while adjusting for gender and age. Three-dimensional statistical maps were adjusted for multiple comparisons using permutation-based statistics with a threshold of p < 0.01.

RESULTS

Compared to NC, AD exhibited significantly greater atrophy in the cornu ammonis (CA)1, CA2-3 and subicular regions bilaterally while DLB showed left-predominant atrophy in the CA1 region and subiculum. Compared directly, AD and DLB did not reveal statistically significant differences.

CONCLUSION

Hippocampal atrophy, while present in mildly impaired DLB subjects, is less severe than atrophy seen in mildly impaired AD subjects, when compared to NC. Both groups show predominant atrophy of the CA1 subfield and subiculum.