Alzheimer's Disease Research Today is a free monthly online journal that collates and summarizes the latest research about Alzheimer's Disease, including details on diagnosis, memory loss, heredity, treatment, medication.

Does Alzheimer's disease affect hippocampal asymmetry? Evidence from a cross-sectional and longitudinal volumetric MRI study.

Barnes J, Scahill RI, Schott JM, Frost C, Rossor MN, Fox NC

Dementia Research Centre, Department of Clinical Neurology, Institute of Neurology, University College London, London, UK. j.barnes@dementia.ion.ucl.ac.uk

OBJECTIVE: To determine whether Alzheimer's disease (AD) is associated with preferential atrophy of either the left or right hippocampus. METHODS: We examined right-left asymmetry in hippocampal volume and atrophy rates in 32 subjects with probable AD and 50 age-matched controls. Hippocampi were measured on two serial volumetric MRI scans using a technique that minimizes laterality bias. RESULTS: We found a non-significant trend for right > left (R > L) asymmetry in controls at both time points (R > L: 1.7%; CI: -0.3-3.7%; p = 0.1). AD subjects showed a similar non-significant trend for R > L asymmetry at baseline (R > L: 1.8%; CI: -1.9-5.5%; p = 0.32), but not at repeat (p = 0.739). Change in R/L ratio between visits in AD patients was significant (p = 0.02). The AD group had significantly higher variance in these ratios than the controls at baseline (p = 0.02), but not repeat (p = 0.06). AD patients had higher atrophy rates than controls (p < 0.001). Mean (CI) annualized atrophy rates for left and right hippocampi were 1.2% (0.5-1.8%) and 1.1% (0.5-1.8%) for the controls, and 4.6% (3.3-6.0%) and 6.3% (4.9-7.8%) for AD subjects. There was no significant asymmetry in atrophy rates in controls (p = 0.9), but borderline significantly higher atrophy rates in the right hippocampus of the AD group (p = 0.05) compared to the left. Presence of an APOEepsilon4 allele had no significant effect on the size, asymmetry or atrophy rates in AD (p > 0.20). CONCLUSIONS: We report minor R > L asymmetry in hippocampal volumes in controls and present some evidence to suggest that there is a change in the natural R > L asymmetry during the progression of AD.

Published 2 May 2005 in Dement Geriatr Cogn Disord, 19(5): 338-44.
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