Family history of Alzheimer disease predicts hippocampal atrophy in healthy middle-aged adults


Okonkwo OC, Xu G, Dowling NM, Bendlin BB, LaRue A, Hermann BP, Koscik R, Jonaitis EM, Rowley HA, Carlsson CM, Asthana S, Sager MA, Johnson SC

Neurology, 2012 May 29;78(22):1769-76

Abstract

Objective: To evaluate the longitudinal influence of family history (FH) of Alzheimer disease (AD) and apolipoprotein E4 (APOE4) on brain atrophy and cognitive decline over 4 years among asymptomatic middle-aged individuals. Methods: Participants were cognitively-healthy adults with (FH+,n=60) and without (FH-,n=48) FH of AD (mean age at baseline=54 years) enrolled in the Wisconsin Registry for Alzheimer's Prevention. They underwent genotyping, cognitive testing, and an MRI scan at baseline and 4 years later. A covariate-adjusted voxel-based analysis interrogated gray matter (GM) modulated probability maps at the 4-year follow-up visit as a function of FH and APOE4. We also examined the influence of “parent of origin” on GM atrophy. Parallel analyses investigated the effects of FH and APOE4 on cognitive decline. Results: Neither FH nor APOE4 had an effect on regional GM or cognition at baseline. Longitudinally, a FH*APOE4 interaction was found in the right posterior hippocampus, which was driven by a significant difference between the FH+ and FH- subjects who were APOE4 negative. Additionally, a significant FH main effect was observed in the left posterior hippocampus. No significant APOE4 main effects were detected. Persons with maternal history of AD were just as likely as those with paternal history of AD to experience posterior hippocampal atrophy. There was no longitudinal decline in cognition within the cohort. Conclusion: Over a 4-year interval, asymptomatic middle-aged adults with FH of AD exhibit significant atrophy in the posterior hippocampi, in the absence of measurable cognitive changes. This provides further evidence that detectable disease-related neuroanatomic changes do occur early in the AD pathological cascade.

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