Multimodal characterization of older APOE2 carriers reveals selective reduction of amyloid load.

TitleMultimodal characterization of older APOE2 carriers reveals selective reduction of amyloid load.
Publication TypeJournal Article
Year of Publication2017
AuthorsGrothe MJ, Villeneuve S, Dyrba M, Bartrés-Faz D, Wirth M
Corporate AuthorsAlzheimer's Disease Neuroimaging Initiative
Date Published2017 Feb 07
KeywordsAged, Aging, Amyloid, Apolipoprotein E2, Apolipoprotein E3, Biomarkers, Brain, Cognitive Dysfunction, Female, Fluorodeoxyglucose F18, Glucose, Gray Matter, Heterozygote, Humans, Magnetic Resonance Imaging, Male, Multimodal Imaging, Neuroimaging, Organ Size, Positron-Emission Tomography, Radiopharmaceuticals

OBJECTIVE: To comprehensively assess neurobiological effects of the protective APOE2 allele in the aged brain using a cross-sectional multimodal neuroimaging approach.METHODS: Multimodal neuroimaging data were obtained from a total of 572 older individuals without dementia (cognitively normal and mild cognitive impairment) enrolled in the Alzheimer's Disease Neuroimaging Initiative and included assessments of regional amyloid load with AV45-PET, glucose metabolism with fluorodeoxyglucose-PET, and gray matter volume with structural MRI. Imaging indexes of APOE2 carriers were contrasted to risk-neutral APOE3 homozygotes, and analyses were controlled for age, sex, education, and clinical diagnosis. Additional models examined genotype-specific effects of age on the imaging markers.RESULTS: In region-of-interest-based analyses, APOE2 carriers had significantly less precuneal amyloid pathology and did not show the typical age-related increase in amyloid load, although the age × genotype interaction was only trend-level significant. In contrast, parietal metabolism and hippocampal volume did not differ between APOE2 and APOE3 genotypes, and both groups showed comparable negative effects of age on these markers. The amyloid specificity of APOE2-related brain changes was corroborated in 2 complementary analyses: spatially unbiased voxel-wise analyses showing widespread reductions in amyloid deposition but no differences in gray matter volume or metabolism and an analysis of CSF-based biomarkers showing a significant effect on amyloid but not on tau pathology.CONCLUSIONS: Regarding the range of Alzheimer disease biomarkers considered in the present study, the APOE2 allele appears to have a relatively selective effect on reduced accumulation of amyloid pathology in the aged brain.

Alternate JournalNeurology
PubMed ID28062720
PubMed Central IDPMC5304459
Grant ListP50 AG005142 / AG / NIA NIH HHS / United States
U24 AG021886 / AG / NIA NIH HHS / United States