Higher Body Mass Index Is Associated with Lower Cortical Amyloid-β Burden in Cognitively Normal Individuals in Late-Life - PubMed (original) (raw)

Higher Body Mass Index Is Associated with Lower Cortical Amyloid-β Burden in Cognitively Normal Individuals in Late-Life

Vineeth Thirunavu et al. J Alzheimers Dis. 2019.

Abstract

Background: Both low and high body mass index (BMI) have been associated with an increased risk of dementia, including that caused by Alzheimer's disease (AD). Specifically, high middle-age BMI or a low late-age BMI has been considered a predictor for the development of AD dementia. Less studied is the relationship between BMI and AD pathology.

Objective: We explored the association between BMI and cortical amyloid-β (Aβ) burden in cognitively normal participants that were either in mid-life (45-60 years) or late-life (>60).

Methods: We analyzed cross-sectional baseline data from the Knight Alzheimer Disease Research Center (ADRC) at Washington University. Aβ pathology was measured in 373 individuals with Aβ PET imaging and was quantified using Centiloid units. We split the cohort into mid- and late-life groups for analyses (n = 96 and n = 277, respectively). We ran general linear regression models to predict Aβ levels from BMI while controlling for age, sex, years of education, and APOE4 status. Analyses were also conducted to test the interaction between BMI and APOE4 genotype and between BMI and sex.

Results: Higher BMI was associated with lower cortical Aβ burden in late-life (β= -0.81, p = 0.0066), but no relationship was found in mid-life (β= 0.04, p > 0.5). The BMI×APOE4+ and BMI×male interaction terms were not significant in the mid-life (β= 0.28, p = 0.41; β= 0.64, p = 0.13) or the late-life (β= 0.17, p > 0.5; β= 0.50, p = 0.43) groups.

Conclusion: Higher late-life BMI is associated with lower cortical Aβ burden in cognitively normal individuals.

Keywords: Alzheimer disease; amyloid-β; apolipoproteins E; body mass index; obesity; positron emission tomography.

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Figures

Fig. 1.

Scatter plot of BMI and cortical Aβ burden by age group. The scatter plot reflects raw values for ease of interpretation. Late-life participants are dark circles, and mid-life participants are grey triangles. Lines of best fit are also shown.

Fig. 2.

Partial regression plot from primary analysis of BMI and cortical Aβ burden (as measured in Centiloid units) in mid- and late-life individuals. The model was adjusted for age, sex, years of education, and APOE4 carrier status. Standardized residuals for Centiloid units were calculated after regressing cortical Aβ burden against all the independent variables except BMI while standardized residuals for BMI were calculated after regressing BMI against the remaining independent variables. BMI was significant in the late-life model but not the mid-life model. These results remained the same even after exclusion of the four individuals with highest BMI.

Fig. 3.

Boxplots of the distributions of cortical Aβ burden in each of the three BMI groups in late-life (A) and mid-life (B) individuals. Pairwise comparisons are denoted as N.S. p > 0.05 and ***p < 0.001.

Fig. 4.

Scatterplot of BMI and cortical Aβ burden within APOE4 subdivisions in mid-life (A) and late-life (B). The scatter plots reflect raw values for ease of interpretation. E4 non-carriers are black circles, and E4 carriers are grey triangles. Lines of best fit are also shown. The BMI × APOE4 interaction term was not significant in the mid-life (β = 0.33, p = 0.296) or the late-life (β = 0.29, p > 0.5) groups.

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Higher Body Mass Index Is Associated with Lower Cortical Amyloid-β Burden in Cognitively Normal Individuals in Late-Life - PubMed (original) (raw)