β-amyloid burden predicts prospective decline in body mass index in clinically normal adults

Abstract In the present study, we tested the hypothesis that higher β-amyloid (Aβ) burden at baseline is associated with greater longitudinal decline in body mass index (BMI) in clinically normal older adults. Participants from the Harvard Aging Brain Study (HABS; n=312) and the Alzheimer’s Disease Neuroimaging Initiative (ADNI; n=336) underwent Aβ positron emission tomography at baseline. BMI was assessed longitudinally over a median of >4 years. Linear mixed models showed that higher baseline Aβ burden was significantly associated with greater decline in BMI in both HABS (t=-1.93; p=0.05) and ADNI cohorts (t=-2.54; p=0.01), after adjusting for covariates, including cognition and depressive symptoms. In addition, the association of Aβ burden with longitudinal decline in BMI persisted after excluding participants with diabetes/endocrine disturbances and participants classified as underweight or obese (BMI 30). These findings suggest that decline in BMI in clinically normal adults may be an early manifestation related to cerebral amyloidosis that precedes objective cognitive impairment. Therefore, unintentional BMI decline in otherwise healthy individuals might alert clinicians to increased risk of AD.