Association of neuropathological lesions with body mass index by the time of death

Abstract

AbstractBackgroundThe association between moderate/severe dementia and lower Body Mass Index (BMI) is well described, but the weight decline seems to also occur in cognitively normal individuals with preclinical dementia. Considering that up to one‐fifth of individuals with normal cognition might meet the criteria for a neuropathological diagnosis, autopsy studies are key detecting neurodegenerative and cerebrovascular diseases that could be underlining weight changes during the life course. Therefore, we investigated the association between dementia‐related brain lesions and BMI and evaluated whether cognitive function was a mediator of this association.MethodNeuropathological study in a population‐based sample of 1,170 Brazilians. Clinical variables and cognition evaluation were obtained through a post mortem interview with a proxy. Linear regression adjusted models were used to investigate the association between each neuropathologic lesion (independent variable) and the BMI (dependent variable). The direct and indirect (considering a mediation by cognitive abilities) effects of each neuropathologic lesion on BMI were evaluated through a mediation model.ResultIndividuals with lower body weight were more likely to have a higher burden of neuropathological lesions and worse cognitive abilities. Neurofibrillary tangles (NFT) and neuropathological comorbidity were associated with low BMI. Mediation analyses showed these lesions were directly associated with BMI and indirectly through cognitive abilities. Despite having normal cognitive abilities, 25% of the sample had at least one neuropathologic diagnosis. High NFT burden was associated with lower BMI even in these participants.ConclusionNeurofibrillary tangles were associated with lower BMI independent of cognitive abilities.