Affiliations: [a] Division of Geriatrics – Laboratório de Investigação Médica no Envelhecimento (LIM 66), University of São Paulo Medical School, São Paulo, Brazil
| [b]
Escola Politécnica of the University of São Paulo, São Paulo, Brazil
| [c]
Department of Pathology, University of São Paulo Medical School, São Paulo, Brazil
| [d]
Memory and Aging Center, University of California San Francisco, San Francisco, CA, USA
| [e] Division of Geriatrics – Laboratório de Patologia Cardiovascular (LIM 22), University of São Paulo Medical School, São Paulo, Brazil
Correspondence:
[*]
Correspondence to: Raul dos Reis Ururahy, MD, Division of Geriatrics, University of São Paulo Medical School, Dr. Enéas Carvalho de Aguiar Ave. 255, CEP 05403-000, São Paulo, SP, Brazil. E-mail: rreisururahy@gmail.com.
Abstract: Background:The association of moderate and severe dementia with low body mass index (BMI) is well described, but weight decline seems to also occur in individuals with preclinical neuropathologies. Considering that up to one-fifth of individuals with normal cognition meet the criteria for a dementia-related neuropathological diagnosis, autopsy studies are key to detecting preclinical neurodegenerative and cerebrovascular diseases that could be underlying weight changes. Objective:We investigated the association between dementia-related brain lesions and BMI and evaluated whether the cognitive function was a mediator of this association. Methods:In 1,170 participants, sociodemographic data, clinical history, and cognitive post-mortem evaluation were assessed with an informant. Neuropathological evaluation was performed in all cases. Linear regression models were used to investigate the association between neuropathological lesions (exposure variable) and BMI (outcome) adjusted for demographic, clinical, and cognitive variables in the whole sample, and in only those with normal cognition. Corrections for multiple comparisons were performed. In addition, a mediation analysis was performed to investigate the direct and indirect effects of cognitive abilities on the association between neuropathology and BMI. Results:Individuals with lower BMI had a higher burden of neuropathological lesions and poorer cognitive abilities. Only neurofibrillary tangles (NFT) and neuropathological comorbidity were associated with low BMI, while other neurodegenerative and cerebrovascular lesions were not. NFT were indirectly associated with BMI through cognitive abilities, and also directly, even in participants with normal cognition. Conclusions:Neurofibrillary tangles were directly associated with low BMI even in individuals with preclinical Alzheimer’s disease.
Keywords: Alzheimer’s disease, autopsy, body mass index, dementia, mediation, neuropathology
