Five-decade trajectories in body mass index in relation to dementia death: follow-up of 33,083 male Harvard University alumni.

In a population likely to be free of dementia neuropathology at BMI measurement, we found no association between BMI at baseline and subsequent dementia-related death. Earlier decline in BMI was, however, associated with dementia, which suggests that findings associating BMI with dementia risk may be influenced by reverse causality.