People who are overweight or obese at the time of a dementia diagnosis tend to live longer than those whose weight falls in the normal range, according to research from the Columbia University Mailman School of Public Health and the NYU School of Global Public Health, published in the Journal of Alzheimer's Disease. The researchers suggest that body weight recorded around the time of diagnosis may carry useful prognostic information about how long someone is likely to survive.
The result sits awkwardly alongside what is already known about obesity. Carrying excess weight raises the risk of heart disease and diabetes, and people who are overweight or obese in midlife are more likely to develop dementia later on. Yet once dementia is diagnosed, several studies have pointed in the opposite direction, linking higher weight to better survival.
That reversal naturally invites suspicion that the pattern is a statistical mirage rather than a real effect. The team tested that possibility directly. "Our analyses suggest that the major sources of bias we examined do not explain the survival advantage associated with higher weight," said Yuan Zhang, PhD, the corresponding author and an assistant professor of sociomedical sciences at Columbia Mailman and the Butler Columbia Aging Center.
For families and clinicians, the practical implication the authors draw is about nutrition. Weight loss and poor intake are common in dementia, and the findings argue for paying closer attention to what people with the condition are eating rather than treating body weight as an afterthought once a diagnosis is made.