HIGHER WEIGHT AT DEMENTIA DIAGNOSIS LINKED TO LOWER DEATH RISK

A study published in the Journal of Alzheimer's Disease has found that people who are overweight or obese at the time they are diagnosed with dementia face a significantly lower risk of death than those diagnosed at a normal weight. Researchers analysed data from 4,523 participants in the Health and Retirement Study, a nationally representative study of American adults aged 51 and over run by the University of Michigan. All of those studied were free of dementia when they joined the research but went on to develop the condition later, with data collected between 1998 and 2022 allowing the team to track weight changes before diagnosis and survival afterwards. The researchers said the lower mortality risk among heavier participants held even after accounting for other health conditions and lifestyle factors.

The survival differences varied according to weight category, the study found. People classed as overweight, with a body mass index of 25 to 29.9, had a 16% lower risk of death than those of normal weight, according to the researchers. Those with class 1 obesity, a BMI of 30 to 34.9, had a 27% lower risk, while people with class 2 or 3 obesity, a BMI of 35 or above, had a 22% lower risk. The researchers noted that these findings contrast with existing evidence that obesity in midlife increases the likelihood of later developing dementia.

The researchers said they could not determine why higher weight at diagnosis was associated with better survival, but their analysis suggested the link could not easily be explained by common sources of statistical bias. One complication they highlighted is that weight loss often begins long before dementia is formally diagnosed. Earlier research by Virginia Chang and Yuan Zhang found that such weight loss can begin up to a decade before diagnosis and accelerate in the years immediately before it.