Why Do Obese People With Alzheimer’s Live Longer?

In a perplexing medical phenomenon, obese Alzheimer’s patients have been found to live longer than their normal-weight counterparts. Over 4,500 individuals, aged 51 and older, were studied from a database spanning 1998 to 2022. Those diagnosed with Alzheimer’s and classified as obese at the time of diagnosis were 16, 27, and 22 percent less likely to die compared to those who were overweight, had class 1 obesity, and had class 2 or 3 obesity, respectively.

This “obesity paradox,” or the survival advantage associated with higher body mass index (BMI), has puzzled researchers since its discovery over 25 years ago. Potential explanations range from statistical artifacts to the disease’s physiological impact. It’s possible that obesity confers a survival benefit due to the increased energy reserves it provides, as issues like difficulty swallowing, loss of appetite, and malnutrition are common in Alzheimer’s.

However, researchers caution against patients with dementia attempting to gain weight. The study's authors suggest that weight status could serve as a useful prognostic signal for dementia patients' survival at the time of diagnosis.