Greater body weight tied to quicker memory decline after 65

Among older adults, a higher body mass index was associated with faster declines in memory and thinking abilities in a study that tracked participants for as long as 24 years. The link was especially clear in people over 65, prompting researchers to examine more closely how weight and brain health may change together with age.

Researchers at the University of Georgia analyzed information from more than 8,200 adults older than 50. Because the participants were assessed repeatedly, the team could compare cognitive changes over time instead of relying on a single test result from one moment in life.

Body mass index, or BMI, is a rough measure of body size based on height and weight. In this study, the researchers examined average BMI across time, which can differ from a person’s weight on the day a memory test is given.

Higher BMI was associated with steeper declines in memory and overall thinking ability. The team also found a relationship with executive function, the skills used to plan, shift between tasks, and organize activities.

The effect was most noticeable in the older participants and was strongest around the eighth year of follow-up. These results reflect group averages and do not predict how fast any one person’s memory will change.

Published in the Journal of Neurology, the findings add to research on factors that may influence thinking later in life. Scientists are exploring whether circulation, inflammation, and the body’s handling of blood sugar may help explain part of the association.

Researchers are also looking at how body weight and inflammation may affect brain health after age 50.

BMI has limitations. Two people with the same BMI can have very different amounts of muscle and body fat, or store fat in different areas. The measure does not reveal which part of body composition may be linked to changes in thinking.

Because the study followed people in everyday life, researchers could not account for every factor that affects weight and brain health. Physical activity, medical conditions, and health changes that occur before thinking problems become obvious could all have influenced the comparison.

The results also do not prove that losing weight on purpose prevents memory decline. To answer that question, researchers would need studies that track people receiving specific support and compare changes in health and cognition over time.

For now, the long follow-up helps identify a group and stage of life that deserve closer study. Future research can test whether measures beyond BMI offer a clearer view of risk and whether health changes can help people maintain everyday thinking skills as they age.

If you are interested in this topic, please read articles about MIND and Mediterranean diets are linked to fewer Alzheimer’s signs in the brain, and High-fat diets may harm brain health, study finds.

For more information, please see articles about A Two-Year Lifestyle Program Helped Older Adults Sharpen Their Memory, and How the Mediterranean diet could slow aging and reduce disease risk.

Source: University of Georgia.