Being Overweight or Obese in Old Age Does Not Increase Risk of Cognitive Decline

While obesity has been shown to contribute to high blood pressure, heart disease and diabetes, being overweight in old age does not lead to memory problems, according to a study by researchers at Rush University Medical Center. The study is published in the September 19 online edition of Neurology, the medical journal of the American Academy of Neurology.

The six year study involved over 3800 participants over the age of 65 from three neighbourhoods on the south side of Chicago: Morgan Park, Beverly, and Washington Heights. Of the participants, nearly 25 percent were obese with a body mass index (BMI) over 30, and 37 percent were overweight with a BMI between 25 and 29.9. Four cognitive tests were given at the beginning of the study and every three years thereafter over the six year period.The study found that being overweight or obese was not associated with significant changes in memory or cognitive function relative to individuals with normal weight. In fact, participants who were underweight had more cognitive decline over time."We do not know yet why being overweight or obese does not increase the risk of cognitive decline in old age, however being underweight may be a correlate of the initial stages of Alzheimer's disease," said study author Dr. Maureen T. Sturman, a researcher at the Rush Institute for Healthy Aging."While past studies have found obesity in middle age increases a person's risk for dementia or Alzheimer's disease, our finding show obesity in old age has no effect on a person's memory. These findings are consistent with previous studies showing that weight loss or low BMI in old age may be a precursor of cognitive decline or Alzheimer's disease,"According to study authors, knowing the role that changes in body weight have on cognition would enhance the ability to target health promotion recommendations for older adults."It may be that lifestyle guidelines such as increasing cognitive activity, cardio respiratory fitness, and dietary recommendations are more important that those that focus on weight loss alone," said Sturman.The study was supported by the National Institute on Aging and the National Institute of Environmental Health Science.(Source: Neurology : Rush University Medical Center : November 2007)