February 1, 2022

expert reaction to study looking at the association between body fat and cognition in adults

A study, published in JAMA Network Open, looked at the association between body fat and cognition in adults.

Prof Sir Stephen O’Rahilly FMedSci, Professor of Clinical Biochemistry and Medicine, & Director, Medical Research Council Metabolic Diseases Unit, University of Cambridge, said:

“The authors studied ~9000 adult volunteers and found that those people with more total body fat and/or more fat in their abdominal cavity were more likely to score lower in one particular test of higher brain function. They report that this association is independent of the classical cardiovascular risk factors often associated with obesity. When a different test of higher brain function was used, no association was seen.  This is not the first study to report an association between obesity and reduced score in tests of cognitive function. So while the results of the two tests in the current study were not consistent with each other, it is plausible that such a relationship is real. The authors conclude by stating “These results suggest that strategies to prevent or reduce adiposity may preserve cognitive function”. This assumes that something about the obese state leads to the impairment of cognition. But other explanations are equally possible. Impaired cognition could predispose to becoming obese in an obesogenic environment or some common factor could impair both the control of body weight and aspects of cognitive function. In summary, this study adds to a long-standing body of data suggesting an association between obesity and reduced cognitive function. However, in the study the effect was restricted to one particular test and was not seen in the other. There are many social, educational and inherent biological influences on cognitive performance and those relating to body weight appear relatively minor in terms of size of impact. There are many highly intelligent people living with obesity.  While weight loss brings many health and other benefits to people living with overweight or obesity, it is premature to conclude that an improvement in cognitive performance is likely to be one of them. ”

‘Evaluation of Adiposity and Cognitive Function in Adults’ by Sonia S. Anand et al. will be published in JAMA Network Open at 16:00 UK time on Tuesday 1 February, which is also when the embargo will lift.

DOI: 10.1001/jamanetworkopen.2021.46324 

Declared interests

Prof Sir Stephen O’Rahilly: No relevant conflicts here.