The influence of adiposity on the interactions between strength, physical function and cognition among older adults in the Australian Diabetes, Obesity and Lifestyle (AusDiab) study

Background Being overweight or obese may be associated with lower physical and cognitive function, but in late-adulthood (>= 65 years) evidence is mixed. This study aimed to investigate how being overweight or obese affected interactions between muscle strength, function and cognition in Australians aged >= 50 years, and whether interactions varied according to age (i.e. >= 50-65 vs > 65 years). Methods This study included 2368 adults [mean (standard deviation) age: 63 (7) years; 56% female] from the 2011/2012 Australian Diabetes, Obesity and Lifestyle (AusDiab) follow-up. Physical function was assessed via timed up-and-go (TUG) and muscle strength from knee extensor strength (KES). Cognition was assessed using Mini-Mental-State Exam (MMSE), Spot-the-Word (STW), California Verbal Learning Test (CVLT) and Symbol-Digit-Modalities Test (SDMT). Beta binomial regression was used to evaluate how being overweight or obese influenced strength, physical and cognitive function associations. Results Being overweight or obese did not affect strength-cognition associations regardless of sex or age. With slower physical function; obese females showed better STW (odds ratio [OR] 95% CI]: 1.070 [1.016, 1.127], P = 0.011); obese men better MMSE (OR [95% CI]: 1.157 [1.012, 1.322], P = 0.033); and obese men aged > 65 better CVLT (OR [95% CI]: 1.122 [1.035, 1.217], P = 0.019) and MMSE (OR [95% CI]: 1.233 [1.049, 1.449], P = 0.017) compared to normal weight participants. Conclusion Slower physical function was associated with better performance in some cognitive domains in obese, but not in non-obese adults aged >= 50 years. These findings suggest some benefits of obesity to aspects of cognition when physical function is slower, but longitudinal follow-up studies are needed.