Effect of an Exercise and Dietary Intervention on Cognitive Function in Obese Older Women

Abstract

BACKGROUND: Cognitive decline in older adults is a public health problem and prior research shows that higher levels of physical activity and dietary factors are associated with higher cognitive function. However, it is unclear how an exercise and diet intervention affects cognitive function in obese older women. PURPOSE: To examine the effect of a combined Tai Chi (TC), resistance training (RT), and diet intervention on cognitive function and to evaluate the relationship between cognitive function and physical function in older obese women. METHODS: This was a non-randomized study where 31 obese (BMI= 37.6 ± 4.5 kg/m2) older (age= 65.1 ± 8.4 years) women (61% African-American) were recruited to a 12-week intervention (EXD) group or to a control (CON) group. Cognitive function was measured via the Repeatable Battery for the Assessment of Neurological Status (RBANS) test. Other outcomes were grip strength, 4 m walk, leg strength, chair stands, and timed up and go. Baseline measures were assessed under standardized conditions prior to the start and at the end of the study by trained staff supervised by a licensed speech-language pathologist. The EXD group (n=17; 5 dropouts) engaged in three 45 min TC sessions and two 45 min RT sessions per week. A registered dietitian conducted the behaviorally based diet sessions once a week. The CON group (n=8; 1 missing data) was asked to maintain a normal lifestyle. Pearson correlations were done for baseline physical function and RBANS score and analysis of covariance was used to compare RBANS score change between groups adjusted for baseline. RESULTS: RBANS score was positively correlated with grip strength (r = 0.51) and negatively correlated with timed up and go, (r = -0.40), chair stand (r = -0.28) and gait speed (r = -0.37) times (all p<0.05). Baseline RBANS score (87.5 ± 19.5) and baseline age were not correlated and RBANS scores were not different between groups (p= 0.80). There were no differences in RBANS score change in the EXD vs. CON groups (3.1 ± 2.0 vs. 2.5 ± 2.9; p=0.86). CONCLUSIONS: An exercise and diet intervention does not change cognitive function in older obese women, but baseline cognitive function is moderately correlated with physical function. A longer intervention needs to be tested in a larger sample to verify these results. Supported by the College of Environment and Life Sciences Community Access to Research and Extension Services (CELS CARES) grant, USDA, at the University of Rhode Island.