The Association between Obesity and Cognitive Function in Otherwise Healthy Premenopausal Arab Women

Objective: To examine the association between obesity and cognitive function in otherwise healthy premenopausal women. Methods: A cohort of 220 women were randomly selected during a healthy lifestyle screening from which 98 were included that provided complete data relevant for this study. Body composition was examined by dual energy X-ray scan; cardio respiratory performance (VO2 max) was assessed by Bruce treadmill test. All participants completed the Cambridge Neuropsychological Test Automated Battery (CANTAB) to assess cognitive performance in three domains: attention, memory, and planning executive function. The Reaction Time (RTI) test was used to assess motor and mental response speeds; Stockings of Cambridge (SOC) test was used to assess planning executive function. For memory assessment, the delayed match to sample (DMS), pattern recognition memory (PRM), and spatial span (SSP) tests were used to assess forced choice recognition memory, visual pattern recognition memory, and working memory capacity, respectively. Results: Of the 98 women included, 36 (36.7%) were morbidly obese, 22 (22.4%) obese, 23 (23.5%) overweight, and the rest belonged to normal body weight group. Performance on RTI simple and complex tasks as well as SOC planning ability were not associated with body mass index(BMI). DMS mean time to correct response, when stimulus is visible or immediately hidden (0ms delay), was higher by 785±302 ms (milliseconds) (p=0.011) and 587±259 ms (p=0.026) in morbidly obese women compared to normal weight women. Memory span length was significantly lower in overweight (5.5±1.3, p=0.008) and obese women (5.6±1.6, p=0.007) compared to normal weight (6.7±0.9). Dexa assessed body fat (%) showed similar associations as BMI, latency to correct response on DMS and PRM was positively correlated with percentage of body fat, but not with VO2 max. Conclusion: In otherwise healthy premenopausal women, obesity did not impact accuracy on cognitive tasks related to attention, memory, or planning executive function but morbid obesity was associated with higher latency to correct response on memory specific tasks and lower memory span length.