Obesity and Brain Health: The Impact of Metabolic Syndrome and Cardiorespiratory Fitness on Cognitive Performances in Middle-Aged Obese Women

Abstract

Background: Mid-life obesity has been reported to be a significant risk factor for later-life dementia and Alzheimer’s disease. Metabolic syndrome (MetS) has been suggested to have an adverse effect while cardiorespiratory fitness (CRF) has been suggested to have a protective effect on cognitive function of older adults. However, studies investigating such effects in middle-aged obese women are limited. Objectives: To compare cognitive performances between obese and normal weight middle-aged women and examine the effects of MetS and CRF on cognitive performances when combined with obesity. Design and Participants: Cross-sectional study with the data of 87 middle-aged women (58 obese and 29 normal weight, with age and education matched). Measurements: The non-invasive screening method for metabolic syndrome (NIM-MetS) was used to detect MetS. CRF was determined by using maximal oxygen consumption (VO2 max) and was classified as high or low (VO2 max higher or lower than 50th percentile) based on the American College of Sports Medicine’s guidelines. Neurocognitive tests including Montreal Cognitive Assessment (MoCA), digit span (DS), trail making test (TMT), hand reaction time (HRT), logical memory (LM), and semantic verbal fluency test (SVFT) were administered to all participants. Results: The obese group demonstrated significantly lower score in MoCA, DS, TMT, HRT, and LM than the normal weight group (p < 0.05). The obese with MetS subgroup (n = 28) showed significantly lower score in LM than the obese non-MetS subgroup (n = 30) (p = 0.002). Normal weight with high CRF participants (NW-high CRF; n = 28) demonstrated significantly higher score in MoCA and HRT than obese with high CRF participants (OB-high CRF; n = 24) (p < 0.05), and demonstrated better score in MoCA, DS, TMT, HRT, and LM than obese with low CRF participants (OB-low CRF; n = 24) (p < 0.05). OB-high CRF showed significantly greater score in DS, TMT and LM than OB-low CRF (p < 0.05). Conclusion: Obesity shows negative impact on several cognitive functions, which memory appears to be further affected when combined with MetS in middle-aged women, whereas CRF is suggested to have benefit on certain aspects of cognitive domains. Maintaining a healthy body weight and improving CRF are beneficial for cognitive function of middle-aged women.