Comparison of cognitive performance between obese and normal weight middle-aged women

Abstract

The number of people with obesity worldwide is constantly on the rise which poses a detrimental impact on public health. Mid-life obesity has been found to be a significant risk factor for dementia in older age. Nonetheless, the impact of obesity on cognitive function is still inconclusive. Metabolic syndrome (MetS) has been suggested to be a risk factor while cardiorespiratory fitness (CRF) has been suggested to be a protective factor for cognitive impairment in older adults. However, studies examining such effects in middle-aged women with obesity are limited. The purposes of this study were 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. Eighty-seven middle-aged women (58 obese and 29 normal weight, with age and education matched) were recruited in this study. 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 assessed in all participants. Analysis of covariance (ANCOVA) was used to compare the differences of cognitive outcome measures between the obese and normal weight groups, the obese with and without metabolic syndrome groups, and among normal weight group with high CRF and obese group with high and low CRF. The results showed that the obese group (n = 58) demonstrated significantly lower score in MoCA, DS, TMT, HRT, and LM than the normal weight group (n = 29) (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 greater 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). The findings of this study demonstrated that obesity has a negative impact on several cognitive performances, which memory appears to be further affected when paired with MetS. CRF appears to have benefit on several areas of cognitive domains. The study findings suggested that maintaining a healthy body weight and enhancing CRF are beneficial for cognitive function of middle-aged women which might consequently lower the risk of cognitive decline in old age.