Association between central obesity and executive function as assessed by stroop task performance: A functional near-infrared spectroscopy study

Recent studies have suggested a link between executive function (EF) and obesity. Studies often adopt body mass index (BMI), which reflects the distribution of subcutaneous fat, as the sole marker of obesity; however, BMI is inappropriate to distinguish central obesity, which indicates the centralized distribution of visceral fat. Visceral fat compared with subcutaneous fat represents greater relative lipid turnover and may increase the risk of cognitive decline in older adults. However, the relationship between EF and central obesity is largely unknown, particularly in young adults. Therefore, we used waist circumference (WC) as a marker of central obesity and investigated different sensitivities between BMI and WC in the brain function. A total of 26 healthy young adults (aged 18-25 years; 42% female) underwent functional near-infrared spectroscopy assessments. EF was assessed using the Stroop task, which is a classical measurement of EF. A significant Stroop effect was observed in the behavioral and hemodynamic data. In addition, we observed that behavioral interference on the Stroop task varied much more in subjects with higher BMI and WC than those subjects with lower. Elevated BMI and WC were associated with a decreased hemodynamic response during the Stroop task specifically in the prefrontal cortex (PFC). Compared to BMI, WC was more closely connected with inhibitory control and revealed right lateralized PFC activation. Our findings suggest that WC is a reliable indicator of brain function in young adults and propose a relationship between EF and central obesity.