Neurocognitive performances of visuospatial attention and the correlations with metabolic and inflammatory biomarkers in adults with obesity.

NEW FINDINGS: What is the central question of this study? Obesity is linked to cognitive deficits, elevated energy metabolic indices and low-grade systemic inflammation. Do the relationships between neurocognitive performance and the biochemical markers (e.g. energy metabolic indices and inflammatory cytokines) occur independently of factors known to be associated with neurocognitive dysfunction (i.e. cardiorespiratory fitness) in young adults? What is the main finding and its importance? Young obese adults showed poorer neuropsychological performances, aberrant neural activity and higher C-reactive protein and energy metabolic indices. The higher leptin and C-reactive protein concentrations showed a significant negative association with lower P3 amplitudes. However, leptin was the sole predictive factor, implicating hyperleptinaemia in the altered neurocognitive function observed in obesity. The present study was designed to explore the neurophysiological mechanism of visuospatial attention deficits in obese adults and to examine the relationships between neurocognitive (neuropsychological and neurophysiological) performances and the biochemical markers. Thirty obese adults and 30 healthy-weight control subjects, categorized by body mass index and percentage fat as measured with dual-energy X-ray absorptiometry, provided a fasting blood sample and performed a visuospatial attention protocol with concomitant electrophysiological recording. The obese group showed slower reaction times and smaller P3 amplitudes when performing the cognitive task. Even when controlling for the covariable of cardiorespiratory fitness, the results remained. In addition, the serum concentrations of insulin, glucose, leptin and C-reactive protein were significantly higher in the obese group relative to the control group, but not those of interleukin-6, interleukin-1β and tumour necrosis factor-α. Partial correlations adjusting for cardiorespiratory fitness showed that leptin and C-reactive protein concentrations in the obese group were negatively associated with poorer neurophysiological (i.e. P3 amplitude) performance. However, the regression analysis showed that leptin was the sole predictor of P3 amplitude in the obese group. These findings indicate that the individuals with obesity exhibited neurocognitive deficits when performing the visuospatial attention task, and serum leptin concentrations could be one of the influential factors.