The Demographic Determinants Of Childhood Aerobic Fitness, Body Composition, And Brain Function: A Quantitative Assessment

Purpose: Individual differences in demographic factors (i.e., age, sex, and socioeconomic status [SES]) shape relationships in physiology and brain function. This secondary data analysis investigates the covariate structure of aerobic fitness and body composition relative to task-based electroencephalography. Methods: Exploratory structural equation models (ESEM) were generated in a subsample of 245 children (ages 8-11; 55% female) from three prior studies (Total N’s = 86, 185, 221) on fitness, adiposity, and neuroelectric indices of brain function. The remaining 247 participants were held out of exploratory analysis for confirmatory model testing. All studies included identical measures of demographics, visceral (VAT) and subcutaneous abdominal adipose tissue (SAT), whole body lean mass (WB-LM), fat-free VO2max, and P300 event-related brain potential amplitude and latency elicited by incongruent trials of a modified flanker task. ESEM specification was tuned to optimized global fit measures (i.e., X2, RMSEA, TLI, CFI) using near-fitting model comparisons indices (i.e., X2diff, PCFI, AIC, BIC) while retaining a tolerable participant-to-parameter ratio (> 5:1), local effect size estimates (all |b| > 0.1), and theoretical plausibility. Results: The resulting ESEM displayed exceptional local and global fit (X2(55) = 63.7, p = 0.16; RMSEA = 0.025 [0.00-0.049]; TLI > 0.98; CFI > 0.99). We found that even in our narrow age range, age was positively related to WB-LM (b = 0.33) and fat-free VO2max (b = 0.22), and negatively related to P300 latency (b = -0.29); SES was positively related to fat-free VO2max (b = 0.21), VAT (b = 0.08), and P300 amplitude (b = 0.15); and sex was related only to SAT (b = -0.54; positive for girls) and VAT (b = 0.61; positive for boys). Path analyses revealed patterns consistent with partial mediation, wherein age, sex, and SES contributed covariance to P300 amplitude indirectly through VAT (b = -0.11). Conclusion: We find evidence for VAT as a mediator for age, sex, and SES in relation to P300 amplitude. This examination of covariate structure shows how demographic factors may influence brain outcomes through physiological mechanisms. VAT, known to confer metabolic risk, may be especially important in understanding how individual differences contribute to brain health in childhood.