The Cognitive Functions of Youth With Obesity: A Meta‐Analysis
Yi‐Chun Lin, Chia‐Chia Chang, Yu‐Tzu Chang, Wei‐Lin Liu, Yu‐Chi Liao, Ro‐Ting LinABSTRACT
Background
This meta‐analysis examined the associations between obesity and performance across seven cognitive domains (inhibition, cognitive flexibility, working memory, verbal fluency, planning, attention, and intelligence quotient [IQ]) in youth under 18 years. Developmental stage (school‐aged children vs. adolescents) and sample sex composition examined as moderators. Evidence on executive function in youth with comorbid obesity and attention‐deficit/hyperactivity disorder (ADHD) was synthesized qualitatively.
Methods
Following PRISMA guidelines, 22 studies comparing youth with obesity to normal‐weight peers were included. Effect sizes (Hedges’ g ) were pooled using a random‐effects model. Subgroup analyses compared school‐aged children and adolescents; meta‐regression examined age and proportion of female participants as study‐level moderators.
Results
Youth with obesity performed significantly worse than normal‐weight peers on inhibition ( g + = −0.193), cognitive flexibility ( g + = −0.499), working memory ( g + = −0.652), verbal fluency ( g + = −0.420), attention ( g + = −0.526), and IQ ( g + = −0.288); planning could not be estimated. School‐aged children showed deficits on inhibition, working memory, and attention; adolescents on working memory and attention only. Between‐subgroup tests were non‐significant for all domains ( p ≥ 0.26), so developmental differences should be interpreted with caution. Meta‐regression showed that a higher proportion of female participants in a study sample, a study‐level characteristic rather than an individual‐level effect, was associated with larger working memory deficits ( p = 0.002); age did not moderate any domain. Two ADHD‐comorbidity studies received qualitative synthesis only.
Discussion
Obesity is associated with poorer cognitive performance in youth across several domains, with sex composition of the study sample emerging as a moderator of the working memory finding; differences between school‐aged children and adolescents were not significant and should be interpreted cautiously. Substantial heterogeneity, predominantly observational designs, inconsistent BMI criteria, and limited ADHD‐stratified data constrain causal inference. Future studies should standardize weight definitions, report age‐ and ADHD‐stratified data, and consider bidirectional pathways.