Relationship Between Metabolic Syndrome and Cognitive Abilities in U.S. Adolescents.

BACKGROUND: Metabolic syndrome is increasingly common in U.S. adolescents and has been linked to cognitive dysfunction. Purpose of this study is to explore associations between metabolic syndrome and cognitive impairment in U.S. adolescents using population-based data. STUDY DESIGN: Participants included adolescents aged 12-16 years who participated in the National Health and Nutrition Examination Survey (NHANES) III. The main outcome measures included assessments of cognitive function using Wide Range Achievement Test-Revised (WRAT-R) and Wechsler Intelligence Scale for Children-Revised (WISC-R) tools. The WRAT-R consisted of mathematics and reading tests. The WISC-R consisted of block design test, which measures spatial visualization and motor skills, and digit span test, which measures working memory and attention. Linear regression models were used to examine associations between metabolic syndrome and cognitive function. We used education levels of the family reference person, while controlling for education levels because of missing data. RESULTS: Presence or absence of metabolic syndrome was tested in 1170 of 2216 NHANES III participants aged 12-16 years. Regression models showed that participants with metabolic syndrome scored an average 1.25 [95% confidence interval (CI) = -2.14 to -0.36] points lower in reading examination and an average 0.89 (95% CI = -1.65 to -0.13) points lower in digit span examination, compared to those without metabolic syndrome. In addition, components of metabolic syndrome-elevated systolic blood pressure and increased waist circumference (WC)-were associated with impaired working memory/attention, and higher fasting glucose and increased WC were associated with poorer reading test scores. CONCLUSIONS: Metabolic syndrome was associated with impaired reading, working memory, and attention among adolescents.