Atopic dermatitis, cognitive function and psychiatric comorbidities across early childhood and adolescence in a population-based UK birth cohort.

Abstract

Atopic dermatitis (AD) may affect cognitive function, but studies are limited and inconsistent. The effect of AD severity on cognition remains underexplored and few previous studies have examined clinically validated or repeated measures of cognition throughout childhood. To evaluate the relationship of AD activity and severity with validated measures of general cognition in a longitudinal birth cohort. We conducted cross-sectional analyses using data from the Avon Longitudinal Study of Parents and Children (ALSPAC), a UK cohort of 14 975 individuals followed prospectively since their birth in 1991-92. AD was assessed 11 times between the age of 6 and 166 months. Mothers were asked if their child had an 'itchy, dry skin rash in the joints and creases', and AD status was time-updated accordingly as 'never', 'maybe', 'inactive', 'active/mild' or 'active/moderate-severe'. General cognition [i.e. intelligence quotient (IQ)] was measured at 18, 49, 103 and 186 months of age using the Griffiths Mental Development Scales (GMDS), Wechsler Preschool and Primary Scale of Intelligence (WPPSI), Wechsler Intelligence Scale for Children (WISC) and Wechsler Abbreviated Scale of Intelligence (WASI), respectively. Multivariable linear regression was used to compare IQ with respect to nearest time-updated AD status. Secondary analyses were stratified by the presence or absence of psychiatric or learning disorders. An exploratory longitudinal analysis of IQ across all four outcome assessments was conducted using generalized estimating equations. No significant associations between AD status and full-scale IQ scores on the GMDS, WPPSI, WISC and WASI were observed after adjustment for sociodemographic factors, atopic comorbidities and sleep characteristics. However, at 8 years of age, WISC Performance IQ was slightly, although statistically significantly, lower among children with active/moderate-severe AD [β coefficient -2.16, 95% confidence interval (CI) -4.12 to -0.19] and Verbal IQ was slightly, but statistically significantly, higher among those with inactive AD (β coefficient 1.31, 95% CI 0.28-2.34) compared with those without AD. Analyses stratified by psychiatric or learning disorders, and exploratory longitudinal analyses of cognition revealed similar findings. We did not find any clinically meaningful associations between AD activity and severity and general cognitive function during early childhood and adolescence. Future studies should incorporate objective measures of AD severity and investigate outcomes beyond IQ.