Child predisposition to attention-deficit/hyperactivity disorder, autism spectrum disorder, and obesity: Predictive variables in the first year of life and growth patterns in a population-based context

Abstract

The prevalence of attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) has increased in the last decades, together with childhood obesity. These conditions often co-occur and may share early biological, environmental, and behavioural risk factors. This thesis explores early predictors and growth patterns to improve early identification and prevention.

Four studies are included: Paper I is a clinical review of changes in body mass index (BMI) in 118 children treated with stimulants for ADHD. Papers II–IV use data from a Swedish population-based birth cohort (n=2,666) to analyse the prevalence and predictors of ADHD and ASD, as well as the impact of breastfeeding. Paper IV also report on early growth in relation to later neurodevelopmental and BMI outcomes.

Key findings include that nearly half of children with ADHD and comorbid overweight or obesity reached normal weight after stimulant treatment was initiated. In the population-based birth cohort, the prevalence of ADHD and ASD at age twelve was 7.6% and 1.1%, respectively. Preterm birth, maternal smoking, high maternal BMI, and lack of breastfeeding at three and six months were associated with ADHD in offspring. An earlier adiposity rebound was observed in children with higher BMI at age ten. No statistically significant different growth patterns were associated to ADHD nor ASD.

Conclusion: ADHD, ASD, and obesity appear to share early-life risk factors and developmental pathways. Stimulant treatment may offer dual benefits in children with ADHD and obesity. Growth monitoring and early behavioural indicators, such as feeding patterns and self-regulation difficulties, may help identify children at risk. These results emphasise the need for integrated, family-centred, and interdisciplinary approaches in early child health surveillance and intervention.