Socioeconomic Disadvantages Explain Maternal Age and ADHD Causal Association

Targeting socioeconomic inequalities and support young pregnant women could reduce the burden of ADHD associated with young motherhood.

The association between young maternal age and childhood attention-deficit/hyperactivity disorder (ADHD) is likely explained primarily by socioeconomic disadvantages, according to study findings published in The Journal of Child Psychology and Psychiatry.

Researchers conducted a cross-sectional analysis using the ABCD Study June 2016 through mid-October 2018. A total of 8514 children aged 8 to 11 years (mean, 9.9±0.6 years) were examined for associations of maternal age with ADHD diagnoses based on the Child Behavior Checklist (CBCL) and National Institutes of Health (NIH) Toolbox Flanker Attention Scores using mixed logistic and linear regression models, respectively.

They used socioeconomic, demographic, genotype array, and prenatal environmental data to conduct confounding and causal mediation analyses to determine which environmental and genetic variables could explain the association between young maternal age and childhood ADHD. Children (46.8% girls) received ADHD clinical range diagnoses based on CBCL parent questionnaires and NIH Flanker Attention Scores (mean, 94.1±9.1). They noted 6.9% of the children with ADHD clinical range diagnoses.

The crude models showed each 10-year increase in maternal age associated with 32% decreased odds of ADHD clinical range diagnosis (odds ratio, 0.68, 95% CI, 0.59-0.78) and increased NIH Flanker Attention Scores of 1.09 points (β=1.09; 95% CI, 0.76-1.41), which indicated improved child visual selective attention. These associations were weakened after adjusting for confounders. The most significant confounders for ADHD clinical range diagnoses were caregiver education, family income, and ADHD polygenic risk score. The most significant confounders for NIH Flanker Attention Scores were caregiver education, family income, and race or ethnicity.

Socioeconomic disadvantages were likely the primary explanation for the association of young maternal age with child ADHD, although genetics and modifiable environmental factors also played a role.

Mediation was attributed to breastfeeding duration (up to 18%), prenatal alcohol exposure (up to 6%), and prenatal tobacco exposure (up to 4%). When maternal age was linearly modeled for the maternal age groups aged younger than 20 years and between 25 and 29 years (vs 30-34 age group), prenatal alcohol exposure was a significant negative mediator for ADHD clinical range diagnosis. Increased maternal age was found to be associated with decreased chances of ADHD clinical range diagnosis and increased maternal age associated with increased maternal alcohol consumption. This increased consumption is associated with increased odds for child ADHD clinical range diagnosis.

Limitations of the study include the cross-sectional design, selection bias, and the inaccurate reporting of prenatal and early-life variables due to memory bias.

Researchers conclude, “Socioeconomic disadvantages were likely the primary explanation for the association of young maternal age with child ADHD, although genetics and modifiable environmental factors also played a role.”

Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

References:

Baker BH, Joo YY, Park J, Cha J, Baccarelli AA, Posner J. Maternal age at birth and child attention-deficit hyperactivity disorder: causal association or familial confounding? J Child Psychol Psychiatry. Published online November 28, 2022. doi:10.1111/jcpp.13726