Prospective associations between ADHD symptoms and physical conditions from early childhood to adolescence: a population-based longitudinal study.

BACKGROUND

The co-occurrence between attention-deficit hyperactivity disorder (ADHD) and physical conditions is frequent but often goes unrecognised. Most available evidence on the links between ADHD and physical conditions relies on cross-sectional studies. Understanding temporal sequences of associations is key to inform appropriate treatment and preventive strategies. We aimed to assess possible longitudinal associations between ADHD symptoms and a broad range of physical conditions, adjusting for several confounding factors.

METHODS

Participants came from the population-based Quebec Longitudinal Study of Child Development. Participants were selected from the Quebec Birth Registry, recruited between October, 1997, and July, 1998, from the province of Quebec, Canada, and followed up in early childhood (n=2120; age 5 months-5 years), middle childhood (n=1750; age 6-12 years), and adolescence (n=1573; age 13-17 years). Main outcome measures included ADHD symptom severity and physical conditions, which were reported by the person most knowledgeable of the child in early childhood, by teachers in middle childhood, and self-reported in adolescence. Multivariable regression analyses were conducted to study the prospective associations between ADHD symptoms and later physical conditions, and physical conditions and later ADHD symptoms, adjusting for multiple confounders.

FINDINGS

We found several prospective associations between ADHD symptoms and physical conditions including asthma, high BMI (≥1 SD above the mean), epilepsy, dental caries, acute infections, injuries, and sleep problems. After adjusting for key confounding factors, several associations remained: ADHD symptoms in early childhood were associated with later high BMI during middle childhood (odds ratio [OR] 1·19 [95% CI 1·05-1·35]) and adolescence (OR 1·14 [1·01-1·29]), and with unintentional injuries during adolescence (OR 1·10 [1·01-1·21]). ADHD symptoms in middle childhood were significantly associated with later dental caries during adolescence (OR 1·10 [1·01-1·20]). Unintentional injuries in early childhood were associated with later ADHD symptoms in middle childhood (standardised mean difference [SMD] 0·15 [0·05-0·24]) and adolescence (SMD 0·13 [0·04-0·23]), and restless legs syndrome symptoms in middle childhood were associated with later ADHD symptoms in adolescence (SMD 0·15 [0·05-0·25]).

INTERPRETATION

Our results point to the need to carefully monitor children with ADHD in early or middle childhood for several physical conditions, and to monitor children with particular physical conditions for ADHD symptoms. Our study also calls for policies to promote more integrated health-care systems for children with complex mental and physical needs, bridging the current gap between mental and physical health-care services.

FUNDING

Québec Government's Ministry of Health, Ministry of Education, and Ministry of Family Affairs; The Lucie and André Chagnon Foundation; the Robert-Sauvé Research Institute of Health and Safety at Work; the Québec Statistics Institute; the Fonds de Recherche du Québec-Santé; the Fonds de Recherche du Québec-Societé et Culture; Canada's Social Science and Humanities Research Council; the Canadian Institutes of Health Research, the Sainte-Justine Research Center; and the French National Research Agency.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Informations de copyright

Copyright © 2023 Elsevier Ltd. All rights reserved.

Déclaration de conflit d'intérêts

Declaration of interests SaC has received (outside the submitted work) honoraria for presentations from the British Association of Psychopharmacology, the Association for Child and Adolescent Mental Health, and the Canadian ADHD Alliance Resource. SaC is currently supported by funding from the UK National Institute for Health and Care Research (NIHR203684, NIHR203035, NIHR130077, NIHR128472, and RP-PG-0618–20003), Solent NHS Trust (Research Capability Funding, 2022), University of Southampton (Knowledge and Exchange Enterprise Fund 2023, Enterprise Development Fund 2022), and the European Research Agency (Horizon: project 101095568). HL has received (outside the submitted work) grant from Shire–Takeda Pharmaceuticals and honoraria for lectures from Medice, Shire–Takeda Pharmaceuticals, and Evolan Pharma AB. All other authors declare no competing interests.