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.

Natural health products, modulation of immune function and prevention of chronic diseases.

The immune system is increasingly found to be involved in the development of several chronic illnesses, for which allopathic medicine has provided limited tools for treatment and especially prevention. In that context, it appears worthwhile to target the immune system in order to modulate the risk of certain chronic illnesses. Meanwhile, natural health products (NHPs) are generating renewed interest, particularly in the prevention and treatment of several chronic diseases. Over 20 scientists from fields related to immune function and NHPs were thus convened to establish the state of knowledge on these subjects and to explore future research directions. This review summarizes the result of discussions held during the symposium. It thus seeks to be thought provoking rather than to comprehensively cover such broad areas of research. Notably, a brief overview of the immune system is presented, including potentially useful targets and strategies to keep it in an equilibrated state, in order to prevent certain disorders. The pertinence and limitations of targeting the immune system to prevent chronic diseases is also discussed. The paper then discusses the usefulness and limitations of current experimental tools available to study the immune modulating effects of NHPs. Finally, a concise review of some of the most studied NHPs showing promising immunomodulatory activity is given, and avenues for future research are described.