6.55 A META-ANALYSIS OF POTENTIALLY MODIFIABLE RISK FACTORS FOR CHILDHOOD ATTENTION-DEFICIT/HYPERACTIVITY DISORDER: CHEMICAL EXPOSURES AND FACTORS RELATED TO PARENTING

Objectives: Both the physical and socioemotional environment impact child development, and risk factors in each of these categories may increase risk of ADHD. As part of a larger ADHD risk factor meta-analysis project, this paper reports on meta-analyses conducted to examine the potential impact of 1) early exposure to specific chemicals and 2) parenting factors on the later development of ADHD or ADHD symptoms. Methods: A review of the chemical exposure literature and parenting literature respectively identified 51 and 26 studies with sufficient information to include in the analyses. Individual risk factors that were evaluated in three or more studies were analyzed. Chemical exposures included: Brominated flame retardants (BFRs), which can be present in household items, such as upholstery, carpet padding, and mattresses; Lead (may be present in paint in older homes); Chemicals potentially ingested through the diet, including cadmium, polychlorinated biphenyls (PCBs), and hexachlorobenzene; and Organophosphates, a common group of pesticides. Parenting factors included: Parenting quality (sensitivity/warmth, intrusion/reactivity, and negative/harsh discipline); and Maltreatment (general maltreatment and physical abuse). Results: Childhood lead exposure was the most heavily studied chemical exposure, and it was consistently strongly associated with ADHD symptoms. Other statistically significant chemical exposures were organophosphates, PCBs, and BFRs. All of the parenting factors showed a significant association with ADHD, with the exception of physical abuse and negative/harsh discipline. Conclusions: Numerous chemical exposures and parenting factors were found through this meta-analysis to be associated with modest, increased risk of ADHD. Findings support the continued need for primary prevention and targeted screening for childhood exposure to lead and other chemicals as potential avenues to prevent or reduce ADHD symptomatology among children. In addition, supporting positive parenting may represent an opportunity to improve ADHD symptoms.