Prenatal Methylmercury, Postnatal Lead Exposure, and Evidence of Attention Deficit/Hyperactivity Disorder among Inuit Children in Arctic Québec

Abstract

Background: Prenatal exposure to methylmercury (MeHg) and polychlorinated biphenyls (PCBs) has been associated with impaired performance on attention tasks in previous studies, but the extent to which these cognitive deficits translate into behavioral problems in the classroom and attention deficit/hyperactivity disorder (ADHD) remains unknown. By contrast, lead (Pb) exposure in childhood has been associated with ADHD and disruptive behaviors in several studies.Objectives: In this study we examined the relation of developmental exposure to MeHg, PCBs, and Pb to behavioral problems at school age in Inuit children exposed through their traditional diet.Methods: In a prospective longitudinal study conducted in the Canadian Arctic, exposure to contaminants was measured at birth and at school age. An assessment of child behavior (n = 279; mean age = 11.3 years) was obtained from the child’s classroom teacher on the Teacher Report Form (TRF) from the Child Behavior Checklist, and the Disruptive Behavior Disorders Rating Scale (DBD).Results: Cord blood mercury concentrations were associated with higher TRF symptom scores for attention problems and DBD scores consistent with ADHD. Current blood Pb concentrations were associated with higher TRF symptom scores for externalizing problems and with symptoms of ADHD (hyperactive-impulsive type) based on the DBD.Conclusions: To our knowledge, this study is the first to identify an association between prenatal MeHg and ADHD symptomatology in childhood and the first to replicate previously reported associations between low-level childhood Pb exposure and ADHD in a population exposed to Pb primarily from dietary sources.

The Role of Heavy Metal Pollution in Neurobehavioral Disorders: a Focus on Autism

“…Recently, Boucher et al (2012) reported the association between prenatal MeHg exposure and ADHD symptomatology at school age, corroborating previous results on the effects of MeHg on attention and learning skills (Grandjean et al 1997;Debes et al 2006). Moreover, the association with ADHD-related behaviors seem to be stronger in boys than in girls, which is consistent with the growing evidence showing differences in the impact of endocrine-disrupting chemicals (including mercury) on neurodevelopment in males and females (Sagiv et al 2012).…”

Genomic and Epigenomic Insights into Nutrition and Brain Disorders

“…Prenatal mercury exposure is associated with an increased risk of neurobehavioral disorders, and lead exposure in childhood has been associated with ADHD [51]. In this study, lead and mercury consumption was positively correlated with the traditional-healthy dietary pattern, but it did not alter the beneficial effects of the traditional-healthy dietary pattern on ADHD.…”

PHDA: Afinal, qual a sua origem? Uma revisão dos fatores etiológicos

“…A maioria das crianças com PHDA não foram expostas ao chumbo e muitas crianças com elevada exposição a este metal não desenvolvem a perturbação (Banerjee et al, 2007;Scassellati, Bonvicini, Faraone, & Gennarelli, 2012). Esta hipótese está longe de ser consensual e requer maior evidência empírica (Boucher et al, 2012;Yoshimasu, Kiyohara, Takemura, & Nakai, 2014).…”