The Association between Lead and Attention-Deficit/Hyperactivity Disorder: A Systematic Review

Abstract

The etiology of Attention-Deficit/Hyperactivity Disorder (ADHD) is complex and multifactorial. Although the development of ADHD symptoms remains to be elucidated, in recent years, epigenetic processes have emerged as candidate mechanisms. Lead is one of the most dangerous environmental pollutants, and it is suspected to be associated with ADHD. The aim of the present study was to review the epidemiological literature currently available on the relation between lead exposure and the diagnosis of ADHD. The PubMed and EMBASE databases were searched from 1 July 2018 up to 31 July 2018. The authors included observational studies (cohort, case–control and cross-sectional studies) published in English carried out on children within the last 5 years, measuring lead exposure and health outcomes related to ADHD. Seventeen studies met the inclusion criteria: 5 of these studies found no association between lead exposure and ADHD whereas the remaining 12 studies showed positive associations, even though not all of them were homogeneous in terms of exposure periods considered or ADHD diagnosis. To conclude, the evidence from the studies allowed us to establish that there is an association between lead and ADHD and that even low levels of lead raise the risk. However, there is still a lack of longitudinal studies about the relationship between lead exposure and the development of ADHD. Given the potential importance for public health, further research that includes the entire potential risk factors for ADHD in children must be encouraged.

Effects of prenatal exposure to NO2 on children’s neurodevelopment: a systematic review and meta-analysis

“…Some studies and reviews have supported the hypothesis that exposure to ambient NO 2 and other air pollution was associated with an increased risk of autism spectrum disorder (ASD) (Chun et al 2020;Flores-Pajot et al 2016) and attention deficit hyperactivity disorder (ADHD) for children (Donzelli and Carducci 2019;Forns et al 2018;Min and Min 2017). However, the effects of prenatal exposure to NO 2 on children's neurodevelopment (including cognitive, psychomotor, language, and behavioral functions) are still unclear for different conclusions in related studies (Ren et al 2019;Porta et al 2016;Sentis et al 2017).…”

The Potential Impact of Mass Media Education in the Psycho-Social Life and Epidemiology of Sickle Cell Disease in Nigeria

“…In cases of attention deficit hypersensitivity, it is common in most children and some adults. Such individuals may find it difficult to pay attention to details, always involved in excessive talking, have difficulty in organizing tasks and activities, fidgeting and difficulty to remain seated in an appropriate position (Gabriele, Annalaura, Agustin, Marco, Agustin, Lorenzo, & María, 2019). Individuals with this disease are at risk of facing some disability challenges.…”

Attention Deficit Hyperactivity Disorder

“…In 1991 recommended level of lead in children's blood (BLL) by CDC is set to 10 micrograms of lead per deciliter of blood (μg/dL) and it has not been changed since then. Donzelli et al [18] performed systematic review of 17 studies assessing the correlation of lead level and ADHD. According to their results there is a direct correlation between low lead level of lead in ADHD children's blood and severity of ADHD symptoms.…”

“…A meta-analysis of 175 research studies worldwide on ADHD prevalence in children aged 18 and under found an overall pooled estimate of 7.2% [2].…”