Environmental risk factors, protective factors, and peripheral biomarkers for ADHD: an umbrella review

Abstract

Background Many potential environmental risk and protective factors, and peripheral biomarkers for ADHD have been investigated, but their consistency and magnitude are unclear. We aimed to systematically appraise the published evidence of association between potential risk factors, protective factors, or peripheral biomarkers, and ADHD. MethodsWe did an umbrella review of meta-analyses. We searched PubMed, Embase, and the Cochrane Database of Systematic Reviews from inception to Oct 31, 2019, and screened the references of relevant articles. We included systematic reviews providing meta-analyses of observational studies that examined associations of potential environmental risk factors, protective factors, or peripheral biomarkers with diagnosis of ADHD. We included meta-analyses using categorical ADHD diagnosis criteria according to DSM, or hyperkinetic disorder according to ICD, and accepted less rigorous criteria such as self-reports. We excluded articles that did not examine environmental risk factors, protective factors, or peripheral biomarkers of ADHD; articles that did not include a meta-analysis; and articles that did not present enough data for re-analysis. We excluded non-human studies, primary studies, genetic studies, and conference abstracts. We calculated the summary effect estimates (odds ratio [OR], relative risk [RR], and weighted mean difference [WMD]), 95% CI, heterogeneity I2 statistic, 95% prediction interval, small study effects, and excess significance biases. We did analyses under credibility ceilings, and assessed the quality of the meta-analyses with AMSTAR 2 (A Measurement Tool to Assess Systematic Reviews 2). This study is registered with PROSPERO, number CRD42019145032. Findings We identified 1839 articles, of which 35 were eligible for inclusion. These 35 articles yielded 63 meta-analyses encompassing 40 environmental risk factors and protective factors (median cases 16 850, median population 91 954) and 23 peripheral biomarkers (median cases 175, median control 187).

Risk and protective factors for mental disorders beyond genetics: an evidence‐based atlas

“…Overall, 1,361 records were retrieved, 800 suitable papers were screened, and 14 umbrella reviews were eligible 6,15,27,[32][33][34][35][36][37][38][39][40][41][42] (see Figure 1). The eligible umbrella reviews were published between 2017 and 2021, and reviewed individual studies published from 1995 to 2020.…”

Genetic estimates of correlation and causality between blood-based biomarkers and psychiatric disorders

“…These studies have endeavoured to find biochemical traits readily detectable in blood, that, in theory, could be diagnostic or prognostic biomarkers for a given psychiatric disorder. Many of these hypotheses stem from the idea that peripheral biochemical traits may exert an effect on the brain, directly or indirectly through their effect on other mediators, and that the manifestation of mental illness is in part attributed to these factors which primarily act in the periphery (11,12,(14)(15)(16). Identifying these biochemical-psychiatric relationships would be clinically valuable as many of these traits can be modulated by existing drugs and/or lifestyle .…”

Association of Prenatal, Early Postnatal, or Current Exposure to Secondhand Smoke With Attention-Deficit/Hyperactivity Disorder Symptoms in Children

“… 1 One recent umbrella review suggested that maternal smoking during pregnancy was strongly associated with the development of ADHD symptoms in their children. 2 When mothers inhale smoke from cigarettes, nicotine distilled from the tobacco is rapidly metabolized in the liver to cotinine, which may disrupt the maturation of the central nervous system, resulting in later development of ADHD symptoms in their offspring. 3 In China, however, the prevalence of smoking among women is low, whereas among men, it is high (2.1% vs 50.5% in 2018).…”