Lead Hair Level Impact on Mongolian Children with Attention Deficit Hyperactivity Disorder

Background: High-prevalence disorders among children are attention-deficit/ hyperactivity disorder (ADHD) and lead exposure. The purpose of this study was to find out the relationship between ADHD symptoms and hair lead levels and neurocognitive function among Mongolian children. Methods: This was the case study to investigate the relationship between hair lead and ADHD in Mongolian school kids. We conducted a pair-matching case-control study with 30 ADHD cases and 30 non ADHD controls for 7 - 12 years of age school children, based on the same age, and sex. Recruitment process was conducted from June 2018 to December 2019. The case and control study children were systematically selected by structured diagnostic interviews, including caregiver interviews based on the Diagnostic and Statistical Manual of Mental Disorders, 4th ed (DSM-IV). Results: The average level of hair lead of the ADHD group was 1.45 ± 2.93 ppm and the control group’s lead level was 0.7 ± 1.59 ppm. We found ADHD-Combined (ADHD-C) patients showed the highest lead levels (p < 0.05). Hair lead levels were positively linked with the severity of ADHD symptoms, negatively linked with the Full-Scale Emotional Intelligence Quotient, but positively correlated with inattention and hyperactivity/impulsivity symptoms (p < 0.05). A statistically significant difference was discovered regarding the lead levels between the study and the control groups with significantly increased risks among boys and children whose mother had preeclampsia during the pregnancy period. Spearman’s correlation coefficient showed a notable negative connection between children’s hair lead levels with ADHD-Hyperactive (ADHD-H), and EQ (Emotional Quotient) level of children (−0.329 and −0.242, for original and log10 transformed, p < 0.001). The lead was linked with vulnerability to ADHD and symptom severity among those school-age children. Conclusions: The child hair lead exposure is one of the risk factors of the development of ADHD and decreasing FSIQ (Full Scale Intelligent Quotient) and EQ level of children and linked with susceptibility to ADHD and symptom severity in school-age children.