Blood Lead Level, Urinary Porphobilinogen and Serum Acetylcholine in Nigerian Children with Autism Spectrum Disorder

Purpose: Autism spectrum disorder (ASD), a common neurodevelopmental disorder characterized by communication and behavioral deficits, remains a subject of unknown etiology. However, the interplay of heavy metal (e.g., Lead) toxicity, which can disrupt the heme synthesis pathway and lead to elevated metabolites like porphobilinogen (PBG), and altered neurotransmission have been implicated in the development of ASD. Therefore, this study examined blood lead level (BLL), serum acetylcholine (ACh), and urine PBG levels in Nigerian children with ASD.
Methods: Forty seven participants aged 3 to 12 years were recruited, including 16 children diagnosed with ASD (cases), 16 children with neurodevelopmental disorders (NDDs) excluding ASD (positive controls), and 15 neurotypical children (negative controls). BLL was measured using atomic absorption spectroscopy (AAS), while serum ACh and urinary PBG levels were assessed using ELISA and modified Mauzerall-Granick methods, respectively.
Results: Mean BLL did not differ significantly between groups, though concerningly high BLLs (up to 112 µg/dL) in some participants indicated significant exposure. Urinary PBG levels were significantly higher in cases (4.03 ± 0.57 µmol/mmol creatinine) compared to negative controls (3.29 ± 0.46 µmol/mmol creatinine). Serum ACh levels were significantly lower in positive controls (439.10 ± 260.69 pg/mL) compared to negative controls (843.19 ± 339.63 pg/mL) but not significantly lower in cases (588.55 ± 239.09 pg/mL). No significant correlation was found between BLL, PBG, and ACh.
Conclusion: The study findings are consistent with the potential metal-induced metabolic perturbation in ASD etiology and the role of altered cholinergic neurotransmission in NDD development.