Positive and inverse correlation of blood lead level with erythrocyte acetylcholinesterase and intelligence quotient in children: implications for neurotoxicity

Abstract

Blood lead level (BLL) is insufficiently sensitive for early detection of Lead-induced neurotoxicity (LIN). This study determined the possible role of the combination of BLL, intelligent quotient (IQ) and erythrocyte acetylcholinesterase (AChE) activity in the early detection of LIN in Children. Apparently healthy children (n=309) from eight public primary schools in Ibadan, Nigeria were recruited and classified into: children with Elevated BLL (EBLL) and children with Acceptable BLL (control) based on CDC cut-off for childhood lead exposure. Neurological indices (speech, memory, cranial nerves and cerebellar functions), IQ, BLL and erythrocyte AChE activity were assessed using standard methods, Standard Progressive Matrices, AAS and HPLC respectively. Statistical analysis involved Student’s t-test, Pearson’s correlation and multivariate regression. p<0.05 was considered significant. There were 169 (54.7%) children with EBLL while there were 140 (45.3%) control children. Both groups exhibited normal speech, memory, cranial nerves and cerebellar functions. However, IQ was lower in EBLL children (85.9±11.6) compared with control (91.5±14.0) while BLL and AChE activity were higher in EBLL children (0.4±0.1 µmol/l; 117.5±25.5 µkat/l) compared with control (0.2±0.0 µmol/l; 59.4±10.2 µkat/l). BLL showed inverse correlation with IQ (r=–0.134, p=0.019) but positive correlation with AChE (r=0.978, p≤0.001). 16.2% of the observed variation in BLL could be accounted for by AChE using the equation; [BLL=–0.007+0.003 AChE] p<0.05. Elevated blood lead level is prevalent among the school children and appears to have adverse effect on their IQ. Erythrocyte AChE could be a promising marker for early recognition of significant environmental lead exposure and lead-induced neurotoxicity in children.

The effect of lead exposure on IQ test scores in children under 12 years: a systematic review and meta-analysis of case-control studies

“…At concentrations above 10 μg/dL, the IQ score was much lower than at concentrations below 10 μg/dL [ 27 ]. In another study performed at a concentration of 10 μg/dL compared to 5 μg/dL, the IQ score in the case group (85.9 11 ± 11.6) and in the control group (91.5 ±14.0) showed a higher IQ score for lower concentrations [ 28 ]. In another study based on the Beery VMI Saudi-based standard scores test, it was found that at concentrations below 10 μg/dL, the IQ score was 101.39 ± 14.18, while at concentrations above 20 μg/dL, the IQ score decreased to 85.14 ± 12.94 [ 29 ].…”

Environmental and public health repercussions of the heavy metal lead (Pb) in the pediatric population

“…This correlates with a supralinear association between lead concentrations and neurobehavioral prognosis. Another finding indicated that blood lead level is inchoately sensitive to recognise or detect lead-induced toxicity early [22]; and suggests erythrocyte AChE as a marker for early detection of veritable environmental lead exposure and lead-induced neurotoxicity in children. Universal cognitive potential or general intelligence comprises diverse correlated attributes.…”