Study finds evidence that lead "erases" memory

MADRID (EFE).— Lead is a toxic metal that the body doesn't metabolize , but rather accumulates. A study of Mexican children shows a statistically significant relationship between greater exposure to this element and higher rates of memory impairment.

The research, published in "Science Advances," was co-authored by Mexicans and Americans who analyzed lead exposure during pregnancy and early childhood in 576 children in Mexico City . All had detectable levels of the metal in their blood.

The study found a “statistically significant relationship indicating that greater lead exposure was associated with worse performance” on a memory test , explained Katherine Svensson of the Icahn School of Medicine at Mount Sinai.

Children aged 6 to 8 participated in a delayed memory-to-sample (DMTS) test. This test involves showing an image for a few seconds and then removing it. After a delay, children are shown several images and have to identify which one is the same as the first one they saw.

The team plotted the children's performance on that test based on a statistical model that used the highest and lowest blood lead levels in the cohort.

Previous studies had shown that children with prenatal lead exposure had lower scores on the DMTS, but it was unclear whether this was due to a reduced ability to form memories or retain them. The new research attributes this phenomenon to the latter.

The study used data from the Progress cohort, which follows mothers and children from pregnancy through adolescence. Blood lead measurements were taken in the second and third trimesters of pregnancy and between ages 4 and 6. Higher postnatal lead concentrations in blood samples from children aged 4 to 6 were associated with a higher rate of forgetfulness . Measurements were taken at that age, and DMTS tests were performed between ages 6 and 8.

The researcher added that "there is no significant difference" between prenatal or postnatal lead exposure, as evidence suggests that exposure even at very low doses "is harmful at any age."

The researchers observed that a mother's higher intelligence quotient (IQ) was associated with better test performance in her children . However, Svensson emphasized that these results "do not allow us to conclude" that a higher maternal IQ reduces the effect of lead exposure ; rather, it is one of the beneficial variables for children's neurodevelopment, and may therefore be a protective factor.

“Although children with mothers with higher maternal IQs performed better, we observed that all children were affected by lead exposure.”

No level of lead is considered safe for child development , either during pregnancy or infancy, so it is essential to continue providing education to the general population to avoid exposure to lead sources so that levels do not continue to accumulate.

People are often exposed to lead through air pollution, dust from old lead-based paints, food and kitchen utensils (if they contain lead), or water pipes. Children are especially susceptible to this poisoning because they are still developing.

Accumulating evidence from studies shows that, in utero and in infancy, lead-induced toxicity, even at low levels , causes impaired performance on global cognitive assessments involving attention, intelligence, visuospatial skills, processing speed, and gross motor functions.

“From a public health perspective, the results highlight the importance of interventions to reduce lead exposure in children, as even “low levels can have detrimental effects on children's cognitive function and development,” the study warns.