Brain MRI shows lead's effects decades later

By Theresa Pablos, AuntMinnie staff writer

November 17, 2020 -- MRI scans revealed structural brain changes in a group of middle-aged adults who were exposed to lead as children. The findings were part of a long-term study published on November 17 in JAMA.

The study included 564 participants born in one New Zealand town in 1972 and 1973. Those in the group, which has been studied nearly continuously, grew up during the peak era of leaded gasoline and had elevated blood levels as children.

Three decades later, the participants, now age 45, had small but significant changes in brain structure corresponding to their lead exposure dosage at age 11. The findings may reflect the long-term consequences of lead exposure, according to the authors.

MRI scans revealed the study population had approximately 1 cm2 less cortical surface area and 0.1 cm3 less hippocampus volume -- regions that affect memory, learning, and emotion. Participants also lost an average of two IQ points for each 5 µg/dL more lead they carried as children.

Furthermore, adults with the highest childhood lead exposure had structural deficits in their white matter. And while participants reported no loss of cognitive abilities, people close to them said they had small daily problems with memory and attention.

"We find that there are deficits and differences in the overall structure of the brain that are apparent decades after exposure," stated Aaron Reuben, a co-first author on the study and a doctoral candidate at Duke University, in a press release. "And that's important because it helps us understand that people don't seem to recover fully from childhood lead exposure and may, in fact, experience greater problems over time."

This population with elevated lead blood levels as children may continue to experience more differences as they age, the authors noted. Reuben and colleagues are particularly curious whether adults with childhood lead exposure may be at an increased risk for degenerative disease in old age.

Copyright © 2020

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