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ngd- The very first scientific paper on development (late 1970) concerned the effect of lead body loads that were less than the then threshold for the diagnosis of lead poisoning. Its conclusion: Lead at one-quarter of the threshold for poisoning is associated with hyperactive attention deficit disorder. There seems to be no better appreciation of this reality 50 years later…
More than three decades after they were found to have elevated blood lead levels as children, a group of middle-aged adults were found to have some small but significant changes in brain structure that corresponded to their dose of lead exposure in early life.
MRI scans at age 45 revealed some small but significant changes in the brains of the people who had higher lead exposures measured at age 11.
For each 5 micrograms per deciliter more lead they carried as children, the study participants lost an average of 2 IQ points by age 45. They also had slightly more than 1 square centimeter less cortical surface area and 0.1 cubic centimeter less volume in the hippocampus, which plays a role in memory, learning and emotions.
Participants with the highest childhood lead exposures also demonstrated structural deficits in the integrity of their brains’ white matter, which is responsible for communication between brain regions.
The research participants themselves reported no loss of cognitive abilities, but people close to them said otherwise, noting that they tended to display small everyday problems with memory and attention, such as getting distracted or misplacing items.
“We find that there are deficits and differences in the overall structure of the brain that are apparent decades after exposure,” said Duke University doctoral candidate Aaron Reuben, who is a co-first author on the study, which appears Nov. 17 in the Journal of the American Medical Association. “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.”