Adults who are exposed to lead as children experience permanent brain damage, according to a new study from the Cincinnati Children’s Environmental Health Center, which used functional magnetic resonance imaging (fMRI) to evaluate brain function.
“Lead exposure has been associated with diminished IQ, poor academic performance, inability to focus and increased risk of criminal behavior.” – Kim Cecil, Ph.D
The study was part of a larger research project, the Cincinnati Lead Study, which followed early childhood and prenatal lead exposure of 376 infants in high-risk areas of Cincinnati between 1979 and 1987.
The new study examined 33 adults enrolled as infants in the Cincinnati Lead Study, and found the participants’ mean blood lead levels ranged from 5 to 37 micrograms per deciliter with a mean of 14. The histories of the study participants showed deficiencies in I.Q., juvenile delinquency and criminal arrests.
Each participant in the study underwent fMRI while they performed two tasks, in order to measure the brain’s executive functioning, the part which governs decision making, attention, and control of impulses. The imaging results revealed that in order to complete a task that required inhibition, those people with increased blood lead levels required activation from additional regions within the frontal and parietal lobes of the brain.
“This tells us that the area of the brain responsible for inhibition is damaged by lead exposure and that other regions of the brain must compensate in order for an individual to perform. However, the compensation is not sufficient.” – Cecil
A second task during the imaging was designed to test attention, and it revealed an association between higher lead levels and decreased activation in the parietal region and other areas of the brain. Dr, Cecil said that the brain’s white matter, which matures at an early age, can adapt to lead exposure, but the frontal lobe, (the last part of the brain to develop), “incurs multiple insults” from exposure to lead as it matures.
“Many people think that once lead blood levels decrease, the effects should be reversible, but, in fact, lead exposure has harmful and lasting effects.” – Cecil
The study was presented at the annual meeting of the Radiological Society of North America (RSNA).
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