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| |  Imaging Studies Find Life-Long Detriments to Lead Exposure: Presented at RSNA By Ed Susman CHICAGO -- December 3, 2009 -- Functional magnetic resonance imaging (MRI) studies indicate that lead exposure in childhood appears to lead to life-long problems with attention and impulsivity control, researchers said here at the Radiological Society of North America (RSNA) 95th Annual Meeting. The researchers found a dose-response relationship with lead exposure -- the higher the blood lead levels, the more likely were individuals to have decreased activity in parts of their brain responsible for executive functioning. “What we have found is that no region of the brain is spared from lead exposure,” said Kim Cecil, PhD, University of Cincinnati College of Medicine and Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, in an RSNA-sponsored press briefing on December 1. Researchers have collected data prospectively on 376 infants in the Cincinnati Lead Study. The children who lived in areas considered high risk for lead exposure due to the age of homes and proximity to highways were followed from 1979 through 1987. In the study reported at RSNA, Dr. Cecil described functional MRI scans performed on 33 individuals -- 14 women and 19 men -- with a mean age of 21 years. She said that the higher a patient’s childhood blood lead levels, the more likely they were to have deficits in executive functioning. In this group, the mean childhood blood lead level was 14.2 mcg/dL, and their mean group intelligence quotient (IQ) score was low at 86.7. “Many people think that once lead blood levels decrease, the effects should be reversible,” Dr. Cecil said. “But in fact, lead exposure has harmful and lasting effects.” Previous research has shown that lead exposure in childhood is associated with diminished intelligence -- most commonly low IQ scores. But less is known about lead’s effect on other functional areas of the brain, including attention, impulsivity control, decision making, abstract thinking, and motivation rewards. Dr. Cecil and her colleagues performed functional MRI on a selection of these patients -- the continuous performance task assessed attention in 33 patients, and the Go-No-Go test evaluated impulsivity in 26 patients. The researchers found that on the attention task, higher blood lead levels were associated with decreased activity in parts of the brain associated with attention. Similar results were observed among those taking the impulsivity task, Dr. Cecil said. However, the brain attempted to “compensate” for deficiencies, she added, as unexpected brain areas lit up during executive functioning task performance. “Our functional MRI studies show both damage and compensation associated with childhood blood levels of lead,” she said. [Presentation title: Functional MRI Studies Examining Executive Functioning in Adults With Childhood Lead Exposure. Abstract SSJ16-06]
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