Functional MRI Demonstrates Impacts of Lead Exposure on Brain Organization

Bruce P. Lanphear, MD, MPH
Cincinnati Children’s Hospital Medical Center
P01ES11261 and R21ES13524

Bruce Lanphear and colleagues at the Cincinnati Children’s Environmental Health Center report new findings related to childhood lead exposure. Using functional magnetic resonance imaging, they saw evidence of reorganization of the language centers of the brains of young adults with a history of childhood lead exposure.

The Cincinnati Lead Study is an on­going epidemiologic investigation into the long­term effects of childhood lead exposure. Recruitment for the study was conducted from 1979 to 1984. The subjects have been followed from birth and have had extensive documentation of lead exposure, medical history, neuromotor function, and academic achievement. Forty­two young adults participated in the current study on language ability. Their average childhood blood lead level was 14.2 micrograms/deciliter­higher than the CDC level of concern of 10 micrograms/deciliter.

Magnetic resonance imaging was conducted on the subjects while they performed a ”verb generation task.” Subjects were instructed to silently think of verbs in response to a noun. For example, if the noun ”ball” was presented, the subject was expected to think of the verbs ”throw,” ”kick,” or ”hit.” Results showed significant diminished activity in known regions of the left hemisphere of the brain responsible for language ability with higher mean childhood blood lead levels along with compensation in regions in the right hemisphere.

Lead exposure is known to cause behavioral problems and learning deficits in children that persist into adulthood. The current study offers new findings that demonstrate a substantial adverse effect of lead on normal language centers, but also simultaneous recruitment of other brain regions. These results are among the first to suggest that lead exposure affects language ability and offer further confirmation of the deleterious effects of lead exposure on cognitive abilities.

Citation: Yuan W, Holland SK, Cecil KM, Dietrich KN, Wessel SD, Altaye M, Hornung RW, Ris MD, Egelhoff JC, Lanphear BP. The impact of early childhood lead exposure on brain organization: a functional magnetic resonance imaging study of language function. Pediatrics. 2006 Sep;118(3):971-7.