Lead Exposure in Childhood Results in Permanent and Pervasive Brain Damage
Wednesday, December 02, 2009
A new study reveals that childhood lead exposure causes permanent brain damage in which no regions of the brain are spared.
The study, using a kind of magnetic resonance imaging to visually evaluate brain function in adults, shows that regions of the brain that control emotional, behavioral and cognitive functions have decreased activity. Regions of the brain that typically don’t govern these “executive functions” show increased activity, likely as a means of compensation, but the amount is insufficient, according to Kim Cecil, PhD, an imaging research scientist at Cincinnati Children’s and the study’s lead author.
Dr. Cecil presented her study at the annual meeting of the Radiological Society of North America in Chicago.
“Lead exposure can produce irreversible brain injury that begins in childhood and lasts throughout life,” says Dr. Cecil. “We have evidence that the action region of the brain, the pathways that lead to and from this region, and the wiring and insulation of white matter – one of the main components of the central nervous systems – are affected. There is also a loss of other key components of the central nervous system in the brain’s frontal lobe. It all adds up to the fact that the negative affects of lead are very powerful.”
Dr. Cecil’s study involved 33 adults who were enrolled as infants in the Cincinnati Lead Study – the world’s longest-running study of individuals exposed to lead in childhood. The mean age of the study participants was 21. Their blood lead levels ranged from 5 to 37 micrograms per deciliter, with a mean of 14. Such levels would be considered moderately elevated by today’s standards.
The Centers for Disease Control and Prevention and the World Health Organization consider a blood lead level of 10 micrograms per deciliter or above a cause for concern. Research shows, however, that there is no known safe lead exposure level.
Each participant in Dr. Cecil’s study underwent functional magnetic resonance imaging – a type of specialized MRI scan – while performing two tasks to measure the brain’s executive functioning related to attention and inhibition. The images revealed decreased activity in areas of the brain that typically managed these executive functions, with increased but insufficient activity in other areas of the brain, suggesting an effort to compensate for the loss of activity.
“The brain’s white matter, which organizes and matures at an early age, adapts to lead exposure, while the frontal lobe, which is the last part of the brain to develop, incurs multiple insults from lead exposure as it matures,” says Dr. Cecil. “Many people think that once blood lead levels decrease, the effects should be reversible, but lead exposure has harmful and lasting effects. That’s why prevention is key.”
Co-authors of the study are Caleb Adler, MD, and Kim Dietrich, PhD, both of the University of Cincinnati College of Medicine, and Bruce Lanphear, MD, Simon Fraser University in Canada.
About Cincinnati Children's Hospital Medical Center
Cincinnati Children’s Hospital Medical Center is one of 10 children’s hospitals in the United States to make the Honor Roll in U.S. News and World Reports 2009-10 America’s Best Children’s Hospitals issue. It is #1 ranked for digestive disorders and is also highly ranked for its expertise in respiratory diseases, cancer, neonatal care, heart care, neurosurgery, diabetes, orthopedics, kidney disorders and urology. One of the three largest children’s hospitals in the U.S., Cincinnati Children’s is affiliated with the University of Cincinnati College of Medicine and is one of the top two recipients of pediatric research grants from the National Institutes of Health.
President Barack Obama in June 2009 cited Cincinnati Children’s as an “island of excellence” in health care. For its achievements in transforming health care, Cincinnati Children’s is one of six U.S. hospitals since 2002 to be awarded the American Hospital Association-McKesson Quest for Quality Prize for leadership and innovation in quality, safety and commitment to patient care. The hospital is a national and international referral center for complex cases. Additional information can be found at www.cincinnatichildrens.org.