Safety Showcase
Lead May Hinder Recovery From Brain Injury
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Lead exposure at a young age not only impedes brain development, but also can affect recovery from brain injury, new research in rats shows.
Scientists have known for decades that when infants and children are exposed to lead, it can harm brain formation and cause learning and behavioral problems later in life.
The new study by researchers at Jefferson Medical College in Philadelphia found that young rats exposed to low levels of lead take significantly longer to recover from a brain injury than animals that were not exposed. The findings were presented Monday before the Society of Neuroscience's annual meeting in San Diego.
Jay Schneider, a professor of pathology, anatomy and cell biology at the college, part of Thomas Jefferson University, notes that the young brain is extremely "plastic" and normally has great capacity to repair itself after injuries.
Yet, while scientists know that lead exposure affects the developing nervous system into adulthood, no one had looked at the effects of lead exposure on the response of the brain to a later injury.
In the experiment, Schneider and colleagues injured a specific part of the brain that controls the hind limbs in two groups of rats, one exposed to lead and one not exposed.
They found that while there was some recovery of function in both groups, those exposed to lead did not recover as fully or as quickly as the unexposed animals.
With one functional test, they compared the animals' ability to walk across a narrow beam -- something rats normally do easily.
"When we create the brain damage, initially all the animals make errors. But the control animals very quickly recover and make far fewer mistakes in the next week. The lead-poisoned animals take longer to improve and improve much less," Schneider said.
"These results potentially add one more item to the long list of reasons why preventing lead exposure early in life is so important," he added.
Schneider said his team wants to do further studies over a longer period on animals to determine if lead-poisoned animals eventually recover to the same degree. They also hope to determine if there is a threshold amount of lead exposure that impedes the brain's ability to recover following injury.
Reprinted with permission. © 2004: Scripps Howard News Service. All rights reserved throughout the world.