Childhood exposure to lead is associated with shrinking ("volume loss") of specific parts of the brain in adulthood, finds a related study in this week's PLoS Medicine. Dr Kim Cecil and colleagues (University of Cincinnati, USA) studied the association between exposure to lead in the uterus and during early childhood and brain volume in adulthood.
Childhood lead exposure has been linked to various types of brain damage, leading to problems such as abnormal thinking and behavior. But up until now, researchers have known little about how lead damages the brain in this way or about which brain regions get damaged by exposure to low to moderate levels of lead in childhood.
Dr Cecil and colleagues studied adults who were born in a poor area of Cincinnati during a time when it had a high concentration of older lead-contaminated housing. They recruited 157 such adults, aged between 15 and 17 years, who agreed to undergo specialized brain scans known as magnetic resonance imaging.
The researchers found that exposure to lead as a child was linked with brain volume loss in adulthood, especially in men. There was a "dose-response" effect--in other words, the greatest brain volume loss was seen in participants with the greatest lead exposure in childhood. The specific regions of the brain involved were those responsible for organizing actions, decisions, and behaviors (known as "executive functions"), regulating behaviors, and coordinating fine movements (known as "fine motor control").
"This analysis," say the authors, "suggests that adverse cognitive and behavioral outcomes may be related to lead's effect on brain development producing persistent alterations in structure."
In an expert commentary on this study, Dr David Bellinger (Harvard Medical School, Boston, USA)--who was uninvolved in the research--says: "the associations observed by Cecil and colleagues provide a clear warning sign that early lead exposure disrupts brain development in ways that are likely to be permanent."
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