Older adults exposed to high levels of lead before the 1980s are showing signs of cognitive decrements as a result of long-term lead exposure in their communities, according to a study published in the online edition of Neurology, the scientific journal of the American Academy of Neurology.
The study involved 985 adults randomly selected throughout the city of Baltimore, Maryland. The participants were between the ages of 50 and 70 years old and had been exposed to higher levels of lead prior to the 1980s when lead had been used extensively in commercial products.
In determining the association between high levels of lead and lower cognitive performance, researchers tested the amount of lead in the tibia, or shinbone, since lead accumulates in bone. Participants also performed 20 cognitive tests to measure language, processing speed, eye-hand coordination, executive functioning, verbal memory and learning, and visual memory.
The study found higher tibia lead levels were consistently associated with worse cognitive performance on tests.
"The analysis showed the effect of community lead exposure was equivalent to two to six years of aging," said principal investigator Brian Schwartz, MD, with Johns Hopkins Bloomberg School of Public Health in Baltimore. "If lead is associated with lower cognitive performance, this may suggest possible treatment and prevention options for older adults."
In addition, the study found tibia lead levels were significantly higher in African Americans compared to Caucasians. Researchers say the difference likely represents the long-term higher environmental lead exposures sustained by African Americans in the United States, but could also be due to different bone mineral densities in African Americans compared to Caucasians.
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