Higher bone-lead levels associated with dementia.

Jun 26, 2009

van Wijngaarden, E, JR Campbell and DA Cory-Slechta. 2009. Bone lead levels are associated with measures of memory impairment in older adults. Neurotoxicology doi:10.1016/j.neuro.2009.05.007.

Synopsis by Kim Harley, Ph.D.

Older adults with higher amounts of lead in their bones exhibit greater memory impairment than adults with low lead levels.

In a study of men and women 55 to 67 years old, higher lead levels were associated with poorer performance on tasks used to assess memory deficits. Poor performance on these same tasks is frequently observed among adults with Alzheimer’s Disease.

Although other studies have found associations between lead exposure and cognitive deficits in older adults, this is the first study to link lead exposure with specific measures of memory impairment that are characteristic of Alzheimer’s Disease.

Alzheimer’s Disease is the most common form of dementia, the loss of memory serious enough to interfere with normal life. Alzheimer’s Disease affects more than 5 million Americans. The disease is characterized by impaired ability to learn new information or recall old information, as well as other alterations of thinking and behavior.

The causes of Alzheimer’s Disease are unknown. However, some studies suggest that environmental exposures may increase the risk of the disease.

In this study, the researchers measured lead levels in the bones of the shin and heel of 47 volunteers using X-ray fluorescence. Lead levels in bone reflect exposure over several years or even decades.

Individuals with higher bone lead level were less able to remember specific patterns or the locations of items. The researchers did not evaluate Alzheimer’s Disease directly, but rather looked for early signs of memory impairment in healthy adults.

Lead is a metal known to interfere with brain development and function and influence high blood pressure and heart effects. Even though lead-based paint and gasoline were banned decades ago, the metal continues to contaminate air and water from such sources as house dust, soil in yards, plumbing pipes and certain kinds of exhaust.