Body lead load linked to dementia
Older adults with higher amounts of lead in their bones exhibit greater memory impairment than adults with low lead levels, researchers have found. In a study of men and women aged 55 to 67 years, higher lead levels were associated with poorer performance on tasks used to assess memory deficits. 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. 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 levels were less able to remember specific patterns or the locations of items. Raised bone lead levels have been linked to a range of chronic health problems, including diminished brain function, kidney and heart disease. Many of these occur at levels a fraction the UK exposure limits. Over 8,000 workers in the UK are monitored for lead exposures at work each year, but only blood lead readings are obtained. These can be useful in identifying acute poisoning cases, but have no use in detecting chronic health problems. Diseases related to lead exposure can be the result of a cumulative dose over years, often occurring in later life, something that cannot be identified in blood tests but is apparent from bone lead tests.
Source: Environmental Health News. E van Wijngaarden, JR Campbell and DA Cory-Slechta. Bone lead levels are associated with measures of memory impairment in older adults. Neurotoxicology, published online 2009. doi:10.1016/j.neuro.2009.05.007.