Mercury not linked to mental problems in older people

Reported by Susan Aldridge, PhD, medical journalist

A study shows that mercury in the blood does not worsen mental performance among older people.
Mercury is very toxic to the nervous system, especially in the form of methylmercury, which occurs in contaminated fish. Given that people are often advised to eat fish because of the beneficial omega-3 fatty acid content, there has been some concern that toxic exposures to mercury may be occurring.

Old people, in particular, could be more sensitive to mercury poisoning. A team at Johns Hopkins Bloomberg School of Public Health, Baltimore, looked at a possible association between mercury and cognitive performance in a group of 474 randomly selected participants from the Baltimore Memory Study.

The participants did 12 different neurobehavioral tests. Their blood mercury levels were measured and they were also asked about fish consumption. There was no consistent trend in the test results, suggesting that levels of mercury exposure in this group, at least, did not affect cognitive performance. People may eat fish for health, it seems, without worrying too much about any adverse effect on the nervous system.

Source
Journal of the American Medical Association 20th April 2005 Volume 293 pages 1875-1882