Lead linked to aging in older brains

Courtesy of Associated Press

Could it be that the "natural" mental decline that afflicts many older people is related to how much lead they absorbed decades before? That's the provocative idea emerging from some recent studies, part of a broader area of new research that suggests some pollutants can cause harm that shows up only years after someone is exposed. The new work suggests long-ago lead exposure can make an aging person's brain work as if it's five years older than it really is. Other pollutants like mercury and pesticides may do the same thing. In fact, some recent research does suggest that being exposed to pesticides raises the risk of getting Parkinson's disease a decade or more later.

Research with lead can measure the amount that has accumulated in the shinbone over decades and get a read on how much lead a person has been exposed to in the past. Lead in the blood, by contrast, reflects recent exposure. Virtually all Americans have lead in their blood, but the amounts are far lower today than in the past. The big reason for the drop: the phasing out of lead in gasoline from 1976 to 1991. Because of that and accompanying measures, the average lead level in the blood of American adults fell 30 percent by 1980 and about 80 percent by 1990.

In 2006, researchers published a study of about 1,000 Baltimore residents. They were ages 50 to 70, old enough to have absorbed plenty of lead before it disappeared from gasoline. They probably got their peak doses in the 1960s and 1970s, Schwartz said, mostly by inhaling air pollution from vehicle exhaust and from other sources in the environment. The researchers estimated each person's lifetime dose by scanning their shinbones for lead. Then they gave each one a battery of mental ability tests. In brief, the scientists found that the higher the lifetime lead dose, the poorer the performance across a wide variety of mental functions, like verbal and visual memory and language ability. From low to high dose, the difference in mental functioning was about the equivalent of aging by two to six years.

For younger people, prevention is a clearer strategy, researchers said. They are calling for tougher federal standards on lead exposure in the workplace. And plenty of low-income neighborhoods could use a strong effort to remove lead from old houses, many of which still have lead paint.

Steve - I love how the reporter call this research a "provocative idea." Lead, mercury, arsenic, etc., etc., etc. are NEUROTOXINS. They are ever-present in our environment. From a genetic and lifestyle standpoint, many have weak defenses against these substances. Of course it is going to hinder our brain function.

The term prevention used by researchers in not accurate in this case. While there are many steps we can take to curtail exposure and buildup, unless you live in a bubble, you cannot prevent toxic exposure in the world we live in.