Research links lead exposure to Alzheimer’s

The new study involved
primates.

SCRIPPS HOWARD

PROVIDENCE, R.I. — A scientific team headed by a researcher at the University of Rhode Island has found a link between early exposure to lead in the environment and the onset of Alzheimer’s disease in old age.

The link was discovered by feeding lead to baby monkeys and then studying their brains 23 years later. Monkeys don’t get Alzheimer’s disease, but every monkey exposed to lead in the study had an accumulation of plaque on their brains similar to what occurs in people who suffer from Alzheimer’s.

Nasser Zawia, a pharmacy professor at URI, said he thinks his work is significant because it is the first time scientists have shown links between lead and Alzheimer’s in primates. He has done similar research showing links involving mice and rats.

Zawia and a spokesman for the national Alzheimer’s Association cautioned that the study should not prompt lead-poisoning victims or their families to fear that their lead exposure will automatically lead to Alzheimer’s.

William H. Thies, vice president of medical and scientific relations at the Alzheimer’s Association in Chicago, called the study “good, solid basic science,” but he also emphasized “making a leap from this paper to saying Alzheimer’s disease is caused by early childhood lead exposures doesn’t fit.”

Some 5 million people are afflicted now, according to the association, and some experts predict there may be 16 million victims by 2050. Some fear Alzheimer’s could bankrupt the Medicare budget.

Zawia has studied the neurological effects of lead and other metals for eight years, using some $700,000 in grants from the National Institutes of Health.

But he said it was a rare, serendipitous find several years ago when he learned that other researchers were working with a small group of monkeys to determine the effect of lead poisoning on their intelligence — research that had nothing to do with Zawia’s work with Alzheimer’s and other diseases.

The researchers worked with two small groups of monkeys, exposing one to lead for 400 days and keeping the other group lead-free. The amount of lead exposure was designed to mimic the levels children are often exposed to. The monkeys were turned over to a National Institutes of Health facility in North Carolina where they lived for 23 years. In 2003, the monkeys were put to death and their tissues examined.

Zawia and his researchers were able to obtain samples and do complex analyses of protein and plaque development. They found that the lead exposures at a young age reprogram the way genes express themselves during the individuals’ lives. Specific genes became more active and created the proteins that make the peptides that create the plaque, said Zawia.