Findings presented on Alzheimer's disease, brain gymnastics, and lead

July 26, 2000

Keeping active outside work, either physically or mentally, in the midlife years may help prevent Alzheimer's disease, according to research at Case Western Reserve University.

Robert Friedland, professor of neurology, highlighted this research on Alzheimer's disease from CWRU's School of Medicine during one of two presentations he made at the American Academy of Neurology's 52nd Annual Meeting in San Diego in early May

Friedland's research team found that people with higher levels of non-occupational activities, such as playing a musical instrument, gardening, physical exercise or even playing board games, were less likely to develop Alzheimer's disease later in life.

"People who were less active were more than three times more likely to have Alzheimer's disease as compared to those who were more active," said Friedland, a neurologist at University Hospitals of Cleveland and primary author of the study.

This is the first study of its kind to examine levels of activity from at least five years before Alzheimer's symptoms appeared. The researchers used a questionnaire to collect data about participation in 26 activities -- passive as well as intellectual and physical. The subjects were 193 people with Alzheimer's disease, with a mean age of 73, and 358 healthy people, with a mean age of 71.

Among the activities categorized as passive were watching television, participating in social activities, and attending church. Intellectual activities ranged from reading and painting to jigsaw puzzles, woodworking, and knitting, whereas physical activity ran the gamut from gardening to racquet sports.

The healthy participants had been more active between the ages of 40 and 60 than had the patients with Alzheimer's, even after the data was adjusted to take into account differences, such as age, income, gender and education.

The study's findings also suggest that it is never too late to get started -- at least as far as intellectual activities are concerned.

"A relative increase in the amount of time devoted to intellectual activities from early adulthood (ages 20-39) to mid-adulthood (ages 40-60) was associated with a significant decrease in the probability of having Alzheimer's disease later in life," said Friedland.

This study builds on previous work showing that people with Alzheimer's had been less physically active and had lower levels of educational and occupational achievement than people without the disease. This latest research, however, suggests that it doesn't take a doctorate to ward off Alzheimer's -- an intellectually or physically stimulating hobby will also be helpful.

Passive activities, such as watching television, however, do not lower the risk for Alzheimer's disease.

"We believe public health measures should be instituted to enhance adult participation in physical and mental activities, and decrease participation in activities that involve little physical or intellectual stimulation, such as television," said Friedland.

The research suggests that the brain stimulation associated with intellectual and physical activities works against the neurodegeneration of diseases such as Alzheimer's. Although scientists cannot rule out the possibility that lower activity levels are themselves symptoms of the disease in its very early stages, Friedland believes that to be unlikely, because the study looked at levels of activity from at least five years before the onset of dementia.

On-the-job lead exposure may increase risk

A second study from Case Western Reserve University reported that occupational lead exposure may have long-term effects and dramatically increase the risk of developing Alzheimer's disease in later years. People who have worked in jobs with high levels of lead exposure are up to 3.4 times more likely to develop Alzheimer's disease.

"Lead exposure remains a major public concern because of its adverse effects on brain development and health in general, even with low exposure levels," said investigator Elisabeth Koss, assistant clinical professor of psychiatry at CWRU's School of Medicine and on staff at UHC. "This study suggests that we also need to be concerned because of very long-lasting changes to the nervous system that may increase the risk for Alzheimer's disease."

The study compared the occupational histories of 185 people with Alzheimer's disease to 303 people without Alzheimer's. Utilizing hazard lists developed by the National Occupational Exposure Survey, researchers estimated the probability of toxic exposure to a variety of agents used in each occupation. That occupation exposure was then multiplied by the number of years a person worked at a job to determine lifetime exposure.

In addition to lead, researchers examined exposure to aluminum, copper, iron, mercury, zinc and solvents (a group of chemicals including paint thinners, cleaning fluids, and benzene). Although previous studies have raised concerns about possible relationships between Alzheimer's and many of these metals, including aluminum and solvents, only lead exposure was found to increase the risk of Alzheimer's. The researchers believe that these concerns may have been due to the unrecognized effect of lead as many occupations involve multiple exposures to numerous potentially toxic materials.

"Although lead has long been known to be toxic -- and is believed to have affected the brains of some of the rulers of the Roman Empire, thereby causing its downfall -- its long-term damages are difficult to measure, and thus, the extent of its negative effects have been largely overlooked," said Koss.

In the workplace, people are most often exposed to lead by either breathing lead dust, which is considered to be the most toxic, or by direct skin contact. Activities that can expose workers to lead are:

* Smelting or casting lead

* Removing lead coatings (welding, brazing, cutting, sanding or blasting old paints)

* Heating, machining or spraying lead products

* Making lead products (lead-acid battery manufacturing, lead glazing pottery making, cable production, ammunition manufacture, production of lead pipe, cable shielding, electronic components, paint and ink manufacture)

In light of earlier studies that have shown a protective effect from education against Alzheimer's, the researchers statistically adjusted for participants' education levels, since people with less education are more likely to work in blue-collar jobs where there is a greater chance of toxic exposure than white-collar jobs,

The Alzheimer's patients in the study were also older than those without the disease. Koss noted that this could be related to a decrease in on-the-job toxic exposures due to more recent governmental regulations that enforce relatively safer work conditions.

"Public health efforts have been successful in removing lead from sources, such as gasoline and lead-soldered food and drink cans," commented Koss. "However, we need to remain vigilant about other sources of lead in the home and in the work place, including decaying old paint, contaminated soil or drinking water, hobbies and occupational exposure."
-end-
The American Academy of Neurology, an association of more than 16,500 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. For more information about the American Academy of Neurology, visit its Web site at http://www.aan.com. For online neurological health and wellness information, visit NeuroVista at http://www.aan.com/neurovista.

Case Western Reserve University

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