Range of jobs tied to degenerative brain disease

A wide range of occupations, from farming to teaching, may be potential risk factors for degenerative brain diseases, such as Alzheimer's and Parkinson's disease, research findings suggest.

In a study of more than 2.6 million U.S. death records, researchers found that a variety of jobs were associated with an increased risk of death from several forms of brain degeneration, namely Alzheimer's and Parkinson's disease, early-onset dementia and motor neuron disease.

Many of the associations had been seen in earlier research and could potentially be explained by on-the-job exposures to the chemicals that farmers, welders and hairdressers routinely use or inhale.

Definition Alzheimer's disease
Alzheimer's disease (AD), one form of dementia, is a progressive, degenerative brain disease. It impairs memory, thinking, and behavior.

Memory impairment is a necessary feature for the diagnosis of this or any type of dementia. Change in one of the following areas must also be present: language, decision-making ability, judgment, attention, and other areas of mental function and personality.
More information: Alzheimer's disease

Other findings, however, such as the elevated disease risks among teachers, clergy and bank tellers, are not easily explained, according to the researchers, led by Robert M. Park of the National Institute for Occupational Safety and Health, Cincinnati, Ohio.

Studies such as this, where death certificates are used to find associations between occupation and disease risk, have their limits. For one, death records are a less-than-ideal measure of a person's work history, Park told.

"At best," he noted, such research can tease out general patterns that can then be studied further.

Parkinson's disease
Parkinson's disease is a disease of the central nervous system that causes problems with body motions, including tremor (shakiness), rigidity (muscle stiffness), slowed body movements, unstable posture and difficulty walking. It happens when nerve cells (neurons) in a part of the brain called the substantia nigra gradually die. These cells normally produce dopamine, a chemical that helps to relay messages between areas of the brain that control body movement. The death of cells in this area of the brain leads to abnormally low levels of dopamine, which makes it difficult for a person with Parkinson's disease to control muscle tension and muscle movement, both at rest and during periods of activity.In their analysis, Park and his colleagues found that the bank tellers, clergy, aircraft mechanics and hairdressers had highest odds of dying from . For , the highest risks were among biological scientists, teachers, clergy members and other religious workers.