Researchers have found that certain occupations, including aircraft mechanics and bank tellers, are linked to an increased risk of death from several forms of brain degeneration, such as Alzheimer’s and Parkinson’s disease:

According to this Yahoo! News/Reuters story, a study of more than 2.6 million U.S. death records has linked a variety of jobs to a heightened risk of death from several forms of brain degeneration, namely Alzheimer’s and Parkinson’s disease, early-onset dementia and motor neuron disease.

The occupations range from farming to teaching.

While many of these job-disease relationships have been observed in previous research and could potentially be attributed to workplace exposures to chemicals (as is the case with farmers, welders and hairdressers), other links were harder to account for (such as the increased risk among teachers, clergy and bank tellers), according to the researchers, led by Robert M. Park of the National Institute for Occupational Safety and Health, Cincinnati, Ohio.

Park readily acknowledges the limitations of studies like this, which use death certificates to find associations between occupation and disease risk. “At best,” he notes to Reuters, such research can reveal general patterns that can then be studied further.

In their analysis, Park and his colleagues found that bank tellers, clergy, aircraft mechanics and hairdressers had the highest risk of dying from Alzheimer’s disease.

Biological scientists, teachers, clergy members and other religious workers had the biggest odds of dying of Parkinson’s disease.

The risk of death from pre-senile dementia–a form of dementia that surfaces before the age of 65–was most pronounced among dentists, graders and sorters in industries other than agriculture and, again, clergy.

Veterinarians, hairdressers and graders and sorters had the highest odds of dying from motor neuron disease, the most common form of which is amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease–a fatal degeneration of the central nervous system.

The findings were based on death records from 22 states for the years 1992 to 1998. The study has been published in the American Journal of Industrial Medicine.

One possible explanation that Park and his colleagues mentioned in the report, is that people in professional jobs have lower risks of common, lifestyle-related diseases like heart disease, which makes them more likely than others to perish from a neurodegenerative disorder. Of all deaths for the years studied (1992-1998), just over 4% were attributed, at least in part, to a neurodegenerative disease.