Newswise — Mayo Clinic researchers have found that an individual’s educational 
and career paths impact Parkinson’s disease risk later in life. This report 
will appear in the Nov. 22 issue of the journal Neurology, 
http://www.aan.com/publications/journal/index.cfm.
The investigators, led by Walter Rocca, M.D., a Mayo Clinic epidemiologist, 
discovered the highest increase in Parkinson’s risk in people with nine or 
more years of education. They also found that risk level rises as years of 
schooling increase. Occupationally, physicians had the greatest increased 
risk for Parkinson’s compared to the general population, while those employed 
as construction and extractive workers (e.g., miners, well drillers), 
production workers (e.g., machine operators, fabricators), metalworkers and 
engineers had the lowest risk increase. The researchers also note that this 
study did not find farmers and other agricultural workers at increased risk 
for Parkinson’s. 
The Mayo Clinic investigators advise caution in interpreting this study. “Our 
findings for education and occupation are complex, and therefore they need to 
be interpreted with care,” says Roberta Frigerio, M.D., the study’s first 
author and former Mayo Clinic research fellow. “These factors may be 
surrogates for a variety of exposures, physical activity, personality or 
socioeconomic status. Further studies are needed to interpret our findings.” 
Demetrius (Jim) Maraganore, M.D., Mayo Clinic neurologist and study 
investigator, agrees. “We really can’t say from this study that education and 
occupation are causal factors in Parkinson’s disease; we can only say that 
they are associated,” says Dr. Maraganore. “I don’t think that schooling or 
wearing a stethoscope causes brain cells to degenerate or that digging holes 
with a digger protects your brain cells from atrophy, but I think that these 
are indirect indicators of factors that may relate to brain degeneration. And 
now what we need to do is use these clues to try and identify those molecular 
level events that differentiate these people.” 
Suggested Applications of Study Findings 
The utility of the study’s findings concerning occupation, education and 
Parkinson’s disease risk is primarily informational rather than actionable 
for members of the public, according to Dr. Maraganore. This is especially 
true in light of the relatively low overall lifetime risk for Parkinson’s for 
any given person, he says. 
“Really, nobody should do anything differently based on these findings,” says 
Dr. Maraganore. “These findings are not at all intended to change anybody’s 
behaviors. I think that the bottom line is that we’re talking about going 
from a baseline risk of 2 percent to develop Parkinson’s disease during a 
lifetime to a risk of 4 percent if you are highly educated or a physician, or 
1 percent if you are less educated or more physically active. So, I wouldn’t 
change your schooling plans or your occupation based on these findings. I 
would just welcome these findings as new clues about possible causes of 
Parkinson’s disease that will hopefully lead to the ultimate answers.” 
Dr. Maraganore also notes that the study’s findings should be reassuring to 
farmers, welders or other metalworkers, who were not found in this study to 
be at increased risk for Parkinson’s due to their occupations, in contrast to 
previous studies. 
Potential Explanations of the Study’s Findings 
The researchers explain that the increased Parkinson’s risk found for 
physicians and more educated individuals could be partly explained by earlier 
recognition and detection of the disease, in addition to better access to 
specialized medical care. However, nonphysicians and physicians in the study 
had a similar time between onset of symptoms and diagnosis of Parkinson’s, 
which would speak against increased recognition of the disease due to 
education or profession. 
The explanation for the four occupational groups found to have a reduced risk 
of Parkinson’s compared to the general population also remains uncertain, 
according to the investigators. The findings may be due to chance, some bias 
due to higher nonparticipation rate in the telephone interview portion of the 
study among these occupational groups, or to confounding due to lower 
education and resulting decreased recognition of Parkinson’s. Occupation may 
be a surrogate for physical activity level in the findings, leading to a 
higher risk in more sedentary professions such as physicians and lower risk 
in service occupations which involve greater motor skills use. The study 
investigators emphasize that these associations do not imply causality, 
however. Physical activity (recreation or work related) may protect against 
Parkinson’s disease, but it is also possible that people predisposed to 
develop Parkinson’s disease avoid strenuous activity earlier in life.
Dr. Maraganore explains that early Parkinson’s disease could account for some 
of the educational and occupational risk findings. “It could be that people 
with Parkinson’s disease have premorbid personalities that make them like 
education,” he says. “For example, dopamine is the reward chemical in the 
brain and is deficient in the brains of people with Parkinson’s disease. So, 
if you have a long-standing deficiency of dopamine, you may be less likely to 
party and more likely to sit at your desk and study. So, in these ways early, 
undetected disease can subtly shape your pattern of behaviors, giving the 
impression that education is a risk factor for the disease when in fact it’s 
really an early manifestation.” 
How the Study Was Conducted 
In this study, the researchers identified medical records of all individuals 
who had developed Parkinson’s from 1976 to 1995 in Olmsted County, Minn., 
home of Mayo Clinic. All Parkinson’s patients were then matched to someone 
similar in age and gender who did not have Parkinson’s. The investigators 
collected information about education and occupations from a medical record 
review and also a telephone interview with the study individuals, using the 
1980 Standard Occupational Classification to code each person’s profession. 

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