May 26, 2015

Household – Not Just Leisure Time -- Activities Protect Against Parkinson’s

Can regular daily exercise – not time spent working out at the gym or playing tennis, but doing housework, commuting to work, walking the dog –  lower one’s risk of developing Parkinson’s disease (PD)?

A large study suggests – yes, it can. Results of that study – published in a recent edition of Brain: A Journal of Neurology – was conducted by researchers at the Karolinska Institutet in Stockholm, Sweden.

Of course, it is already accepted wisdom that exercise – walking, dancing, yoga, tai chi -- helps people who already have PD. Now, this new study adds powerful evidence to the notion that regular everyday exercise brings a neuroprotective benefit.

After this blog reviewed last week’s news about two conditions (loss of smell and history of depression) linked to increased risk of developing PD, it’s good to share some information about reducing one’s risk of developing the disease.

A Large Study
In September, 1997, as part of the “Swedish National March Cohort,” 43,368 people (64.3% female, 35.7% male) completed a 36-page questionnaire that included detailed information about physical activity and exercise habits earlier in life. None had Parkinson’s disease.

Regular follow-ups of this large group ended in 2010, 13 years later.

During that interval, 286 participants – 128 women and 158 men – were diagnosed with PD.

Men at Greater Risk
While men represented only about 36% of all participants in the survey, they accounted for over 55% of all PD cases. That imbalance is consistent with data from the Parkinson’s Disease Foundation estimating that men are 1.5 times more likely to develop PD than women. Possible reasons?

  • Men are at greater risk of head injury and exposure to toxic chemicals, both of which are associated with the disease.
  • There is some possible protective effect of the female hormone estrogen on the nervous system.
  • There may be some increased genetic susceptibility to PD linked to the Y (male) chromosome.

All Activity, Not Just Leisure Time Pursuits
In the past, efforts to discern links between exercise and PD focused almost exclusively on leisure time activities: numbers of hours at the gym, riding the bike, lifting weights, gardening, etc. This Swedish study went further, by collecting information on all types of exercise, including housework, commuting, leisure time activity, and total daily physical activities, like walking the dog and washing  the car.

Researchers then converted all activity into “metabolic equivalent” (MET) hours per day, using estimated oxygen consumption associated with each type of activity.

The data led to these conclusions:
  • Participants who spent more than six hours per week on physical household and commuting activities had on average a 43 percent lower risk of developing PD than those who spent two hours or less per week on those activities. The risk was reduced slightly more for men than for women.
  • Although overall physical activity was associated with decreased PD risk, leisure-time exercise alone was not. 
  • Changes in leisure-time exercise between ages 30 and 49, or at age 50 or older, were not associated with PD risk one way or the other.
  • Not surprisingly, people who developed PD tended to be older at the beginning of the study (age 65 on average) than those who did not (age 50 on average).

The Study’s Strengths
Lead researcher Karin Wirdefeldt, who teaches epidemiology, biostatics and clinical neuroscience at Karolinska Institutet, said, “Our study has a number of strengths. This was a prospective study including both males and females, and all information on physical activity was assessed before the disease occurrence….”

She added, “Another major strength of this study is that we considered the entire spectrum of daily energy output, rather than purely focusing on dedicated exercising. Further, we conducted a rich set of sensitivity analyses to test the robustness of our findings.”



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