Spending more than 6 hours a day doing medium physical activity is linked to a 43% lower risk of developing Parkinson's disease, according to the latest study.
Researchers from Sweden's Karolinska Institutet in Stockholm report their findings in Brain: A Journal of Neurology. Study leader Dr. Karin Wirdefeldt, a researcher in medical epidemiology, biostatistics and clinical neuroscience, explains the strengths of their study:
"This was a prospective study including both males and females, and all information on physical activity was assessed before the disease occurrence, making recall bias and reverse causation less likely."
"Another major strength of this study is that we considered the entire spectrum of daily energy output, rather than purely focusing on dedicated exercising," she adds. "Further, we conducted a rich set of sensitivity analyses to test the robustness of our findings."
A prospective study is one that follows a group of individuals over a period and looks for outcomes, such as the development of a disease.
Dr. Wirdefeldt and colleagues analyzed comprehensive information on 43,000 men and women collected over 12 years as they participated in the Swedish National March Cohort. Through extensive questionnaires, the participants gave information on all kinds of physical activity, including that associated with household chores, commuting, job-related and leisure, as well as a daily total.
To be able to analyze the data statistically, the researchers converted the activity information into metabolic equivalent (MET) hours per day, using estimated oxygen consumption associated with each type of activity.
Medium amount of physical activity linked to 43% lower risk of Parkinson's
None of the participants had Parkinson's diseases at the start of the study follow-up period in October 1997. Over the follow-up, which lasted until the end of 2010, information was collected on each participant until either Parkinson's disease was diagnosed, they died or left the country.
During the follow-up, 286 of the participants were diagnosed with Parkinson's disease.
In their statistical analysis, the researchers found participants who spent more than 6 hours a day doing physical activity related to household chores and commuting had a 43% lower risk of developing Parkinson's disease, compared with counterparts who only spent 2 hours a day on the same physical activity.
Also, in men, a medium level of total physical activity - defined as an average of 39.1 MET hours per day - was linked to a 45% lower risk of developing Parkinson's, compared with a low level of total physical activity.
When the team looked only at leisure time physical activity, they found no links with Parkinson's disease risk.
New analysis of pooled data from other studies supported the findings
The team also carried out a fresh analysis where they pooled the data from the study with that of five earlier prospective studies and found it supported the finding that more physical activity is tied to less risk of Parkinson's disease.
"These findings are important for both the general population and the health care of patients with Parkinson's disease," they note.
Parkinson's disease belongs to a group of conditions known as motor system disorders that occur when the brain loses cells that produce dopamine. It usually affects people aged 50 and over.
The four main symptoms of Parkinson's disease are: trembling in the arms, hands, legs, jaw and face; stiffness of arms and legs and trunk; slowness of movement; and impaired balance and coordination. As symptoms get worse, walking, talking and simple daily tasks become more and more difficult.
In 2012, the Centers for Disease Control and Prevention (CDC) listed Parkinson's disease as the 14th leading cause of death among Americans.
Meanwhile, Medical News Today recently reported a breakthrough in stem cell treatment for Parkinson's disease, where an animal study shows it is possible to make dopamine cells from embryonic stem cells and transplant them into the brain to replace those lost to the disease.