The findings, published in the Journal of the American Medical Association (JAMA) Neurology, suggest that the current standard of care for early-stage patients may be a waste of time and money.
Parkinson's disease attacks the central nervous system, and affects about seven million people across the world, including about four percent of those over age 80.
The randomized trial involved 762 patients with mild to moderate Parkinson's disease, recruited from 38 sites in Britain.
Half were assigned to physical therapy and the other half to occupational therapy -- both practiced in hour-long sessions that took place several times over the course of the study.
Physical therapy tends to focus on diagnosing and treating injuries, while occupational therapy aims to help patients adapt to injury and improve life skills.
After three months, researchers at the University of Birmingham found "no difference between the groups" in their ability to perform daily tasks or in their answers on a health-related quality of life questionnaire.
Therefore, more time should be spent on exploring "the development and testing of more structured and intensive physical therapy programs in patients with all stages of Parkinson's disease," the study said.
An accompanying editorial by J. Eric Ahlskog, a doctor at the Mayo Clinic in Rochester, Minnesota, pointed out that doctors for all the patients in the study had already decided they were unlikely to benefit from such therapies.
