A new study may prove exercise to be an effective treatment for Parkinson's Disease (PD).

'Our data suggest the possibility that exercise can make dopamine neurons resistant to neurotoxins and may therefore be a useful therapy for Parkinson's Disease,' said Annie Cohen, a doctoral student at the University of Pittsburgh School of Medicine. Researchers presented their findings at the Annual Meeting of the Society for Neuroscience in San Diego, Calif.

In Parkinson's, cells in the brain that contain a messenger called dopamine, a neurotransmitter essential for purposeful and facile muscle control, progressively die until only a small percentage remains. The lowered number of transmitters result in uncontrollable tremors, rigidity of limbs, slow movements and stooped posture.

Rats in the study had one foreleg immobilized in a cast for seven days, placing more physical demands on the opposite limb. A toxin called 6-OHDA was then injected into the brain on the side with the cast leg. This would normally be expected to induce Parkinson’s symptoms in the free limb on the opposite side. Next the cast was removed, and the toxin delivered to the other side of the brain. No Parkinson’s-induced movement problems were seen in either limb in the exercised animals. However, prior to exposing the rats to the toxin, the researchers forced the rats to exercise for a period of seven days.

Forced exercise was found to have a major impact on rats given a toxin that induces Parkinson's. Brain exams showed they lost only six per cent of the neurons linked to the disease, while those not made to exercise lost 87 per cent. Researchers are now planning a study with human volunteers.

Yet, there is some disagreement within the Parkinson's research community as to the benefits of intense exercise for people with PD. Although none have reported harm from the physical activity, some studies have shown no statistical positive influence of exercise. The team is now looking at more clinically relevant forms of exercise, such as running.