There's finally some hope for patients suffering from Parkinson's - a degenerative disorder of the central nervous system that affects movement, speech and posture with no known cause and no available cure.

In what is being regarded as a major advance, scientists have for the first time successfully eased the symptoms of Parkinson's disease in monkeys with the help of human stem cell transplants. Primates with severe Parkinson's were later able to walk, move and eat better. They also reported diminished tremors after being injected with the stem cells.

Surprisingly, rather than replacing the damaged cells as anticipated, the stem cells actually worked to protect damaged brain cells preventing further deterioration.

Even though they called the results "promising", the research team from Yale, Harvard, the University of Colorado and the Burnham Institute, which reported their study in the journal Proceedings of the National Academy of Sciences said it would be years before it is known whether a similar procedure would have therapeutic value for humans.

Parkinson's is caused by a degeneration of dopamine neurons in an area of the midbrain known as the substantia nigra, which is responsible for dopamine production. Reduced production of dopamine in late stage Parkinson's causes symptoms such as severe difficulty in walking, fewer movements, delays in moving, lack of appetite, difficulty in eating, periods of remaining motionless known as freezing, and head and limb tremors. In this study, five of eight monkeys with advanced Parkinson's were injected with human neural stem cells and three received sham injections.

The monkeys were observed four months before and four months after surgery. Those injected with stem cells improved progressively for the entire post-treatment period and were significantly different from the monkeys that received sham injections. Twenty-one additional monkeys were studied for up to eight months for other biological effects of the stem cells. No tumours or toxic effects were found.

According to doctors in India, more and more patients in their late 30s are being diagnosed with the disease. Till recently, less than 3% of Indians suffering from Parkinson's were in their 30s and 40s. Now, doctors say, the number has easily crossed 10%