The protein, called Apolipoprotein D, also known as ApoD, appears to play a protective and restorative role in the brains of people with neurodegenerative diseases, a condition in which cells of the brain and spinal cord are lost, the researchers say in a study published in two journals, Aging Cell and Journal of Neuroscience.

The researchers experimented with two groups of mice -- one with increased levels of ApoD in the brain and the other with no ApoD.

Both types were exposed to paraquat, a widely used herbicide shown to increase the risk of Parkinson's. A similar group of two mice types was injected with a virus that causes encephalitis, an acute inflammation of the brain.

In both cases, the mice modified for increased levels of ApoD had the best outcomes, with a better ability to combat the diseases and a higher survival rate than the unmodified mice, the researchers from the University of Quebec at Montreal, Quebec's Armand-Frappier Institute and Spain's University of Valladolid said.

"We have successfully demonstrated the role of ApoD, but now we need to understand the action of this protein," University of Quebec biological sciences Professor Eric Rassart said.

"Only then will we be able to think about creating a drug to prevent these types of diseases and to slow their progression," he said.