Parkinson's UK has revealed that its campaign for more brain donors was a great success in 2010, but more are needed.
Following the charity's April campaign, the number of people on the Parkinson's Brain Donor register more than doubled.
However, more donors are still needed, according to the site - particularly young people with Parkinson's.
In addition, the number of women who signed up was more than twice that of men, so Parkinson's UK is calling for more male donors.
Dr Kieran Breen, our director of research and development at the charity said: "We are delighted with the response to our appeal so far. Scientific research on brains from people both with and without Parkinson's is essential to help us move closer to our goal."
This comes after researchers at Auckland University announced they are to investigate the link between Parkinson's disease and the illegal drug cannabis.