Parkinson's disease is caused by a loss of cells in the part of the brain called the substantia nigra.
 

 
These cells produces a neuro chemical called dopamine, this sends messages to the parts of the brain that co-ordinate and control movement.

You may not notice any changes until about 80% of the dopamine has been lost and this may have been happening over many years.

The exact cause of why this happens in the brain is still unknown. But research shows exposure to environmental toxins may increase the risk. There may also be a link between use of herbicides and pesticides and the development of Parkinson's. Research also shows 9 genes that may make people more suceptable to Parkinson's but these are very rare.