As the world's population get older, there's growing concern about increased rates of Parkinson's disease.

From 1990 to 2015, the number of people with Parkinson disease doubled to over 6 million - and the number is predicted to double again by 2040.

Naturopath and wellness expert Erin O'Hara says it's unclear why these rates have gone up - but there are plenty of environmental factors believed to influence the condition. 

LISTEN ABOVE