3. Genes and environment both play a role
In the recent study, one in four people (25 per cent) had a family history of Parkinson’s. But only 10–15 per cent of Parkinson’s cases are caused by – or strongly linked to – mutations in specific genes. It’s important to remember that families don’t only share genes but often their environment. Multiple environmental factors, such as pesticide exposure and traumatic brain injury, also increase risk of Parkinson’s. The majority (85–90 per cent) of cases of Parkinson’s are likely due to complex interaction between genetic and environmental risk factors, and advancing age.
The study showed environmental exposures linked to Parkinson’s risk were common:
• 36 per cent of people reported pesticide exposure
• 16 per cent had a prior history of traumatic brain injury
• 33 per cent had worked in high-risk occupations (such as agriculture, or petrochemicals or metal processing).
• These exposures were significantly higher in men than in women.