Causes

Genetic Factors

Approximately 15% of people with Parkinson’s disease have a family history of the condition, indicating a genetic component. Certain genetic mutations, such as those in the LRRK2, PARK7, PINK1, and SNCA genes, have been linked to an increased risk of developing Parkinson’s. The Australian Parkinson’s Genetics Study (APGS) is actively researching these genetic variants to better understand their role and potential for guiding targeted therapies (1). Genetic testing and counselling can help identify at-risk individuals and provide early intervention strategies.

Lifestyle Factors

Adopting a healthy lifestyle, including a balanced diet and regular physical activity, has been shown to lower the risk of developing Parkinson’s disease (2). A diet rich in fruits, vegetables, whole grains, and lean proteins can support overall brain health. Regular exercise, such as aerobic activities, strength training, and flexibility exercises, can improve motor function and may help delay the onset of symptoms. Engaging in physical activities also promotes mental well-being and reduces stress, which are crucial for managing Parkinson’s disease.

Age & Sex as Risk Factors

Age is the most significant risk factor for Parkinson’s, with the average age of onset being around 65 years. However, young onset Parkinson’s occurs in people diagnosed between 20 and 50 years of age. The risk increases with age due to the natural decline in dopamine-producing neurons in the brain. As people age, their ability to produce and maintain dopamine decreases, leading to the motor and non-motor symptoms characteristic of Parkinson’s. Early diagnosis and intervention can help manage symptoms more effectively in older adults.

While studies cite more males than females are at risk of developing Parkinson’s, this may be confounded by males traditionally in occupations that have higher exposure to toxins, e.g. farming. A study from Japan where females are predominantly in a farming role also shows a higher prevalence of PD in females (); however

Environmental Factors

Prolonged exposure to certain environmental toxins, such as pesticides, herbicides, and heavy metals, has been linked to an increased risk of Parkinson’s. Rural living and occupations involving frequent contact with these chemicals have shown higher incidences of the disease. Chemicals like paraquat and rotenone are known to interfere with mitochondrial function and oxidative stress in neurons, contributing to the neurodegenerative process. Reducing exposure to these toxins and advocating for safer agricultural practices can help mitigate the risk.

Toxicity of trichloroethylene (TCE), a chemical commonly used historically, in dry cleaning and used as a degreaser for metal parts and in various consumer products like paint removers, adhesives, and stain removers has been linked to a range of cancers and diseases (). However, due to its toxicity, ability to contaminate sites and associated health risks, its use in dry cleaning has been largely phased out in favour of safer alternatives. It is banned in Australia for use in consumer products and dry cleaning. However, it is still used in some industrial applications, such as metal cleaning and degreasing.

Head Injuries

Sustaining head injuries, especially multiple or severe ones, has been associated with an increased risk of developing Parkinson’s later in life. Traumatic brain injuries (TBIs) can lead to chronic inflammation and damage to the brain’s neurons, disrupting dopamine production. Individuals who have experienced concussions or head trauma should be monitored for early signs of Parkinson’s and may benefit from preventive measures and regular neurological check-ups to mitigate long-term effects.

Why don’t we know what caused my Parkinson’s?

Besides the percentage of people who have known genetic mutations, it is tough to pinpoint the origins of what causes Parkinson’s in most people. This complexity arises with the long lead time to the presentation of physical symptoms (estimates of >30 years from the start of neuron loss to physical symptoms like slowness and tremor) and therefore clinical diagnosis; the lack of biomarkers and the fact that environmental contaminants are rarely if ever, encountered in isolation. The term “environment” encompasses any outside (i.e. non-endogenous) factors, such as pathogenic infection, head trauma (TBI), diet, pharmaceutical, supplement, drug use, other physiological stressors (e.g., PTSD), and chemical toxicants in water, air, and soil.