What Do We Know About The Cause Of Parkinson's Disease?

Nearly 90,000 people in the United States are diagnosed with Parkinson's disease each year, and these numbers are on the rise, according to the Parkinson's Foundation.

Although Parkinson's Disease can start with a small tremor of the hand, some signs can go unnoticed (via Mayo Clinic). Other symptoms of Parkinson's disease include impaired walking, such as walking with shorter steps or walking slowly. People with Parkinson's might also feel their muscles growing stiff, which limits their range of motion. Poor balance and posture can also be a sign of Parkinson's, and speech and writing could grow more difficult as the disease progresses. According to the Parkinson's Foundation, some people might experience non-motor symptoms of Parkinson's, such as constipation, depression, sleep disorders, or loss of smell.

Britain's National Health Service says that Parkinson's begins in the part of the brain called the substantia nigra, which controls our movements. When nerve cells in this region of the brain begin to die, less dopamine is produced. Dopamine is a key communicator between our brain and our nervous system. With less dopamine in the substantia nigra, there is slower communication between our brain and our body.

Researchers are still unclear on what might cause the nerve cells in the substantia nigra to die, because people with Parkinson's often have different symptoms, according to the Parkinson's Foundation. A 2019 article in Translational Neurodegeneration said Parkinson's is a complex interaction of age, genetics, and environmental factors, meaning that these factors work differently in different people with Parkinson's disease.

The National Health Service says that the Parkinson's gene can run in families, but it's rare to inherit the disease from your parents. Although much research focuses on the genetic factors of Parkinson's Disease, a 2022 review in Toxicology Letters has linked Parkinson's with pesticides, exposure to metals (specifically iron and manganese), an unhealthy gut microbiome, certain viruses, and air pollution.

Because the cause is unknown, it's difficult to take preventative measures against Parkinson's disease, according to the Mayo Clinic. People who consume caffeine may have fewer incidences of Parkinson's, though why this might be is unknown. Green tea is also associated with a lower risk of developing Parkinson's, but more research is needed about the cause-and-effect relationship.