Risk Factors for Parkinson's Disease

A genetic predisposition for Parkinson's disease is possible. In July 2014, the National Institutes of Health (NIH) reported that more than two dozen genetic risk factors involved in Parkinson’s disease have been identified—including six that had not been previously reported.

In a small number of cases of Parkinson's disease worldwide, there is a strong inheritance pattern for the disorder. In these cases, the onset of the disease and its gradual development depend on a trigger, such as trauma, other illness, or exposure to an environmental toxin.

The risk for Parkinson's increases with age and the disease generally manifests in the middle or later years of life.

Parkinson's Disease Causes

The cause of Parkinson's disease is unknown. Many researchers believe that a combination of several factors is involved in the development of Parkinson's. These factors include free radicals, accelerated aging, environmental toxins, and genetic predisposition.

It may be that free radicals—unstable and potentially damaging molecules that lack an electron—are involved in the degeneration of dopamine-producing cells. Free radicals add an electron by reacting with nearby molecules in a process called oxidation. This process can damage nerve cells.

Chemicals called antioxidants normally protect cells from oxidative stress and damage. If antioxidative action fails to protect dopamine-producing nerve cells, these cells may be damaged, resulting in Parkinson's disease.

Dysfunctional antioxidative mechanisms are associated with older age, which suggests that the acceleration of age-related changes in dopamine production also may be a factor in Parkinson's.

Exposure to an environmental toxin, such as a pesticide, that inhibits dopamine production and produces free radicals and oxidation damage may be involved in Parkinson's disease development.

In some cases, the use of certain drugs can produce parkinsonian symptoms (called drug-induced parkinsonism). These drugs include chlorpromazine and haloperidol, which are prescribed for psychiatric patients, and metoclopramide, which often is used to treat stomach disorders. Changing the medication or adjusting the dosage of the drug moderates or eliminates Parkinson's symptoms in many cases.

Roughly one-fifth of Parkinson's disease patients have at least one relative with parkinsonian symptoms, suggesting that a genetic factor may be involved in the disorder. Several genes that cause symptoms in younger patients have been identified. However, most cases are not thought to be caused by genetic factors alone.

Publication Review By: Gordon R. Kelley, M.D.

Published: 01 Jan 2000

Last Modified: 29 Sep 2015