Risk Factors

Parkinson's disease affects about 3% of Americans over 65 years old. Experts estimate that this percentage could double in the next 30 - 40 years. The symptoms of parkinsonism (tremor, gait disturbance, bradykinesia, and rigidity) occur in even more people, estimated to be 8 million over age 65. In a study that included very mild symptoms, parkinsonism occurred in about 15% of people 65 - 74 years of age, about 30% in those 75 - 84, and over half of people older than age 85.

Age

The average age of onset of Parkinson's disease is 55. About 10% of Parkinson's cases are in people younger than 40 years old. Older adults are at higher risk for both parkinsonism and Parkinson's disease. There is some evidence, however, that the risk declines significantly after age 75 and that the very elderly are at low risk.

Gender

Some research indicates that men may face up to twice the risk as women. Estrogen may offer some protection for women up until menopause. A 2001 study, for example, reported a higher rate of Parkinson's disease in women who had undergone hysterectomy. Other studies suggest that the disease also progresses more rapidly in men than women. Older women seem to be more at risk for gait disturbance and men for rigidity and tremor.

Family History of PD

People with siblings or parents who developed Parkinson's at a younger age are at higher risk for Parkinson's disease, but relatives of those who were elderly when they had the disease appear to have an average risk.

Ethnicity

African- and Asian-Americans have a lower risk than Caucasians. Some evidence suggests that non-Caucasians may be more vulnerable to an atypical form of PD, which causes early impairment in thinking and has a poor response to levodopa, the primary PD treatment.

Middle-Age Weight Gain

Increasing weight gain in middle age was associated with a higher risk of PD in a 2002 study.

Review Date: 12/21/2006
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2007 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.