Special Populations Affected By Parkinson's Disease

It is estimated that as many as one million Americans are living with Parkinson’s disease (PD), and approximately 60,000 are diagnosed with the disease each year. While scientists believe it results from a combination of genetic and environmental factors, the exact cause is not known. Most cases of PD are sporadic, occurring in people without a family history of the disease.1

Special populations affected by Parkinson's

PD is usually diagnosed in people over the age of 60; however, there is a small percentage of people who develop the disease at a younger age.1 Within the PD patient population, there are some special populations with unique characteristics.


If someone 40 years or younger receives a diagnosis of PD, it is referred to as young-onset PD (YOPD). It is estimated that approximately 5% of the cases of PD occur in people younger than the age of 40. However, PD is often overlooked as a potential diagnosis in younger patients, and the actual number of people with YOPD may be higher. Scientists believe genetics play a larger role in YOPD. People with YOPD have some differences in symptoms, disease progression, and response to treatment.2,3 People with YOPD typically have a slower disease progression. People with YOPD may also have more involuntary movements, called dyskinesia, in response to levodopa. People with YOPD are less likely to develop dementia. In addition, people with YOPD tend to respond better to physical therapy.


PD is known as a disease that affects older people, and it is the second most common age-related nerve degenerating disease after Alzheimer’s disease. Aging is the biggest risk factor for developing PD. PD occurs in 1% of the population over the age of 60, and this increases to 5% of the population over the age of 85.4


PD is less common in women than in men. While researchers continue to uncover the reasons behind the difference in prevalence between the genders, one area of interest is the role of estrogen. Estrogen seems to have protective effects on the nerve cells, as well as having multiple effects on dopamine, the chemical messenger (neurotransmitter) that is responsible for producing smooth, purposeful movement. Loss of dopamine-producing neurons in the brain is the cause of the motor symptoms that are characteristic of PD, including tremor, rigidity, and loss of spontaneous movement. There are also some differences noted in the symptoms of PD in women and the response to treatment.5,6


PD occurs in men approximately 50% more than in women. Although the exact reasons for this difference are unclear, some suggested explanations include the higher rate of minor head trauma and exposure to occupational toxins in men, and genetic susceptibility genes on the sex chromosomes. There are some differences in how the symptoms of PD appear in men compared to women, and the dosage of treatment is higher for men than women.1,5,7,8

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Written by: Emily Downward | Last reviewed: March 2017