Parkinson's disease risk factors: who is more likely to get it

What Parkinson's disease is

PD is a disorder of the nervous system. Nerve cells in parts of the brain weaken, become damaged and die. Most symptoms come from losing cells in an area called the substantia nigra, which makes dopamine, a chemical messenger the brain needs for smooth, purposeful movement. By the time symptoms appear, most people have lost 60 to 80% or more of these cells (NINDS).

In most people with PD the cause is unknown. Researchers think the risk comes from both genes and environmental factors (NINDS). MedlinePlus puts it this way: sometimes PD is genetic, but most cases do not seem to run in families, and exposure to chemicals in the environment might play a role (MedlinePlus).

Risk factors

NINDS says it is hard to predict who will get PD, but these factors are linked to a higher risk (NINDS):

• Age. The average age PD starts is the early to mid-60s, and the chance goes up with age. A small share of people have early-onset PD, which begins before 50.
• Sex. PD affects more men than women.
• Family history. People with one or more close relatives who have PD are more likely to get it. This could come from sharing the same genes or similar surroundings and daily habits.
• Environmental exposure. People exposed to some types of pesticides and other pollutants have a greater risk, for example through farming or landscaping work.
• Other factors. Other health conditions, gut bacteria and sleep can also affect the risk.

MedlinePlus agrees on the main points: PD usually begins around age 60 but can start earlier, and it is more common in men than in women (MedlinePlus).

Genes linked to Parkinson's

Some cases are inherited and can be traced to specific gene changes. NINDS names several genes linked to PD (NINDS):

• GBA1: variants in this gene are the most common genetic risk factor for PD.
• LRRK2 and SNCA: SNCA was the first gene linked to PD.
• PINK1, PRKN and DJ-1: changes in these genes are linked to rare, early-onset forms that start before 50.

Genetic testing can find these changes in inherited forms of PD. If you think someone in your family may have PD, or that you may carry a linked gene change, NINDS suggests asking a doctor about genetic testing; a genetic counselor can explain what the results mean (NINDS).

Early signs to bring to a doctor

Symptoms begin gradually, often on one side of the body, and later affect both sides (MedlinePlus). NINDS names four common symptoms (NINDS):

• Tremor: rhythmic shaking that often starts in a hand, most obvious when the hand is at rest. Some people never get a tremor.
• Rigidity: muscles that stay tense and tight, causing stiffness or aches.
• Slow movement: everyday tasks such as washing or dressing take much longer, and the face may show less expression.
• Balance problems and changes in posture that raise the risk of falls.

Depression or anxiety may appear early, even before movement problems start. Other possible symptoms include sleep problems such as acting out dreams, constipation, a quiet or flat voice, dizziness on standing, and later trouble with thinking and memory (NINDS). To check for PD, a doctor uses your medical history and a neurological exam, and may order lab tests to rule out other disorders (NINDS).

Because balance problems raise the risk of falls, the fall risk check and our guide to fall risk factors may help. Some people with PD later develop dementia; see dementia risk factors.

Common questions

At what age does Parkinson's usually start?

The average age at onset is the early to mid-60s (NINDS), and MedlinePlus says it usually begins around 60 (MedlinePlus). Early-onset PD starts before 50, and in very rare cases parkinsonian symptoms appear before 20 (NINDS).

Is Parkinson's disease hereditary?

Sometimes. Some cases are inherited, and having a close relative with PD raises your risk, but most cases do not seem to run in families (NINDS) (MedlinePlus).

Can Parkinson's be prevented?

Neither source names a proven way to prevent PD. NINDS notes NIH-funded research on whether caffeine, supplements and other nutrients may help prevent or treat it, and trials on whether hard exercise can slow it down (NINDS).

Is there a cure?

No. Medicines such as carbidopa-levodopa and, for some people, surgery including deep brain stimulation can help symptoms (NINDS) (MedlinePlus).

Also see ALS risk factors, multiple sclerosis risk factors, osteoporosis risk factors and screening tests by age.