16/08/2026
How Many People Have Parkinsonās and the Various Parkinsonisms?
We talk a lot about Parkinsonās disease, but Parkinsonās is only one condition within a much larger conversation.
The word parkinsonism describes a group of movement symptomsāsuch as slowness, rigidity, tremor and balance problemsāthat can occur because of several different neurological conditions.
And when you look at the numbers, one thing becomes very clear:
Parkinsonās disease is by far the most common cause of parkinsonism.
Parkinsonās disease: about 11.8 million worldwide
A Global Burden of Disease analysis estimated that approximately 11.77 million people worldwide were living with Parkinsonās disease in 2021.
That works out to roughly 139 people per 100,000 worldwide.
Compare that with an estimated 3.15 million people in 1990.
Population growth and an aging population help explain much of the increase in the total number of people living with Parkinsonās. But age-standardized prevalence has also increased, suggesting that changing demographics alone may not explain the entire rise.
Either way, Parkinsonās has become an enormousāand growingāglobal health challenge.
What about the atypical parkinsonisms?
This is where the numbers become much less certain.
Conditions such as progressive supranuclear palsy (PSP), multiple system atrophy (MSA) and corticobasal degeneration (CBD) are considerably rarer than Parkinsonās disease.
Published prevalence estimates suggest roughly:
PSP: 6ā10 cases per 100,000 people
MSA: 2ā5 cases per 100,000
CBD: 2ā4 cases per 100,000
If those prevalence rates are extrapolated across todayās world population, they suggest populations in the hundreds of thousands for each disorder.
But thereās an important warning here:
Those are NOT actual worldwide patient counts.
They are mathematical extrapolations from prevalence studies. We simply donāt have an accurate worldwide census of people living with PSP, MSA or CBD.
Why donāt we know?
One enormous problem is misdiagnosis.
Early PSP, MSA and CBD can resemble Parkinsonās disease. Someone may initially receive a PD diagnosis only to have that diagnosis changed several years later as additional symptoms emerge.
The reverse problem occurs too. Some people with these uncommon conditions may never receive the correct diagnosis.
Diagnostic criteria have changed over time. Different studies use different methodologies. And many parts of the world simply donāt have the medical resources necessary to identify and track rare neurological diseases.
Thatās why we need to be careful about presenting these numbers as though theyāre precise.
They arenāt.
Then there are the secondary parkinsonisms
Not everyone with parkinsonism has a progressive neurodegenerative parkinsonian disease.
For example, vascular parkinsonism can occur in association with strokes and cerebral small-vessel disease. Some studies have estimated that it represents roughly 3ā6% of parkinsonism cases, although estimates vary considerably depending upon how the condition is defined.
Thereās also drug-induced parkinsonism.
Certain medicationsāparticularly some antipsychotic and anti-nausea medicationsācan interfere with dopamine activity and produce parkinsonian symptoms.
Drug-induced parkinsonism is especially difficult to count because symptoms may improve after the medication is stopped. In other cases, medication may reveal underlying Parkinsonās disease that was already developing.
Other, much rarer causes of parkinsonism can include brain injury, tumors, infections, normal-pressure hydrocephalus, toxins and certain metabolic or genetic disorders.
So what does all of this mean?
Probably the most important lesson isnāt the exact number.
Itās understanding that Parkinsonās disease and parkinsonism are not interchangeable terms.
Think of parkinsonism as the umbrella.
Parkinsonās disease sits underneath that umbrellaāand it is by far its most common member.
PSP, MSA and CBD can produce similar movement symptoms, but they are different diseases with different patterns of progression, additional symptoms, treatment responses and prognoses.
Secondary parkinsonism is different again because the underlying cause may be vascular disease, medication or another medical condition.
Thatās one reason getting the correct diagnosis matters so much.
And itās also why someoneās diagnosis can occasionally change after several years.
The neurologist wasnāt necessarily āwrongā the first time. Sometimes the defining characteristics of a particular disease simply hadnāt appeared yet.
One final thought
Behind every one of these statistics is a person.
11.8 million sounds enormous.
Six people out of 100,000 sounds tiny.
But if you or someone you love is one of those six people, it isnāt rare to you.
Whether someone is living with Parkinsonās disease, PSP, MSA, CBD, vascular parkinsonism, drug-induced parkinsonism or another parkinsonian disorder, they deserve knowledgeable medical care, continued research and a community that understands what theyāre facing.
Different diseases. Different journeys. One shared goal: better treatments, better care and ultimately better answers.
