Types of Parkinsonism

Parkinsonism is an umbrella term for any condition that produces the core motor features of tremor, bradykinesia (slowness of movement), and rigidity. While idiopathic Parkinson's disease accounts for roughly 80 percent of all parkinsonism cases, several other conditions can cause similar symptoms. These include atypical parkinsonism syndromes (progressive supranuclear palsy, multiple system atrophy, corticobasal degeneration, and dementia with Lewy bodies) and secondary causes such as drug-induced and vascular parkinsonism. Distinguishing between these conditions matters because they differ in prognosis, treatment response, and underlying biology.

Idiopathic Parkinson's Disease (IPD)

Idiopathic Parkinson's disease is by far the most common cause of parkinsonism, accounting for approximately 80 percent of cases. “Idiopathic” means the cause is not known in a given individual, though the disease is characterized by progressive loss of dopamine-producing neurons in the substantia nigra and the accumulation of Lewy bodies (abnormal alpha-synuclein aggregates) in affected neurons.

Key features that distinguish IPD from other forms of parkinsonism include:

• Asymmetric onset — symptoms typically begin on one side of the body and remain more pronounced on that side for years
• Prominent resting tremor — present in about 70 percent of IPD cases
• Clear, sustained response to levodopa therapy — the single most important distinguishing feature
• Gradual, relatively slow progression over years to decades
• Development of levodopa-induced dyskinesia over time
• Characteristic non-motor features — loss of smell, REM sleep behavior disorder, constipation, depression

When people refer to “Parkinson's disease” without qualification, they almost always mean idiopathic Parkinson's disease.

Atypical Parkinsonism Syndromes

Atypical parkinsonism syndromes — sometimes called “Parkinson's-plus” syndromes — share some motor features with Parkinson's disease but have additional distinctive clinical features, generally progress faster, and respond poorly or not at all to levodopa. These conditions are less common than IPD (collectively accounting for roughly 10 to 20 percent of parkinsonism cases) and are often more difficult to diagnose, especially in early stages when they may closely mimic IPD. Diagnosis is often delayed by 2 to 4 years after symptom onset.

Progressive Supranuclear Palsy (PSP)

Progressive supranuclear palsy is the most common atypical parkinsonism syndrome, with an estimated prevalence of 5 to 7 per 100,000 people. It is caused by the accumulation of tau protein (not alpha-synuclein) in specific brain regions, particularly the midbrain, subthalamic nucleus, and basal ganglia. PSP is not a single disease but a spectrum of clinical presentations, the most common being “Richardson syndrome.”

Key features of PSP include:

• Early falls, often backward, within the first year of symptom onset — in contrast to PD, where falls typically occur much later
• Vertical gaze palsy — difficulty looking up and especially down, which is the hallmark clinical feature. Patients may report difficulty reading or difficulty eating because they cannot look down at their plate.
• Axial rigidity — stiffness predominantly in the neck and trunk rather than the limbs, often causing a distinctly upright or hyperextended posture (contrast with the stooped posture of PD)
• Poor or absent response to levodopa
• Pseudobulbar affect — involuntary, inappropriate laughing or crying
• Frontal lobe cognitive dysfunction — apathy, impulsivity, reduced verbal fluency, and executive dysfunction that appears early, unlike PD where cognitive decline is typically late
• Dysarthria and dysphagia — speech and swallowing difficulties that appear earlier and progress faster than in PD

PSP typically progresses faster than Parkinson's disease. Average survival from symptom onset is approximately 6 to 9 years, compared to more than 14 years for idiopathic PD. MRI of the brain may show midbrain atrophy, producing the characteristic “hummingbird sign” on sagittal view (the midbrain shrinks while the pons remains normal, creating a profile resembling a hummingbird).

Multiple System Atrophy (MSA)

Multiple system atrophy is a progressive neurodegenerative disorder that involves dysfunction in multiple brain systems simultaneously, with a prevalence of approximately 3 to 5 per 100,000 people. Like PD, MSA involves alpha-synuclein pathology, but the aggregates are found predominantly in oligodendrocytes (the cells that produce myelin) rather than in neurons, forming structures called glial cytoplasmic inclusions. MSA is subdivided into two types based on predominant clinical features:

• MSA-P (parkinsonian type). Predominantly motor symptoms resembling Parkinson's disease — slowness, rigidity, and gait difficulty — but with poor or transient response to levodopa and faster progression. Tremor is typically irregular (“jerky”) rather than the smooth pill-rolling tremor of PD.
• MSA-C (cerebellar type). Predominantly cerebellar symptoms — limb and gait ataxia (coordination problems, unsteady gait, difficulty with fine motor tasks), and cerebellar dysarthria (slurred, scanning speech) — with parkinsonism developing later. MSA-C is more common in East Asian populations.

The hallmark of MSA that often differentiates it from PD is early and severe autonomic dysfunction: orthostatic hypotension (dramatic drops in blood pressure upon standing, often causing syncope), urinary incontinence or retention, erectile dysfunction, and constipation. These autonomic features often appear before or simultaneously with motor symptoms and are more severe than the autonomic dysfunction seen in PD. Respiratory stridor (noisy breathing, particularly during sleep) is another characteristic feature that can be life-threatening.

Average survival from diagnosis is approximately 6 to 10 years. MRI may show characteristic findings: the “hot cross bun” sign in the pons (MSA-C), putaminal atrophy with a hyperintense lateral rim, or cerebellar atrophy.

Corticobasal Degeneration (CBD)

Corticobasal degeneration is a rare tau-mediated neurodegenerative disorder, with an estimated prevalence of 5 to 7 per 100,000 people, characterized by a combination of progressive motor and cognitive symptoms. Its clinical presentation is highly variable, which makes diagnosis particularly challenging — it has one of the lowest diagnostic accuracy rates of any neurodegenerative condition. The classic clinical syndrome (now called “corticobasal syndrome”) may be caused by CBD pathology but can also be caused by other pathologies (Alzheimer's, PSP), and CBD pathology can present as other clinical syndromes.

Common features of corticobasal syndrome include:

• Markedly asymmetric rigidity and bradykinesia, typically affecting one arm far more than the other — often dramatically so, with one limb barely functional while the other is relatively preserved
• Alien limb phenomenon — the sensation that one's arm or hand is moving independently, outside of voluntary control; the affected limb may grasp objects involuntarily or interfere with tasks performed by the other hand
• Apraxia — inability to carry out learned, purposeful motor tasks (like using a key, brushing teeth, or waving goodbye) despite normal strength and sensation
• Myoclonus — sudden, brief involuntary muscle jerks in the affected limb
• Cortical sensory loss — impaired ability to identify objects by touch, discriminate between two points of touch, or determine the direction of a stimulus drawn on the skin
• Poor response to levodopa

CBD is frequently initially misdiagnosed as Parkinson's disease, particularly when the presentation is predominantly motor. The extreme asymmetry, cortical features (apraxia, cortical sensory loss), and alien limb phenomenon are the strongest clinical clues. Definitive diagnosis currently requires neuropathological examination, though clinical diagnostic criteria continue to improve. Average survival from symptom onset is approximately 6 to 8 years.

Dementia with Lewy Bodies (DLB)

Dementia with Lewy bodies is the second most common cause of neurodegenerative dementia after Alzheimer's disease, accounting for approximately 5 to 10 percent of all dementia cases. Like PD, DLB involves alpha-synuclein accumulation in the brain (Lewy bodies), and the two conditions exist on a spectrum of Lewy body disease. The critical distinction is in the timing of cognitive versus motor symptoms:

• In DLB, cognitive impairment and dementia develop before or at the same time as motor parkinsonism (within one year of each other, the “one-year rule”).
• In Parkinson's disease dementia (PDD), motor parkinsonism precedes cognitive decline by more than one year.

Whether DLB and PDD are truly separate diseases or different presentations of a single Lewy body disease spectrum is actively debated among researchers. Many now view them as part of a continuum.

Core clinical features of DLB include:

• Fluctuating cognition — pronounced day-to-day or even hour-to-hour variations in attention, alertness, and coherent thought; the person may appear almost normal one day and severely confused the next
• Recurrent well-formed visual hallucinations — typically vivid, detailed images of people, children, or animals; often benign initially but can become distressing
• REM sleep behavior disorder — acting out dreams; may precede cognitive symptoms by years
• Parkinsonism — often milder than in IPD; may present with rigidity and bradykinesia but with less prominent resting tremor
• Extreme sensitivity to antipsychotic medications — neuroleptic hypersensitivity can cause severe, sometimes fatal worsening of symptoms; this is a critical safety consideration

DLB requires specialized management because standard antipsychotic medications can be dangerous. Cholinesterase inhibitors (rivastigmine, donepezil), used for cognitive symptoms, may also reduce hallucinations. Average survival from diagnosis is approximately 5 to 8 years.

Comparison of Major Parkinsonism Types

Secondary Parkinsonism

Secondary parkinsonism refers to parkinsonism caused by an identifiable external factor rather than a primary neurodegenerative process. Unlike the conditions above, some forms of secondary parkinsonism may be partially or fully reversible when the cause is addressed.

Drug-Induced Parkinsonism (DIP)

Drug-induced parkinsonism is the second most common cause of parkinsonism after idiopathic PD. Any medication that blocks dopamine receptors or depletes dopamine stores can cause parkinsonian symptoms. The most common offending medications include:

• Typical (first-generation) antipsychotics: haloperidol, chlorpromazine, perphenazine — highest risk
• Atypical (second-generation) antipsychotics: risperidone and olanzapine carry moderate risk; quetiapine and clozapine carry the lowest risk among antipsychotics
• Anti-emetic drugs: metoclopramide (Reglan) and prochlorperazine — commonly prescribed for nausea and frequently overlooked as a cause of parkinsonism
• Certain calcium channel blockers: flunarizine and cinnarizine (more common outside the U.S.)
• Dopamine-depleting agents: tetrabenazine, valbenazine (used for tardive dyskinesia)

DIP typically develops within weeks to months of starting the offending medication. It usually presents bilaterally and symmetrically (unlike the asymmetric onset of IPD), though this is not always the case. DIP usually improves after the drug is discontinued, though resolution can take weeks to months — and in some cases, the drug may have unmasked underlying early PD. A DaTscan is the most useful diagnostic tool: it is normal in pure DIP (because dopamine neurons are intact; the problem is receptor blockade) and abnormal in degenerative parkinsonism.

Vascular Parkinsonism

Vascular parkinsonism results from small strokes (lacunar infarcts) or chronic small-vessel disease affecting the basal ganglia or their white matter connections. It tends to affect the lower body disproportionately — patients often have a characteristic “lower body parkinsonism” with shuffling gait, postural instability, and difficulty with turning, but relatively preserved arm function and little or no tremor. This pattern contrasts with IPD, where upper limb tremor is often the earliest and most prominent symptom.

Additional distinguishing features include:

• Stepwise rather than gradual progression (symptoms worsen in discrete episodes corresponding to vascular events)
• Vascular risk factors (hypertension, diabetes, hyperlipidemia, smoking)
• Brain MRI shows confluent white matter hyperintensities and/or lacunar infarcts in the basal ganglia
• Minimal or no response to levodopa
• Pseudobulbar affect and urinary incontinence may be present

Treatment focuses on managing vascular risk factors to prevent further strokes, physical therapy for gait and balance, and a cautious trial of levodopa (which helps a minority of patients).

Other Secondary Causes

• Toxin-induced parkinsonism. Exposure to MPTP (a synthetic opioid contaminant that caused an outbreak of parkinsonism in the 1980s), manganese (in welders and miners), carbon monoxide, and methanol can damage the basal ganglia and cause parkinsonism. MPTP-induced parkinsonism was pivotal in PD research because it demonstrated that selective destruction of dopaminergic neurons could be caused by an external toxin.
• Normal pressure hydrocephalus (NPH). Characterized by the classic triad of gait difficulty (magnetic gait), urinary incontinence, and cognitive decline. Brain MRI shows enlarged ventricles disproportionate to cortical atrophy. NPH is critically important to identify because it is one of the few treatable causes of parkinsonism and dementia — a ventriculoperitoneal shunt can improve symptoms in selected patients.
• Post-traumatic parkinsonism. Repeated head injuries, as seen in boxers (“dementia pugilistica”), American football players, and other contact-sport athletes, can lead to parkinsonism as part of chronic traumatic encephalopathy (CTE). The pathology involves tau accumulation rather than alpha-synuclein.
• Post-encephalitic parkinsonism. Historically associated with the 1918 influenza pandemic (encephalitis lethargica), this is now rare but can occur following viral encephalitis.

Why Accurate Classification Matters

Getting the type of parkinsonism right is essential for patients, caregivers, and clinicians. The practical implications include:

• Treatment expectations. A patient with IPD can expect significant, sustained benefit from levodopa. A patient with PSP, MSA, or CBD will not — and inappropriately high doses of levodopa can cause side effects without therapeutic benefit. A patient with DLB must avoid certain antipsychotic medications that could be dangerous.
• Prognosis and planning. Atypical syndromes generally progress faster than IPD. Families need accurate prognostic information to plan care, finances, and advance directives appropriately.
• Reversible causes. Drug-induced parkinsonism can resolve after stopping the offending medication. Normal pressure hydrocephalus can be treated with surgery. These opportunities are missed if the diagnosis is assumed to be IPD.
• Clinical trial eligibility. Most clinical trials for disease-modifying therapies target specific conditions (PD, MSA, or PSP). Accurate diagnosis determines trial eligibility.

If you or a loved one have parkinsonism that does not follow the typical Parkinson's disease pattern — particularly if symptoms progress rapidly, affect both sides equally from the start, do not respond to levodopa, or are accompanied by early falls, severe autonomic failure, prominent cognitive decline, or visual hallucinations — evaluation by a movement disorder specialist is strongly recommended. The Parkinson's Foundation Helpline (1-800-4PD-INFO / 1-800-473-4636) can help locate specialists in your area.