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# Parkinson disease

Parkinson disease is a slowly progressive brain disease from loss of dopamine-making cells; it causes slow movement, tremor and stiffness.

Updated 2026-10-29

## Structures involved

Tap one to see what it is and open it in 3D.

- [Substantia nigra](https://durgical.com/en/anatomy/substantia-nigra/)
- [Putamen](https://durgical.com/en/anatomy/putamen/)
- [Caudate nucleus](https://durgical.com/en/anatomy/caudate-nucleus/)
- [Globus pallidus](https://durgical.com/en/anatomy/globus-pallidus/)
- [Thalamus](https://durgical.com/en/anatomy/thalamus/)
- [Midbrain](https://durgical.com/en/anatomy/midbrain/)
- [Motor cortex](https://durgical.com/en/anatomy/precentral-gyrus/)
- [Red nucleus](https://durgical.com/en/anatomy/red-nucleus/)
- [Medulla oblongata](https://durgical.com/en/anatomy/medulla-oblongata/)

## In biochemistry

- [Catecholamine synthesis and breakdown: Step 2 · Aromatic L-amino acid decarboxylase (AADC, DOPA decarboxylase)](https://durgical.com/en/biochemistry/pathways/catecholamine-synthesis-and-breakdown/#paso-2)
- [Tyrosine hydroxylase](https://durgical.com/en/biochemistry/enzymes/tyrosine-hydroxylase/)
- [Molecules derived from amino acids](https://durgical.com/en/biochemistry/topics/molecules-derived-from-amino-acids/)
- [Glucocerebrosidase (acid β-glucosidase)](https://durgical.com/en/biochemistry/enzymes/glucocerebrosidase/)
- [Molecular chaperones and heat shock proteins](https://durgical.com/en/biochemistry/topics/molecular-chaperones-and-heat-shock-proteins/)
- [Ubiquitin–proteasome system](https://durgical.com/en/biochemistry/topics/ubiquitin-proteasome-system/)
- [Catecholamines: synthesis and breakdown](https://durgical.com/en/biochemistry/topics/catecholamines-synthesis-and-breakdown/)
- [Dopamine](https://durgical.com/en/biochemistry/molecules/dopamine/)
- [L-DOPA (levodopa)](https://durgical.com/en/biochemistry/molecules/l-dopa/)

## In histology

- [The neuron and synapse](https://durgical.com/en/histology/the-neuron-and-synapse/)

## In the clinical exam

- [Orthostatic vital signs](https://durgical.com/en/clinical-exam/orthostatic-vital-signs/)
- [Diagnostic facies](https://durgical.com/en/clinical-exam/diagnostic-facies/)
- [Inspection of gait and posture (orthopedic)](https://durgical.com/en/clinical-exam/inspection-of-gait-and-posture/)
- [Motor examination: bulk, tone and strength grading](https://durgical.com/en/clinical-exam/motor-examination-bulk-tone-and-strength-grading/)
- [Abnormal gaits: hemiparetic, parkinsonian, ataxic, steppage, waddling](https://durgical.com/en/clinical-exam/abnormal-gaits-hemiparetic-parkinsonian-ataxic-steppage-waddling/)
- [Parkinsonian syndrome](https://durgical.com/en/clinical-exam/parkinsonian-syndrome/)

## In physiology

- [Basal ganglia and movement control](https://durgical.com/en/physiology/basal-ganglia-and-movement-control/)
- [The main neurotransmitters](https://durgical.com/en/physiology/the-main-neurotransmitters/)
- [Taste and smell](https://durgical.com/en/physiology/taste-and-smell/)

## Why it happens

- [Intracellular accumulations: cholesterol, proteins, hyaline, glycogen](https://durgical.com/en/general-pathology/intracellular-accumulations-cholesterol-proteins-hyaline-glycogen/)
- [Autophagy](https://durgical.com/en/general-pathology/autophagy/)
- [Endoplasmic reticulum stress and the unfolded protein response](https://durgical.com/en/general-pathology/endoplasmic-reticulum-stress-and-the-unfolded-protein-response/)
- [Apoptosis: the intrinsic and extrinsic pathways](https://durgical.com/en/general-pathology/apoptosis-the-intrinsic-and-extrinsic-pathways/)

## What it is

A progressive neurodegenerative disease caused mainly by loss of dopamine-producing neurones in the [substantia nigra](https://durgical.com/en/anatomy/substantia-nigra/). It causes slowness of movement with tremor or rigidity, plus many non-motor symptoms.

## Who gets it

The second most common neurodegenerative disease after Alzheimer disease. Onset is usually after age 60 and it is somewhat more common in men; early-onset forms are often genetic. Cases are increasing as Latin American populations age.

## Causes

- Mostly sporadic, from a combination of ageing, genetic susceptibility and environmental factors
- Genetic forms in a minority (e.g. LRRK2, PRKN, GBA variants)
- Exposure to pesticides and some toxins has been associated

## Risk factors

- Older age
- Male sex
- Family history
- Pesticide exposure and rural farm work
- Head injury (association)

## Pathophysiology

Dopaminergic neurones of the substantia nigra pars compacta degenerate, with Lewy bodies of misfolded alpha-synuclein. Loss of dopamine in the striatum ([caudate nucleus](https://durgical.com/en/anatomy/caudate-nucleus/) and [putamen](https://durgical.com/en/anatomy/putamen/)) unbalances the basal ganglia circuits, increasing inhibitory output to the [thalamus](https://durgical.com/en/anatomy/thalamus/) and [motor cortex](https://durgical.com/en/anatomy/precentral-gyrus/). Motor signs appear only after many neurones are lost; changes elsewhere explain non-motor symptoms.

## Symptoms and signs

- Bradykinesia: slowness and progressive reduction of repetitive movements (required for diagnosis)
- Rest tremor, often pill-rolling, usually asymmetric at onset
- Rigidity (lead-pipe or cogwheel)
- Shuffling gait with reduced arm swing, stooped posture; postural instability later
- Reduced facial expression, small handwriting, soft voice
- Non-motor: loss of smell, constipation, REM sleep behaviour disorder, depression, orthostatic hypotension, cognitive decline

## Red flags

- Early falls, rapid progression or poor response to levodopa (suggests atypical parkinsonism)
- Recent exposure to antipsychotics or antiemetic dopamine blockers (drug-induced parkinsonism)
- Severe rigidity and fever after stopping dopaminergic drugs
- Hallucinations or sudden confusion

## Diagnosis

**Clinical**
Clinical diagnosis: bradykinesia plus rest tremor or rigidity, using accepted criteria (e.g. Movement Disorder Society), supported by a clear response to dopaminergic treatment and absence of features of other causes.

**Tests**
No blood test confirms it. Tests exclude mimics when indicated (e.g. thyroid function, copper studies in young patients for Wilson disease). Genetic testing in selected early-onset cases.

**Imaging**
Brain MRI is usually normal and is used to exclude other causes. Dopamine transporter imaging (SPECT) can help when the diagnosis is uncertain, for example versus essential tremor.

## Differential diagnosis

- Essential tremor
- Drug-induced parkinsonism
- Vascular parkinsonism
- Atypical parkinsonism (progressive supranuclear palsy, multiple system atrophy, dementia with Lewy bodies)
- Normal pressure hydrocephalus
- Wilson disease (young patients)

## Goal of treatment

Control symptoms and preserve function and quality of life; no current treatment stops progression.

## Treatment

**Medical**
Levodopa combined with a peripheral decarboxylase inhibitor: the most effective drug for motor symptoms.

**Medical**
Other options: dopamine agonists, MAO-B inhibitors, COMT inhibitors and amantadine, chosen by age, symptoms and side effects.

**Medical**
Treatment of non-motor symptoms: constipation, orthostatic hypotension, depression, sleep problems and psychosis.

**Surgical**
Deep brain stimulation of the subthalamic nucleus or [globus pallidus](https://durgical.com/en/anatomy/globus-pallidus/) for selected patients with motor fluctuations or tremor not controlled by drugs.

**Rehabilitation**
Physiotherapy, exercise, occupational therapy and speech and swallowing therapy throughout the disease.

## Drugs for this condition

- [Rivastigmine](https://durgical.com/en/pharmacology/rivastigmine/)
- [Levodopa + carbidopa](https://durgical.com/en/pharmacology/levodopa-carbidopa/)
- [Benzatropine](https://durgical.com/en/pharmacology/benzatropine/)
- [Pramipexole](https://durgical.com/en/pharmacology/pramipexole/)
- [Cabergoline](https://durgical.com/en/pharmacology/cabergoline/)
- [Amantadine](https://durgical.com/en/pharmacology/amantadine/)
- [Bromocriptine](https://durgical.com/en/pharmacology/bromocriptine/)
- [Ropinirole](https://durgical.com/en/pharmacology/ropinirole/)
- [Selegiline](https://durgical.com/en/pharmacology/selegiline/)
- [Rasagiline](https://durgical.com/en/pharmacology/rasagiline/)
- [Entacapone](https://durgical.com/en/pharmacology/entacapone/)
- [Trihexyphenidyl](https://durgical.com/en/pharmacology/trihexyphenidyl/)
- [Biperiden](https://durgical.com/en/pharmacology/biperiden/)
- [Levodopa + benserazide](https://durgical.com/en/pharmacology/levodopa-benserazide/)
- [Tolcapone](https://durgical.com/en/pharmacology/tolcapone/)
- [Safinamide](https://durgical.com/en/pharmacology/safinamide/)

## Complications

- Motor fluctuations (wearing off) and dyskinesias with long-term levodopa
- Falls and fractures
- Dysphagia and aspiration pneumonia
- Dementia, psychosis and depression
- Impulse control disorders with dopamine agonists
- Parkinsonism-hyperpyrexia syndrome if medication is stopped suddenly

## Prognosis

Slowly progressive over many years. Most patients respond well to treatment at first; disability later comes from fluctuations, falls, swallowing problems and cognitive decline.

## Test yourself

Think of the answer, then tap the question to see it.

## Which neurones are lost in Parkinson disease?

Dopaminergic neurones of the substantia nigra pars compacta, which project to the striatum.

## Which motor sign is required for the diagnosis of parkinsonism?

Bradykinesia, plus rest tremor or rigidity.

## What protein forms Lewy bodies?

Misfolded alpha-synuclein.

## Why is levodopa given with a peripheral decarboxylase inhibitor?

To stop its conversion to dopamine outside the brain, increasing brain delivery and reducing nausea and other peripheral effects.

## Which features suggest an atypical parkinsonism rather than Parkinson disease?

Early falls, rapid progression, symmetric onset, early autonomic failure, gaze palsy or poor response to levodopa.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/parkinson-disease/)

## Related conditions

- [Alzheimer disease](https://durgical.com/en/conditions/alzheimer-disease/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Parkinson Disease](https://www.ncbi.nlm.nih.gov/books/NBK470193/) (StatPearls (NCBI Bookshelf), 2025).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/conditions/parkinson-disease/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/parkinson-disease/