Parkinson’s disease — dopamine deficiency movement disorder

Parkinson’s disease (PD) is progressive neurodegeneration of dopaminergic neurons in substantia nigra — motor circuit dysfunction — tremor, bradykinesia, rigidity, postural instability.

~145,000 UK — incidence rising with ageing population.

Average onset ~60 — young-onset <50 — 10% — often genetic.

Cardinal motor features

TRAP:

  • Tremor — 4–6 Hz, resting, pill-rolling, asymmetric onset
  • Rigidity — cogwheel
  • Akinesia/bradykinesia — slowness, reduced amplitude — most disabling
  • Postural instability — later — falls

Gait: shuffling, festination, freezing

Non-motor symptoms (often earlier)

Diagnosis

Clinical — neurologist — UK Parkinson’s Disease Society Brain Bank criteria

DaTscan SPECT — if uncertain — not routine

Exclude:

  • drug-induced parkinsonism — antipsychotics, metoclopramide
  • vascular parkinsonism
  • essential tremor — action tremor, no bradykinesia
  • progressive supranuclear palsy, MSA — atypical parkinsonism — poor levodopa response

Treatment

Medicines

Levodopa + carbidopa — gold standard — best motor control

Dopamine agonists — ropinirole, pramipexole — younger onset — delay levodopa — impulse control disorder risk

MAO-B inhibitors — selegiline, rasagiline — mild early benefit

COMT inhibitors — entacapone — wearing off

Anticholinergics — rare now — tremor — cognitive side effects

Advanced

Apomorphine — rescue injection/infusion

Duodopa — intestinal gel

DBS — subthalamic nucleus/globus pallidus — motor fluctuations, dyskinesia

Non-drug

Physiotherapy, speech and language, occupational therapy

Exercise — forced rate cycling, LSVT BIG/LOUD

Motor complications (chronic levodopa)

  • wearing off
  • on-off fluctuations
  • dyskinesias — involuntary movements

Specialist titration — fractionate doses, agonist, DBS

Prognosis

Progressive — individual rates vary

Not Alzheimer’s — many independent years

Advanced — dysphagia, falls, dementia — palliative input

Persistent one-hand rest tremor + slowness — neurology — levodopa trial diagnostic and therapeutic.

Common questions about Parkinson's disease

What are the early signs of Parkinson's disease?
Tremor at rest — often one hand — slowness doing buttons or walking, reduced facial expression, softer voice, smaller handwriting, stiffness, shuffling gait, reduced arm swing when walking. Loss of smell and constipation can precede diagnosis by years.
What causes Parkinson's disease?
Loss of substantia nigra dopamine neurons and Lewy body protein deposits — cause multifactorial — age, genetics (minority familial), environmental factors debated. Not contagious. Parkinsonism from drugs (antipsychotics) or vascular causes — different management — exclude.
Is there a cure for Parkinson's?
No cure — medicines replace dopamine (levodopa) or mimic/stabilise it (dopamine agonists, MAO-B inhibitors). Deep brain stimulation for selected patients with motor fluctuations. Research into disease modification ongoing — exercise and multidisciplinary care improve quality of life.
What is levodopa?
Most effective Parkinson's drug — converted to dopamine in brain — combined with carbidopa to reduce peripheral side effects. Sinemet brand common. Motor complications — wearing off, dyskinesias — after 5–10 years — managed by specialist dose adjustment, agonists, or DBS.
How long can you live with Parkinson's?
Normal or near-normal lifespan — Parkinson's not directly fatal — complications — falls, aspiration pneumonia, frailty — contribute in advanced disease. Many live well 15–20 years after diagnosis with treatment and support.

Sources

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