Medical Encyclopaedia › Parkinson’s disease (short definition)
In brief: Parkinson’s disease is a slowly progressive disease of the nervous system in which dopamine-producing nerve cells in the brain die. Slowed movements, muscle stiffness and tremor at rest are typical; it usually begins after the age of 60.
Causes
In the substantia nigra, a region of the midbrain, nerve cells that produce the messenger substance dopamine die; in the process, the protein alpha-synuclein is deposited in nerve cells. Why this happens is usually unclear (idiopathic Parkinson’s syndrome). A small proportion is hereditary; environmental factors such as certain pesticides are discussed as risk factors. Parkinsonian syndromes caused by medicines or other neurodegenerative diseases must be distinguished from it.
Symptoms
The core symptom is bradykinesia, a slowing and reduction of movement: steps become smaller, facial expression more rigid, handwriting smaller. In addition, there is muscle stiffness (rigidity), a resting tremor that often begins on one side and, over time, gait and balance disorders. Years before the movement disorders, loss of smell, constipation, depression and a sleep disorder in which dreams are acted out (REM sleep behaviour disorder) can occur.
Diagnosis
The diagnosis is made clinically on the basis of the typical symptoms and a neurological examination. A good response to dopamine medicines supports it. Imaging procedures such as MRI or nuclear medicine imaging of dopamine transporters (DaTSCAN) help to rule out other causes. New biomarkers, such as the detection of misfolded alpha-synuclein, have so far been used mainly in research.
Treatment
The medicines replace or enhance dopamine: the most effective is levodopa, combined with carbidopa or benserazide; dopamine agonists, MAO-B inhibitors and COMT inhibitors are also used. Over time, fluctuations in effect and involuntary excessive movements can occur, requiring treatment to be adjusted. Dopamine agonists can trigger impulse control disorders such as gambling or shopping addiction, which relatives should watch out for. In advanced stages, medication pumps or deep brain stimulation may be considered. Regular exercise, physiotherapy, occupational therapy and speech therapy are an integral part of treatment. A cure is not yet possible, but quality of life can be well maintained for many years.
When to see a doctor?
A newly occurring tremor, slowed movements, handwriting that is becoming smaller or unsteady gait should be assessed by a neurologist. Not every tremor is Parkinson’s; essential tremor, for example, is more common.
Related terms in the encyclopaedia
Dopamine, Substantia nigra, Levodopa, Carbidopa, Dopamine agonists, MAO-B inhibitors, Deep brain stimulation, Rigidity, Tremor, Essential tremor
Further reading on Medizin Aktuell
Sources
- Deutsche Gesellschaft für Neurologie (DGN): S2k-Leitlinie „Parkinson-Krankheit“, AWMF-Register 030-010
- Postuma R. B. et al.: MDS clinical diagnostic criteria for Parkinson’s disease, Movement Disorders 2015
- Deutsche Parkinson Vereinigung: Patienteninformationen
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor or pharmacist. Last updated: October 2026.