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Risk factors for non-motor symptoms in Parkinson’s disease

Non-dopaminergic symptoms include dementia, hallucinations and apathy

Non-dopaminergic symptoms include dementia, hallucinations and apathy


Excessive daytime sleepiness is a non-motor symptom of Parkinson's disease. Picture: iStock

The classic view of Parkinson’s disease is that its main effect is damage to the dopamine-producing neurones of the substantia nigra causing movement disorder.

Nowadays, the main feature is the widespread and progressive aggregation of the protein α-synuclein.

It is this clumping of cells that underlies the non-motor symptoms of the disease including dementia, hallucinations, depression, apathy, excessive daytime sleepiness and autonomic dysfunction that results in constipation and swallowing difficulties among other problems. These symptoms are designated as predominantly non-dopaminergic because they do not improve when patients are given medication to increase levels of dopamine.

Patients newly diagnosed with Parkinson’s disease may already have mild cognitive defects and almost 50% will have dementia within ten years of diagnosis. Hallucinations are common in patients with Parkinson’s disease. Mild hallucinations, such as the sense of a presence or of a visual hallucination in the peripheral visual field, may manifest before the onset of motor symptoms.

Implications for practice

Nurses should be aware of these non-motor symptoms so that they can offer appropriate support to patients with Parkinson's disease and their carers.

Hallucinations can be benign if the patient retains insight, but can become frightening as the disease progresses. Major depression can be difficult to diagnose as symptoms overlap with those of the disease or medication, but it occurs in 23% of patients with Parkinson’s disease.

Apathy, with lack of concern, motivation and interest in social or spiritual life, is seen in 40% of patients and greatly adds to the burden for caregivers.


Marinus J, Zhu K, Marras C et al (2018) Risk factors for non-motor symptoms in Parkinson’s disease. The Lancet. Neurology. 17, 6, 559-568.

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