Dementia in Parkinson disease

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By Jared R Brosch MD and Martin Farlow MD

Parkinson disease dementia is clinically distinct from other forms of dementia, including Alzheimer dementia and vascular dementia. Although it shares many of the pathologic features of dementia with Lewy bodies, it remains a separate and distinct entity. Understanding the distinguishing features of Parkinson disease dementia is helpful for screening patients, offering evidence-based treatments, and providing valuable information to patients and their caregivers.

Key points

  • Parkinson disease dementia is a clinically distinct entity, separate from dementia with Lewy bodies, Alzheimer disease, vascular dementia, and other forms of neurodegenerative disease.
  • Longitudinal studies have shown that the risk of Parkinson disease dementia increases with age, akinetic/postural instability forms of Parkinson disease, early hallucinations, early executive dysfunction, and duration of disease (63% after 12 years and 83% after 20 years).
  • Attention (particularly fluctuations), visuospatial construction, and executive function are more impaired in Parkinson disease dementia compared with Alzheimer disease. In general, short-term memory and language are less impaired compared to Alzheimer disease.
  • Patients with Parkinson disease dementia have a cholinergic deficit thought to be greater than that in Alzheimer disease patients. Cholinesterase inhibitors are approved as a treatment for Parkinson disease dementia and have shown benefit in terms of both cognitive function and behavioral function (including reduction in visual hallucinations).

In This Article

Historical note and nomenclature
Clinical manifestations
Clinical vignette
Pathogenesis and pathophysiology
Differential diagnosis
Diagnostic workup
Prognosis and complications
References cited