Neurobiology of cognitive impairment in Parkinson’s disease

Abstract

Cognitive impairment is a frequent complication of Parkinson’s disease (PD). Mild cognitive impairment (MCI) may progress to dementia more frequently and rapidly. PD dementia (PDD) and PD-MCI have a mean prevalence up to 75% each; a four- to six-times increased incidence rate compared with controls. Recent diagnostic clinical criteria for both PDD and PD-MCI require validation. Cognitive decline in PD can be probed clinically, comprehensive neuropsychological assessment being the best way to define it. Neuroimaging in both disorders revealed cortical atrophy, hypometabolism, white matter changes, dopaminergic/cholinergic dysfunction and increased amyloid burden. Combined analysis of imaging and cerebrospinal fluid markers (tau and Aβ-42) is the most promising method for indentifying PD-MCI and PDD. Morphological substrates are a combination of Lewy and Alzheimer pathologies causing destruction of essential neuronal networks. PDD and dementia with Lewy bodies are considered similar parts of a disease spectrum. Treatment with cholinesterase inhibitors revealed mild-to-moderate results.

Keywords::

• biomarkers
• clinical features
• consensus guidelines
• dementia with Lewy bodies
• diagnostic criteria
• mild cognitive impairment
• neuroimaging
• neuropathology
• Parkinson’s disease dementia
• treatment options

Financial & competing interests disclosure

KA Jellinger is Director of the Institute of Clinical Neurobiology, Vienna, Austria, which is supported by the Society for Support of Research in Experimental Neurology, Vienna, Austria. The study was partially supported by the Society for Support of Research in Experimental Neurology. The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Notes

^†Subtype classifications are applicable only to those PD-MCI who have had at least two tests within each of the five cognitive domains administered.

MCI: Mild cognitive impairment; MDSTF: Movement Disorder Society Task Force; PD: Parkinson’s disease; SD: Standard deviation.

Data taken from [11,33,221]. Modified from [53].