Cognitive impairment and dementia in Parkinson's disease: clinical features, diagnosis, and management

Abstract

Parkinson's disease (PD) is a common, disabling, neurodegenerative disorder. In addition to classical motor symptoms, non-motor features are now widely accepted as part of the clinical picture, and cognitive decline is a very important aspect of the disease, as it brings an additional significant burden for the patient and caregivers. The diagnosis of cognitive decline in PD, namely mild cognitive impairment (MCI) and dementia, can be extremely challenging, remaining largely based on clinical and cognitive assessments. Diagnostic criteria and methods for PD dementia and MCI have been recently issued by expert work groups. This manuscript has synthesized relevant data in order to obtain a pragmatic and updated review regarding cognitive decline in PD, from milder stages to dementia. This text will summarize clinical features, diagnostic methodology, and therapeutic issues of clinical decline in PD. Relevant clinical genetic issues, including recent advances, will also be approached.

Keywords: Parkinson’s disease; Parkinson’s disease dementia; cognition; dementia; diagnosis; diagnostic criteria; mild cognitive impairment; non-motor symptoms.

Figure 1

schematic representation of the progression of PD patients until the stage of dementia. Functional impairment in PD is multifactorial (motor symptoms, cognitive decline, other non-motor symptoms). Please note that this graph is merely pictorial; it is not intended to represent proportions between variables nor is the progression linear, despite the drawing.