Purpose: Cognitive changes in Parkinson's disease (PD) can occur at any stage of the disease and have been shown to significantly impact well-being and life participation. The nature and pattern of cognitive decline in PD remains unclear due to the heterogeneity of symptoms and lack of a clear explanatory model. This review aims to draw attention to several theoretical models of cognitive decline in PD to deepen our understanding of the complex milieu of symptoms and begin to offer clinical implications for rehabilitation fields.
Method:The domains of cognition typically affected by PD are reviewed along with key aspects of five prominent models of cognition in PD. Implications are discussed through the lens of cognitive heterogeneity and clinical practice.Results: Multiple cognitive domains are vulnerable to PD neuropathology, however, variability exists in the presence and severity of functional changes. Theoretical models that highlight disease progression, vulnerable neural networks, and neurotransmitter involvement provide insight into the variability of cognitive changes.
Conclusion:Although one single model cannot account for the wide variability in presentation and rate of cognitive decline in PD, consideration of multiple models provides important insight for research and clinical practice, such as the delineation of cognitive phenotypes.