The Role of Cerebrovascular Disease in Parkinson’s Disease Related Cognitive Impairment

demonstrated significantly more severe SVD-associated pathology compared to controls, which suggests that SVD may have a role in the pathophysiology of PD [12]. Another longitudinal study by Foo et al. demonstrated that progression of SVD was associated with significant cortical thinning in the frontoparietal regions with concomitant decline in memory, executive functions, and motor functions in PD patients [13]. This implies that the extent and progression of SVD could be associated with focal cerebral atrophy and domain-specific cognitive dysfunction. Furthermore, it could be possible that concomitant SVD in PD could alter the clinical-cognitive symptom presentation and treatment response of PD [14]. Additionally, Arena et al. showed that deep WMH burden was not only associated with worse performance on UPDRS, such as speech, facial expression, neck rigidity, postural stability, posture, and global spontaneous movements, but also worse response to L-Dopa [15]. This has important clinical relevance in patient management. Presence of WMH may impact response to L-dopa treatment and deep brain stimulation surgery (DBS), since evidence has established the correlations between response to L-Dopa and DBS [15]. Despite the consequence of SVD in PD, there is a paucity of literature investigating the impact of SVD as a whole in the pathophysiology of PD. Even within those who examined SVD in PD, the findings have been heterogeneous. This could be a result of the challenges to image and investigate small vessels in vivo, especially when imaging of small vessel disease are typically measured using subjective visual ratings instead of objective volumetric analysis; and the imprecise and inconsistent methods of classifying the lesions that could lead to under or over diagnosis of SVD [8]. In turn, it is imperative to establish the contributions of SVD to the underlying neuropathophysiology of PD in order to benefit subsequent patient management and treatment.