Mild cognitive impairment in patients with Parkinson's disease is associated with increased cortical degeneration

Abstract

Mild cognitive impairment (MCI) can occur early in the course of Parkinson's disease (PD), and its presence increases the risk of developing dementia. Determining the cortical changes associated with MCI in PD, thus, may be useful in predicting the future development of dementia. To address this objective, 37 patients with PD, divided into 2 groups according to the presence or absence MCI (18 with and 19 without) and 16 matched controls, underwent anatomic magnetic resonance imaging. Corticometry analyses were performed to measure the changes in cortical thickness and surface area as well as their correlation with disease duration. Compared with healthy controls, the PD-MCI group exhibited increased atrophy and changes of local surface area in the bilateral occipital, left temporal, and frontal cortices; whereas the PD non-MCI group exhibited only unilateral thinning and decreased surface area in the occipital lobe and in the frontal cortex. In addition, a comparison between the PD-MCI and PD non-MCI groups revealed increased local surface area in the occipital lobe, temporal lobe, and postcentral gyrus for the cognitively impaired patients. It is noteworthy that, in the PD-MCI group, cortical thickness had a significant negative correlation with disease duration in the precentral, supramarginal, occipital, and superior temporal cortices; whereas, in the PD non-MCI group, such a correlation was absent. The findings from this study reveal that, at the same stage of PD evolution, the presence of MCI is associated with a higher level of cortical changes, suggesting that cortical degeneration is increased in patients with PD because of the presence of MCI.

Longitudinal brain volumetric changes and their predictive effects on cognition among cognitively asymptomatic patients with Parkinson's disease

“…Thus, early identification of MCI among PD patients is of clinical importance in order to retard progression to PDD. Neuroimaging studies have indicated alterations in widespread cortical regions among PD-MCIs, compared to healthy controls [8,9], though some have reported negative findings [6,10]. Compared with cognitively asymptomatic PD patients, our previous work [11] and the work of others have revealed reduced gray matter (GM) volume in PD-MCI [3,12], especially in the frontal and subcortical regions, supporting the frontostriatal dysfunctional theory for cognitive impairment in PD.…”

Imaging changes associated with cognitive abnormalities in Parkinson’s disease

“…A few studies consistently showed that PD with MCI may be associated with gray matter atrophy in limited regions of frontal and temporal regions (Hanganu et al 2013;Melzer et al 2012;Song et al 2011) while one of them additionally showed parietal volume loss (Melzer et al 2012) and others, occipital volume loss (Hanganu et al 2013;Song et al 2011). A longitudinal study also demonstrated higher rates of cortical thinning in the frontal and temporal regions, extending to parietal cortex .…”

“…Furthermore, non-demented PD patients show faster progression of gray matter changes including atrophy and cortical thinning than healthy controls (HCs) in diffuse areas including frontal, temporal and parietal regions (Hu et al 2001;Ibarretxe-Bilbao et al 2012), restricted regions to cortical motor areas and cerebellum (Ibarretxe-Bilbao et al 2010), or limbic, paralimbic, and temporo-occipital regions (Ramirez-Ruiz et al 2007). Among PD patients, variability in cortical thickness and/or subcortical volume is also associated with cognitive measures (Biundo et al 2011;Camicioli et al 2009;IbarretxeBilbao et al 2009;Melzer et al 2012;Pellicano et al 2012;Zarei et al 2013), facial emotion recognition , duration of disease (Hanganu et al 2013;Jubault et al 2011;Lyoo et al 2011), motor severity (Lyoo et al 2011;Melzer et al 2012;Zarei et al 2013) and stage (Zarei et al 2013) as well as dopamine (DA) non-responsive symptoms (Brenneis et al 2003;Camicioli et al 2009). …”

“…This is largely due to the lack of imaging studies investigating both structural group differences, and relationships between these differences and various clinical and cognitive measures. For example, brain regions displaying significant group differences in structure have not been specifically investigated for correlation analyses (Camicioli et al 2009;Hanganu et al 2013;Jubault et al 2011;Tinaz et al 2011). Even though brain regions demonstrating significant group differences have been shown to correlate with cognition, PD patients did not show impairment on cognitive tasks (Theilmann et al 2013).…”

Dementia-Predicting Cognitive Risk Score and Its Correlation with Cortical Thickness in Parkinson Disease

“…Additionally, the risk score for PD patients could be a neuropsychological biomarker integrating the dementia-predicting values of various neuropsychological tests. Considering that cortical thickness in PD patients has a significant correlation with general cognition and could reflect structural changes from cognitively normal PD to PD dementia (PDD) [12,13], finding cortical regions that are related to the cognitive risk score in nondemented PD patients could reveal the most important brain region for future dementia progression in PD patients.…”