Objective: To analyze the integrity of visual and executive network of patients with Parkinson’s disease (PD) with psychosis (PD-P) and those without psychosis (PD-NP) and healthy controls (HC).

Background: Psychosis is one of the common non-motor symptoms of PD but its neural correlates are not fully understood. Although visuospatial and executive dysfunction have been reported in PD patients with psychosis, there is no direct evidence of alteration in the neural networks involved in these two functions.

Methods: Diffusion MR images were obtained from 69 subjects (PD-P: 28, PD-NP: 24, HC: 17, age-gender-education matched, MMSE > 24). Structural connectivity within the executive and visual networks was computed by using probabilistic fiber tracking. Edge-wise analysis and topological analyses were carried out using a MANCOVA model. Frontal assessment battery (FAB) and stroop test were done to assess the executive functions whereas Corsi block tapping test and complex figure test were done to evaluate the visuospatial functions.

Results: There was no significant difference between the demographic and disease characteristics of the two PD subgroups. In the visual network, the global and nodal level analysis revealed reduced clustering coefficient and reduced participation coefficient of right lingual gyrus in PD-P compared to controls. Edge-wise analysis revealed decreased connectivity across several nodes in PD-P compared to controls (r-lingual to r-entorhinal, l-entorhinal to l-fusiform, l-lingual to r-lingual, l-cuneus to l-lateraloccipital, r-inferiortempral to r-lateraloccipital). Connectivity of the left and right lingual gyrus had significant positive correlation with the scores of Corsi block tapping test and complex figure test. The executive network revealed poor participation coefficient of left medio-orbitofrontal cortex in PD-P compared to controls. There was a significant positive correlation of the connectivity of left and right medio-orbitofrontal cortex with scores of FAB. There was no significant difference between PD-P and PD-NP; however,the strength of connectivity of PD-NP in both networks was numerically between that of PD-P and controls, suggesting the possibility that genesis of psychosis represents a continuum of structural alterations.

Conclusions: Patients with PD-P have altered structural connectivity within the visual and executive network compared to healthy individuals. Future studies (longitudinal design) with higher sample size are warranted to obtain better insights into the pathogenesis of PD associated psychosis.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/patients-with-parkinsons-disease-and-psychosis-have-altered-structural-connectivity-of-the-executive-and-visual-networks/