Neural Correlates of Cognitive Impairment in Patients with Parkinson’s Disease with Hallucinations
Poster No:
252
Submission Type:
Late-Breaking Abstract Submission
Authors:
Lada Kohoutova1, Fosco Bernasconi2, Jevita Potheegadoo3, Olaf Blanke3
Institutions:
1EPFL, Geneva, Switzerland, 2EPFL, Geneva, GE, 3Ecole Polytechnique Federale de Lausanne, Geneva, Switzerland
First Author:
Co-Author(s):
Introduction:
Hallucinations are a common non-motor symptom in Parkinson's disease (PD). They range from minor hallucinations, including passage and presence hallucinations, and visual illusions, to well-structured hallucinations, and are linked to a more rapid cognitive decline (Bejr‐Kasem et al., 2021; Anang et al., 2014). To enable the study of hallucinations in controlled laboratory settings, our group has developed a robotic system that, via somatomotor conflict, induces presence hallucination-like symptoms, or in other words the false perception of someone else being nearby (Blanke et al., 2014). Notably, PD patients who experience hallucinations as one of their daily symptoms exhibit heightened sensitivity to this somatomotor conflict (Bernasconi et al., 2021). Our current study integrates behavioural data from the robot experiment with neuropsychological assessments (PD Cognitive Rating Scale; PD-CRS) and resting state functional magnetic resonance imaging (rs-fMRI), to investigate neural correlates of cognitive impairment in PD patients with symptomatic hallucinations. Our results suggest that mainly the functional connectivity (FC) between subcortical (SBC) areas and the visual network (VN) is associated with both the sensitivity to the robot task and frontal subcortical cognitive scores in three subgroups of PD patients.
Methods:
Our dataset includes a total of 53 patients categorised into three groups through a clinical interview: no hallucinations (nH; n = 19), minor hallucinations (mH; n = 18), and complex, that is, a combination of minor and well-structured, hallucinations (xH; n = 16). All patients completed a set of neuropsychological tests, underwent an 8 min rs-fMRI session, and performed the somatomotor robot task outside the MRI. During the robot task, participants were instructed to move the front part of the robotic system while the back robot delivered a tactile stimulus on the participant's back with a 0 ms, 250 ms or 500 ms delay. There were 12 trials of each delay and after each trial participants were asked whether they experienced the sensation of someone nearby. We fitted a linear model in each individual to the mean of "yes" answers in each delay and used the slope of the regression in our further analyses. fMRI data were preprocessed, denoised, and parcellated into 265 regions based on a combination of the Schaefer (Schaefer et al., 2018) and Brainnetome (Fan et al., 2016) atlases, with periaqueductal grey and brainstem regions from previous studies (Beissner et al., 2014; Roy et al., 2014). Whole brain FC was obtained for each individual. To analyse the data, we performed a partial least squares correlation (PLSC) with the whole brain FC as the x-variable and robot responses, frontal subcortical cognitive scores of the PD-CRS, and the clinical group assignment as the y-variable. We ran a permutation test with 5,000 iterations to determine the significant latent components, and a bootstrap test with 10,000 samples to find features significantly contributing to those components.
Results:
The permutation test in the PLSC analysis revealed one significant latent component (LC1) explaining 96 % of covariance (p = 0.005). The bootstrap test showed that LC1 captured mainly the difference between mH and nH groups as well as the robot task sensitivity and frontal subcortical cognitive scores and their interactions with the mH vs. nH contrast (Fig. 1a). Associated significant loadings of FC were found mostly between SBC and VN and somatomotor (SMN) areas, between frontoparietal (FPN) and SMN, and between ventral attention and SMN (Fig. 1b).
Conclusions:
Our findings revealed an interplay of mainly SBC-VN and SBC-SMN FC linked to cognitive impairment, somatomotor robot task sensitivity, and hallucinations in PD patients. This extends previous studies showing altered cortico-SBC FC in PD patients (Tang et al., 2022) and changes in FC between SMN, FPN and VN associated with hallucinations in PD patients (Baik et al., 2024; Bernasconi et al., 2021).
Disorders of the Nervous System:
Neurodegenerative/ Late Life (eg. Parkinson’s, Alzheimer’s) 1
Higher Cognitive Functions:
Higher Cognitive Functions Other 2
Modeling and Analysis Methods:
Task-Independent and Resting-State Analysis
Novel Imaging Acquisition Methods:
BOLD fMRI
Keywords:
FUNCTIONAL MRI
Other - Parkinson's disease, hallucinations, cognitive impairment
1|2Indicates the priority used for review
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