Objective: To determine the prevalence of mild cognitive impairment (PD-MCI) in Parkinson’s disease (PD) patients, candidates to subthalamic deep brain stimulation (STN-DBS) as well as the frequency of the PD-MCI subtypes. We also sought to identify MRI structural markers associated with cognitive impairment.

Background: There is no consensus about the influence of PD-MCI on STN-DBS outcomes. Moreover, PD-MCI is heterogeneous, and biomarkers of this heterogeneity are missing.

Method: Baseline data from the French multicentric PREDISTIM cohort were used. PD patients, candidates to STN-DBS were classified according to their cognitive performance at a comprehensive neuropsychological tests battery in PD with normal cognition (PD-NC) or PD-MCI. The latter included frontostriatal (PD-FS) and posterior cortical (PD-PC) subtypes. All underwent an MRI with T1-weighted sequences. Volume, voxel-based morphometry, shape and radiomic analyses of bilateral caudate nuclei, thalami and hippocampi along with vertex-wise and global average cortical thickness analysis for both hemispheres were performed. Between-group comparisons (PD-NC vs PD-MCI as well as PD-FS vs PD-PC subtypes) of these parameters were performed.

Results: 320 patients were included, with 167 (52%) PD-NC and 153 (48%) PD-MCI patients. The latter group included 123 (80%) PD-FS and 30 (20%) PD-PC patients. Compared to PD-NC, PD-MCI patients had (a) cortical thinning in both hemispheres, (b) lower global average cortical thickness in the left hemisphere, (c) higher radiomic-based interquartile range values in the left caudate nucleus and hippocampus and (d) lower radiomic-based kurtosis values in the left hippocampus. There were no significant differences between the PD-MCI subtypes.

Conclusion: About half of candidates to STN-DBS have PD-MCI. Among them, about 20% had posterior cortical deficits, a subtype considered to be at higher risk of developing earlier dementia. Compared to PD-NC, PD-MCI patients had structural cortical and subcortical alterations, namely several clusters of cortical thinning in both hemispheres and changes in grey levels distribution of the left caudate nucleus and hippocampus. All these modifications were independent of age, disease duration and severity. With the follow-up at 1-, 3- and 5-years after surgery, the predictive value of this markers regarding STN-DBS outcomes will be investigated.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/pd-mci-is-frequent-in-candidates-to-subthalamic-deep-brain-stimulation-and-is-associated-with-structural-brain-alterations/