Objective: To study the performance of PD-CRS before and after STN-DBS and compare their results with other recognized cognitive scales.

Background: Deep brain stimulation of subthalamic nucleus (STN-DBS) is a widely performed surgical method to treat advanced PD. STN- DBS can alleviate motor symptoms of PD, but its effects on cognitive function remain unclear. After surgery some studies have found significant decline of verbal fluency , deficits in inhibitory and executive control, and other works have found minor cognitive detrimental. The Parkinson’s Disease Cognitive Rating Scale (PD-CRS) was designed to evaluate and capture cortical and subcortical deficits in PD, but we don´t know if it can detect cognitive changes after STN-DBS. Also, any study has compared its performance with other cognitive scales.

Methods: We conducted a prospective study including 22 patients with PD who underwent STN-DBS (63,9.2 ± 3,4 years old; time evolution 12,8 ± 2,9 years). All patients were assessed before STN-DBS and six moths after surgery. The cognitive battery included PD-CRS, Mini-Mental State Examination (MMSE), Mattis Dementia Rating Scale (MDRS) and verbal fluencies.

Results: Performance of PD-CRS six moths after STN-DBS was significantly lower in the subtests of sustain attention ( 8,48 ± 1,53; 7,67 ± 1,71; p < .020), working memory (5,95 ± 1,66; 4,95 ± 1,75; p < .011) and alternant (9,43 ± 4,13; 7,00 ± 4,68; p < .019) and action fluency (13,86 ± 4,98; 11,14 ± 3,89; p < .031). Also, we found significantly lower performance in the Subcortical index: (57,33 ± 9,82; 50,90 ± 11,00; p < .003). Performance in the MDRS was significantly lower at six months in the subtest of initiation-perseveration (36,00 ± 2,07; 33,14 ± 4,36; p < .001) and in the total score: 136,38 ± 4,189; 132,33 ± 5,70, p < .013). Not significant differences were found in the MMSE.

Conclusions: After surgery, the PD-CRS showed a significantly lower performance in sustained attention, working memory, fluency task and subcortical index, in line with previous published studies . The MDRS showed lower performance in the subtest of initiation-perseveration and total score. We conclude that PD-CRS is a useful scale in the detection of cognitive changes of PD patients after STN-DBS.

References: Parkinson’s disease-cognitive rating scale: a new cognitive scale specific for Parkinson’s disease. Pagonabarraga J, Kulisevsky J, Llebaria G, García-Sánchez C, Pascual-Sedano B, Gironell A. Mov Disord. 2008 May 15;23(7):998-1005. doi: 10.1002/mds.22007. The effect of deep brain stimulation of the subthalamic nucleus on executive functions: impaired verbal fluency and intact updating, planning and conflict resolution in Parkinson’s disease.Demeter G, Valálik I, Pajkossy P, Szőllősi Á, Lukács Á, Kemény F, Racsmány M.Neurosci Lett. 2017 Apr 24;647:72-77. doi: 10.1016/j.neulet.2017.03.026. Epub 2017 Mar18.PMID: 28323092.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/performance-of-parkinsons-disease-cognitive-scale-rating-scale-pd-crs-after-subthalamic-nucleus-deep-brain-stimulation-comparison-with-mattis-dementia-rating-scale-mdrs-and-mini-mental-stat/