Objective: To identify pre-operative factors of fast cognitive decline after subthalamic nucleus stimulation (STN DBS) in Parkinson’s disease (PD).

Background: Cognitive outcome after STN DBS remains controversial. Profound, rapid and negative changes in cognition have been reported in consecutive series. Although rare, they deeply impair the quality of life of PD patients despite motor improvement. Thus, identifying the patients with a higher risk of significant rapid cognitive decline after STN DBS is essential. Some factors have already been identified as predictors of cognitive impairment but not consistently found and no specific of rapid cognitive impairment (1). The direct role of STN DBS is also debated (2). Moreover, none study specially focus on fast cognitive impairment after STN DBS, occurring during the first year after surgery.

Methods: Our multicenter retrospective cohort study aimed to analyze the evolution of the Mattis dementia rating scale specially one year after STN DBS in PD patients and to identify pre-operative factors in the subgroup of “decliners”. “Decliners” patients were defined as having a negative difference of Mattis score of at least five points between preoperative and one year assessments.

Results: 265 patients were included, 201 patients had complete baseline and post-surgery evaluations. First, the principal component analysis failed to show any significant predictive factors of cognitive decline considering the whole group of PD patients. Then, we specially compared two groups of patients, “stable patients” (n= 99, 49.3%) versus “decliners” (n = 41, 20.4%). “Decliners” had significantly lower categorical verbal fluency and higher levodopa equivalent dose at baseline than stable patients (respectively p=0.0003 and p =0.003). The results of the multivariate logistic regression model showed that only pre-operative categorical verbal fluency z-scores appeared statistically significant (OR=0.51 IC 95% (0.35-0.75), p<0.001), meaning that lower categorical verbal fluency z scores is predictive of a higher cognitive decline.

Conclusions: STN DBS in PD is most of the time safe from a cognitive point of view. However, PD patients with low categorical verbal fluency Z score might be at risk of a fast cognitive negative outcome and should be ruled out of neurosurgical project.

References: 1. Daniels C, Krack P, Volkmann J, Pinsker MO, Krause M, Tronnier V, Kloss M, Schnitzler A, Wojtecki L, Bötzel K, Danek A, Hilker R, Sturm V, Kupsch A, Karner E, Deuschl G, Risk factors for executive dysfunction after subthalamic nucleus stimulation in Parkinson’s disease. Mov Disord. 2010; 15;25(11):1583-9 2. Witt K, Granert O, Daniels C, Volkmann J, Falk D, van Eimeren T, Deuschl G. Relation of lead trajectory and electrode position to neuropsychological outcomes of subthalamic neurostimulation in Parkinson’s disease: results from a randomized trial. Brain. 2013 ;136(Pt 7):2109-19.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/predictive-factors-of-fast-cognitive-decline-in-parkinsons-disease-after-subthalamic-stimulation-myth-or-reality/