Objective: The study aimed to examine the neurocognitive changes following STN-DBS in patients with PD.

Background: Neurocognitive evaluation is a standard procedure preoperatively in patients with PD for STN-DBS in Hong Kong. There have been increasing reports on postoperative neurocognitive outcomes; reduction of verbal fluency was consistently reported (Højlund et al., 2017). Unlike the fluency tests used in the West where most studies were conducted, phonemic fluency is not measurable in the Chinese language structure. Instead, semantic fluency is used. Previously, our group reported reduction of semantic verbal fluency among a small cohort (n=27) at 6-month through 1-year postoperation (Tang et al., 2015); alongside other cognitive changes including memory improvement. The present study aimed to investigate the interval changes of neurocognitive functions following STN-DBS from baseline to 2-year postoperation.

Method: A neurocognitive battery was performed, included Chinese-validated tests on global cognitive function (HK-MoCA), attention/working memory, memory, language, visuospatial abilities, executive functions and mood. All patients were evaluated at their optimal functioning at baseline, 1-year and 2-year postoperation.

Results: A total of 51 patients (mean age=57.2; range 38-72) underwent bilateral STN-DBS in the Prince of Wales Hospital Hong Kong between 2008 and 2016 were analyzed. 31 (60.8%) were male. 33 (65%) completed high school education. The average year of disease duration was 10.84 (SD=3.90; range 4-23 years). Using repeated measure ANOVA, there were significant deterioration postoperatively, including reaction time in visual attention [F(1.84, 100.21)=15.42, p<0.001], nonverbal memory [F(1.81, 11.17)=5.95, p=0.005], naming [F(1.81, 18.51)=5.61, p=0.007], and semantic verbal fluency [F(1.81, 151.55)=15.52, p<0.001]. On the contrary, there were significant improvement on verbal memory [F(1.91, 402.36)=9.87, p<0.001] and reduction on false alarm in memory recognition [F(1.74, 17.19)=5.18, p=0.01]. Post hoc analyses showed that all significant changes occurred from baseline to 1-year postoperation.

Conclusion: Details of postoperative cognitive changes will be discussed, including the possible mechanisms of memory improvement the performance of our cohorts in semantic fluency. The results also provided information that allowed better patient education among Chinese-Cantonese patients.

References: Højlund A, Petersen MV, Sridharan KS, Østergaard K. Worsening of Verbal Fluency After Deep Brain Stimulation in Parkinson’s Disease: A Focused Review. Computational and Structural Biotechnology Journal 2017; 15: 68-74 Tang V, Zhu CXL, Chan D, Lau C, Chan A, Mok V, Yeung J, Poon WS. Evidence of improved immediate verbal memory and diminished category fluency following STN-DBS in Chinese-Cantonese patients with idiopathic Parkinson’s disease. Neurological Sciences 2015; 36: 1371-1377.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neurocognitive-changes-after-stn-dbs-among-pd-patients-a-2-year-follow-up-study-in-hong-kong/