Performance on the Dementia Rating Scale-2 and deep brain stimulation screening : a retrospective review

Abstract

Deep brain stimulation (DBS) is considered as a neurotherapeutic treatment option for Parkinson’s disease (PD) patients’ with medically intractable motor symptoms. With the increasing implementation of DBS surgery in South Africa, research on the neuropsychological prescreening criteria would be beneficial when considering DBS candidacy suitability. International and national screening procedures often use the Dementia Rating Scale-2 (DRS-2) global cognitive functioning score as one of the determinants for cognitive stratification and DBS candidacy determination. Understanding the potential predictors of DRS-2 global cognitive functioning as measured by the Total Dementia Rating Scale score (TDRS) can aid in adapting the screening process by considering other cognitive markers, efficaciously treating and managing psychiatric symptoms influencing cognitive functioning, and determining which candidates can be considered for follow-up reassessment. The aim of this exploratory study was to determine the sociodemographic, cognitive, and psychiatric correlates of global cognitive functioning on the DRS-2 in a South African cohort with PD presenting for DBS presurgical screening. A quantitative research design was employed and a total of 144 participant protocols were reviewed and analysed using correlation analysis, t-tests and regression analysis. Data from the DRS-2, the Beck Depression Inventory, the Beck Anxiety Inventory , and the sociodemographic questionnaire were included in the analyses. The results showed that education level and age correlated significantly with the TDRS score. Significant predictors of the TDRS score were DRS-2 cognitive subscales, where Initiation/Perseveration (I/P) (verbal fluency) accounted for the highest variance. Depression was also a significant predictor of the TDRS score. This exploratory study contributes to research on prescreening of DBS PD patients in South Africa and highlights the importance of considering several factors when using the DRS-2 on a local cohort for the purpose of DBS candidacy determination.