Bidirectional Interplay between Deep Brain Stimulation and Cognition in Parkinson's Disease: A Systematic Review.

BACKGROUND: Deep brain stimulation (DBS) is efficacious for treating motor symptoms in Parkinson's disease (PD). OBJECTIVES: The aim is to evaluate the evidence regarding DBS effectiveness after postoperative cognitive deterioration, the impact of preoperative cognition on DBS effectiveness, and the impact of DBS on cognition. METHODS: Literature searches were performed on MEDLINE, EMBASE, and CENTRAL (Cochrane library). Primary outcomes were OFF-drug Unified Parkinson Disease Rating Scale Part III score and cognitive test scores. RESULTS: DBS effectiveness did not differ in patients with postoperative declining compared to stable cognition (n = 5 studies). Preoperative cognition did not influence DBS effectiveness (n = 1 study). DBS moderately decreased verbal fluency compared to the best medical treatment (n = 24 studies), which may be transient. CONCLUSION: DBS motor effectiveness in PD does not appear to be influenced by cognition. DBS in PD seems cognitively safe, except for a moderate decline in verbal fluency. Further research is warranted. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Efficacy and safety of adjunctive oral therapy in Parkinson's disease with motor complications: a systematic review and network meta-analysis.

Background: The aim of this manuscript is to review the evidence and compare the efficacy and safety of catechol-O-methyltransferase inhibitors (COMT-Is), dopamine receptor agonists (DRAs) and monoamine-oxidase B inhibitors (MAOB-Is) as adjunctive treatment to levodopa in patients with Parkinson's disease (PD) experiencing motor complications. Methods: In this systematic review and network meta-analysis, literature searches were performed in MEDLINE and Embase to identify eligible randomised controlled trials (RCTs) with a minimal follow-up of at least 4 weeks published in English between 1980 and 2021. RCTs were included if either a COMT-I, DRA or MAOB-I was evaluated as an adjunctive therapy to levodopa in patients with PD experiencing motor complications and dyskinesia. The main outcomes included daily off-medication time, motor and non-motor examination scales, and adverse events including dyskinesia. Results: 74 RCTs reporting on 18 693 patients were included. All three studied drug classes decreased daily off-medication time compared with placebo (COMT-Is mean -0.8 hours (95% CI -1.0 to -0.6), DRAs -1.1 hours (95% CI -1.4 to -0.8), MAOB-Is -0.9 hours (95% CI -1.2 to -0.6)). Safety analysis showed an increased risk of dyskinesia for all three drug classes (COMT-Is OR 3.3 (95% CI 2.7 to 4.0), DRAs 3.0 (95% CI 2.5 to 3.5), MAOB-Is 1.6 (95% CI 1.2 to 2.2)). According to surface under the cumulative ranking curve scores, pramipexole IR was associated with the most favourable benefit-risk profile. Conclusions: COMT-Is, DRAs and MAOB-Is effectively reduce motor complications and increase incidence of dyskinesia. In the network meta-analysis, adjunctive use of DRAs appeared most effective.

Directional versus ring-mode deep brain stimulation for Parkinson's disease: protocol of a multi-centre double-blind randomised crossover trial.

BACKGROUND: The effectiveness of Deep Brain Stimulation (DBS) therapy for Parkinson's disease can be limited by side-effects caused by electrical current spillover into structures adjacent to the target area. The objective of the STEEred versus RING-mode DBS for Parkinson's disease (STEERING) study is to investigate if directional DBS for Parkinson's disease results in a better clinical outcome when compared to ring-mode DBS. METHODS: The STEERING study is a prospective multi-centre double-blind randomised crossover trial. Inclusion criteria are Parkinson's disease, subthalamic nucleus DBS in a 'classic' ring-mode setting for a minimum of six months, and optimal ring-mode settings have been established. Participants are categorised into one of two subgroups according to their clinical response to the ring-mode settings as 'responders' (i.e., patient with a satisfactory effect of ring-mode DBS) or 'non-responder' (i.e., patient with a non-satisfactory effect of ring-mode DBS). A total of 64 responders and 38 non-responders will be included (total 102 patients). After an optimisation period in which an optimal directional setting is found, participants are randomised to first receive ring-mode DBS for 56 days (range 28-66) followed by directional DBS for 56 days (28-66) or vice-versa. The primary outcome is the difference between ring-mode DBS and directional DBS settings on the Movement Disorders Society Unified Parkinson's Disease Rating Scale - Motor Evaluation (MDS-UPDRS-ME) in the off-medication state. Secondary outcome measures consist of MDS-UPDRS-ME in the on-medication state, MDS-UPDRS Activities of Daily Living, MDS-UPDRS Motor Complications-Dyskinesia, disease related quality of life measured with the Parkinson's Disease Questionnaire 39, stimulation-induced side-effects, antiparkinsonian medication use, and DBS-parameters. Participants' therapy preference is measured at the end of the study. Outcomes will be analysed for both responder and non-responder groups, as well as for both groups pooled together. DISCUSSION: The STEERING trial will provide insights into whether or not directional DBS should be standardly used in all Parkinson's disease DBS patients or if directional DBS should only be used in a case-based approach. TRIAL REGISTRATION: This trial was registered on the Netherlands Trial Register, as trial NL6508 ( NTR6696 ) on June 23, 2017.