Predictors of short-term impulsive and compulsive behaviour after subthalamic stimulation in Parkinson disease

No evidence for an association of voxel-based morphometry with short-term non-motor outcomes in deep brain stimulation for Parkinson's disease

Deep brain stimulation of the subthalamic nucleus (STN-DBS) is an established therapy in advanced Parkinson's disease (PD). Motor and non-motor outcomes, however, show considerable inter-individual variability. Preoperative morphometry-based metrics have recently received increasing attention to explain treatment effects. As evidence for the prediction of non-motor outcomes is limited, we sought to investigate the association between metrics of voxel-based morphometry and short-term non-motor outcomes following STN-DBS in this prospective open-label study. Forty-nine PD patients underwent structural MRI and a comprehensive clinical assessment at preoperative baseline and 6-month follow-up. Voxel-based morphometry was used to assess associations between cerebral volume and non-motor outcomes corrected for multiple comparisons using a permutation-based approach. We replicated existing results associating volume loss of the superior frontal cortex with subpar motor outcomes. Overall non-motor burden, however, was not significantly associated with morphometric features, limiting its use as a marker to inform patient selection and holistic preoperative counselling.

Rethinking Movement Disorders

At present, clinical practice and research in movement disorders (MDs) focus on the "normalization" of altered movements. In this review, rather than concentrating on problems and burdens people with MDs undoubtedly have, we highlight their hidden potentials. Starting with current definitions of Parkinson's disease (PD), dystonia, chorea, and tics, we outline that solely conceiving these phenomena as signs of dysfunction falls short of their complex nature comprising both problems and potentials. Such potentials can be traced and understood in light of well-established cognitive neuroscience frameworks, particularly ideomotor principles, and their influential modern derivatives. Using these frameworks, the wealth of data on altered perception-action integration in the different MDs can be explained and systematized using the mechanism-oriented concept of perception-action binding. According to this concept, MDs can be understood as phenomena requiring and fostering flexible modifications of perception-action associations. Consequently, although conceived as being caught in a (trough) state of deficits, given their high flexibility, people with MDs also have high potential to switch to (adaptive) peak activity that can be conceptualized as hidden potentials. Currently, clinical practice and research in MDs are concerned with deficits and thus the "deep and wide troughs," whereas "scattered narrow peaks" reflecting hidden potentials are neglected. To better delineate and utilize the latter to alleviate the burden of affected people, and destigmatize their conditions, we suggest some measures, including computational modeling combined with neurophysiological methods and tailored treatment. © 2024 International Parkinson and Movement Disorder Society.

Neurostimulation for Advanced Parkinson Disease and Quality of Life at 5 Years: A Nonrandomized Controlled Trial

Importance

Deep brain stimulation of the subthalamic nucleus (STN-DBS) improves quality of life (QOL) in patients with advanced Parkinson disease (PD). However, controlled studies with more than 3 years of follow-up are lacking.

Objective

To investigate the long-term effects of STN-DBS on QOL compared with standard-of-care medication (MED).

Design, Setting, and Participants

In this prospective, observational, quasi-experimental, longitudinal nonrandomized controlled trial, 183 patients were screened for eligibility and 167 were enrolled from March 1, 2011, to May 31, 2017, at 3 European university centers. Propensity score matching for demographic and clinical characteristics was applied to 108 patients with PD (62 in the STN-DBS group and 46 in the MED group), resulting in a well-balanced, matched subcohort of 25 patients per group. Data analysis was performed from September 2022 to January 2023.

Exposure

Treatment for PD of STN-DBS or MED.

Main Outcomes and Measures

Assessments included Parkinson's Disease Questionnaire 8 (PDQ-8), Unified PD Rating Scale-motor examination, Scales for Outcomes in PD-activities of daily living (ADL) and motor complications, and levodopa-equivalent daily dose. Within-group longitudinal outcome changes, between-group differences, and correlations of change scores were analyzed.

Results

The study population in the analysis included 108 patients (mean [SD] age, 63.7 [8.3] years; 66 [61.1%] male). At 5-year follow-up, PDQ-8 and ADL worsened only in the MED group (PDQ-8 change, -10.9; 95% CI, -19.0 to -2.7; P = .01; ADL change: -2.0; 95% CI, -3.1 to -0.8; P = .002), whereas both outcomes remained stable in the STN-DBS group (PDQ-8 change, -4.3; 95% CI, -13.2 to 4.7; P = .34; ADL change, -0.8; 95% CI, -2.5 to 1.0; P = .38). Changes in PDQ-8 and ADL correlated moderately (rs = .40, P = .008). Furthermore, STN-DBS outcomes were favorable for motor complications (median difference in change scores between STN-DBS and MED, -2.0; 95% CI, -4.0 to -1.0; P = .003), mobility (-1.0; 95% CI, -2.0 to 0; P = .03), and levodopa-equivalent daily dose reduction (-821.4; 95% CI, -1111.9 to -530.8; P < .001).

Conclusions and Relevance

This study provides evidence of differences in QOL outcomes at 5-year follow-up between STN-DBS (stable) and MED (worsened), mainly driven by the favorable effect of STN-DBS on mobility (class IIb evidence). The association between changes in QOL and ADL, but not motor impairment or complications, highlights the relative importance of ADL outcomes for long-term DBS assessments.

Trial Registration

German ClinicalTrials Registry: DRKS00006735.

Stratifying quality of life outcome in subthalamic stimulation for Parkinson's disease

BACKGROUND

Subthalamic nucleus deep brain stimulation (STN-DBS) for Parkinson's disease (PD) improves quality of life (QoL), motor and non-motor symptoms (NMS). However, in previous studies, 43%-49% of patients did not experience clinically relevant postoperative QoL improvement. To inform individualised prediction of postoperative QoL improvement, we developed a stratification analysis of QoL outcomes based on preoperative non-motor total burden, severity of motor progression and motor response in levodopa challenge tests.

METHODS

This was a prospective, open-label, multicentre, international study with a 6-month follow-up. A distribution-based threshold identified 'QoL responders' in the PDQuestionnaire-8 Summary Index (PDQ-8 SI). After baseline stratification based on the NMS Scale, Hoehn and Yahr Scale and levodopa response assessed with the Unified PD Rating Scale-III, we compared postoperative QoL response between these strata. To assess the clinical usefulness and statistical feasibility of stratifications, we compared cumulative distribution function curves, respectively PDQ-8 within-stratum variation.

RESULTS

All main outcomes improved postoperatively. Based on the 8.1 points threshold for clinically meaningful PDQ-8 SI improvement, only 80/161 patients were classified as 'QoL responders'. The absolute risk reductions for QoL non-response among respective non-motor, motor progression and levodopa response strata were 23%, 8% and 3%, respectively. Only non-motor stratification reduced PDQ-8 within-stratum variation compared with the overall cohort.

CONCLUSIONS

Non-motor stratification, but not motor progression or levodopa response stratification, is clinically useful and statistically feasible for personalised preoperative prediction of postoperative QoL outcome of STN-DBS for PD. Our findings highlight that non-motor assessments are necessary components of a case-based, holistic approach of DBS indication evaluations geared towards optimising postoperative QoL outcomes.

TRIAL REGISTRATION NUMBER

GermanClinicalTrialsRegister: #6735.

Course of Impulse Control Disorder Symptoms in Parkinson's Disease: Deep Brain Stimulation Versus Medications

Background

The effect of surgery on impulse control disorders (ICDs) remains unclear in Parkinson's disease (PD) patients undergoing deep brain stimulation (DBS).

Objective

To examine changes in ICD symptoms in PD patients undergoing DBS compared to a medication-only control group.

Methods

The study was a 2-center, 12-month, prospective, observational investigation of PD patients undergoing DBS and a control group matched on age, sex, dopamine agonist use, and baseline presence of ICDs. Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS) and total levodopa equivalent daily dose (LEDD) were collected at baseline, 3, 6, and 12 months. Linear mixed-effects models assessed changes in mean QUIP-RS score (sum of buying, eating, gambling, and hypersexuality items).

Results

The cohort included 54 participants (DBS = 26, controls = 28), mean (SD) age 64.3 (8.1) and PD duration 8.0 (5.2) years. Mean baseline QUIP-RS was higher in the DBS group at baseline (8.6 (10.7) vs. 5.3 (6.9), P = 0.18). However, scores at 12 months follow-up were nearly identical (6.6 (7.3) vs. 6.0 (6.9) P = 0.79). Predictors of change in QUIP-RS score were baseline QUIP-RS score (β = 0.483, P < 0.001) and time-varying LEDD (β = 0.003, P = 0.02). Eight patients (four in each group) developed de novo ICD symptoms during follow-up, although none met diagnostic criteria for an impulse control disorder.

Conclusions

ICD symptoms (including de novo symptoms) at 12 months follow-up were similar between PD patients undergoing DBS and patients treated with pharmacological therapy only. Monitoring for emergence of ICD symptoms is important in both surgically- and medication-only-treated PD patients.

Predicting Motor Outcome and Quality of Life After Subthalamic Deep Brain Stimulation for Parkinson's Disease: The Role of Standard Screening Measures and Wearable-Data

BACKGROUND

Standardized screening for subthalamic deep brain stimulation (STN DBS) in Parkinson's disease (PD) patients is crucial to determine eligibility, but its utility to predict postoperative outcomes in eligible patients is inconclusive. It is unknown whether wearable data can contribute to this aim.

OBJECTIVE

To evaluate the utility of universal components incorporated in the DBS screening, complemented by a wearable sensor, to predict motor outcomes and Quality of life (QoL) one year after STN DBS surgery.

METHODS

Consecutive patients were included in the OPTIMIST cohort study from two DBS centers. Standardized assessments included a preoperative Levodopa Challenge Test (LCT), and questionnaires on QoL and non-motor symptoms including cognition, psychiatric symptoms, impulsiveness, autonomic symptoms, and sleeping problems. Moreover, an ambulatory wearable sensor (Parkinson Kinetigraph (PKG)) was used. Postoperative assessments were similar and also included a Stimulation Challenge Test to determine DBS effects on motor function.

RESULTS

Eighty-three patients were included (median (interquartile range) age 63 (56-68) years, 36% female). Med-OFF (Stim-OFF) motor severity deteriorated indicating disease progression, but patients significantly improved in terms of Med-ON (Stim-ON) motor function, motor fluctuations, QoL, and most non-motor domains. Motor outcomes were not predicted by preoperative tests, including covariates of either LCT or PKG. Postoperative QoL was predicted by better preoperative QoL, lower age, and more preoperative impulsiveness scores in multivariate models.

CONCLUSION

Data from the DBS screening including wearable data do not predict postoperative motor outcome at one year. Post-DBS QoL appears primarily driven by non-motor symptoms, rather than by motor improvement.

Non-motor effects of deep brain stimulation in Parkinson's disease motor subtypes

INTRODUCTION

Deep brain stimulation (DBS) is a well-established treatment for patients with Parkinson's disease (PD) improving quality of life, motor, and non-motor symptoms. However, non-motor effects in PD subtypes are understudied. We hypothesized that patients with 'postural instability and gait difficulty' (PIGD) experience more beneficial non-motor effects than 'tremor-dominant' patients undergoing DBS for PD.

METHODS

In this prospective, observational, international multicentre study with a 6-month follow-up, we assessed the Non-Motor Symptom Scale (NMSS) as primary and the following secondary outcomes: Unified PD Rating Scale-motor examination (UPDRS-III), Scales for Outcomes in PD (SCOPA)-activities of daily living (ADL) and -motor complications, PDQuestionnaire-8 (PDQ-8), and levodopa-equivalent daily dose (LEDD). We analysed within-group longitudinal changes with Wilcoxon signed-rank test and Benjamini-Hochberg correction for multiple comparisons. Additionally, we explored outcome between-group differences of motor subtypes with Mann-Whitney U-tests.

RESULTS

In 82 PIGD and 33 tremor-dominant patients included in this study, baseline NMSS total scores were worse in PIGD patients, both groups experienced postoperative improvements of the NMSS sleep/fatigue domain, and between-group differences in postoperative outcomes were favourable in the PIGD group for the NMSS total and miscellaneous domain scores.

CONCLUSIONS

This study provides evidence of a favourable outcome of total non-motor burden in PIGD compared to tremor-dominant patients undergoing DBS for PD. These differences of clinical efficacy on non-motor aspects should be considered when advising and monitoring patients with PD undergoing DBS.

Bioinformatic Analysis of Genetic Factors from Human Blood Samples and Postmortem Brains in Parkinson's Disease

Parkinson's disease (PD) is one of the most prevalent neurodegenerative disorders characterized by motor and nonmotor symptoms due to the selective loss of midbrain dopaminergic neurons. Pharmacological and surgical interventions have not been possible to cure PD; however, the cause of neurodegeneration remains unclear. Here, we performed and tested a multitiered bioinformatic analysis using the GEO and Proteinexchange database to investigate the gene expression involved in the pathogenesis of PD. Then we further validated individual differences in gene expression in whole blood samples that we collected in the clinic. We also made an interaction analysis and prediction for these genetic factors. There were in all 1045 genes expressing differently in PD compared with the healthy control group. Protein-protein interaction (PPI) networks showed 10 top hub genes: ACO2, MDH2, SDHA, ATP5A1, UQCRC2, PDHB, SUCLG1, NDUFS3, UQCRC1, and ATP5C1. We validated the ten hub gene expression in clinical PD patients and showed the expression of MDH2 was significantly different compared with healthy control. Besides, we also identified the expression of G6PD, GRID2, RIPK2, CUL4B, BCL6, MRPS31, GPI, and MAP 2 K1 were all significantly increased, and levels of MAPK, ELAVL1, RAB14, KLF9, ARF1, ARFGAP1, ATG7, ABCA7, SFT2D2, E2F2, MAPK7, and UHRF1 were all significantly decreased in PD. Among them, to our knowledge, we presently have the most recent and conclusive evidence that GRID2, RIPK2, CUL4B, E2F2, and ABCA7 are possible PD indicators. We confirmed several genetic factors which may be involved in the pathogenesis of PD. They could be promising markers for discriminating the PD and potential factors that may affect PD development.

Early hyperdopaminergic state following sub-thalamic nucleus deep brain stimulation in Parkinson disease

BACKGROUND

Hyperdopaminergic state (HS), especially impulse control behaviors (ICBs), are not rare in Parkinson's disease (PD). Controversial data regarding HS prevalence one year following sub-thalamic nucleus deep brain stimulation (STN-DBS) are reported.

OBJECTIVE

Our objectives were to describe early postoperative HS (PoOHS) including ICBs, hypomania and psychotic symptoms during the first 3 months following STN-DBS (V1) and their prognosis at 1 year (V2).

METHODS

This descriptive study included 24 PD patients treated successively with bilateral STN-DBS between 2017 and 2019. The primary endpoint was prevalence of PoOHS at V1 according to the Ardouin Scale of Behaviour in Parkinson's Disease.

RESULTS

Prior to STN-DBS (V0), 25% patients had HS (only ICBs) whereas at V1 (during the 3 first months), 10 patients (41.7%) had one or several HS (P=0.22) (de novo in 29.2%): 7 (29.2%) ICBs, 4 (16.7%) hypomanic mood, 1 (4.7%) psychotic symptoms. At V2, all V0 and V1 HS had disappeared, while 1 patient (4.2%) presented de novo HS (P<0.01). No correlation was found between the occurrence of PoOHS at V1 and any V0 data. Higher levodopa equivalent dose of dopamine agonists at V1 was correlated with ICB at V1 (P=0.04).

CONCLUSION

We found that early PoOHS are frequent in PD after STN-DBS, mostly de novo, with ICBs and hypomania being the most frequent. Despite a good prognosis of PoOHS at one year, our work emphasizes the importance of both a cautious adjustment of dopamine agonist doses and a close non-motor monitoring pre- and post-STN-DBS in PD.

Gender gap in deep brain stimulation for Parkinson's disease

Previous studies have shown less access to deep brain stimulation (DBS) for Parkinson’s disease (PD) in women compared to men raising concerns about a potential gender gap resulting from nonclinical factors or gender differences in clinical efficacy for postoperative quality of life (QoL), motor, and nonmotor symptoms (NMS) outcomes. This was a cross-sectional and a longitudinal, prospective, observational, controlled, quasi-experimental, international multicenter study. A total sample size of 505 consisted of 316 consecutively referred patients for DBS indication evaluation at the University Hospital Cologne (01/2015–09/2020) and 189 consecutively treated patients at DBS centers in the University Hospitals Cologne and Marburg, Salford’s Royal Hospital Manchester, and King’s College Hospital London. In the cross-sectional cohort, we examined gender proportions at referral, indication evaluations, and DBS surgery. In the longitudinal cohort, clinical assessments at preoperative baseline and 6-month follow-up after surgery included the PD Questionnaire-8, NMSScale, Scales for Outcomes in PD-motor scale, and levodopa-equivalent daily dose. Propensity score matching resulted in a pseudo-randomized sub-cohort balancing baseline demographic and clinical characteristics between women with PD and male controls. 316 patients were referred for DBS. 219 indication evaluations were positive (women n = 102, respectively n = 82). Women with PD were disproportionally underrepresented in referrals compared to the general PD population (relative risk [RR], 0.72; 95%CI, 0.56–0.91; P = 0.002), but more likely to be approved for DBS than men (RR, 1.17; 95%CI, 1.03–1.34; P = 0.029). Nonetheless, their total relative risk of undergoing DBS treatment was 0.74 (95%CI, 0.48–1.12) compared to men with PD. At baseline, women had longer disease duration and worse dyskinesia. Exploring QoL domains, women reported worse mobility and bodily discomfort. At follow-up, all main outcomes improved equally in both genders. Our study provides evidence of a gender gap in DBS for PD. Women and men with PD have distinct preoperative nonmotor and motor profiles. We advocate that more focus should be directed toward the implementation of gender equity as both genders benefit from DBS with equal clinical efficacy. This study provides Class II evidence of beneficial effects of DBS in women with PD compared to male controls.

Validation of the Japanese Version of the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease-Rating Scale (QUIP-RS)

Introduction

The Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease (PD)-Rating Scale (QUIP-RS) was developed to assess the severity of impulsive and compulsive behaviors (ICBs) in PD. We aimed to validate the Japanese version of QUIP-RS and determine the characteristics of ICBs in Japan.

Methods

We translated the QUIP-RS into Japanese, back-translated it to English, and obtained confirmation from the original author that the questionnaire remained appropriate. The participants for the validation study were 161 PD patients, identified by continuous sampling at two institutions, who were diagnosed with ICBs through a semistructured interview and completed the QUIP-RS-J. Sensitivity, specificity, and cutoff values were calculated using receiver operating characteristic (ROC) curves. Interinstitutional reliability and test-retest reliability were also assessed for a subset of participants.

Results

Twenty-six (16.1%) participants were diagnosed with ICB. The optimal cutoff value of the QUIP-RS-J total score was 6, with area under the curve (AUC) = 0.889 and sensitivity/specificity of 0.92/0.71. Each subscale also showed high AUC (0.89–1.00), sensitivity (0.92–1.00), and specificity (0.71–1.00). Compared with the English version, the optimal cutoff point for binge eating was higher and hypersexuality lower. The total score tended to be higher when described by an informant.

Conclusion

The present study validated the Japanese version of QUIP-RS. Use of QUIP-RS-J enables standardized assessment of ICBs and can be used in clinical research, including international multicenter studies.