Level I PD‐MCI using global cognitive tests and the risk for Parkinson's disease dementia

Background

The criteria for PD‐MCI allow the use of global cognitive tests. Their predictive value for conversion from PD‐MCI to PDD, especially compared to comprehensive neuropsychological assessment, is unknown.

Methods

The MDS PD‐MCI Study Group combined four datasets containing global cognitive tests as well as a comprehensive neuropsychological assessment to define PD‐MCI (n = 467). Risk for developing PDD was examined using a Cox model. Global cognitive tests were compared to neuropsychological test batteries (Level I&II) in determining risk for PDD.

Results

PD‐MCI based on a global cognitive test (MMSE or MoCA) increases the hazard for developing PDD (respectively HR = 2.57, P = 0.001; HR = 4.14, P = <0.001). The C‐statistics for MMSE (0.72) and MoCA (0.70) were lower than those based on neuropsychological tests (Level I = 0.82; Level II = 0.81). Sensitivity, specificity and diagnostic accuracy balance was best in Level II.

Conclusion

MMSE and MoCA predict conversion to PDD. However, Level II neuropsychological assessment seems the preferred assessment for PD‐MCI.

Impact of Mild Cognitive Impairment on Quality of Life in Young and Typical Onset Parkinson's Disease

Introduction

Younger age of onset and mild cognitive impairment (MCI) are both independently associated with poorer quality of life (QOL) in Parkinson's disease (PD).

Objectives

The primary objective was to determine whether MCI differentially impacts QOL in young-onset PD (YOPD) and typical-onset PD (TOPD).

Methods

YOPD patients (n = 77) were diagnosed at age 50 or younger, TOPD (n = 77) were diagnosed after age 50, and the groups were matched for cognitive status, education, and disease duration. Patients' cognitive status was classified as MCI or cognitively normal (CN) based on MDS Level II criteria. QOL was assessed using the Parkinson's Disease Questionnaire (PDQ-39). ANCOVAs were conducted for each PDQ-39 subscale, with age of onset and cognitive status as between-subjects factors and several covariates included.

Results

An interaction for the Cognition domain revealed that in TOPD, PD-MCI patients reported poorer QOL than CN patients, whereas there was no effect of MCI on cognitive satisfaction in YOPD. There was a main effect of age on Emotional Well-Being, as YOPD reported poorer QOL than TOPD in this domain. There were main effects of cognitive status, with PD-MCI patients reporting worse QOL than CN patients in the domains of Social Support, Communication, ADLs, and Mobility.

Conclusions

The interaction revealed that PD-MCI has a greater impact on degree of cognitive concerns ("cognitive QOL") in TOPD versus YOPD. A more nuanced understanding of the effects of age of onset, MCI, and their interactions on QOL in PD will inform interventions aimed at improving quality of life in this population.

Subthalamic nucleus deep brain stimulation with a multiple independent constant current-controlled device in Parkinson's disease (INTREPID): a multicentre, double-blind, randomised, sham-controlled study

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus is an established therapeutic option for managing motor symptoms of Parkinson's disease. We conducted a double-blind, sham-controlled, randomised controlled trial to assess subthalamic nucleus DBS, with a novel multiple independent contact current-controlled (MICC) device, in patients with Parkinson's disease.

METHODS

This trial took place at 23 implanting centres in the USA. Key inclusion criteria were age between 22 and 75 years, a diagnosis of idiopathic Parkinson's disease with over 5 years of motor symptoms, and stable use of anti-parkinsonian medications for 28 days before consent. Patients who passed screening criteria were implanted with the DBS device bilaterally in the subthalamic nucleus. Patients were randomly assigned in a 3:1 ratio to receive either active therapeutic stimulation settings (active group) or subtherapeutic stimulation settings (control group) for the 3-month blinded period. Randomisation took place with a computer-generated data capture system using a pre-generated randomisation table, stratified by site with random permuted blocks. During the 3-month blinded period, both patients and the assessors were masked to the treatment group while the unmasked programmer was responsible for programming and optimisation of device settings. The primary outcome was the difference in mean change from baseline visit to 3 months post-randomisation between the active and control groups in the mean number of waking hours per day with good symptom control and no troublesome dyskinesias, with no increase in anti-parkinsonian medications. Upon completion of the blinded phase, all patients received active treatment in the open-label period for up to 5 years. Primary and secondary outcomes were analysed by intention to treat. All patients who provided informed consent were included in the safety analysis. The open-label phase is ongoing with no new enrolment, and current findings are based on the prespecified interim analysis of the first 160 randomly assigned patients. The study is registered with ClinicalTrials.gov, NCT01839396.

FINDINGS

Between May 17, 2013, and Nov 30, 2017, 313 patients were enrolled across 23 sites. Of these 313 patients, 196 (63%) received the DBS implant and 191 (61%) were randomly assigned. Of the 160 patients included in the interim analysis, 121 (76%) were randomly assigned to the active group and 39 (24%) to the control group. The difference in mean change from the baseline visit (post-implant) to 3 months post-randomisation in increased ON time without troublesome dyskinesias between the active and control groups was 3·03 h (SD 4·52, 95% CI 1·3-4·7; p<0·0001). 26 serious adverse events in 20 (13%) patients occurred during the 3-month blinded period. Of these, 18 events were reported in the active group and 8 in the control group. One death was reported among the 196 patients before randomisation, which was unrelated to the procedure, device, or stimulation.

INTERPRETATION

This double-blind, sham-controlled, randomised controlled trial provides class I evidence of the safety and clinical efficacy of subthalamic nucleus DBS with a novel MICC device for the treatment of motor symptoms of Parkinson's disease. Future trials are needed to investigate potential benefits of producing a more defined current field using MICC technology, and its effect on clinical outcomes.

FUNDING

Boston Scientific.

Non-motor symptoms and striatal dopamine transporter binding in early Parkinson's disease

BACKGROUND

Non-motor symptoms (NMS) are common in Parkinson's disease (PD), but their relationships to nigrostriatal degeneration remain largely unexplored.

METHODS

We evaluated 18 NMS scores covering 5 major domains in relation to concurrent and future dopamine transporter (DAT) imaging in 344 PD patients from the Parkinson's Progression and Markers Initiative (PPMI). We standardized NMS assessments into z-scores for side-by-side comparisons. Patients underwent sequential DaTSCAN imaging at enrollment and at months 12, 24, and 48. Specific binding ratios (SBR) were calculated using the occipital lobe reference region. We evaluated the association of striatal DAT binding at the four time points with each baseline NMS using mixed-effects regression models.

RESULTS

Multiple baseline NMS were significantly associated with DAT binding at baseline and at follow-up scans. REM sleep behavior disorder (RBD) symptoms showed the strongest association - mean striatal SBR declined with increasing RBD symptom z-score (average of time-point-specific slopes per unit change in z-score: β_AVG = -0.083, SE = 0.017; p < 0.0001). In addition, striatal DAT binding was linearly associated with increasing baseline z-scores: positively for the memory (β_AVG=0.055, SE = 0.022; p = 0.01) and visuospatial (β_AVG=0.044, SE = 0.020; p = 0.03) cognitive domains, and negatively for total anxiety (β_AVG= -0.059, SE = 0.018; p = 0.001). Striatal DAT binding showed curvilinear associations with odor identification, verbal discrimination recognition, and autonomic dysfunction z-scores (p = 0.001, p = 0.0009, and p = 0.0002, respectively). Other NMS were not associated with DAT binding.

CONCLUSIONS

Multiple NMS, RBD symptoms in particular, are associated with nigrostriatal dopaminergic changes in early PD.

Risk of Parkinson's disease dementia related to level I MDS PD-MCI

BACKGROUND

The International Parkinson and Movement Disorders Society criteria for mild cognitive impairment in PD need validation. The objectives of this present study were to evaluate prognostic validity of level I (abbreviated) International Parkinson and Movement Disorders Society mild cognitive impairment in PD criteria for development of PD dementia and compared them with level II (comprehensive) criteria.

METHODS

We analyzed data from 8 international studies (1045 patients) from our consortium that included baseline data on demographics, motor signs, depression, detailed neuropsychological testing, and longitudinal follow-up for conversion to Parkinson's disease dementia. Survival analysis evaluated their contribution to the hazard of Parkinson's disease dementia.

RESULTS

Level I mild cognitive impairment in PD, increasing age, male sex, and severity of PD motor signs independently increased the hazard of Parkinson's disease dementia. Level I and level II mild cognitive impairment in PD classification had similar discriminative ability with respect to the time to Parkinson's disease dementia.

CONCLUSIONS

Level I mild cognitive impairment in PD classification independently contributes to the hazard of Parkinson's disease dementia. This finding supports the prognostic validity of the abbreviated mild cognitive impairment in PD criteria. © 2019 International Parkinson and Movement Disorder Society.

Detecting Mild Cognitive Deficits in Parkinson's Disease: Comparison of Neuropsychological Tests

BACKGROUND

Numerous neuropsychological tests and test versions are used in Parkinson's disease research, but their relative capacity to detect mild cognitive deficits and their comparability across studies are unknown. The objective of this study was to identify neuropsychological tests that consistently detect cognitive decline in PD across studies.

METHODS

Data from 30 normed neuropsychological tests across 20 international studies in up to 2908 nondemented PD patients were analyzed. A subset of 17 tests was administered to up to 1247 healthy controls. A 2-step meta-analytic approach using standardized scores compared performance in PD with normative data.

RESULTS

Pooled estimates of the differences between PD and site-specific healthy controls identified significant cognitive deficits in PD patients on 14 test scores across 5 commonly assessed cognitive domains (attention or working memory, executive, language, memory, and visuospatial abilities), but healthy control performance was statistically above average on 7 of these tests. Analyses based on published norms only, as opposed to direct assessment of healthy controls, showed high between-study variability that could not be accounted for and led to inconclusive results.

CONCLUSIONS

Normed neuropsychological tests across multiple cognitive domains consistently detect cognitive deficits in PD when compared with site-specific healthy control performance, but relative PD performance was significantly affected by the inclusion and type of healthy controls versus the use of published norms only. Additional research is needed to identify a cognitive battery that can be administered in multisite international studies and that is sensitive to cognitive decline, responsive to therapeutic interventions, and superior to individual cognitive tests. © 2018 International Parkinson and Movement Disorder Society.

Cognitive impairment in Parkinson's disease: a report from a multidisciplinary symposium on unmet needs and future directions to maintain cognitive health

People with Parkinson's disease (PD) and their care partners frequently report cognitive decline as one of their greatest concerns. Mild cognitive impairment affects approximately 20-50% of people with PD, and longitudinal studies reveal dementia in up to 80% of PD. Through the Parkinson's Disease Foundation Community Choice Research Award Program, the PD community identified maintaining cognitive function as one of their major unmet needs. In response, a working group of experts across multiple disciplines was organized to evaluate the unmet needs, current challenges, and future opportunities related to cognitive impairment in PD. Specific conference goals included defining the current state in the field and gaps regarding cognitive issues in PD from patient, care partner, and healthcare professional viewpoints; discussing non-pharmacological interventions to help maintain cognitive function; forming recommendations for what people with PD can do at all disease stages to maintain cognitive health; and proposing ideas for how healthcare professionals can approach cognitive changes in PD. This paper summarizes the discussions of the conference, first by addressing what is currently known about cognitive dysfunction in PD and discussing several non-pharmacological interventions that are often suggested to people with PD. Second, based on the conference discussions, we provide considerations for people with PD for maintaining cognitive health and for healthcare professionals and care partners when working with people with PD experiencing cognitive impairment. Furthermore, we highlight key issues and knowledge gaps that need to be addressed in order to advance research in cognition in PD and improve clinical care.

Introduction to the Special Issue on Clinical Neuropsychology of Movement Disorders

The special issue on the clinical neuropsychology of movement disorders provides an overview for the non-subspecialist clinical neuropsychologist and other clinical neuroscientists of the neuropsychological features, assessment and treatment of Parkinson's disease and Lewy body dementias, atypical parkinsonian disorders (corticobasal syndrome, progressive supranuclear palsy, and multiple system atrophy), Huntington's disease, dystonia, and amyotrophic lateral sclerosis. Additionally, articles provide overviews of neuropsychological and ethical issues related to deep brain stimulation and a discussion of non-pharamcologic and non-invasive treatment of cognitive dysfunction in Parkinson's disease. A search of PubMed using neuropsycholog* and parkinson* as search terms indicates that the number of articles dealing with neuropsychology of parkinsonian disorders has more than doubled in each of the past three decades (1990-99:269 entries, 2000-09:575 entries, 2010-17:967 entries). This rapid growth of research makes a special issue on the topic very timely.

Some Clinically Useful Information that Neuropsychology Provides Patients, Carepartners, Neurologists, and Neurosurgeons About Deep Brain Stimulation for Parkinson's Disease

Deep brain stimulation (DBS) is an effective (but non-curative) treatment for some of the motor symptoms and treatment complications associated with dopaminergic agents in Parkinson's disease (PD). DBS can be done relatively safely and is associated with quality of life gains. In most DBS centers, neuropsychological evaluations are performed routinely before surgery, and sometimes after surgery. The purpose of such evaluation is not to decide solely on its results whether or not to offer DBS to a given candidate, but to provide the patient and treatment team with the best available information to make reasonable risk-benefit assessments. This review provides information relevant to the questions often asked by patients and their carepartners, neurologists, and neurosurgeons about neuropsychological outcomes of DBS, including neuropsychological adverse event rates, magnitude of cognitive changes, outcomes after unilateral versus bilateral surgery directed at various targets, impact of mild cognitive impairment (MCI) on outcome, factors implicated in neurobehavioral outcomes, and safety of newer interventions or techniques such as asleep surgery and current steering.

Initial cognitive changes in Parkinson's disease

The focus on cognitive impairment in neurodegenerative diseases, including PD, is shifting from the dementia stage to earlier stages of impairment, including mild cognitive impairment. This shift is driven primarily by the desire to improve long-term outcomes by delivering therapeutic interventions earlier in the clinical course, even presymptomatically in those at highest risk, and at the initial stage in the pathophysiological cascade that underpins common dementia syndromes. This article focuses on key findings and challenges in studying earliest stages of cognitive decline in PD, including a detailed examination of neuropsychological testing, cognitive performance in early and prodromal PD, epidemiological research for PD mild cognitive impairment to date, and expert recommendations for assessment. © 2018 International Parkinson and Movement Disorder Society.

Strengths and challenges in conducting clinical trials in Parkinson's disease mild cognitive impairment

Treatments to slow the progression of cognitive dysfunction to dementia and improve the quality of life of persons with Parkinson's disease (PD) are desperately needed. Because PD mild cognitive impairment is considered a transitional stage before dementia, it opens a window to timely intervention. This article critically reviews the strengths and challenges of pharmacologic and nonpharmacologic clinical therapeutic trials in PD mild cognitive impairment conducted during the past 5 years, including ongoing trials. Relatively few high-quality trials have been conducted, and some important factors in designing future clinical trials are discussed. © 2018 International Parkinson and Movement Disorder Society.

Clinical outcomes following awake and asleep deep brain stimulation for Parkinson disease

OBJECTIVE

Recent studies have shown similar clinical outcomes between Parkinson disease (PD) patients treated with deep brain stimulation (DBS) under general anesthesia without microelectrode recording (MER), so-called “asleep” DBS, and historical cohorts undergoing “awake” DBS with MER guidance. However, few studies include internal controls. This study aims to compare clinical outcomes after globus pallidus internus (GPi) and subthalamic nucleus (STN) DBS using awake and asleep techniques at a single institution.

METHODS

PD patients undergoing awake or asleep bilateral GPi or STN DBS were prospectively monitored. The primary outcome measure was stimulation-induced change in motor function off medication 6 months postoperatively, measured using the Unified Parkinson’s Disease Rating Scale part III (UPDRS-III). Secondary outcomes included change in quality of life, measured by the 39-item Parkinson’s Disease Questionnaire (PDQ-39), change in levodopa equivalent daily dosage (LEDD), stereotactic accuracy, stimulation parameters, and adverse events.

RESULTS

Six-month outcome data were available for 133 patients treated over 45 months (78 GPi [16 awake, 62 asleep] and 55 STN [14 awake, 41 asleep]). UPDRS-III score improvement with stimulation did not differ between awake and asleep groups for GPi (awake, 20.8 points [38.5%]; asleep, 18.8 points [37.5%]; p = 0.45) or STN (awake, 21.6 points [40.3%]; asleep, 26.1 points [48.8%]; p = 0.20) targets. The percentage improvement in PDQ-39 and LEDD was similar for awake and asleep groups for both GPi (p = 0.80 and p = 0.54, respectively) and STN cohorts (p = 0.85 and p = 0.49, respectively).

CONCLUSIONS

In PD patients, bilateral GPi and STN DBS using the asleep method resulted in motor, quality-of-life, and medication reduction outcomes that were comparable to those of the awake method.

Cognitive outcome after ventral capsule/ventral striatum stimulation for treatment-resistant major depression

BACKGROUND

We report the neuropsychological outcome of 25 patients with treatment-resistant major depressive disorder (TRD) who participated in an Institutional Review Board (IRB)-approved randomised double-blind trial comparing active to sham deep brain stimulation (DBS) in the anterior limb of the ventral capsule/ventral striatum (VC/VS).

METHODS

Participants were randomised to active (n=12) versus sham (n=13) DBS for 16 weeks. Data were analysed at the individual and group levels. Group differences were analysed using repeated measures ANOVAs. Relationships between depression severity and cognition were examined using partial correlations. The false discovery rate method controlled for multiple analyses.

RESULTS

No significant interactions comparing active versus sham stimulation over time were evident. Change in depression was unrelated to change in neuropsychological measures. Twenty patients declined by ≥1 SD on at least one measure (41.3% of declines occurred in active group participants; 63.0% in older participants regardless of stimulation status). Twenty-two patients exhibited improvements >1 SD on neuropsychological measures (47.7% in the active group; 63.1% in younger participants).

CONCLUSIONS

These data suggest that VC/VS DBS in patients with TRD does not significantly affect neuropsychological function. Age at surgery, regardless of stimulation status, may be related to cognitive outcome at the individual patient level.

TRIAL REGISTRATION NUMBER

NCT00837486; Results.

Neuropsychological outcomes from constant current deep brain stimulation for Parkinson's disease

Objective

The aim of this study was to evaluate the neurobehavioral safety of constant‐current subthalamic deep brain stimulation and to compare the neuropsychological effects of stimulation versus electrode placement alone.

Methods

A total of 136 patients with Parkinson's disease underwent bilateral subthalamic device implantation in this randomized trial. Patients received stimulation either immediately after device implantation (n = 101; active stimulation) or beginning 3 months after surgery (n = 35; delayed activation control). Patients were administered neuropsychological tests before, 3, and 12 months after device implantation.

Results

Neuropsychological change in stimulation and control groups were comparable. Within‐group analyses revealed declines in category and switching verbal fluency in both groups, but only the stimulation group had letter verbal fluency and Stroop task declines. Depression symptom improvements occurred in both groups, but more often in the stimulation group. Letter fluency declines were associated with worse Parkinson's Disease Questionnaire Communication subscale scores. Baseline and 12‐month comparisons (in the combined group) revealed gains in verbal and visual delayed recall scores and improvement in depression symptoms, but decrements in verbal fluency and Stroop scores.

Conclusions

Constant‐current bilateral subthalamic stimulation had a good cognitive safety profile except for decrements in verbal fluency and on the Stroop task. These abnormalities are related to device implantation, but stimulation likely had an additive effect. One year after surgery, the cognitive changes did not exert a detrimental effect on quality of life, although letter fluency declines were associated with communication dissatisfaction at 12 months. Improvement in depressive symptom severity appears dependent on stimulation and not placebo or lesion effects. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Test-Retest Stability of the Wisconsin Card Sorting Test

Eighty-seven normal older persons were administered the Wisconsin Card Sorting Test (WCST) on two occasions an average of 1.1 years apart. Means for age and education were 68.79 years ( SD = 6.21) and 14.80 years ( SD = 2.42), respectively. Stability coefficients ranged from .12 on the Learning to Learn scale to .66 for the Total Number of Errors scale. The majority of individuals improved on retest with five WCST scores demonstrating significant average retest gains of 5 to 7 standard score points. The standard error of prediction, standard error of difference, and abnormal test-retest discrepancy scores were calculated to assist clinicians in detecting possible meaningful changes in WCST scores on retest.

Proceedings of the Third Annual Deep Brain Stimulation Think Tank: A Review of Emerging Issues and Technologies

The proceedings of the 3rd Annual Deep Brain Stimulation Think Tank summarize the most contemporary clinical, electrophysiological, imaging, and computational work on DBS for the treatment of neurological and neuropsychiatric disease. Significant innovations of the past year are emphasized. The Think Tank's contributors represent a unique multidisciplinary ensemble of expert neurologists, neurosurgeons, neuropsychologists, psychiatrists, scientists, engineers, and members of industry. Presentations and discussions covered a broad range of topics, including policy and advocacy considerations for the future of DBS, connectomic approaches to DBS targeting, developments in electrophysiology and related strides toward responsive DBS systems, and recent developments in sensor and device technologies.

Parkinson’s disease outcomes after intraoperative CT-guided “asleep” deep brain stimulation in the globus pallidus internus

OBJECT

Recent studies show that deep brain stimulation can be performed safely and accurately without microelectrode recording ortest stimulation but with the patient under general anesthesia. The procedure couples techniques for direct anatomical targeting on MRI with intraoperative imaging to verify stereotactic accuracy. However, few authors have examined the clinical outcomes of Parkinson’s disease (PD) patients after this procedure. The purpose of this study was to evaluate PD outcomes following “asleep” deep brain stimulation in the globus pallidus internus (GPi).

METHODS

The authors prospectively examined all consecutive patients with advanced PD who underwent bilateral GPi electrode placement while under general anesthesia. Intraoperative CT was used to assess lead placement accuracy. The primary outcome measure was the change in the off-medication Unified Parkinson’s Disease Rating Scale motor score 6 months after surgery. Secondary outcomes included effects on the 39-Item Parkinson’s Disease Questionnaire (PDQ-39) scores, on-medication motor scores, and levodopa equivalent daily dose. Lead locations, active contact sites, stimulation parameters, and adverse events were documented.

RESULTS

Thirty-five patients (24 males, 11 females) had a mean age of 61 years at lead implantation. The mean radial error off plan was 0.8 mm. Mean coordinates for the active contact were 21.4 mm lateral, 4.7 mm anterior, and 0.4 mm superior to the midcommissural point. The mean off-medication motor score improved from 48.4 at baseline to 28.9 (40.3% improvement) at 6 months (p < 0.001). The PDQ-39 scores improved (50.3 vs 42.0; p = 0.03), and the levodopa equivalent daily dose was reduced (1207 vs 1035 mg; p = 0.004). There were no significant adverse events.

CONCLUSIONS

Globus pallidus internus leads placed with the patient under general anesthesia by using direct anatomical targeting resulted in significantly improved outcomes as measured by the improvement in the off-medication motor score at 6 months after surgery.

The pattern of gray matter atrophy in Parkinson's disease differs in cortical and subcortical regions

Cortical and subcortical gray matter (GM) atrophy may progress differently during the course of Parkinson's disease (PD). We delineated and compared the longitudinal pattern of these PD-related changes. Structural MRIs and clinical measures were obtained from 76 PD with different disease durations and 70 Controls at baseline, 18-, and 36 months. Both cortical and subcortical (putamen, caudate, and globus pallidus) GM volumes were obtained, compared, and associated with PD clinical measures at baseline. Their volumes and rates of change also were compared among Controls, PDs, and PD subgroups based on duration of illness [≤1 year (PD(E)), 1-5 years (PD(M)), and >5 years (PD(L))]. Compared to Controls, PD subjects displayed smaller cortical GM and striatal(putamen, caudate, ps ≤0.001), volumes at baseline. Cortical GM volumes were negatively associated with disease duration at baseline, whereas striatal volumes were not. PD subjects demonstrated accelerated volume loss in cortical GM (p = 0.006), putamen (p = 0.034), and caudate (p = 0.008) compared to Controls. Subgroup analyses demonstrated that accelerated cortical atrophy reached statistical significance in PD subjects with duration of illness 1-5 years (PD(M), ps<0.001) and the trend of accelerated atrophy seemed to persist until later stages, whereas striatal atrophy occurred in PD subjects with PD(E) (p = 0.021 for putamen, p = 0.005 for caudate) and PD(M) (p = 0.002 for putamen, p = 0.001 for caudate) that significantly slowed down in PD(L) (ps for PD(L) vs PD(E) or PD(M): <0.01). The pattern of GM loss in PD differs in cortical and subcortical regions, with striatal atrophy occurring earlier and extra-striatal cortical atrophy later.

Validation of the QUEST for German-speaking countries

OBJECTIVE

To explore the clinimetric attributes of the German version of the quality of life in essential tremor (ET) questionnaire (QUEST) as a tremor-specific measure of quality of life.

METHODS

This was an observational, cross-sectional study. The QUEST German version was obtained by translation-back translation procedure. ET cases were diagnosed according to the tremor investigation group criteria. Assessments included Archimedes spirals rating, EQ-5D, Beck Depression Inventory (BDI-II) and QUEST German version. Missing data were imputed for those cases in which the loss of data for one domain of the QUEST was <30%.

RESULTS

Ninety three patients out of 138 (67.4%) with definite or probable ET had complete QUEST data after 43 item imputations and they constituted the sample for this study. The QUEST summary index (QSI) displayed no floor or ceiling effects. QUEST internal consistency (Cronbach's alpha) ranged between 0.50 and 0.89. Item-total domain correlations ranged from 0.26 to 0.82 and the item homogeneity indexes were satisfactory (range: 0.28-0.60). The QSI correlated weakly with the EQ-5D (rS=0.20) and moderately with the BDI-II (rS = 0.31) and the QUEST self-evaluation of tremor severity (rS = 0.44).

CONCLUSIONS

The QUEST German version has, despite recognized data quality problems, satisfactory acceptability and internal consistency as a whole. The correlation analysis showed that tremor in the head, voice and right hand was moderately associated with quality of life.

Proceedings of the Second Annual Deep Brain Stimulation Think Tank: What's in the Pipeline

The proceedings of the 2nd Annual Deep Brain Stimulation Think Tank summarize the most contemporary clinical, electrophysiological, and computational work on DBS for the treatment of neurological and neuropsychiatric disease and represent the insights of a unique multidisciplinary ensemble of expert neurologists, neurosurgeons, neuropsychologists, psychiatrists, scientists, engineers and members of industry. Presentations and discussions covered a broad range of topics, including advocacy for DBS, improving clinical outcomes, innovations in computational models of DBS, understanding of the neurophysiology of Parkinson's disease (PD) and Tourette syndrome (TS) and evolving sensor and device technologies.

Potential sex differences in nonmotor symptoms in early drug-naive Parkinson disease

OBJECTIVE

To examine potential sex differences in nonmotor symptoms (NMS) among drug-naive patients with Parkinson disease (PD), and to identify NMS that can best differentiate patients with early PD from controls.

METHODS

Our cross-sectional analysis included 414 newly diagnosed, untreated patients with PD (269 men and 145 women) and 188 healthy controls (121 men and 67 women) in the Parkinson's Progression Markers Initiative Study. NMS were measured using well-validated instruments covering sleep, olfactory, neurobehavioral, autonomic, and neuropsychological domains.

RESULTS

Male and female patients with PD were fairly comparable on motor presentations but differed on several nonmotor features. Male patients with PD had significantly more pronounced deficits in olfaction (p = 0.02) and in certain cognitive measurements (all p < 0.01) than female patients, whereas female cases experienced higher trait anxiety (p = 0.02). Multiple stepwise logistic regression analysis showed that the combination of NMS measures-University of Pennsylvania Smell Identification Test (UPSIT), Montreal Cognitive Assessment (MoCA), Scales for Outcomes in Parkinson's Disease-Autonomic (SCOPA-AUT), and state anxiety from the State-Trait Anxiety Inventory-effectively differentiated patients with PD from controls with an area under the receiver operating characteristic curve (AUC) of 0.913 (95% confidence interval [CI]: 0.89-0.94). UPSIT, MoCA, and SCOPA-AUT were the most predictive NMS measurements in men (AUC = 0.919; 95% CI: 0.89-0.95) as compared to UPSIT, MoCA, and REM Sleep Behavior Disorder Screening Questionnaire in women (AUC = 0.903; 95% CI: 0.86-0.95).

CONCLUSIONS

Our analysis revealed notable sex differences in several nonmotor features of patients with de novo PD. Furthermore, we found a parsimonious NMS combination that could effectively differentiate de novo cases from healthy controls.

Long-term efficacy and safety of thalamic stimulation for drug-resistant partial epilepsy

OBJECTIVE

To report long-term efficacy and safety results of the SANTE trial investigating deep brain stimulation of the anterior nucleus of the thalamus (ANT) for treatment of localization-related epilepsy.

METHODS

This long-term follow-up is a continuation of a previously reported trial of 5- vs 0-V ANT stimulation. Long-term follow-up began 13 months after device implantation with stimulation parameters adjusted at the investigators' discretion. Seizure frequency was determined using daily seizure diaries.

RESULTS

The median percent seizure reduction from baseline at 1 year was 41%, and 69% at 5 years. The responder rate (≥50% reduction in seizure frequency) at 1 year was 43%, and 68% at 5 years. In the 5 years of follow-up, 16% of subjects were seizure-free for at least 6 months. There were no reported unanticipated adverse device effects or symptomatic intracranial hemorrhages. The Liverpool Seizure Severity Scale and 31-item Quality of Life in Epilepsy measure showed statistically significant improvement over baseline by 1 year and at 5 years (p < 0.001).

CONCLUSION

Long-term follow-up of ANT deep brain stimulation showed sustained efficacy and safety in a treatment-resistant population.

CLASSIFICATION OF EVIDENCE

This long-term follow-up provides Class IV evidence that for patients with drug-resistant partial epilepsy, anterior thalamic stimulation is associated with a 69% reduction in seizure frequency and a 34% serious device-related adverse event rate at 5 years.

Parkinson's disease mild cognitive impairment: application and validation of the criteria

Dementia in Parkinson's disease (PD) is a serious health issue and a major concern for many patients. In most cases mild cognitive impairment (MCI) is considered a transitional stage between normal cognitive functioning and dementia which is of potential importance in the early identification of patients at risk for dementia. Recently, the Movement Disorder Society (MDS) proposed diagnostic criteria for MCI in PD (PD-MCI). These criteria comprise two operationalizations: Level I (based on an abbreviated assessment) and Level II (based on comprehensive neuropsychological evaluation permitting MCI subtyping). These criteria need to be validated. This paper describes a project aiming to validate the MDS PD-MCI criteria by pooling and analyzing cross-sectional and longitudinal neuropsychological databases comprising ≥5,500 PD patients and ≥1,700 controls. After applying the MDS PD-MCI Level I and Level II criteria, rates of conversion to PD-dementia and predictive variables for conversion to PD-dementia will be established. This study will also assist in identifying whether revisions of the PD-MCI criteria are required.

Frontal cognitive function and memory in Parkinson's disease: toward a distinction between prospective and declarative memory impairments?

Memory dysfunction is a frequent concomitant of Parkinson's disease (PD). Historically, two classes of hypotheses, focusing on different cognitive mechanisms, have been advanced to explain this memory impairment: one postulating retrieval deficits (common to several neurodegenerative disorders involving the basal ganglia), and the other postulating frontally mediated executive deficits as fundamental to memory impairment. After outlining empirical support for the retrieval deficit hypothesis, research on the more recent "frontal executive deficit hypothesis" is reviewed, and major challenges to this hypothesis are identified. It is concluded that the frontal executive deficit hypothesis cannot adequately account for all memory impairments in PD, and that a more parsimonious theoretical account might invoke a distinction between prospective and declarative memory impairments. It is suggested that there may be three subgroups of PD patients: one demonstrating prospective memory dysfunction only, one with declarative memory dysfunction only, and one with both prospective and declarative memory dysfunction. Consequently, PD might provide a useful model within which to investigate the relationship between prospective and declarative memory.

Neuropsychological outcomes after psychosocial intervention for depression in Parkinson's disease

The authors describe neuropsychological outcomes in people with Parkinson's disease (PD) after their participation in an NIH-sponsored, randomized, controlled trial of cognitive-behavioral treatment for depression. Improvements in mood were associated with modest gains in verbal memory and executive functioning over the 10-week treatment period and accounted for greater variance in neuropsychological outcomes at the end of treatment than other known correlates of cognitive functioning in PD, such as disease severity, age, and education. Baseline working memory and executive skills were also associated with depression improvement over time.

Research on the premotor symptoms of Parkinson's disease: clinical and etiological implications

BACKGROUND

The etiology and natural history of Parkinson's disease (PD) are not well understood. Some non-motor symptoms such as hyposmia, rapid eye movement sleep behavior disorder, and constipation may develop during the prodromal stage of PD and precede PD diagnosis by years.

OBJECTIVES

We examined the promise and pitfalls of research on premotor symptoms of PD and developed priorities and strategies to understand their clinical and etiological implications.

METHODS

This review was based on a workshop, Parkinson's Disease Premotor Symptom Symposium, held 7-8 June 2012 at the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina.

DISCUSSION

Research on premotor symptoms of PD may offer an excellent opportunity to characterize high-risk populations and to better understand PD etiology. Such research may lead to evaluation of novel etiological hypotheses such as the possibility that environmental toxicants or viruses may initiate PD pathogenesis in the gastrointestinal tract or olfactory bulb. At present, our understanding of premotor symptoms of PD is in its infancy and faces many obstacles. These symptoms are often not specific to PD and have low positive predictive value for early PD diagnosis. Further, the pathological bases and biological mechanisms of these premotor symptoms and their relevance to PD pathogenesis are poorly understood.

CONCLUSION

This is an emerging research area with important data gaps to be filled. Future research is needed to understand the prevalence of multiple premotor symptoms and their etiological relevance to PD. Animal experiments and mechanistic studies will further understanding of the biology of these premotor symptoms and test novel etiological hypothesis.

Criteria for the diagnosis of corticobasal degeneration

Current criteria for the clinical diagnosis of pathologically confirmed corticobasal degeneration (CBD) no longer reflect the expanding understanding of this disease and its clinicopathologic correlations. An international consortium of behavioral neurology, neuropsychology, and movement disorders specialists developed new criteria based on consensus and a systematic literature review. Clinical diagnoses (early or late) were identified for 267 nonoverlapping pathologically confirmed CBD cases from published reports and brain banks. Combined with consensus, 4 CBD phenotypes emerged: corticobasal syndrome (CBS), frontal behavioral-spatial syndrome (FBS), nonfluent/agrammatic variant of primary progressive aphasia (naPPA), and progressive supranuclear palsy syndrome (PSPS). Clinical features of CBD cases were extracted from descriptions of 209 brain bank and published patients, providing a comprehensive description of CBD and correcting common misconceptions. Clinical CBD phenotypes and features were combined to create 2 sets of criteria: more specific clinical research criteria for probable CBD and broader criteria for possible CBD that are more inclusive but have a higher chance to detect other tau-based pathologies. Probable CBD criteria require insidious onset and gradual progression for at least 1 year, age at onset ≥ 50 years, no similar family history or known tau mutations, and a clinical phenotype of probable CBS or either FBS or naPPA with at least 1 CBS feature. The possible CBD category uses similar criteria but has no restrictions on age or family history, allows tau mutations, permits less rigorous phenotype fulfillment, and includes a PSPS phenotype. Future validation and refinement of the proposed criteria are needed.

Diagnostic criteria for mild cognitive impairment in Parkinson's disease: Movement Disorder Society Task Force guidelines

Mild cognitive impairment is common in nondemented Parkinson's disease (PD) patients and may be a harbinger of dementia. In view of its importance, the Movement Disorder Society commissioned a task force to delineate diagnostic criteria for mild cognitive impairment in PD. The proposed diagnostic criteria are based on a literature review and expert consensus. This article provides guidelines to characterize the clinical syndrome and methods for its diagnosis. The criteria will require validation, and possibly refinement, as additional research improves our understanding of the epidemiology, presentation, neurobiology, assessment, and long-term course of this clinical syndrome. These diagnostic criteria will support future research efforts to identify at the earliest stage those PD patients at increased risk of progressive cognitive decline and dementia who may benefit from clinical interventions at a predementia stage.

MDS Task Force on mild cognitive impairment in Parkinson's disease: critical review of PD-MCI

There is controversy regarding the definition and characteristics of mild cognitive impairment in Parkinson's disease. The Movement Disorder Society commissioned a Task Force to critically evaluate the literature and determine the frequency and characteristics of Parkinson's disease-mild cognitive impairment and its association with dementia. A comprehensive PubMed literature review was conducted using systematic inclusion and exclusion criteria. A mean of 26.7% (range, 18.9%-38.2%) of nondemented patients with Parkinson's disease have mild cognitive impairment. The frequency of Parkinson's disease-mild cognitive impairment increases with age, disease duration, and disease severity. Impairments occur in a range of cognitive domains, but single domain impairment is more common than multiple domain impairment, and within single domain impairment, nonamnestic is more common than amnestic impairment. A high proportion of patients with Parkinson's disease-mild cognitive impairment progress to dementia in a relatively short period of time. The primary conclusions of the Task Force are that: (1) Parkinson's disease-mild cognitive impairment is common, (2) there is significant heterogeneity within Parkinson's disease-mild cognitive impairment in the number and types of cognitive domain impairments, (3) Parkinson's disease-mild cognitive impairment appears to place patients at risk of progressing to dementia, and (4) formal diagnostic criteria for Parkinson's disease-mild cognitive impairment are needed.

A differential deficit in time- versus event-based prospective memory in Parkinson's disease

OBJECTIVE

The aim of the current study was to clarify the nature and extent of impairment in time- versus event-based prospective memory in Parkinson's disease (PD). Prospective memory is thought to involve cognitive processes that are mediated by prefrontal systems and are executive in nature. Given that individuals with PD frequently show executive dysfunction, it is important to determine whether these individuals may have deficits in prospective memory that could impact daily functions, such as taking medications. Although it has been reported that individuals with PD evidence impairment in prospective memory, it is still unclear whether they show a greater deficit for time- versus event-based cues.

METHOD

Fifty-four individuals with PD and 34 demographically similar healthy adults were administered a standardized measure of prospective memory that allows for a direct comparison of time-based and event-based cues. In addition, participants were administered a series of standardized measures of retrospective memory and executive functions.

RESULTS

Individuals with PD demonstrated impaired prospective memory performance compared to the healthy adults, with a greater impairment demonstrated for the time-based tasks. Time-based prospective memory performance was moderately correlated with measures of executive functioning, but only the Stroop Neuropsychological Screening Test emerged as a unique predictor in a linear regression.

CONCLUSIONS

Findings are interpreted within the context of McDaniel and Einstein's (2000) multiprocess theory to suggest that individuals with PD experience particular difficulty executing a future intention when the cue to execute the prescribed intention requires higher levels of executive control.

A recommended scale for cognitive screening in clinical trials of Parkinson's disease

Cognitive impairment is common in Parkinson's disease (PD). There is a critical need for a brief, standard cognitive screening measure for use in PD trials whose primary focus is not on cognition. The Parkinson Study Group (PSG) Cognitive/Psychiatric Working Group formed a Task Force to make recommendations for a cognitive scale that could screen for dementia and mild cognitive impairment in clinical trials of PD where cognition is not the primary outcome. This Task Force conducted a systematic literature search for cognitive assessments previously used in a PD population. Scales were then evaluated for their appropriateness to screen for cognitive deficits in clinical trials, including brief administration time (<15 minutes), assessment of the major cognitive domains, and potential to detect subtle cognitive impairment in PD. Five scales of global cognition met the predetermined screening criteria and were considered for review. Based on the Task Force's evaluation criteria the Montreal Cognitive Assessment (MoCA), appeared to be the most suitable measure. This Task Force recommends consideration of the MoCA as a minimum cognitive screening measure in clinical trials of PD where cognitive performance is not the primary outcome measure. The MoCA still requires further study of its diagnostic utility in PD populations but appears to be the most appropriate measure among the currently available brief cognitive assessments. Widespread adoption of a single instrument such as the MoCA in clinical trials can improve comparability between research studies on PD.

Manganese accumulation in the olfactory bulbs and other brain regions of "asymptomatic" welders

Welding-generated metallic fumes contain a substantial amount of manganese (Mn), making welders susceptible to Mn toxicity. Although overt Mn toxicity manifests as a type of parkinsonism, the consequences of chronic, low-level Mn exposure are unknown. To explore region-specific Mn accumulation and its potential functional consequences at subclinical levels of Mn exposure, we studied seven welders without obvious neurological deficits and seven age- and gender-matched controls. Mn exposure for welders was estimated by an occupational questionnaire. High-resolution brain magnetic resonance imaging (MRI), Grooved Pegboard performance of both hands, Trail making, and olfactory function tests were obtained from all subjects. Compared with controls, the welders had a significantly higher T1 relaxation rate (R1) in the olfactory bulb (OB, p = 0.02), mean T1-weighted intensity at frontal white matter (FWM; p = 0.01), bilateral globus pallidus (GP; p = 0.03), and putamen (p = 0.03). The welders scored worse than the controls on the Grooved Pegboard test for both dominant (p = 0.06) and nondominant hand (p = 0.03). The dominant hand Grooved Pegboard scores correlated best with mean MRI intensity of FWM (R² = 0.51, p = 0.004), GP (R² = 0.51, p = 0.004), putamen (R² = 0.49, p= 0.006), and frontal gray matter (R² = 0.42, p = 0.01), whereas the nondominant hand scores correlated best with intensity of FWM (R² = 0.37, p = 0.02) and GP (R² = 0.28, p = 0.05). No statistical differences were observed in either the Trail-making test or the olfactory test between the two groups. This study suggests that Mn accumulates in OB and multiple other brain regions in "asymptomatic" welders and that MRI abnormalities correlate with fine motor but not cognitive deficits. Further investigations of subclinical Mn exposure are warranted.

Neuropsychological characteristics of dementia with Lewy bodies and Parkinson's disease with dementia: differentiation, early detection, and implications for "mild cognitive impairment" and biomarkers

Parkinson's disease with dementia (PDD) and dementia with Lewy bodies (DLB) are neurodegenerative conditions sharing a disorder of alpha-synuclein metabolism. Temporal differences in the emergence of symptoms and clinical features warrant the continued clinical distinction between DLB and PDD. While DLB and PDD groups' neuropsychological profiles often differ from those in Alzheimer's disease (AD), the diagnostic sensitivity, specificity, and predictive values of these profiles remain largely unknown. PDD and DLB neuropsychological profiles share sufficient similarity to resist accurate and reliable differentiation. Although heterogeneous cognitive changes (predominantly in memory and executive function) may manifest earlier and more frequently than previously appreciated in Parkinson's disease (PD), and executive deficits may be harbingers of dementia, the enthusiasm to uncritically extend the concept of mild cognitive impairment (MCI) to PD should be tempered. Instead, future research might strive to identify the precise neuropsychological characteristics of the prodromal stages of PD, PDD, and DLB which, in conjunction with other potential biomarkers, facilitate early and accurate diagnosis, and the definition of neuroprotective, neurorestorative, and symptomatic treatment endpoints.

Asymmetrical ventricular enlargement in Parkinson's disease

Parkinson's disease (PD) typically manifests with asymmetric motor symptom onset. Ventricular enlargement, a nonspecific measure of brain atrophy, has been associated with cognitive decline in PD, but not with motor symptom asymmetry. Asymmetrical ventricular enlargement on magnetic resonance images was explored in a monozygotic twin pair discordant for PD and in nine healthy monozygotic twin pairs. The left-right lateral ventricular volumetric difference of the PD-twin was greater than that of his twin and all other healthy twins, with the larger ventricle observed contralateral to the more symptomatic side. Moreover, the lateral ventricle asymmetry difference between twin pairs was significantly higher for the discordant PD-twin pair than for the healthy twin pairs. This is the first report to suggest the presence of asymmetrical ventricular enlargement in PD, findings that may be worthy of further study.

Assessing cognitive change in Parkinson's disease: Development of practice effect-corrected reliable change indices

Serial assessments of cognitive functioning in individuals with Parkinson's disease (PD) are commonly used for the detection of incident dementia and neurobehavioral changes associated with treatments using neuromodulation (e.g., deep brain stimulation) and pharmacological agents (e.g., cholinesterase inhibitors). This study provides test-retest stability, expected practice effects, and practice-corrected reliable change indices for several commonly used neuropsychological tests from 62 older adults with mostly mild PD who underwent repeat evaluations approximately 17 months apart. At the group level, results showed adequate test-retest reliability (Spearman's rho range=0.24-0.86) and generally small practice effects (Cohen's d range=0.00-0.50). Application of reliable change indices using 90% confidence intervals showed the expected number of individuals (generally 10% or fewer) with statistically meaningful improvements (range=0-12%) or declines (range=2-8%) in cognitive performance at retest. Limitations discussed include ceiling effects at test baseline, sample homogeneity, interpretative cautions, and generalizability of study results. These data may be useful to researchers and clinicians interested in determining the statistical significance of changes in cognitive test performance in persons with PD over a 1- to 2-year interval.