Predictive value of abbreviated olfactory tests in prodromal Parkinson disease

There is disagreement in the literature whether olfaction may show specific impairments in Parkinson Disease (PD) and if olfactory tests comprised of selected odors could be more specific for diagnosis. We sought to validate previously proposed subsets of the University of Pennsylvania Smell Identification Test (UPSIT) odors for predicting conversion to PD in an independent, prodromal cohort. Conversion to PD was assessed in 229 participants in the Parkinson At Risk Study who completed baseline olfactory testing with the UPSIT and up to 12 years of clinical and imaging evaluations. No commercially available or proposed subset performed better than the full 40-item UPSIT. The proposed "PD-specific" subsets also did not perform better than expected by chance. We did not find evidence for selective olfactory impairment in Parkinson disease. Shorter odor identification tests, including commercially available 10-12 item tests, may have utility for ease of use and cost, but not for superior predictive value.

Deploying Digital Health Technologies for Remote Physical Activity Monitoring of Rural Populations with Chronic Neurologic Disease

Objective

The objective of this pilot study was to examine the feasibility of a remote physical activity monitoring program, quantify baseline activity levels, and examine predictors of activity among rurally residing adults with Parkinson disease (PD) or stroke.

Design

Thirty-day observational study. Participants completed standardized assessments, connected a wearable device, and synced daily step counts via a remote monitoring platform.

Setting

Community-based remote monitoring.

Participants

Rurally residing adults with PD or stroke enrolled in the Veterans Health Administration.

Intervention

N/A.

Main Outcome Measures

Feasibility was evaluated using recruitment data (response rates), study completion (completed assessments and connected the wearable device), and device adherence (days recording ≥100 steps). Daily step counts were examined descriptively. Predictors of daily steps were explored across the full sample, then by diagnosis, using linear mixed-effects regression analyses.

Results

Forty participants (n=20 PD; n=20 stroke) were included in the analysis with a mean (SD) age of 72.9 (7.6) years. Participants resided 252.6 (105.6) miles from the coordinating site. Recruitment response rates were 11% (PD) and 6% (stroke). Study completion rates were 71% (PD) and 80% (stroke). Device adherence rates were 97.0% (PD) and 95.2% (stroke). Participants with PD achieved a median [interquartile range] of 2618 [3896] steps per day and participants with stroke achieved 4832 [7383] steps. Age was the only significant predictor of daily steps for the full sample (-265 steps, 95% confidence interval [-407, -123]) and by diagnosis (PD, -175 steps, [-335, -15]; stroke, -357 steps [-603, -112]).

Conclusions

A remote physical activity monitoring program for rurally residing individuals with PD or stroke was feasible. This study establishes a model for a scalable physical activity program for rural, older populations with neurologic conditions from a central coordinating site.

Selected autonomic signs and symptoms as risk markers for phenoconversion and functional dependence in prodromal Parkinson's disease

PURPOSE

To determine whether dysautonomia can stratify individuals with other prodromal markers of Parkinson's disease (PD) for risk of phenoconversion and functional decline, which may help identify subpopulations appropriate for experimental studies.

METHODS

Data were obtained from Parkinson's Progression Markers Initiative. Cohorts without PD but with at-risk features were included (hyposmia and/or rapid-eye-movement-sleep behavior disorder, LRRK2 gene mutation, GBA gene mutation). Dysautonomia measures included Scales-for-Outcomes-in-Parkinson's-Disease Autonomic (SCOPA-AUT), seven SCOPA-AUT subscales, and cardiovascular dysfunction (supine hypertension, low pulse pressure, neurogenic orthostatic hypotension). Outcome measures were phenoconversion and Schwab-and-England Activities-of-Daily-Living (SE-ADL) ≤ 70, which indicates functional dependence. Cox proportional-hazards regression was used to evaluate survival to phenoconversion/SE-ADL ≤ 70 for each dysautonomia measure. If a significant association was identified, a likelihood-ratio test was employed to evaluate whether a significant interaction existed between the measure and cohort. If so, regression analysis was repeated stratified by cohort.

RESULTS

Median follow-up was 30 months. On multivariable analysis, gastrointestinal and female sexual dysfunction subscales were associated with increased risk of phenoconversion, while the cardiovascular subscale and neurogenic orthostatic hypotension were associated with increased risk of SE-ADL ≤ 70; respective hazard ratios (95% confidence intervals) were 1.13 (1.01-1.27), 3.26 (1.39-7.61), 1.87 (1.16-2.99), 5.45 (1.40-21.25). Only the association between the cardiovascular subscale and SE-ADL ≤ 70 was modified by cohort.

CONCLUSIONS

Symptoms of gastrointestinal and female sexual dysfunction predict phenoconversion in individuals with other risk markers for PD, while signs and symptoms of cardiovascular dysfunction may be associated with functional decline.

Serial olfactory testing for the diagnosis of prodromal Parkinson's disease in the PARS study

BACKGROUND

The Parkinson Associated Risk Syndrome (PARS) study was designed to evaluate whether screening with olfactory testing and dopamine transporter (DAT) imaging could identify participants at risk for developing Parkinson's disease (PD).

OBJECTIVE

Hyposmia on a single test has been associated with increased risk of PD, but, taken alone, lacks specificity. We evaluated whether repeating olfactory testing improves the diagnostic characteristics of this screening approach.

METHODS

Participants completed up to 10 years of clinical and imaging evaluations in the PARS cohort. Olfaction was assessed with the University of Pennsylvania Smell Identification Test at baseline and on average 1.4 years later. Multiple logistic regression and Cox proportional hazards regression were used to estimate the hazard of development of clinical PD or abnormal DAT imaging.

RESULTS

Of 186 participants who were initially hyposmic, 28% reverted to normosmia on repeat testing (reverters). No initially normosmic subjects and only 2% of reverters developed DAT imaging progression or clinical PD, compared to 29% of subjects with persistent hyposmia who developed abnormal DAT and 20% who developed clinical PD. The relative risk of clinical conversion to PD was 8.3 (95% CI:0.92-75.2, p = 0.06) and of abnormal DAT scan was 12.5 (2.4-156.2, p = 0.005) for persistent hyposmia, compared to reversion.

CONCLUSIONS

Persistent hyposmia on serial olfactory testing significantly increases the risk of developing clinical PD and abnormal DAT imaging, compared to hyposmia on a single test. Repeat olfactory testing may be an efficient and cost-effective strategy to improve identification of at-risk patients for early diagnosis and disease modification studies.

Non-tremor motor dysfunction in Lewy body dementias is associated with AD biomarkers

Motor features of Parkinson's disease (PD) are heterogeneous and well-studied; non-tremor features of postural instability and gait dysfunction (PIGD) have been linked to worse outcomes and Alzheimer's disease (AD) co-pathology. However, these features are understudied in Lewy body dementias (LBD). Here we perform retrospective analysis of a unique cohort of LBD (n = 30) with Unified Parkinson's Disease Rating Scale (UPDRS) data collected at baseline in proximity to cerebrospinal fluid collection to test the hypothesis that LBD patients with a positive AD biomarker profile (LBD + AD = 13) would have higher PIGD burden compared with LBD patients without AD biomarker positivity (LBD-AD = 17). We find novel evidence for selective impairment of PIGD burden in LBD + AD vs LBD-AD (OR = 1.95, 95%CI = 1.02-3.70, p = 0.04) and a direct association of increasing CSF tau/Aβ_1-42 ratio with increasing PIGD disability in the total cohort (β = 0.23, SE = 0.08, p = 0.01). This unique biomarker stratification approach suggests AD co-pathology may contribute to PIGD motor signs in LBD.

Olfaction as an early marker of Parkinson's disease and Alzheimer's disease

Olfactory impairment is a common and early sign of Parkinson's disease (PD) and Alzheimer's disease (AD), the two most prevalent neurodegenerative conditions in the elderly. This phenomenon corresponds to pathologic processes emerging in the olfactory system prior to the onset of typical clinical manifestations. Clinically available tests can establish hyposmia through odor identification assessment, discrimination, and odor detection threshold. There are significant efforts to develop preventative or disease-modifying therapies that slow down or halt the progression of PD and AD. Due to the convenience and low cost of its assessment, olfactory impairment could be used in these studies as a screening instrument. In the clinical setting, loss of smell may also help to differentiate PD and AD from alternative causes of Parkinsonism and cognitive impairment, respectively. Here, we discuss the pathophysiology of olfactory dysfunction in PD and AD and how it can be assessed in the clinical setting to aid in the early and differential diagnosis of these disorders.

Cognitive Profile and Markers of Alzheimer Disease-Type Pathology in Patients With Lewy Body Dementias

OBJECTIVE

To determine whether patients with Lewy body dementia (LBD) with likely Alzheimer disease (AD)-type copathology are more impaired on confrontation naming than those without likely AD-type copathology.

METHODS

We selected 57 patients with LBD (dementia with Lewy bodies [DLB], n = 38; Parkinson disease dementia [PDD], n = 19) with available AD CSF biomarkers and neuropsychological data. CSF β-amyloid1-42 (Aβ42), phosphorylated-tau (p-tau), and total-tau (t-tau) concentrations were measured. We used an autopsy-validated CSF cut point (t-tau:Aβ42 ratio > 0.3, n = 43), or autopsy data when available (n = 14), to categorize patients as having LBD with (LBD + AD, n = 26) and without (LBD - AD, n = 31) likely AD-type copathology. Analysis of covariance tested between-group comparisons across biologically defined groups (LBD + AD, LBD - AD) and clinical phenotypes (DLB, PDD) on confrontation naming (30-item Boston Naming Test [BNT]), executive abilities (letter fluency [LF], reverse digit span [RDS]), and global cognition (Mini-Mental State Examination [MMSE]), with adjustment for age at dementia onset, time from dementia onset to test date, and time from CSF to test date. Spearman correlation related cognitive performance to CSF analytes.

RESULTS

Patients with LBD + AD performed worse on BNT than patients with LBD - AD (F = 4.80, p = 0.03); both groups performed similarly on LF, RDS, and MMSE (all p > 0.1). Clinically defined PDD and DLB groups did not differ in performance on any of these measures (all p > 0.05). A correlation across all patients showed that BNT score was negatively associated with CSF t-tau (ρ = -0.28, p < 0.05) and p-tau (ρ = -0.26, p = 0.05) but not Aβ42 (p > 0.1).

CONCLUSION

Markers of AD-type copathology are implicated in impaired language performance in LBD. Biologically based classification of LBD may be advantageous over clinically defined syndromes to elucidate clinical heterogeneity.

Modifiable Comorbidities Associated with Cognitive Decline in Parkinson's Disease

Background

Cognitive impairment (CI) is one of the most feared and debilitating complications of PD. No therapy has been shown to slow or prevent CI in PD.

Objective

To determine associations between modifiable comorbidities, including cardiovascular disease risk factors, mood disorders, and sleep characteristics, and rate of cognitive decline in Parkinson's disease (PD).

Methods

Data from the Parkinson's Progression Markers Initiative (PPMI) cohort was queried for baseline cardiovascular disease risk factors, mood disorders, and sleep characteristics. Linear mixed- effects models (LME) were used to examine the association between baseline factors and change in cognition, evaluated by the Montreal Cognitive Assessment (MoCA) over time. Baseline comorbidities found to affect MoCA decline were assessed for an association with focal cognitive domains using LME.

Results

Higher Body Mass Index (BMI) (β = -0.009, P = 0.039), State Trait Anxiety Inventory (STAI) (β = -0.005, P < 0.001), Geriatric Depression Scale (GDS) (β = -0.034, P < 0.001), Epworth Sleepiness Scale (ESS) (β = -0.017, P = 0.003), and REM Sleep Behavior Disorder Screening Questionnaire (RBDSQ) (β = -0.037, P < 0.001) were associated with faster rates of MoCA decline. Using established cut-offs for clinically significant symptoms, being overweight, or the presence of depression, excessive day time sleepiness (EDS), and possible REM sleep behavior disorder (pRBD), were all associated with faster rate of cognitive decline.

Conclusion

Several modifiable baseline comorbidities are associated with faster rate of CI over time in patients with PD. These associations identify potential opportunities for early intervention that could influence CI in PD.

Tau pathology associates with in vivo cortical thinning in Lewy body disorders

OBJECTIVES

To investigate the impact of Alzheimer's disease (AD) co-pathology on an in vivo structural measure of neurodegeneration in Lewy body disorders (LBD).

METHODS

We studied 72 LBD patients (Parkinson disease (PD) = 2, PD-MCI = 25, PD with dementia = 10, dementia with Lewy bodies = 35) with either CSF analysis or neuropathological examination and structural MRI during life. The cohort was divided into those harboring significant AD co-pathology, either at autopsy (intermediate/high AD neuropathologic change) or with CSF signature indicating AD co-pathology (t-tau/Aβ1-42  > 0.3) (LBD+AD, N = 19), and those without AD co-pathology (LBD-AD, N = 53). We also included a reference group of 25 patients with CSF biomarker-confirmed amnestic AD. We investigated differences in MRI cortical thickness estimates between groups, and in the 21 autopsied LBD patients (LBD-AD = 14, LBD+AD = 7), directly tested the association between antemortem MRI and post-mortem burdens of tau, Aβ, and alpha-synuclein using digital histopathology in five representative neocortical regions.

RESULTS

The LBD+AD group was characterized by cortical thinning in anterior/medial and lateral temporal regions (P < 0.05 FWE-corrected) relative to LBD-AD. In LBD+AD, cortical thinning was most pronounced in temporal neocortex, whereas the AD reference group showed atrophy that equally encompassed temporal, parietal and frontal neocortex. In autopsied LBD, we found an inverse correlation with cortical thickness and post-mortem tau pathology, while cortical thickness was not significantly associated with Aβ or alpha-synuclein pathology.

INTERPRETATION

LBD+AD is characterized by temporal neocortical thinning on MRI, and cortical thinning directly correlated with post-mortem histopathologic burden of tau, suggesting that tau pathology influences the pattern of neurodegeneration in LBD.

Revisiting amantadine as a treatment for drug-induced movement disorders

BACKGROUND

Amantadine, an aliphatic primary amine with complex actions on neurotransmitter systems in the basal ganglia, is approved for treating Parkinson's disease and drug-induced movement disorders (DIMDs). These disorders have a significant impact on clinical outcomes and quality of life in patients receiving antipsychotic treatment.

METHODS

We searched PubMed up to June 1, 2019 to identify relevant studies. The following search terms were used: "amantadine" AND "dystonia," "parkinsonism, " "akathisia," "tardive dyskinesia," "catatonia," "neuroleptic malignant syndrome." Reference lists were reviewed for additional material.

RESULTS

Evidence from multiple, small, controlled trials supports the efficacy of amantadine as a treatment for drug-induced parkinsonism. Studies show amantadine has a more favorable tolerability profile than anticholinergic medications in these patients. Clinical evidence from observational studies and case reports suggests that further trials might be warranted to support use of amantadine in select patients for preventing dystonic reactions and as a second-line agent for treating catatonia, neuroleptic malignant syndrome, and tardive dyskinesia. Evidence is lacking on the use of amantadine specifically for akathisia relative to other treatments.

CONCLUSIONS

Amantadine is an evidence-based pharmacologic strategy for treating drug-induced parkinsonism and might be an alternative treatment for other DIMDs in select patients. Additional randomized controlled trials are needed.

Subjective Cognitive Complaint in Parkinson's Disease Patients With Normal Cognition: Canary in the Coal Mine?

OBJECTIVE

The objective of this study was to determine the frequency and impact of subjective cognitive complaint (SCC) in Parkinson's disease (PD) patients with normal cognition.

METHODS

Patients with PD with expert consensus-determined normal cognition at baseline were asked a single question regarding the presence of SCC. Baseline (N = 153) and longitudinal (up to 4 follow-up visits during a 5-year period; N = 121) between-group differences in patients with PD with (+SCC) and without (-SCC) cognitive complaint were examined, including cognitive test performance and self-rated and informant-rated functional abilities.

RESULTS

A total of 81 (53%) participants reported a cognitive complaint. There were no between-group differences in global cognition at baseline. Longitudinally, the +SCC group declined more than the -SCC group on global cognition (Mattis Dementia Rating Scale-2 total score, F_1,431 = 5.71, P = 0.02), processing speed (Symbol Digit Modalities Test, F_1,425 = 7.52, P = 0.006), and executive function (Trail Making Test Part B, F_1,419 = 4.48, P = 0.04), although the results were not significant after correction for multiple testing. In addition, the +SCC group was more likely to progress to a diagnosis of cognitive impairment over time (hazard ratio = 2.61, P = 0.02). The +SCC group also demonstrated significantly lower self-reported and knowledgeable informant-reported cognition-related functional abilities at baseline, and declined more on an assessment of global functional abilities longitudinally.

CONCLUSIONS

Patients with PD with normal cognition, but with SCC, report poorer cognition-specific functional abilities, and are more likely to be diagnosed with cognitive impairment and experience global functional ability decline long term. These findings suggest that SCC and worse cognition-related functional abilities may be sensitive indicators of initial cognitive decline in PD. © 2020 International Parkinson and Movement Disorder Society.

Physical Activity in Early Parkinson Disease

Background:

Physical activity and exercise improve outcomes in Parkinson disease (PD), however little is known about activity levels in early PD patients.

Objective and Methods:

We examined self-reported activity scores and examined associations with clinical characteristics in 383 PD subjects and 175 healthy controls from the Parkinson Progression Markers Initiative (PPMI).

Results:

Activity scores were 8% lower for PD subjects than HC (162.6±86.2 vs 175.0±78.5, p = 0.10). Higher scores were associated with younger age and male sex. Only 47% of PD subjects and 44% of HC reported activity consistent with standard recommendations for adults.

Conclusions:

Our findings highlight the need to encourage exercise even in early PD.

Early and Accurate Identification of Parkinson Disease Among US Veterans

Early and accurate identification and management of veterans at risk for Parkinson disease is an important priority area for the US Department of Veterans Affairs because of the substantial impact on quality of life and disability-adjusted life years.

Cognitive Functional Abilities in Parkinson's Disease: Agreement Between Patients and Informants

Background

The Penn Parkinson's Daily Activities Questionnaire-15 (PDAQ-15) assesses cognition-related instrumental activities of daily living (IADL) in Parkinson's disease (PD).

Objectives

To assess the degree and predictors of disagreement between patients (PT) and knowledgeable informants (KI) on the PDAQ-15.

Methods

We recruited 254 PT and KI pairs (PT-KI), determined predictors of agreement, and compared scores to a performance-based functional measure (Direct Assessment of Functional Status [DAFS]; N = 61).

Results

PT and KI total score (intraclass correlation = 0.57) and individual item (Cohen's kappa = 0.46-0.62) agreement were moderate. Patient depression, global cognition, and caregiver burden (all P < 0.05), predicted PT-KI discrepancy. PT-KI discrepancy was highest in patients with a dementia diagnosis, followed by mild cognitive impairment and then normal cognition (all P < 0.01), with PT rating themselves relatively more functionally intact as cognition worsened. DAFS performance was more highly correlated with KI (r = 0.82; P < 0.001) than PT (r = 0.62; P < 0.001) PDAQ-15 score.

Conclusions

Our results support using KI as proxies when assessing cognitive IADLs in PD PTs, particularly in cases of more advanced cognitive decline.

Understanding physical activity in Veterans with Parkinson disease: A mixed-methods approach

INTRODUCTION

Physical activity is critical in Parkinson disease (PD) management, but barriers and motivators of activity in Veterans with PD may be unique. We examined activity habits, including barriers and motivators, in this population.

METHODS

Participants completed the Physical Activity Scale in the Elderly (PASE). Compliance with American Heart Association (AHA) recommendations was assessed. Veterans also completed the Exercise Perceptions Questionnaire (EPQ), assessing knowledge, barriers, and motivators of activity. Free-text barriers/motivators were analyzed by the overlapping clusters method.

RESULTS

Seventy-five Veterans were recruited; mean age (standard deviation [SD]) was 70.5 (8.2) years and mean disease duration (SD) was 5.4 (5.2) years. Raw median PASE was 120.4 (interquartile range [IQR] 68.8-165.7); age-adjusted median PASE was 135.3. Only 9 Veterans (14.3%) were AHA-compliant. There were trends toward negative association between PASE and UPDRS-3 (r = -0.24, p = 0.06) and between PASE and PDQ-8 (r = -0.23, p = 0.08). Sixty-three subjects (84%) completed the EPQ; 27 (42.9%) preferred scheduled exercise, and only 33 (53.2%) reported that they preferred to exercise with others. Common themes of 46 free-text responses included desire to improve PD symptoms (n = 15, 32.6%) and social engagement (n = 12, 26.1%).

CONCLUSIONS

Self-reported activity in Veterans with PD is low, with less than 15% of subjects meeting recommended activity targets. Qualitative analysis of barriers and motivators revealed that although many Veterans enjoy the social aspects of group exercise, they may not feel comfortable in general exercise classes aimed at younger participants without chronic illnesses. These data will be useful in designing Veteran- and/or PD-specific interventions to increase activity levels.

Statins and Cognition in Parkinson's Disease

BACKGROUND

The relationship between statins and cognition in Parkinson's disease (PD) is poorly understood.

OBJECTIVES

Analyses were performed to determine associations between statin use and cross-sectional and longitudinal cognitive performance in PD.

METHODS

Neuropsychological tests, medication logs, and ratings of functional abilities were collected from 313 PD participants longitudinally.

RESULTS

At baseline, statin users (SU; N = 129) were older, more likely male, and had shorter PD duration than non-statin users (NSU; N = 184). In Cross-sectional analysis, SU performed better on global cognition, Trails B, semantic fluency, and phonemic fluency tasks. Rate of long-term global cognitive (Dementia Rating Scale-2 and MoCA) decline was significantly less in SU.

Optimizing olfactory testing for the diagnosis of Parkinson's disease: item analysis of the university of Pennsylvania smell identification test

The 40-item University of Pennsylvania Smell Identification Test (UPSIT) is an effective instrument to detect olfactory dusfunction in Parkinson's disease (PD). It is not clear, however, whether tests of this length are necessary to detect such dysfunction. Several studies have suggested that detection of certain odors is selectively compromised in PD, and that a test comprised of these odors could be shorter and more specific for this purpose. Therefore, we attempted to identify a subset of UPSIT odors that distinguish PD from controls with similar or improved test characteristics compared to the full test. The discriminatory power of each odor was examined using UPSIT data from a discovery cohort of 314 PD patients and 314 matched controls and ranked using multiple methods (including odds ratios, regression coefficients and discriminant analysis). To validate optimally discriminant subsets, we calculated test characteristics using data from two independent cohorts (totaling 306 PD and 343 controls). In the discovery cohort, multiple novel 12-item subsets (and the previously described Brief Smell Identification Test-B) performed similarly or improved upon the UPSIT and were better than 12 random items. However, in validation studies from independent cohorts, multiple subsets retained test characteristics similar to the full UPSIT, but did not outperform 12 random items. Differential discriminatory power of individual items is not conserved across independent cohorts arguing against selective hyposmia in PD. However, multiple 12-item subsets performed as well as the full UPSIT. These subsets could form the basis for shorter olfactory tests in the clinical evaluation of Parkinsonism.

Neuropsychological Subgroups in Non-Demented Parkinson's Disease: A Latent Class Analysis

BACKGROUND

Methods to detect early cognitive decline and account for heterogeneity of deficits in Parkinson's disease (PD) are needed. Quantitative methods such as latent class analysis (LCA) offer an objective approach to delineate discrete phenotypes of impairment.

OBJECTIVE

To identify discrete neurocognitive phenotypes in PD patients without dementia.

METHODS

LCA was applied to a battery of 8 neuropsychological measures to identify cognitive subtypes in a cohort of 199 non-demented PD patients. Two measures were analyzed from each of four domains: executive functioning, memory, visuospatial abilities, and language. Additional analyses compared groups on clinical characteristics and cognitive diagnosis.

RESULTS

LCA identified 3 distinct groups of PD patients: an intact cognition group (54.8%), an amnestic group (32.2%), and a mixed impairment group with dysexecutive, visuospatial and lexical retrieval deficits (13.1%). The two impairment groups had significantly lower instrumental activities of daily living ratings and greater motor symptoms than the intact group. Of those diagnosed as cognitively normal according to MDS criteria, LCA classified 23.2% patients as amnestic and 9.9% as mixed cognitive impairment.

CONCLUSIONS

Non-demented PD patients exhibit distinct neuropsychological profiles. One-third of patients with LCA-determined impairment were diagnosed as cognitively intact by expert consensus, indicating that classification using a statistical algorithm may improve detection of initial and subtle cognitive decline. This study also demonstrates that memory impairment is common in non-demented PD even when cognitive impairment is not clinically apparent. This study has implications for predicting eventual emergence of significant cognitive decline, and treatment trials for cognitive dysfunction in PD.

Olfactory Impairment Predicts Underlying Dopaminergic Deficit in Presumed Drug-Induced Parkinsonism

Drug-induced parkinsonism (DIP) is common, and the motor symptoms can be indistinguishable from Parkinson's disease (PD). When symptoms persist after drug withdrawal, this may represent "unmasking" of underlying PD. We previously reported that hyposmia, a common nonmotor feature of PD, was associated with persistent DIP. Here, we report on a series of 33 consecutive patients who underwent dopamine transporter imaging to evaluate DIP. We examined the clinical correlates of underlying dopaminergic denervation by comparing subjects with normal and abnormal scans. Imaging was abnormal in 7 of 33 (21%) cases. Motor features were similar in patients with normal and abnormal scans. Olfactory testing was available for 30 subjects and was concordant with imaging in 27 of 30 (odds ratio = 63; 95% confidence interval: 4.8-820; P = 0.002). Olfactory testing may be a simple screen to help identify DIP patients with underlying dopaminergic denervation, consistent with unmasking of incipient PD.

High patient satisfaction with telehealth in Parkinson disease: A randomized controlled study

BACKGROUND

Parkinson disease (PD) is a complex neurodegenerative disorder that benefits from specialty care. Telehealth is an innovative resource that can enhance access to this care within a patient-centered framework. Research suggests that telehealth can lead to increased patient satisfaction, equal or better clinical outcomes, and cost savings, but these outcomes have not been well-studied in PD.

METHODS

We conducted a dual active-arm 12-month randomized controlled trial to assess patient satisfaction, clinical outcomes, travel burden, and health care utilization in PD using video telehealth for follow-up care with specialty providers. Telehealth visits took place either at a facility nearer to the patient (satellite clinic arm) or in the patient's home (home arm). Each control group received usual in-person care. Patient satisfaction, assessed by quantitative questionnaires, was the primary outcome.

RESULTS

Eighty-six men were enrolled (home arm: 18 active, 18 control; satellite clinic arm: 26 active, 24 control) with a mean age of 73 years (range 42-87). There were no differences in baseline characteristics between the active group and the controls in each arm (p > 0.05). A significant difference in overall patient satisfaction was not found; however, high levels of patient satisfaction were found in all groups. Greater satisfaction for the telehealth modality was found in assessments of convenience and accessibility/distance. Clinical outcomes were similar between groups, travel burden was reduced using telehealth, and health care utilization was largely similar in both groups.

CONCLUSIONS

As the need for PD subspecialty care increases, innovative patient-centered solutions to overcoming barriers to access, such as video telehealth, will be invaluable to patients and may provide high patient satisfaction.

Olfactory impairment predicts cognitive decline in early Parkinson's disease

OBJECTIVE

To evaluate the association between baseline olfaction and both cross-sectional and longitudinal cognitive assessments, motor symptoms, non-motor symptoms (NMS), and CSF biomarkers in early Parkinson's disease (PD).

METHODS

Parkinson's Progression Marker's Initiative (PPMI) participants underwent baseline olfactory testing with the University of Pennsylvania Smell Identification Test (UPSIT). Serial assessments included measures of motor symptoms, NMS, neuropsychological assessment, and CSF biomarkers. Up to three years follow-up data were included.

RESULTS

At baseline, worse olfaction (lowest tertile) was associated with more severe NMS, including anxiety and autonomic symptoms. Those in the lowest olfactory tertile were more likely to report cognitive impairment (37.4%) compared to those in the middle (24.4%) and highest olfactory tertiles (14.2%, p < 0.001). Aβ1-42 was significantly lower, and tau/Aβ1-42 ratio was higher in those with worse olfaction. In longitudinal analyses, lower UPSIT score was associated with greater decline in MoCA score (β = 0.02 [0.01, 0.03], p = 0.001) over time, as were composite measures of UPSIT score and either Aβ1-42 or tau/Aβ1-42 ratio. In a Cox proportional hazards model, a composite measure of olfaction and Aβ1-42 was a significant predictor of conversion from normal cognition to mild cognitive impairment (MCI; i.e., MoCA < 26), with subjects most impaired on both measures being 87% more likely to develop incident MCI (HR = 1.87 [1.16, 3.01], p = 0.01).

CONCLUSIONS

Worse baseline olfaction is associated with long-term cognitive decline. The addition of AD CSF biomarkers to olfactory testing may increase the likelihood of identifying those at highest risk for cognitive decline and progression to MCI.

Memantine and Cognition in Parkinson's Disease Dementia/Dementia With Lewy Bodies: A Meta-Analysis

Background

The aim of this work was to utilize meta-analysis in examining the effects of memantine on neuropsychological functioning in patients with Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB).

Methods

Included studies fulfilled these criteria: included objective cognitive measures, a comparison group of participants not taking memantine, and provided sufficient data for calculation of effect size. We examined effect sizes across global cognition and five specific neuropsychological domains. Moderator variables examined included neuropsychological domain, diagnostic cohort (PDD, DLB, or mixed PDD-DLB cohort), study design (open label or placebo-controlled), and trial length.

Results

Six publications met inclusion criteria totaling 57 effects. Homogeneity analysis across cognitive domains revealed a small overall effect size (d = 0.25) that was significantly heterogeneous (P < 0.001). Specific neuropsychological domains did not moderate effect size, though. Moderator analysis studies using a mix of DLB and PDD subjects showed larger effects than those that included DLB or PDD patients only. Additionally, open-label trials had significantly (P < 0.001) larger effect sizes (d = 1.32) than placebo-controlled trials (d = 0.12).

Conclusions

The present study indicates that effect-size heterogeneity across studies of memantine in DLB and PDD patients is moderated by diagnostic makeup of the cohort and study design. The small overall effect size noted in placebo-controlled trials versus open-label trials indicates that memantine has minimal effects on cognition in PDD and DLB and is unlikely to demonstrate clinically significant improvements in cognition.

Longitudinal study of normal cognition in Parkinson disease

OBJECTIVE

To report the rates and predictors of progression from normal cognition to either mild cognitive impairment (MCI) or dementia using standardized neuropsychological methods.

METHODS

A prospective cohort of patients diagnosed with Parkinson disease (PD) and baseline normal cognition was assessed for cognitive decline, performance, and function for a minimum of 2 years, and up to 6. A panel of movement disorders experts classified patients as having normal cognition, MCI, or dementia, with 55/68 (80.9%) of eligible patients seen at year 6. Kaplan-Meier curves and Cox proportional hazard models were used to examine cognitive decline and its predictors.

RESULTS

We enrolled 141 patients, who averaged 68.8 years of age, 63% men, who had PD on average for 5 years. The cumulative incidence of cognitive impairment was 8.5% at year 1, increasing to 47.4% by year 6. All incident MCI cases had progressed to dementia by year 5. In a multivariate analysis, predictors of future decline were male sex (p = 0.02), higher Unified Parkinson's Disease Rating Scale motor score (p ≤ 0.001), and worse global cognitive score (p < 0.001).

CONCLUSIONS

Approximately half of patients with PD with normal cognition at baseline develop cognitive impairment within 6 years and all new MCI cases progress to dementia within 5 years. Our results show that the transition from normal cognition to cognitive impairment, including dementia, occurs frequently and quickly. Certain clinical and cognitive variables may be useful in predicting progression to cognitive impairment in PD.

Olfactory dysfunction in Parkinson's disease: Positive effect of cigarette smoking

BACKGROUND

There is compelling evidence from over 60 epidemiological studies that smoking significantly reduces the risk of Parkinson's disease (PD). In general, those who currently smoke cigarettes, as well as those with a past history of such smoking, have a reduced risk of PD compared to those who have never smoked. Recently it has been suggested that a cardinal nonmotor sensory symptom of PD, olfactory dysfunction, may be less severe in PD patients who smoke than in PD patients who do not, in contrast to the negative effect of smoking on olfaction described in the general population.

METHODS

We evaluated University of Pennsylvania Smell Identification Test (UPSIT) scores from 323 PD patients and 323 controls closely matched individually on age, sex, and smoking history (never, past, or current).

RESULTS

Patients exhibited much lower UPSIT scores than did the controls (P < 0.0001). The relative decline in dysfunction of the current PD smokers was less than that of the never- and past-PD smokers (respective Ps = 0.0005 and 0.0019). Female PD patients outperformed their male counterparts by a larger margin than did the female controls (3.66 vs. 1.07 UPSIT points; respective Ps < 0.0001 and 0.06). Age-related declines in UPSIT scores were generally present (P < 0.0001). No association between the olfactory measure and smoking dose, as indexed by pack-years, was evident.

CONCLUSIONS

PD patients who currently smoke do not exhibit the smoking-related decline in olfaction observed in non-PD control subjects who currently smoke. The physiological basis of this phenomenon is yet to be defined.

Use of hyposmia and other non-motor symptoms to distinguish between drug-induced parkinsonism and Parkinson's disease

Drug-induced Parkinsonism (DIP) secondary to antipsychotics and other dopamine antagonists is common and can be clinically indistinguishable from idiopathic Parkinson's disease (PD). Making the correct diagnosis is essential as it has important implications both for management of the underlying psychiatric condition and potentially lifelong therapy with antiparkinsonian agents. Additionally, because Parkinsonism does not always resolve with withdrawal of the offending agent or can recur years later, DIP may sometimes represent unmasking of incipient PD. The problem is increasing in scope as antipsychotic drugs are prescribed for a widening variety of indications, and understanding the factors that distinguish pharmacologic from degenerative Parkinsonism represents a significant unmet need. In this review, we discuss the rationale and evidence for using pre-clinical manifestations of PD, particularly non-motor symptoms, to distinguish between the conditions.

Comparative study of Parkinson's disease and leucine-rich repeat kinase 2 p.G2019S parkinsonism

Parkinson disease is a progressive neurodegenerative disease for which leucine-rich repeat kinase 2 (LRRK2 carriers) p.G2019S confers substantial genotypic and population attributable risk. With informed consent, we have recruited clinical data from 778 patients from Tunisia (of which 266 have LRRK2 parkinsonism) and 580 unaffected subjects. Motor, autonomic, and cognitive assessments in idiopathic Parkinson disease and LRRK2 patients were compared with regression models. The age-associated cumulative incidence of LRRK2 parkinsonism was also estimated using case-control and family-based designs. LRRK2 parkinsonism patients had slightly less gastrointestinal dysfunction and rapid eye movement sleep disorder. Overall, disease penetrance in LRRK2 carriers was 80% by 70 years but women become affected a median 5 years younger than men. Idiopathic Parkinson disease patients with younger age at diagnosis have slower disease progression. However, age at diagnoses does not predict progression in LRRK2 parkinsonism. LRRK2 p.G2019S mutation is a useful aid to diagnosis and modifiers of disease in LRRK2 parkinsonism may aid in developing therapeutic targets.

Lewy pathology is not the first sign of degeneration in vulnerable neurons in Parkinson disease

OBJECTIVE

To determine whether evidence of neuronal dysfunction or demise preceded deposition of Lewy pathology in vulnerable neurons in Parkinson disease (PD).

METHODS

We examined the extent of nigral dysfunction and degeneration among 63 normal, incidental Lewy body disease (ILBD), and PD cases based on tyrosine hydroxylase (TH) immunoreactivity and neuron densities, respectively. The relationship between these markers and Lewy pathology (LP) burden in the substantia nigra (SN) and Braak PD stage was assessed.

RESULTS

Compared with normal subjects, ILBD cases displayed a significantly higher percentage of TH-negative cells and lower neuronal densities in the SN as early as Braak PD stages 1 and 2, before LP deposition in the nigrostriatal system. ILBD nigral neuron densities were intermediate between normal subjects and PD cases, and TH-negative percentages were higher in ILBD than either normal or PD cases. Furthermore, neuron density and neuronal dysfunction levels remained relatively constant across Braak PD stages in ILBD.

CONCLUSIONS

These results suggest that significant neurodegeneration and cellular dysfunction precede LP in the SN, challenging the pathogenic role of LP in PD and the assumption that ILBD always represents preclinical PD.

Disease modification in Parkinson’s disease: are we there yet with currently available therapies?

SUMMARY Management of Parkinson’s disease (PD) is currently based primarily on dopamine-replacement therapy for the alleviation of motor symptoms. Current medical and surgical therapies can provide long-lasting symptomatic benefit, but they do not modify progression of the disease. Research is ongoing to find a therapy that can provide neuroprotection, defined herein as preventing vulnerable neurons from dying. Studies of neuroprotection are limited by a lack of adequate biomarkers of PD progression and by the confounding symptomatic effects of many putative neuroprotective therapies. Studies have shown that levodopa prolongs life, but they have not clearly shown that it modifies disease progression. Trials of dopamine agonists have demonstrated symptomatic effect but no unequivocal neuroprotective benefits. While some studies of monamine oxidase B inhibitors have been promising, they have not conclusively proven disease modification. Exercise provides many benefits to patients with PD, may modify the progression of the disease and should be part of each patient’s treatment plan.

Genetic influences on cognitive decline in Parkinson's disease

The role of genetic factors in cognitive decline associated with Parkinson's disease (PD) is unclear. We examined whether variations in apolipoprotein E (APOE), microtubule-associated protein tau (MAPT), or catechol-O-methytransferase (COMT) genotypes are associated with cognitive decline in PD. We performed a prospective cohort study of 212 patients with a clinical diagnosis of PD. The primary outcome was change in Mattis Dementia Rating Scale version 2 score. Linear mixed-effects models and survival analysis were used to test for associations between genotypes and change in cognitive function over time. The ε4 allele of APOE was associated with more rapid decline (loss of 2.9; 95% confidence interval [CI]: 1.7-4.1) of more points per year; P < 0.001) in total score and an increased risk of a ≥ 10 point drop during the follow-up period (hazard ratio, 2.8; 95% CI: 1.4-5.4; P = 0.003). MAPT haplotype and COMT genotype were associated with measures of memory and attention, respectively, over the entire follow-up period, but not with the overall rate of cognitive decline. These results confirm and extend previously described genetic associations with cognitive decline in PD and imply that individual genes may exert effects on specific cognitive domains or at different disease stages. Carrying at least one APOE ε4 allele is associated with more rapid cognitive decline in PD, supporting the idea of a component of shared etiology between PD dementia and Alzheimer's disease. Clinically, these results suggest that genotyping can provide information about the risk of future cognitive decline for PD patients.

Olfactory dysfunction is associated with neuropsychiatric manifestations in Parkinson's disease

Hyposmia, psychiatric disorders, and cognitive problems are common nonmotor manifestations in Parkinson's disease, but how they are related remains unclear. We investigated the relationship between olfactory dysfunction and neuropsychiatric manifestations and performed a cross-sectional study of 248 patients at two movement disorders clinics at academic medical centers. Psychiatric measures were the Geriatric Depression Scale-15, Inventory of Depressive Symptomatology, State Anxiety Inventory, Apathy Scale, and Parkinson's Psychosis Rating Scale. Cognitive measures were the Mini-Mental State Examination, Hopkins Verbal Learning Test-Revised, Digit Span, Tower of London-Drexel, and the Stroop Color Word Test. Olfaction was tested with the University of Pennsylvania Smell Identification Test. There was no significant association between olfaction and mood measures, but psychotic symptoms were more common in patients with olfaction scores below the median (30% vs. 12%; P < 0.001). Worse olfaction was associated with poorer memory (Hopkins Verbal Learning Test-Revised delayed recall items: mean [standard deviation], 6.2 [3.2] vs. 8.4 [2.8]; P < 0.001) and executive performance (Tower of London total moves, 52 [38] vs. 34 [21]; P < 0.001). Odor-identification score was a significant predictor of abnormal performance on these cognitive tests after adjustment for age, sex, and disease characteristics in logistic regression models. The relationship between hyposmia, psychosis, and specific cognitive impairments may reflect the anatomic distribution of Lewy pathology and suggests that olfactory dysfunction could be a biomarker of additional extranigral disease. Future prospective studies are warranted to assess whether hyposmia, a very early feature of Parkinson's disease, might be used to predict the appearance of other common nonmotor symptoms.

Olfaction as a biomarker in Parkinson’s disease

Olfactory dysfunction in Parkinson’s disease is common and of interest, both as a clinical finding and potential biomarker. In this article, we discuss studies characterizing the olfactory deficit in Parkinson’s disease and pathological analysis that suggests the olfactory system is a likely induction site of the neurodegenerative process. These studies have enabled research to explore the potential of olfactory dysfunction as a key component in early diagnostic strategies, as a biomarker for diagnostic purposes, a predictor of clinical outcomes and a potential therapy-independent marker of disease progression.

The stress of misfolded proteins: C. elegans models for neurodegenerative disease and aging

A growing number of human neurodegenerative diseases are associated with the expression of misfolded proteins that oligomerize and form aggregate structures. Over time, accumulation of misfolded proteins leads to the disruption of cellular protein folding homeostasis and eventually to cellular dysfunction and death. To investigate the relationship between misfolded proteins, neuropathology and aging, we have developed models utilizing the nematode C. elegans. In addition to being genetically tractable, C. elegans have rapid growth rates and short life-cycles, providing unique advantages for modeling neurodegenerative diseases of aging caused by the stress of misfolded proteins. The C. elegans models described here express polyglutamine expansion-containing proteins, as occur in Huntington's disease. Through the use of tissue-specific expression of different lengths of fluorescently tagged polyglutamine repeats, we have examined the dynamics of aggregate formation both within individual cells and over time throughout the lifetime of individual animals, identifying aging and other genetic modifiers as an important physiologic determinant of aggregation and toxicity.

Modeling Polyglutamine Pathogenesis in C. elegans

A growing number of human neurodegenerative diseases are associated with disruption of cellular protein folding homeostasis, leading to the appearance of misfolded proteins and deposition of protein aggregates and inclusions. Recent years have been witness to widespread development of invertebrate systems (specifically Drosophila and Caenorhabditis elegans) to model these disorders, bringing the many advantages of such systems, particularly the power of genetic analysis in a metazoan, to bear on these problems. In this chapter, we describe our studies using the nematode, C. elegans, as a model to study polyglutamine expansions as occur in Huntington's disease and related ataxias. Using fluorescently tagged polyglutamine repeats of different lengths, we have examined the dynamics of aggregate formation both within individual cells and over time throughout the lifetime of individual organisms, identifying aging as an important physiological determinant of aggregation and toxicity. Expanding on these observations, we demonstrate that a genetic pathway regulating longevity can alter the time course of aging-related polyglutamine-mediated phenotypes. To identify novel targets and better understand how cells sense and respond to the appearance of misfolded and aggregation-prone proteins, we use a genome-wide RNA interference-based genetic screen to identify modifiers of age-dependent polyglutamine aggregation. Throughout these studies, we used fluorescence-based, live-cell biological and biophysical methods to study the behavior of these proteins in a complex multicellular environment.

Regulation of longevity in Caenorhabditis elegans by heat shock factor and molecular chaperones

The correlation between longevity and stress resistance observed in long-lived mutant animals suggests that the ability to sense and respond to environmental challenges could be important for the regulation of life span. We therefore examined the role of heat shock factor (HSF-1), a master transcriptional regulator of stress-inducible gene expression and protein folding homeostasis, in the regulation of longevity. Down-regulation of hsf-1 by RNA interference suppressed longevity of mutants in an insulin-like signaling (ILS) pathway that functions in the nervous system of Caenorhabditis elegans to influence aging. hsf-1 was also required for temperature-induced dauer larvae formation in an ILS mutant. Using tissue-specific expression of wild-type or dominant negative HSF-1, we demonstrated that HSF-1 acts in multiple tissues to regulate longevity. Down-regulation of individual molecular chaperones, transcriptional targets of HSF-1, also decreased longevity of long-lived mutant but not wild-type animals. However, suppression by individual chaperones was to a lesser extent, suggesting an important role for networks of chaperones. The interaction of ILS with HSF-1 could represent an important molecular strategy to couple the regulation of longevity with an ancient genetic switch that governs the ability of cells to sense and respond to stress.

The threshold for polyglutamine-expansion protein aggregation and cellular toxicity is dynamic and influenced by aging in Caenorhabditis elegans

Studies of the mutant gene in Huntington's disease, and for eight related neurodegenerative disorders, have identified polyglutamine (polyQ) expansions as a basis for cellular toxicity. This finding has led to a disease hypothesis that protein aggregation and cellular dysfunction can occur at a threshold of approximately 40 glutamine residues. Here, we test this hypothesis by expression of fluorescently tagged polyQ proteins (Q29, Q33, Q35, Q40, and Q44) in the body wall muscle cells of Caenorhabditis elegans and show that young adults exhibit a sharp boundary at 35-40 glutamines associated with the appearance of protein aggregates and loss of motility. Surprisingly, genetically identical animals expressing near-threshold polyQ repeats exhibited a high degree of variation in the appearance of protein aggregates and cellular toxicity that was dependent on repeat length and exacerbated during aging. The role of genetically determined aging pathways in the progression of age-dependent polyQ-mediated aggregation and cellular toxicity was tested by expressing Q82 in the background of age-1 mutant animals that exhibit an extended lifespan. We observed a dramatic delay of polyQ toxicity and appearance of protein aggregates. These data provide experimental support for the threshold hypothesis of polyQ-mediated toxicity in an experimental organism and emphasize the importance of the threshold as a point at which genetic modifiers and aging influence biochemical environment and protein homeostasis in the cell.

A new cyclic AMP-independent, Gs-mediated stimulatory mechanism via the adenosine A2a receptor in the intact cardiac cell

The objectives of this study were to investigate the mechanism underlying the adenosine A2a receptor (A2aR)-mediated positive inotropic response and to define its contractile function using chick embryo ventricular cells as a model. Activation of the A2aR caused a marked stimulation of calcium entry and cell contractility, which were blocked by verapamil or nifedipine. The effects elicited by maximal concentrations of the A2aR agonist 2-[4-(2-carboxyethyl)phenylethylamino]-5'-N-ethylcarboxamidoadenos ine and the beta-adrenergic agonist isoproterenol were additive, indicating that the two receptors do not share a common stimulatory mechanism. The cAMP antagonist (Rp)-adenosine cyclic 3':5'-monophosphorothioate was ineffective in inhibiting the A2aR-mediated stimulation of contractility or the L-type calcium channel, while it completely abolished the isoproterenol effects. Activation of the A2aR had no effect on Na+/Ca2+ exchange or inositol 1,4,5-trisphosphate accumulation. Blocking of the A2aR resulted in unopposed A1 receptor-mediated inhibitory effects and led to an inhibition of basal contractility and an enhanced anti-adrenergic effect by A1 agonist. The adenosine A2a receptor mediates a new cyclic AMP-independent mechanism and a new contractile function in the cardiac cell.