Cognitive Interventions in Parkinson's Disease: Where We Want to Go within 20 Years

Stemming the Tide: The Proactive Role of Allied Health Therapy in Parkinson's Disease

Motor and nonmotor symptoms occur in early Parkinson's disease (PD), or even in the prodromal stage. Many of these symptoms can be addressed by allied health therapies, including physical therapy, occupational therapy, speech therapy, and psychological therapies. However, referrals to these services early in the disease are low. We provide a review summarizing the efficacy of proactive allied health interventions on motor and nonmotor symptoms and daily function in prodromal and early disease. We also highlight areas for additional research and provide recommendations to improve care for individuals with early PD within each discipline. We recognize the overlapping roles of the allied health disciplines and support integrated or transdisciplinary care beginning soon after diagnosis to help stem the tide in the progression of PD symptoms and disability.

The Effectiveness of Inpatient Rehabilitation in Parkinson's Disease: A Systematic Review of Recent Studies

Background

Parkinson's disease (PD) is a progressive disease, which is associated with the loss of activities of daily living independency. Several rehabilitation options have been studied during the last years, to improve mobility and independency.

Objective

This systematic review will focus on inpatient multidisciplinary rehabilitation (MR) in people with Parkinson's disease (PwPD), based on recent studies from 2020 onwards.

Methods

Search strategy in three databases included: multidisciplinary rehabilitation, Parkinson's Disease, inpatient rehabilitation, motor-, functional- and cognitive performance, cost-effectiveness, Quality of Life, and medication changes/Levodopa equivalent daily doses.

Results

Twenty-two studies were included, consisting of 13 studies dealing with inpatient MR and 9 studies on inpatient non-MR interventions. Inpatient PD multidisciplinary rehabilitation proved to be effective, as well as non-MR rehabilitation.

Conclusions

This review confirms the efficacy of inpatient MR and non-MR in PD, but is skeptical about the past and current study designs. New study designs, including new physical training methods, more attention to medication and costs, new biomarkers, artificial intelligence, and the use of wearables, will hopefully change rehabilitation trials in PwPD in the future.

Cognitive Self-Efficacy in Parkinson's Disease

Cognitive self-efficacy (CSE), one's belief in their ability to control their cognitive performance, is important for participation in daily activities and rehabilitation. This study aims to understand how Parkinson's disease (PD) affects CSE. The Cognitive Self-Efficacy Questionnaire (CSEQ) was administered to 47 non-demented PD and 52 healthy comparison (HC) participants. Groups were compared on their self-reported ability to recognize (Part 1) and manage (Part 2) cognitive symptoms and to perform cognitively complex functional activities (Part 4). Relationships between CSEQ scores and individual characteristics were assessed within PD. The PD group had lower CSEQ scores than the HC group for all Parts. Within PD, Part 2 scores were lower than Parts 1 and 4, and worse depressive symptoms and higher medication dosage correlated with lower CSE. People with PD may have low CSE, which can contribute to participation restrictions and reduced engagement in treatment. Occupational therapists should consider CSE with clients with PD.

Neurocognitive functioning of patients with early-stage Parkinson's disease

Parkinson's disease (PD) is a neurological disorder commonly associated with motor deficits. However, cognitive impairment is also common in patients with PD. Cognitive concerns in PD may affect multiple domains of neurocognition and vary across different stages of the disease. Extant research has focused mainly on cognitive deficits in middle to late stages of PD, whereas few studies have examined the unique cognitive profiles of patients with early-stage PD. This study addressed this gap in the published literature and examined neurocognitive functioning and functional capacity of patients with de novo PD, focusing on the unique pattern of cognitive deficits specific to the early stage of the disease. Results indicated that the pattern of cognitive deficits in patients with PD (n = 55; mean age = 72.93) was significantly different from healthy controls (n = 59; mean age = 71.88). Specifically, tasks related to executive functioning, attention, and verbal memory demonstrated the most pronounced deficits in patients with early-stage PD. Clinical implications of these findings are discussed.

Effect of eight-week online cognitive training in Parkinson's disease: A double-blind, randomized, controlled trial

INTRODUCTION

Cognitive training (CT) has been proposed as a treatment option for cognitive impairment in Parkinson's disease (PD). We aimed to assess the efficacy of adaptive, computerized CT on cognitive function in PD.

METHODS

In this double-blind, randomized controlled trial we enrolled PD patients that experienced substantial subjective cognitive complaints. Over a period of eight weeks, participants underwent 24 sessions of computerized multi-domain CT or an active control intervention for 45 min each (randomized 1:1). The primary outcome was the accuracy on the Tower of London task; secondary outcomes included effects on other neuropsychological outcomes and subjective cognitive complaints. Outcomes were assessed before and after training and at six-months follow-up, and analyzed with multivariate mixed-model analyses.

RESULTS

The intention-to-treat population consisted of 136 participants (n = 68 vs. n = 68, age M: 62.9y, female: 39.7%). Multivariate mixed-model analyses showed no group difference on the Tower of London accuracy corrected for baseline performance (n = 130): B: -0.06, 95% CI: -0.27 to 0.15, p = 0.562. Participants in the CT group were on average 0.30 SD (i.e., 1.5 s) faster on difficulty load 4 of this task (secondary outcome): 95% CI: -0.55 to -0.06, p = 0.015. CT did not reduce subjective cognitive complaints. At follow-up, no group differences were found.

CONCLUSIONS

This study shows no beneficial effect of eight-week computerized CT on the primary outcome (i.e., planning accuracy) and only minor improvements on secondary outcomes (i.e., processing speed) with limited clinical impact. Personalized or ecologically valid multi-modal intervention methods could be considered to achieve clinically meaningful and lasting effects.

Cognitive Performance and Learning Parameters Predict Response to Working Memory Training in Parkinson's Disease

BACKGROUND

Working memory (WM) training (WMT) is a popular intervention approach against cognitive decline in patients with Parkinson's disease (PD). However, heterogeneity in WM responsiveness suggests that WMT may not be equally efficient for all patients.

OBJECTIVE

The present study aims to evaluate a multivariate model to predict post-intervention verbal WM in patients with PD using a supervised machine learning approach. We test the predictive potential of novel learning parameters derived from the WMT and compare their predictiveness to other more commonly used domains including demographic, clinical, and cognitive data.

METHODS

37 patients with PD (age: 64.09±8.56, 48.6% female, 94.7% Hoehn & Yahr stage 2) participated in a 5-week WMT. Four random forest regression models including 1) cognitive variables only, 2) learning parameters only, 3) both cognitive and learning variables, and 4) the entire set of variables (with additional demographic and clinical data, 'all' model), were built to predict immediate and 3-month-follow-up WM.

RESULT

The 'all' model predicted verbal WM with the lowest root mean square error (RMSE) compared to the other models, at both immediate (RMSE = 0.184; 95% -CI=[0.184;0.185]) and 3-month follow-up (RMSE = 0.216; 95% -CI=[0.215;0.217]). Cognitive baseline parameters were among the most important predictors in the 'all' model. The model combining cognitive and learning parameters significantly outperformed the model solely based on cognitive variables.

CONCLUSION

Commonly assessed demographic, clinical, and cognitive variables provide robust prediction of response to WMT. Nonetheless, inclusion of training-inherent learning parameters further boosts precision of prediction models which in turn may augment training benefits following cognitive interventions in patients with PD.

Time-course of decline in different cognitive domains in Parkinson's disease: a retrospective study

Cognitive impairment and dementia are common non-motor symptoms in Parkinson's disease (PD). To elucidate the potentially typical progression of cognitive decline in PD and its variation, we retrospectively surveyed neuropsychological data obtained at the Parkinson-Klinik Ortenau, Germany in the years 1996-2015. Many of the patients in the surveyed period were repeatedly admitted to our clinic and we were thus able to compile neuropsychological re-test data for 252 patients obtained at varying time intervals. Neuropsychological testing was conducted with the NAI (Nürnberger Alters-Inventar). This battery provides sub-tests that examine cognitive processing speed, executive function, working memory, and verbal/visual memory functions. The re-test time span varied across patients from below 1 year up to about 12 years. Most patients were seen twice, but some patients were tested up to eight times. The steepest rates of cognitive decline were observed for the NAI sub-tests Trail-Making, Maze Test, and Stroop-Word Reading/Color Naming. Intermediate rates of decline were found for Digit Span, Word List-Immediate Recall, and Picture Test. Stroop Test-Interference, Word List-Delayed Recognition, and Figure Test exhibited the slowest decline rates. We did not observe a significant effect of age at diagnosis or gender on the rate of decline. In sum, this study retrospectively evaluated cognitive decline in a sample of patients with PD. Our data suggest a broad cognitive decline that particularly affects the cognitive capacities for processing speed, executive functions, and immediate memory functions.

Premature cognitive decline in specific domains found in young veterans with mTBI coincide with elder normative scores and advanced-age subjects with early-stage Parkinson's disease

Importance

Epidemiologists report a 56% increased risk of veterans with (+) mild traumatic brain injury (mTBI) developing Parkinson’s disease (PD) within 12-years post-injury. The most relevant contributors to this high risk of PD in veterans (+) mTBI is unknown. As cognitive problems often precede PD diagnosis, identifying specific domains most involved with mTBI-related PD onset is critical.

Objectives

To discern which cognitive domains underlie the mTBI-PD risk relationship proposed in epidemiology studies.

Design and setting

This exploratory match-controlled, cross-sectional study was conducted in a medical school laboratory from 2017–2020.

Participants

Age- and IQ-matched veterans with (+) and without mTBI, non-veteran healthy controls, and IQ-matched non-demented early-stage PD were compared. Chronic neurological, unremitted/debilitating diseases, disorders, dementia, and substance use among others were excluded.

Exposure

Veterans were or were not exposed to non-penetrating combat-related mTBI occurring within the past 7-years. No other groups had recent military service or mTBI.

Main outcomes / measures

Cognitive flexibility, attention, memory, visuospatial ability, and verbal fluency were examined with well-known standardized neuropsychological assessments.

Results

Out of 200 volunteers, 114 provided evaluable data. Groups significantly differed on cognitive tests [F (21,299) = 3.09, p<0.0001]. Post hoc tests showed veterans (+) mTBI performed significantly worse than matched-control groups on four out of eight cognitive tests (range: p = .009 to .049), and more often than not performed comparably to early-stage PD (range: p = .749 to .140).

Conclusions and relevance

We found subtle, premature cognitive decline occurring in very specific cognitive domains in veterans (+) mTBI that would typically be overlooked in a clinic setting, This result potentially puts them at-risk for continual cognitive decline that may portend to the eventual onset of PD or some other neurodegenerative disease.

Fist-Edge-Palm (FEP) test has a high sensitivity in differentiating dementia from normal cognition in Parkinson's disease

BACKGROUND

The Fist-Edge-Palm (FEP) test takes 0.5-3 min to complete and is highly sensitive in differentiating Alzheimer's disease and frontotemporal dementia from normal cognition, but it has not yet been studied in Parkinson's disease (PD).

OBJECTIVE

To determine the sensitivity and specificity of the FEP test in screening patients with PD for cognitive impairment and dementia.

METHODS

PD patients were recruited and divided into three groups based on cognitive status: normal cognition, mild cognitive impairment (MCI) and dementia according to 2015 MDS clinical diagnostic criteria for PD and clinical dementia rating scale (CDR) assessment for cognitive status. MMSE, FEP and clock drawing test (CDT) were tested in all recruited PD patients. Chi-square test was used to compare the sensitivity of FEP and CDT in detecting PDD and PD-MCI.

RESULTS

A total of 108 PD patients were included: 52 normal cognition, 28 MCI, and 28 dementia. The sensitivity of FEP in differentiating PDD from PD-NC was 96.4% and the sensitivity for PD-MCI from PD-NC was 71.4%. The sensitivity of CDT in differentiating PDD from PD-NC was 71.4% and PD-MCI from PD-NC was 53.6%. The sensitivities of FEP and CDT were 83.9% and 62.5%, respectively, in identifying cognitive impairment (CDR ≥ 0.5) in PD patients.

CONCLUSION

FEP is a sensitive screening tool in differentiating PDD or PD-MCI from PD-NC, and it is much faster than MMSE and more sensitive than CDT. FEP may be a practical screening tool for daily clinical practice.

Cognitive profiles of patients with mild cognitive impairment due to Alzheimer's versus Parkinson's disease defined using a base rate approach: Implications for neuropsychological assessments

INTRODUCTION

Large studies on cognitive profiles of patients with mild cognitive impairment (MCI) due to Alzheimer's disease (AD-MCI) compared to Parkinson's disease (PD-MCI) are rare.

METHODS

Data from two multicenter cohort studies in AD and PD were merged using a unified base rate approach for the MCI diagnosis. Cognitive profiles were compared using scores derived from the Consortium to Establish a Registry for Alzheimer's Disease battery.

RESULTS

Patients with AD-MCI showed lower standardized scores on all memory test scores and a language test. Patients with PD-MCI showed lower standardized scores in a set-shifting measure as an executive task. A cross-validated logistic regression with test scores as predictors was able to classify 72% of patients correctly to AD-MCI versus PD-MCI.

DISCUSSION

The applied test battery successfully discriminated between AD-MCI and PD-MCI. Neuropsychological test batteries in clinical practice should always include a broad spectrum of cognitive domains to capture any cognitive changes.

Initial performance predicts improvements in computerized cognitive training: Evidence from a selective attention task

Computerized cognitive training (CCT) has been found to improve a range of skills such as attention, working memory, inhibition control, and decision making. However, the relationship between the initial performance, amount of improvement, time constant, and asymptotic performance level in CCT is still unclear. In the current study, we performed selective attention training on college students and addressed this issue by mathematically modeling the learning curve with an exponential function. Twenty-nine students completed approximately 10 days of CCT. Presentation time served as the dependent variable and was measured by three-down/one-up adaptive algorithms. We fitted an exponential function to the estimated block thresholds during CCT and obtained three learning parameters (amount of improvement, time constant, and asymptotic performance level) for all subjects. The initial performance was defined by the sum of the amount of improvement and the asymptotic performance level. Pearson correlation analyses were conducted between the initial performance and the three leaning parameters. The initial performance was positively correlated with the amount of improvement and asymptotic performance level, but was negatively correlated with the time constant. The time constant was negatively correlated with the amount of improvement and asymptotic performance level. Poorer initial performance was linked to a larger amount of improvement, shorter time constant, and higher asymptotic threshold, which supported the compensation account. Our results may help improve the present understanding of the nature of the CCT process and demonstrate the advantages of using a customized training protocol to enhance the efficiency of cognitive training in practical applications.

Predicting Working Memory Training Responsiveness in Parkinson's Disease: Both "System Hardware" and Room for Improvement Are Needed

Background. Patients with Parkinson's disease (PD) are highly vulnerable to develop cognitive dysfunctions, and the mitigating potential of early cognitive training (CT) is increasingly recognized. Predictors of CT responsiveness, which could help to tailor interventions individually, have rarely been studied in PD. This study aimed to examine individual characteristics of patients with PD associated with responsiveness to targeted working memory training (WMT). Methods. Data of 75 patients with PD (age: 63.99 ± 9.74 years, 93% Hoehn & Yahr stage 2) without cognitive dysfunctions from a randomized controlled trial were analyzed using structural equation modeling. Latent change score models with and without covariates were estimated and compared between the WMT group (n = 37), who participated in a 5-week adaptive WMT, and a waiting list control group (n = 38). Results. Latent change score models yielded adequate model fit (χ²-test p > .05, SRMR ≤ .08, CFI ≥ .95). For the near-transfer working memory composite, lower baseline performance, younger age, higher education, and higher fluid intelligence were found to significantly predict higher latent change scores in the WMT group, but not in the control group. For the far-transfer executive function composite, higher self-efficacy expectancy tended to significantly predict larger latent change scores. Conclusions. The identified associations between individual characteristics and WMT responsiveness indicate that there has to be room for improvement (e.g., lower baseline performance) and also sufficient "hardware" (e.g., younger age, higher intelligence) to benefit in training-related cognitive plasticity. Our findings are discussed within the compensation versus magnification account. They need to be replicated by methodological high-quality research applying advanced statistical methods with larger samples.

Enhancement of Executive Functions but Not Memory by Multidomain Group Cognitive Training in Patients with Parkinson's Disease and Mild Cognitive Impairment: A Multicenter Randomized Controlled Trial

Background

Meta-analyses have demonstrated cognitive training (CT) benefits in Parkinson's disease (PD) patients. However, the patients' cognitive status has only rarely been based on established criteria. Also, prediction analyses of CT success have only sparsely been conducted.

Objective

To determine CT effects in PD patients with mild cognitive impairment (PD-MCI) on cognitive and noncognitive outcomes compared to an active control group (CG) and to analyze CT success predictors.

Methods

Sixty-four PD-MCI patients (age: 67.61 ± 7.70; UPDRS-III: 26.58 ± 13.54; MoCA: 24.47 ± 2.78) were randomized to either a CT group or a low-intensity physical activity CG for six weeks (twice weekly, 90 minutes). Outcomes were assessed before and after training. MANOVAs with follow-up ANOVAs and multiple regression analyses were computed.

Results

Both interventions were highly feasible (participation, motivation, and evaluation); the overall dropout rate was 4.7%. Time × group interaction effects favoring CT were observed for phonemic fluency as a specific executive test (p=0.018, η_p²=0.092) and a statistical trend for overall executive functions (p=0.095, η_p²=0.132). A statistical trend for a time × group interaction effect favoring CG was shown for the digit span backward as a working memory test (p=0.098, η_p²=0.043). Regression analyses revealed cognitive baseline levels, education, levodopa equivalent daily dose, motor scores, and ApoE status as significant predictors for CT success.

Conclusions

CT is a safe and feasible therapy option in PD-MCI, yielding executive functions improvement. Data indicate that vulnerable individuals may show the largest cognitive gains. Longitudinal studies are required to determine whether CT may also attenuate cognitive decline in the long term. This trial is registered with DRKS00010186.

Effects of an Innovative Telerehabilitation Intervention for People With Parkinson's Disease on Quality of Life, Motor, and Non-motor Abilities

Parkinson's disease (PD) often leads to multifactorial motor and non-motor disabilities with resultant social restrictions. Continuity of care in this pathology, including a tailored home rehabilitation, is crucial to improve or maintain the quality of life for patients. The aim of this multicenter study was to test in a pilot sample of PD patients the efficiency and efficacy of the Human Empowerment Aging and Disability (HEAD) program. The virtual reality HEAD program was administered in two consecutive phases: (1) in clinic (ClinicHEAD, 12 45-minutes sessions, 3 sessions/week); (2) at home (HomeHEAD, 60 45-minutes sessions, 5 sessions/week). Thirty-one PD outpatients were enrolled [mean age (SD) = 66.84 (9.13)]. All patients performed ClinicHEAD, and after allocation (ratio 1:2) were assigned to the HomeHEAD or the Usual Care (UC) group. Motor, cognitive and behavioral outcome measures were assessed at enrollment (T0), at hospital discharge (T1), at 4 (T2) and 7 (T3) months after baseline. After ClinicHEAD (T1 vs. T0 comparison) a significant (p < 0.05) improvement in functional mobility, balance, upper limb mobility, global cognitive function, memory, quality of life and psychological well-being was observed. After the HomeHEAD intervention there was an additional enhancement for upper limb mobility. At T3 follow-up, the UC group that did not continue the HEAD program at home showed a worsening with respect to the HomeHEAD group in balance and functional mobility. Furthermore, in the HomeHEAD group, a positive association was observed between adherence, mental and physical health (SF-12). A trend was also registered between adherence and positive affect. The digital health patient-tailored rehabilitation program resulted in improving motor and non-motor abilities and quality of life in clinical setting, enhancing the motor function in telerehabilitation at home, and maintaining the non-motor abilities and quality of life at follow-up. In the near future, people with PD can be supported also at home with individualized rehabilitation strategies for a better quality of life and wellbeing along with lower costs for society.

Effects of working memory training in patients with Parkinson's disease without cognitive impairment: A randomized controlled trial

OBJECTIVE

To determine the feasibility and evaluate effects of a computerized working memory (WM) training (WMT) in patients with Parkinson's Disease (PD) on cognitive and clinical outcomes.

METHODS

76 patients with PD without cognitive impairment were randomized to either the WMT group (n = 37), who participated in a 5-week adaptive WMT, or a passive waiting-list control group (CG, n = 39). Patients underwent clinical and neuropsychological examination at baseline, after training, and at 3-months follow-up, with verbal WM and non-verbal WM as primary outcomes. Outcome assessors were blinded for group allocation.

RESULTS

All WMT participants completed the training successfully and reported high levels of motivation for and satisfaction with the training. Repeated-measures, linear mixed-effects models revealed positive training effects for the WMT group compared to the CG in verbal working memory with a small relative effect size 0.39 [95%CI 0.05; 0.76] for the 3-months follow-up only. No other reliable training effects in cognitive and clinical variables were found for either point of time.

CONCLUSIONS

In this randomized controlled trial, WMT was feasible and yielded some evidence for 3-months follow-up training gains in patients with PD. WMT might be an effective intervention to prevent cognitive decline in this patient group, however, more longitudinal studies with longer follow-up periods and more sensitive assessment tools will have to proof this concept.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS00009379).

Effects of Home-Based Working Memory Training on Visuo-Spatial Working Memory in Parkinson's Disease: A Randomized Controlled Trial

BACKGROUND

Cognitive impairment is a very frequent and severe nonmotor symptom of Parkinson's disease (PD). Early intervention in this at-risk group for cognitive decline may be crucial for long-term preservation of cognitive functions. Computerized working memory training (WMT) has been proven beneficial in non-PD patient populations, but such evidence is still needed for patients with PD.

OBJECTIVE

This study aimed to evaluate the effect of WMT on visuo-spatial working memory (WM) in cognitively unimpaired patients with PD.

METHODS

A single-blind randomized controlled trial encompassing 76 patients with PD but no cognitive impairment according to level II diagnostic criteria was conducted. Thirty-seven patients engaged in home-based adaptive WMT 5 times per week for a period of 5 weeks, whereas the remaining patients were in the waiting list arm of the study (control group [CG]). Working memory performance was evaluated using a computerized task before and after intervention and at 14-week follow-up, allowing to quantify the precision of WM on a continuous scale, ie, to test not only if an item was remembered but also how well the location of this item was retained.

RESULTS

Coincidently, the WMT group showed slightly worse WM performance compared with the CG at baseline, which was ameliorated after WMT. This training-induced effect remained stable until follow-up.

CONCLUSION

Patients showing relatively low WM performance, despite not formally diagnosable as Parkinson's disease with mild cognitive impairment (PD-MCI), seem to benefit from home-based WMT. Thus, WMT could potentially be implemented in future trials as a time- and cost-efficient route to counteract subtle cognitive changes in early disease stages.

TRIAL REGISTRATION

German Clinical Trial Register (drks.de, DRKS00009379).