Cognitive Training and Noninvasive Brain Stimulation for Cognition in Parkinson's Disease: A Meta-analysis

German Society of Neurology guidelines for the diagnosis and treatment of cognitive impairment and affective disorders in people with Parkinson's disease: new spotlights on diagnostic procedures and non-pharmacological interventions

BACKGROUND AND OBJECTIVE

Cognitive impairment and dementia as well as affective disorders are common and debilitating syndromes that develop in people with Parkinson's disease (PwPD). The authors summarized recommendations for the 2023 updated German guidelines on "Parkinson's disease" from the German Neurological Society (DGN), focusing on the diagnosis and treatment of these disorders.

METHODS

The recommendations were based on literature reviews, other relevant guidelines, and expert opinions.

RESULTS

Measurements to assess cognitive and affective states were reviewed for psychometric properties, use in routine clinical practice, and availability in German. To improve mild cognitive impairment, cognitive training and physical aerobic training are recommended. To treat Parkinson's disease (PD)-related dementia, cognitive stimulation (as a non-pharmacological intervention) and acetylcholinesterase inhibitors (AChEIs, i.e., rivastigmine) are recommended. Cognitive behavioral therapy is recommended to treat depression, anxiety, and fear of progression. Physical interventions are recommended to treat depression, fatigue, and apathy. Optimized dopaminergic treatment is the first-line pharmacological strategy recommended to manage depression, apathy, anhedonia, fatigue, and mood swings. Major depression can be additionally treated using venlafaxine or desipramine, while moderate depression can be treated pharmacologically according to its clinical phenotype (psychomotor retardation or agitation) and comorbidities (e.g., sleep disturbances, pain). Venlafaxine and nortriptyline can be used to treat anhedonia, while citalopram can be used for anxiety.

CONCLUSIONS

In addition to the updated pharmacological treatment options, new insights into recommendations for standardized diagnostics and non-pharmacological interventions were provided for the German health care system. However, more studies are needed to explore the full potential of non-pharmacological interventions to treat and prevent cognitive impairment and affective disorders.

The effect of intermittent theta burst stimulation for cognitive dysfunction: a meta-analysis

BACKGROUND

Growing evidence suggests that cognitive dysfunction significantly impacts patients' quality of life. Intermittent theta burst stimulation (iTBS) has emerged as a potential intervention for cognitive dysfunction. However, consensus on the iTBS protocol for cognitive impairment is lacking.

METHODS

We conducted searches in the Cochrane Central Register of Controlled Trials, EMBASE, PubMed, Chinese National Knowledge Infrastructure, Wanfang Database and the Chongqing VIP Chinese Science and Technology Periodical Database from their inception to January 2024. Random-effects meta-analyzes were used to calculate standardized mean differences and 95% confidence intervals. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation approach.

RESULTS

Twelve studies involving 506 participants were included in the meta-analysis. The analysis showed a trend toward improvement of total cognitive function, activities of daily living and P300 latency compared to sham stimulation in patients with cognitive dysfunction. Subgroup analysis demonstrated that these effects were restricted to patients with post-stroke cognitive impairment but not Alzheimer's disease or Parkinson's disease. Furthermore, subthreshold stimulation also exhibited a significant improvement.

CONCLUSIONS

The results suggest that iTBS may improve cognitive function in patients with cognitive dysfunction, although the quality of evidence remains low. Further studies with better methodological quality should explore the effects of iTBS on cognitive function.

Cognitive training and promoting a healthy lifestyle for individuals with isolated REM sleep behavior disorder: study protocol of the delayed-start randomized controlled trial CogTrAiL-RBD

BACKGROUND

Isolated REM sleep behavior disorder (iRBD) is an early α-synucleinopathy often accompanied by incipient cognitive impairment. As executive dysfunctions predict earlier phenotypic conversion from iRBD to Parkinson's disease and Lewy body dementia, cognitive training focusing on executive functions could have disease-modifying effects for individuals with iRBD.

METHODS

The study CogTrAiL-RBD investigates the short- and long-term effectiveness and the feasibility and underlying neural mechanisms of a cognitive training intervention for individuals with iRBD. The intervention consists of a 5-week digital cognitive training accompanied by a module promoting a healthy, active lifestyle. In this monocentric, single-blinded, delayed-start randomized controlled trial, the intervention's effectiveness will be evaluated compared to an initially passive control group that receives the intervention in the second, open-label phase of the study. Eighty individuals with iRBD confirmed by polysomnography will be consecutively recruited from the continuously expanding iRBD cohort at the University Hospital Cologne. The evaluation will focus on cognition and additional neuropsychological and motor variables. Furthermore, the study will examine the feasibility of the intervention, effects on physical activity assessed by accelerometry, and interrogate the intervention's neural effects using magnetic resonance imaging and polysomnography. Besides, a healthy, age-matched control group (HC) will be examined at the first assessment time point, enabling a cross-sectional comparison between individuals with iRBD and HC.

DISCUSSION

This study will provide insights into whether cognitive training and psychoeducation on a healthy, active lifestyle have short- and long-term (neuro-)protective effects for individuals with iRBD.

TRIAL REGISTRATION

The study was prospectively registered in the German Clinical Trial Register (DRKS00024898) on 2022-03-11, https://drks.de/search/de/trial/DRKS00024898 .

PROTOCOL VERSION

V5 2023-04-24.

Effect of different modalities of transcranial magnetic stimulation on Parkinson's patients cognitive impairment and long-term effectiveness: a systematic review and network meta-analysis

Objective

This study used network Meta-analysis to compare the effects of different transcranial magnetic stimulation (TMS) modalities on the effectiveness and long-term validity of improving cognitive function in Parkinson's patients.

Methods

Computer searches of the Cochrane Library, PubMed, Web of Science, Embass, CNKI and Wanfang Data were conducted to collect randomized controlled clinical studies on TMS to improve cognitive function in Parkinson's patients published from the time of library construction to December 2023.

Results

A total of 22 studies and 1,473 patients were included, comprising 5 interventions: high frequency repetitive transcranial magnetic stimulation (HF-rTMS), low frequency repetitive transcranial magnetic stimulation (LF-rTMS), intermittent theta burst stimulation (iTBS), sham stimulation and conventional rehabilitation therapy (CRT). Network Meta-analysis showed that the ranking results of different TMS intervention modalities in terms of MoCA scores were: HF-rTMS > LF-rTMS > iTBS > sham > CRT, the ranking results of different TMS intervention modalities in terms of MMSE scores were: HF-rTMS > LF-rTMS > sham > CRT. The effect of TMS on improving Parkinsonian cognitive function lasted for 1 month compared to the no-stimulation group.

Conclusion

TMS has some long-term sustained effects on improving cognitive function in Parkinson's patients. HF-rTMS is more effective in improving cognitive function in Parkinson's patients.Systematic review registration: https://www.crd.york.ac.uk/PROSPERO, identifier: CRD42023463958.

Cost-Effectiveness Analyses of Non-Pharmacological and Non-Surgical Interventions in Idiopathic Parkinson's Disease: A Systematic Review

Background

Interest in non-pharmacological/non-surgical interventions to treat Parkinson's disease (PD) has substantially increased. Although a few health-economic studies have been conducted, summary information on the cost-effectiveness is still scarce.

Objective

To give an overview of cost-effectiveness analyses (CEA) focusing on non-pharmacological/non-surgical interventions in PD patients.

Methods

A systematic literature search was conducted in five databases. Studies were included that provided cost-effectiveness analysis (CEA) or cost-utility analysis (CUA) of non-pharmacological/non-surgical interventions in PD patients. Study quality was assessed with the Drummond and CHEERS 2022 checklists, respectively for economic evaluation.

Results

N = 9 studies published between 2012-2023 were identified. Most studies undertook a CUA (n = 5); n = 3 reported a combination of CEA and CUA, and n = 1 a pure CEA. Most studies (n = 6) examined physical exercise. The CEA studies identified additional costs of 170€ -660€  for the improvement of one single unit of a clinical outcome and savings of 18.40€ -22.80€  per score gained as measured with established instruments. The four studies that found significant quality of life benefits show large variations in the incremental cost effectiveness ratio (ICER) of 3,220€ -214,226€  per quality-adjusted life year (QALY); notably interventions were heterogenous regarding content and intensity.

Conclusions

Despite increasing numbers of non-pharmacological/non-surgical intervention trials in PD patients, health-economic evaluations are rare. The examined intervention types and health-economic results vary greatly. Together with the heterogeneity of the health-economic studies these factors limit the conclusions that can be drawn. Further research and a standardization of methods is needed to allow decision makers to make meaningful interpretations, and to allocate scarce resources.

Sex matters for the enhancement of cognitive training with transcranial direct current stimulation (tDCS)

BACKGROUND

Transcranial direct current stimulation (tDCS) can influence brain network activity and associated cognitive and behavioural functions. In addition to the extensive variety in stimulation parameters, numerous biological factors drive these effects, however these are yet poorly understood. Here, we investigate one of the major biological factors by focusing on sex-dependent effects of tDCS on a challenging cognitive control task (adaptive paced auditory serial addition task [PASAT]) in healthy humans.

METHODS

This sex-specific re-analysis was performed on data of 163 subjects who underwent a 2-week cognitive control training (6 sessions in total). Subjects received either verum (anodal/cathodal) or sham tDCS. Electrodes were placed over the left or right dorsolateral prefrontal cortex and the respective contralateral deltoid muscle. Cognitive control was measured as performance in the PASAT and was analysed in respect to stimulation conditions (sham, anodal, cathodal) and sex.

RESULTS

Regardless of stimulation condition, performance gains between the sexes were higher in females compared to males (p = 0.0038). Female's performance during anodal tDCS exceeded male's (p = 0.0070), yet no effects were found for cathodal or sham tDCS. Moreover, in females we found a superior effect for anodal tDCS over sham stimulation (fanodal: p = 0.0354; fcathodal: p = 0.6181), but no such effect in males (manodal: p = 0.6882; mcathodal: p = 0.4822).

CONCLUSIONS

This study highlights the relevance of biological sex for the effects of tDCS on cognitive training. Thus, an increased attention to biological sex is advisable in future brain stimulation research to highlight and in consequence better understand potentially underlying sex-specific mechanisms. Considering biological sex will further advance customisation and individualisation of tDCS interventions. Trial registration ClinicalTrials.gov, NCT04108663.

Noninvasive brain stimulation for cognitive rehabilitation following traumatic brain injury: A systematic review

Traumatic brain injury (TBI) can cause numerous cognitive deficits. These deficits are associated with disability and reduction in quality of life. Noninvasive brain stimulation (NIBS) provides excitatory or inhibitory stimuli to the cerebral cortex. This review aimed to examine the effectiveness of NIBS (i.e., rTMS and tDCS) on cognitive functions in patients with TBI. PubMed, SCOPUS, PEDro, CINAHL, MEDLINE, REHABDATA, and Web of Science were searched from inception to May 2021. The risk of bias in the randomized controlled trials was assessed using the Cochrane Collaboration's instrument. The Physiotherapy Evidence Database (PEDro) scale was applied to evaluate the risk of bias in the non-randomized controlled trials. Ten studies met our inclusion criteria. Six studies used repetitive Transcranial Magnetic Stimulation (rTMS), and four used transcranial Direct Current Stimulation (tDCS) as cognitive rehabilitation interventions. The results showed heterogenous evidence for the effects of rTMS and tDCS on cognitive function outcomes in individuals with TBI. The evidence for the effects of NIBS on cognition following TBI was limited. TDCS and rTMS are safe and well-tolerated interventions post-TBI. The optimal stimulation sites and stimulation parameters remain unknown. Combining NIBS with traditional rehabilitation interventions may contribute to greater enhancements in cognitive functions post-TBI.

Effectiveness of music-based interventions for cognitive rehabilitation in Parkinson's disease: a systematic review of randomized controlled clinical trials

BACKGROUND

Music-based interventions are promising for cognitive rehabilitation in Parkinson's disease; however, systematic reviews covering the topic are scarce.

OBJECTIVE

To analyze the effectiveness of music-based interventions for cognitive rehabilitation in PD.

METHOD

Systematic review study based on PRISMA criteria. The descriptors Parkinson's disease, Parkinson's disease, idiopathic Parkinson's disease, music-based interventions, music therapy, music training, auditory stimulation, music, rhythm, rhythmic, cognition, and cognitive were used. Five databases were searched PubMed/MEDLINE, PsycInfo, Scopus, Web of Science, and Cochrane in May 2022. Only randomized controlled trials with no limit on publication date or language were included. Risk of bias was assessed following Cochrane Collaboration criteria for development of systematic intervention reviews.

RESULTS

Nine hundred nineteen articles were found by the descriptors; 266 were excluded for being repeated; 650 for not meeting the inclusion criteria. The remaining three articles were included and analyzed. The interventions consisted of practices with emphasis on rhythm and were conducted in groups. Risks of important biases were observed, such as lack of blinding in the allocation of participants and in the assessment of outcomes, as well as incomplete data for some outcomes.

CONCLUSION

Overall, the results showed no evidence of efficacy of music-based interventions for cognitive outcomes in PD.

A comprehensive review on algal nutraceuticals as prospective therapeutic agent for different diseases

Ongoing research in the food supplement sector provides insightful information regarding algae as a new-generation nutritional supplement and is also referred to as a superfood. Due to the diverse nutritional components, algae have documented numerous health benefits like fighting microbial diseases, hypertension, obesity, and diabetes. Therefore, algae-derived nutraceuticals account for a rapidly expanding market in the food supplements sector. The concept of algal prebiotics and their role in modulating gut microbiota have also been a chief contributor to this. This review evaluates the use of possible algal species and their specific bioactive compounds for the management of several chronic diseases. Proteins, peptides, polysaccharides, phenolics, and vitamins give an insight into the significance of algae in boosting the immune system and improving the body's nutritional makeup. In addition, phyco-compounds such as polysaccharides and polyphenols are also receiving a lot more interest in cosmeceutical applications for protecting skin from photodamage. The incorporation of algae in the diet for the management and prevention of chronic diseases like cancer, lung, and heart disease has been discussed in this review along with their action mechanism. This review provides a brief overview of several bioactive compounds present in micro and macroalgae and their therapeutic effect on lifestyle diseases, gastrointestinal diseases as well as neurodegenerative diseases.

Efficacy of repetitive transcranial magnetic stimulation in Parkinson's disease: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive form of brain stimulation that positively regulates the motor and non-motor symptoms of Parkinson's disease (PD). Although, most reviews and meta-analysis have shown that rTMS intervention is effective in treating motor symptoms and depression, very few have used randomised controlled trials (RCTs) to analyse the efficacy of this intervention in PD. We aimed to review RCTs of rTMS in patients with PD to assess the efficacy of rTMS on motor and non-motor function in patients with PD.

METHODS

In this systematic review and meta-analysis, we searched PubMed, MEDLINE and Web of Science databases for RCTs on rTMS in PD published between January 1, 1988 to January 1, 2022. Eligible studies included sham-controlled RCTs that used rTMS stimulation for motor or non-motor symptoms in PD. RCTs not focusing on the efficacy of rTMS in PD were excluded. Summary data were extracting from those RCTs by two investigators independently. We then calculated standardised mean difference with random-effect models. The main outcome included motor and non-motor examination of scales that were used in PD motor or non-motor assessment. This study was registered with PROSPERO, CRD42022329633.

FINDINGS

Fourteen studies with 469 patients met the criteria for our meta-analysis. Twelve eligible studies with 381 patients were pooled to analyse the efficacy of rTMS on motor function improvement. The effect size on motor scale scores was 0.51 (P < 0.0001) and were not distinctly heterogeneous (I² = 29%). Five eligible studies with 202 patients were collected to evaluate antidepressant-like effects. The effect size on depression scale scores was 0.42 (P = 0.004), and were not distinctly heterogeneous (I² = 25%), indicating a significant anti-depressive effect (P = 0.004). The results suggest that high-frequency of rTMS on primary motor cortex (M1) is effective in improving motor symptoms; while the dorsolateral prefrontal cortex (DLPFC) may be a potentially effective area in alleviating depressive symptom.

INTERPRETATION

The findings suggest that rTMS could be used as a possible adjuvant therapy for PD mainly to improve motor symptoms, but could have potential efficacy on depressive symptoms of PD. However, further investigation is needed.

FUNDING

The National Natural Science Foundation of China (NO: 81873777, 82071414), Initiated Foundation of Zhujiang Hospital (NO: 02020318005), Scientific Research Foundation of Guangzhou (NO: 202206010005), and Science and Technology Program of Guangdong of China (NO: 2020A0505100037).

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.

Effects of repetitive transcranial magnetic stimulation on gait disorders and cognitive dysfunction in Parkinson's disease: A systematic review with meta-analysis

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is acknowledged to be crucial to manage freezing of gait (FOG) and cognitive impairment for patients with Parkinson's disease (PD), but its effectiveness is unclear.

OBJECTIVE

To determine the effects of rTMS on FOG and cognitive function in people with PD and to investigate potential factors that modulate the rTMS effects.

METHODS

Databases searched included PubMed, Web of Science, EMBASE, and the Cochrane Library from inception to December 31, 2021. Eligible studies include a controlled randomized clinical trial of rTMS intervention for FOG and cognitive dysfunction in PD patients. The weighted mean difference (WMD) with 95% confidence intervals (CI) were calculated with fixed-effects models. The outcome of the study included gait and cognitive assessments.

RESULTS

Sixteen studies with a total of 419 patients were included. Fixed-effects analysis revealed that rTMS was effective in improving freezing of gait questionnaire scores (short-term effect: WMD = -0.925, 95% CI: -1.642 to -0.209, p = .011; long-term effect: WMD = -2.120, 95% CI: -2.751 to -1.489, p = .000), 10-m walking time (short-term effect: WMD = -0.456, 95% CI: -0.793 to -0.119, p = .008; long-term effect: WMD = -0.526, 95% CI: -0.885 to -0.167, p = .004), Timed Up-and-Go scores (short-term effect: WMD = -1.064, 95% CI: -1.555 to -0.572, p = .000; long-term effect: WMD = -1.097, 95% CI: -1.422 to -0.772, p = .000), Montreal cognitive assessment (WMD = 3.714, 95% CI: 2.567 to 4.861, p = .000), and frontal assessment battery (WMD = -0.584, 95% CI: -0.934 to -0.234, p = .001).

CONCLUSIONS

RTMS showed a beneficial effect on FOG and cognitive dysfunction in parkinsonism. However, the optimal rTMS protocol has not been determined and further high-quality studies are needed.

Computerized Cognitive Training in Parkinson's Disease: A Systematic Review and Meta-Analysis

Cognitive impairment is a central non-motor symptom of Parkinson's disease (PD), and there are no established treatments. Computerized cognitive training (CCT) is a safe and efficacious strategy but its efficacy in PD is unclear. We aimed to investigate the efficacy of CCT on cognitive, psychosocial and daily function, and assess potential effect moderators in people with PD without dementia. Randomized controlled trials of CCT were included in multivariate meta-analyses and meta-regressions. Seventeen studies (16 trials) encompassing 679 participants were included. The pooled effect of CCT relative to control was small and statistically significant for overall cognitive function (g=0.16; 95% CI 0.02-0.29). There was robust evidence for benefit on clinical measures of global cognition across 10 trials (g=0.33; 95% CI 0.19-0.48), especially in PD with mild cognitive impairment (PD-MCI), as well as on individual cognitive domains. Greater CCT dose and PD-MCI population were associated with larger effect sizes, but no statistically significant differences were found between subgroups. There was no significant difference in the efficacy of home-based compared to supervised training. Our findings suggest that CCT is associated with cognitive benefits in PD, including when delivered remotely. Larger, well-powered trials are warranted to examine what specific CCT regimens are most likely to promote cognitive and everyday functioning in the long-term.

Cognitive Syndromes Associated With Movement Disorders

PURPOSE OF REVIEW

This article reviews the recognition and management of cognitive syndromes in movement disorders, including those with parkinsonism, chorea, ataxia, dystonia, and tremor.

RECENT FINDINGS

Cognitive and motor syndromes are often intertwined in neurologic disorders, including neurodegenerative diseases such as Parkinson disease, atypical parkinsonian syndromes, Huntington disease, and other movement disorders. Cognitive symptoms often affect attention, working memory, and executive and visuospatial functions preferentially, rather than language and memory, but heterogeneity can be seen in the various movement disorders. A distinct cognitive syndrome has been recognized in patients with cerebellar syndromes. Appropriate recognition and screening for cognitive changes in movement disorders may play a role in achieving accurate diagnoses and guiding patients and their families regarding progression and management decisions.

SUMMARY

In the comprehensive care of patients with movement disorders, recognition of cognitive syndromes is important. Pharmacologic treatments for the cognitive syndromes, including mild cognitive impairment and dementia, in these movement disorders lag behind the therapeutics available for motor symptoms, and more research is needed. Patient evaluation and management require a comprehensive team approach, often linking neurologists as well as neuropsychologists, psychologists, psychiatrists, social workers, and other professionals.

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.

Goal management training and psychoeducation / mindfulness for treatment of executive dysfunction in Parkinson’s disease: A feasibility pilot trial

Introduction

As there is currently no pharmacological treatment for Parkinson’s Disease Mild Cognitive Impairment (PD-MCI) with executive dysfunctions, specific cognitive interventions must be investigated. Most previous studies have tested bottom-up cognitive training programs but have not shown very good results.

Objectives

The aim of this study was to test ease of implementation, differential safety and preliminary efficacy of two top-down (strategy-learning) home-based, individualized, cognitive interventions: Goal Management Training (GMT), adapted for PD-MCI (Adapted-GMT), and a psychoeducation program combined with mindfulness exercises (PSYCH-Mind).

Methods

This was a single-blind block-randomized between-group comparative study. Twelve PD-MCI with mild executive dysfunctions were divided in four blocks and randomly assigned to any of the two interventions. The participants were included if they had PD-MCI diagnosis (no dementia), with stabilized medication. Both groups (Adapted-GMT and PSYCH-mind) received five intervention sessions each lasting 60–90 minutes for five weeks. Measures were collected at baseline, mid-point, one-week, four-week and 12-week follow-ups. Executive functions were assessed with the Dysexecutive questionnaire (DEX) and the Zoo Map Test (ZMT). Quality of life (QoL) and psychiatric symptoms were also evaluated. Repeated measures ANCOVAs (mixed linear analysis) were applied to all outcomes.

Results

There was one drop out, and both interventions were feasible and acceptable. Despite the small sample size limiting statistical power, patients of both groups significantly improved executive functions per the DEX-patient (Time: F(4,36) = 2.96, p = 0.033, CI95%: 10.75–15.23) and DEX-caregiver scores (Time: F(4,36) = 6.02, p = 0.017, CI95%: 9.63–17.23). Both groups significantly made fewer errors between measurement times on the ZMT (Time: F(3,36) = 16.66, p = 0.001, CI95%: 1.07–2.93). However, QoL significantly increased only in PSYCH-Mind patients at four-week follow-up (interaction Time*Group: F(4,36) = 5.31, p = 0.002, CI95%: 15.33–25.61).

Conclusion

Both interventions were easily implemented and proved to be safe. Because both interventions are arguably cost-effective, these pilot findings, although promising, need to be replicated in large samples.

ClinicalTrials.gov Identifier

NCT04636541.

Transcranial Direct Current Stimulation (tDCS) as a Useful Rehabilitation Strategy to Improve Cognition in Patients With Alzheimer's Disease and Parkinson's Disease: An Updated Systematic Review of Randomized Controlled Trials

Alzheimer's disease (AD) and Parkinson's disease (PD) are neurodegenerative disorders characterized by cognitive impairment and functional decline increasing with disease progression. Within non-pharmacological interventions, transcranial direct current stimulation (tDCS) might represent a cost-effective rehabilitation strategy to implement cognitive abilities with positive implications for functional autonomy and quality-of-life of patients. Our systematic review aimed at evaluating the effects of tDCS upon cognition in people suffering from AD and PD. We searched for randomized controlled trials (RCTs) into PubMed, Web of Science, and Cochrane Library. Three review authors extracted data of interest, with neuropsychological tests or experimental cognitive tasks scores as outcome measures. A total of 17 RCTs (10 trials for AD and 7 trials for PD) were included. Compared with sham stimulation, tDCS may improve global cognition and recognition memory in patients with AD and also some executive functions (i.e., divided attention, verbal fluency, and reduction of sensitivity to interference) in patients with PD. Criticism remains about benefits for the other investigated cognitive domains. Despite preliminary emerging evidences, larger RCTs with common neuropsychological measures and long-term follow-ups establishing longevity of the observed effects are necessary for future research in applied psychology field, alongside improved clinical guidelines on the neurodegenerative disorders pertaining electrodes montage, sessions number, duration and intensity of the stimulation, and cognitive battery to be used.

Current concepts in treating mild cognitive impairment in Parkinson's disease

Impairment in various aspects of cognition is recognized as an important non-motor symptom of Parkinson's disease (PD). Mild cognitive impairment in PD (PD-MCI) is common in non-demented PD patients and is often associated with severity of motor symptoms, disease duration and increasing age. Further, PD-MCI can have a significant negative effect on performance of daily life activities and may be a harbinger of development of PD dementia. Thus, there is significant interest in developing therapeutic strategies to ameliorate cognitive deficits in PD and improve cognitive functioning of PD patients. However, due to significant questions that remain regarding the pathophysiology of cognitive dysfunction in PD, remediation of cognitive dysfunction in PD has proven difficult. In this paper, we will focus on PD-MCI and will review some of the current therapeutic approaches being taken to try to improve cognitive functioning in patients with PD-MCI.

Noninvasive neuromodulation in Parkinson's disease: Neuroplasticity implication and therapeutic perspectives

Noninvasive brain stimulation techniques can be used to study in vivo the changes of cortical activity and plasticity in subjects with Parkinson's disease (PD). Also, an increasing number of studies have suggested a potential therapeutic effect of these techniques. High-frequency repetitive transcranial magnetic stimulation (rTMS) and anodal transcranial direct current stimulation (tDCS) represent the most used stimulation paradigms to treat motor and nonmotor symptoms of PD. Both techniques can enhance cortical activity, compensating for its reduction related to subcortical dysfunction in PD. However, the use of suboptimal stimulation parameters can lead to therapeutic failure. Clinical studies are warranted to clarify in PD the additional effects of these stimulation techniques on pharmacologic and neurorehabilitation treatments.

Computer-Delivered Cognitive Training and Transcranial Direct Current Stimulation in Patients With HIV-Associated Neurocognitive Disorder: A Randomized Trial

Objective: HIV infection is associated with impaired cognition, and as individuals grow older, they may also experience age-related changes in mental abilities. Previous studies have shown that computer-based cognitive training (CCT) and transcranial direct current stimulation (tDCS) may be useful in improving cognition in older persons. This study evaluated the acceptability of CCT and tDCS to older adults with HIV-associated neurocognitive disorder, and assessed their impact on reaction time, attention, and psychomotor speed. Methods: In a single-blind randomized study, 46 individuals with HIV-associated mild neurocognitive disorder completed neuropsychological assessments and six 20-min training sessions to which they had been randomly assigned to one of the following conditions: (1) CCT with active tDCS; (2) CCT with sham tDCS, or (3) watching educational videos with sham tDCS. Immediately after training and again 1 month later, participants completed follow-up assessments. Outcomes were evaluated via repeated measures mixed effects models. Results: Participant ratings of the intervention were positive. Effects on reaction time were not significant, but measures of attention and psychomotor speed suggested positive effects of the intervention. Conclusion: Both CCT and tDCS were highly acceptable to older persons with HIV infection. CCT and tDCS may improve cognitive in affected individuals. Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [NCT03440840].

Parkinson disease-associated cognitive impairment

Parkinson disease (PD) is the second most common neurodegenerative disorder, affecting >1% of the population ≥65 years of age and with a prevalence set to double by 2030. In addition to the defining motor symptoms of PD, multiple non-motor symptoms occur; among them, cognitive impairment is common and can potentially occur at any disease stage. Cognitive decline is usually slow and insidious, but rapid in some cases. Recently, the focus has been on the early cognitive changes, where executive and visuospatial impairments are typical and can be accompanied by memory impairment, increasing the risk for early progression to dementia. Other risk factors for early progression to dementia include visual hallucinations, older age and biomarker changes such as cortical atrophy, as well as Alzheimer-type changes on functional imaging and in cerebrospinal fluid, and slowing and frequency variation on EEG. However, the mechanisms underlying cognitive decline in PD remain largely unclear. Cortical involvement of Lewy body and Alzheimer-type pathologies are key features, but multiple mechanisms are likely involved. Cholinesterase inhibition is the only high-level evidence-based treatment available, but other pharmacological and non-pharmacological strategies are being tested. Challenges include the identification of disease-modifying therapies as well as finding biomarkers to better predict cognitive decline and identify patients at high risk for early and rapid cognitive impairment.

Effectiveness of Cognitive Rehabilitation in Parkinson's Disease: A Systematic Review and Meta-Analysis

Cognitive deficits influence the quality of life of Parkinson’s disease (PD) patients. In order to reduce the impact of cognitive impairment in PD, cognitive rehabilitation programs have been developed. This study presents a systematic review and meta-analysis regarding the effectiveness of cognitive rehabilitation in non-demented PD patients. Twelve articles were selected according to PRISMA guidelines. The systematic review showed that attention, working memory, verbal memory, executive functions and processing speed were the most frequently improved domains. Meta-analysis results showed moderate effects on global cognitive status (g = 0.55) and working memory (g = 0.50); small significant effects on verbal memory (g = 0.41), overall cognitive functions (g = 0.39) and executive functions (g = 0.30); small non-significant effects on attention (g = 0.36), visual memory (g = 0.29), verbal fluency (g = 0.27) and processing speed (g = 0.24); and no effect on visuospatial and visuoconstructive abilities (g = 0.17). Depressive symptoms showed small effect (g = 0.24) and quality of life showed no effect (g = −0.07). A meta-regression was performed to examine moderating variables of overall cognitive function effects, although moderators did not explain the heterogeneity of the improvement after cognitive rehabilitation. The findings suggest that cognitive rehabilitation may be beneficial in improving cognition in non-demented PD patients, although further studies are needed to obtain more robust effects.

Memory enhancement by multidomain group cognitive training in patients with Parkinson's disease and mild cognitive impairment: long-term effects of a multicenter randomized controlled trial

BACKGROUND

Meta-analyses indicate positive effects of cognitive training (CT) in patients with Parkinson's disease (PD), however, most previous studies had small sample sizes and did not evaluate long-term follow-up. Therefore, a multicenter randomized controlled, single-blinded trial (Train-ParC study) was conducted to examine CT effects in PD patients with mild cognitive impairment (PD-MCI). Immediately after CT, an enhancement of executive functions was demonstrated. Here, we present the long-term results 6 and 12 months after CT.

METHODS

At baseline, 64 PD-MCI patients were randomized to a multidomain CT group (n = 33) or to a low-intensity physical activity training control group (PT) (n = 31). Both interventions included 90 min training sessions twice a week for 6 weeks. 54 patients completed the 6 months (CT: n = 28, PT: n = 26) and 49 patients the 12 months follow-up assessment (CT: n = 25, PT: n = 24). Primary study outcomes were memory and executive functioning composite scores. Mixed repeated measures ANOVAs, post-hoc t tests and multiple regression analyses were conducted.

RESULTS

We found a significant time x group interaction effect for the memory composite score (p = 0.006, η² = 0.214), but not for the executive composite score (p = 0.967, η² = 0.002). Post-hoc t tests revealed significant verbal and nonverbal memory improvements from pre-intervention to 6 months, but not to 12 months follow-up assessment in the CT group. No significant predictors were found for predicting memory improvement after CT.

CONCLUSIONS

This study provides Class 1 evidence that multidomain CT enhances memory functioning in PD-MCI after 6 months but not after 12 months, whereas executive functioning did not change in the long-term.

CLINICAL TRIAL REGISTRATION

German Clinical Trials Register (ID: DRKS00010186), 21.3.2016 (The study registration is outlined as retrospective due to an administrative delay. The first patient was enrolled three months after the registration process was started. A formal confirmation of this process from the German Clinical Trials Register can be obtained from the authors.).

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.

Computerised cognitive training in Parkinson's disease: a protocol for a systematic review and updated meta-analysis

INTRODUCTION

Cognitive impairment is recognised as an important non-motor symptom in Parkinson's disease (PD) and there is a need for evidence-based non-pharmacological interventions that may prevent or slow cognitive decline in this patient group. One such intervention is computerised cognitive training (CCT), which has shown efficacious for cognition across older adult populations. This systematic review aims to investigate the efficacy of CCT across cognitive, psychosocial and functional domains for people with PD and examine study and intervention design factors that could moderate CCT effects on cognition.

METHODS AND ANALYSIS

Randomised controlled trials investigating the effects of CCT in patients with PD without dementia, on cognitive, psychosocial or functional outcomes, will be included. The primary outcome is overall cognitive function. Secondary outcomes are domain-specific cognitive function, psychosocial functioning and functional abilities. We systematically searched MEDLINE, Embase and PsycINFO through 14 May 2020 to identify relevant literature. Risk of bias will be assessed using the revised Cochrane Risk of Bias tool. Effect sizes will be calculated as standardised mean difference of baseline to postintervention change (Hedges' g) with 95% CI for each eligible outcome measure. Pooling of outcomes across studies will be conducted using random-effects models, accounting for dependency structure of effect sizes within studies. Heterogeneity will be assessed using τ² and I² statistic. Potential moderators, based on key study and intervention design factors, will be investigated using mixed-effects meta-regression models.

ETHICS AND DISSEMINATION

No ethical approval is required. The findings will be disseminated in a peer-reviewed scientific journal.

PROSPERO REGISTRATION NUMBER

CRD42020185386.

Repetitive transcranial magnetic stimulation (rTMS) fails to improve cognition in patients with parkinson's disease: a Meta-analysis of randomized controlled trials

BACKGROUND

Cognitive decline is one of the greatest concerns for patients with Parkinson's disease (PD) and their care partners. Repetitive transcranial magnetic stimulation (rTMS) is a nonpharmacological treatment option used to improve cognitive function in PD, but its efficacy is unclear. We performed a meta-analysis to determine whether rTMS improves cognition in PD patients.

METHODS

Eligibility criteria (PICOS) were as follows: (1) 'P': The patients participating were diagnosed with idiopathic PD; (2) 'I': Intervention using rTMS; (3) 'C': Sham stimulation as control; (4) 'O': The outcome of the study included cognitive evaluations; (5) 'S': The study adopted randomized controlled design. The standardized mean difference (SMD) of change of score was applied to measure efficacy, and we used Version 2 of the Cochrane tool to assess risk of bias.

RESULTS

Twelve studies met the inclusion criteria. Compared with sham-controlled group, the pooled result showed a non-significant short-term effect of rTMS on global cognition (SMD: -0.15, 95% CI: -0.59 to 0.29, I² = 36.7%), executive function (SMD: 0.03, 95% CI: -0.21 to 0.26, I² = 0.0%), and attention and working memory (SMD: 0.05, 95% CI: -0.25 to 0.35, I² = 0.0%). Long-term outcomes were either shown to be statistically nonsignificant.

CONCLUSIONS

Based on a limited number of studies, rTMS fails to improve cognition in PD. We call for additional high-quality randomized controlled trials with adequate sample sizes to determine the efficacy of rTMS.

Association Between REM Sleep Behavior Disorder and Cognitive Dysfunctions in Parkinson's Disease: A Systematic Review and Meta-Analysis of Observational Studies

Background: Rapid eye movement sleep behavior disorder (RBD) is thought to be a prodromal symptom of Parkinson's disease (PD). RBD is also thought to be involved in cognitive decline and dementia in PD. In PD, although the relationship between RBD and cognitive dysfunctions was confirmed by considerable studies, whether RBD was associated with distinct types of cognitive defects is worth of study. Objectives: This systematic review summarizes the evidence relating to cognitive dysfunction in PD patients with RBD (PD-RBD) and those without and explores their specificity to cognitive domains. Methods: A meta-analysis using a random-effects model was performed for 16 different cognitive domains, including global cognitive function, memory (long-term verbal recall, long-term verbal recognition, long-term visual recall, short-term spatial recall, and short-term verbal recall), executive function (general, fluid reasoning, generativity, shifting, inhibition, and updating), language, processing speed/complex attention/working memory, visuospatial/constructional ability, and psychomotor ability. The cognitive difference between the groups of patients was measured as a standardized mean difference (SMD, Cohen's d). PD-RBD patients were classified into Confirmed-RBD (definite diagnosis with polysomnography, PSG) and Probable-RBD (without PSG re-confirmation). In some domains, RBD patients could not be analyzed separately due to the exiguity of primary studies; this analysis refers to such RBD patients as "Mixed-RBD." Results: Thirty-nine studies with 6,695 PD subjects were finally included. Confirmed-RBD patients showed worse performance than those without in global cognitive function, long-term verbal recall, long-term verbal recognition, generativity, inhibition, shifting, language, and visuospatial/constructional ability; Probable-RBD, in global cognitive function and shifting; and Mixed-RBD, in long-term visual recall, short-term spatial recall, general executive function, and processing speed/complex attention/working memory. Conclusion: This meta-analysis strongly suggests a relationship between RBD, Confirmed-RBD in particular, and cognitive dysfunctions in PD patients. Early and routine screening by sensitive and targeted cognitive tasks is necessary for all PD-RBD patients because it may offer the therapeutic time window before they evolve to irreversible dementia.

Effect of rTMS on Parkinson's cognitive function: a systematic review and meta-analysis

Background

To evaluate the effects and optimal parameters of repetitive transcranial magnetic stimulation (rTMS) on cognition function of patients with Parkinson’s disease (PD) and to estimate which cognitive function may obtain more benefits from rTMS.

Method

The articles dealing with rTMS on cognitive function of PD patients were retrieved from the databases until April 2019. Outcomes of global cognitive function and different cognitive domains were extracted. The standardized mean differences (SMDs) with 95% confidence interval (CI) of cognitive outcome for different parameters, scales, and cognitive functions were estimated.

Results

Fourteen studies involving 173 subjects were included in this meta-analysis. A significant effect size was observed with the mini-mental state examination (MMSE) for the global cognitive outcome based on the evidence of four published articles. Further subtests for different cognitive domains demonstrated prominent effect for the executive function. The significant effect sizes for executive function were found with multiple sessions of high-frequency rTMS over frontal cortex; especially over dorsolateral prefrontal cortex (DLPFC). All of the other cognitive domains, which included memory, attention, and language ability, did not obtain significant effects.

Conclusions

Multiple sessions of high-frequency rTMS over the DLPFC may have positive effect on executive function in PD patients. Further well designed studies with large sample sizes are needed to verify our results and ascertain the long-term effects of rTMS.

Approach to Cognitive Impairment in Parkinson's Disease

Cognitive dysfunction is common in Parkinson's disease (PD) and predicts poor clinical outcomes. It is associated primarily with pathologic involvement of basal forebrain cholinergic and prefrontal dopaminergic systems. Impairments in executive functions, attention, and visuospatial abilities are its hallmark features with eventual involvement of memory and other domains. Subtle symptoms in the premotor and early phases of PD progress to mild cognitive impairment (MCI) which may be present at the time of diagnosis. Eventually, a large majority of PD patients develop dementia with advancing age and longer disease duration, which is usually accompanied by immobility, hallucinations/psychosis, and dysautonomia. Dopaminergic medications and deep brain stimulation help motor dysfunction, but may have potential cognitive side effects. Central acetylcholinesterase inhibitors, and possibly memantine, provide modest and temporary symptomatic relief for dementia, although there is no evidence-based treatment for MCI. There is no proven disease-modifying treatment for cognitive impairment in PD. The symptomatic and disease-modifying role of physical exercise, cognitive training, and neuromodulation on cognitive impairment in PD is under investigation. Multidisciplinary approaches to cognitive impairment with effective treatment of comorbidities, proper rehabilitation, and maintenance of good support systems in addition to pharmaceutical treatment may improve the quality of life of the patients and caregivers.

Evaluating a frontostriatal working-memory updating-training paradigm in Parkinson's disease: the iPARK trial, a double-blinded randomized controlled trial

BACKGROUND

Cognitive decline and dementia are common in Parkinson's disease (PD). Cognitive deficits have been linked to the depletion of dopamine in the nigrostriatal pathway, but pharmacological treatments for PD have little evidence of improving or delaying cognitive decline. Therefore, exploring non-pharmacological treatment options is important. There have been some promising results of cognitive training interventions in PD, especially for improvements in working memory and executive functions. Yet, existing studies are often underpowered, lacking appropriate control condition, long term follow-up, a thorough description of the intervention and characteristics of the participants. Working memory updating training has previously shown to increase striatal activation in healthy young and old participants as well as dopaminergic neurotransmission in healthy young participants. In the light of dopamine dysfunction in PD, with negative effects on both motor and cognitive functions it is of interest to study if an impaired striatal system can be responsive to a non-invasive, non-pharmacological intervention.

METHODS AND DESIGN

The iPARK trial is a double-blinded, randomized controlled trial with a parallel-group design that aims to recruit 80 patients with PD (during the period 02/2017-02/2023). Included patients need to have PD, Hoehn and Yahr staging I-III, be between 45 to 75 years of age and not have a diagnosis of dementia. All patients will undergo 30 sessions (6-8 weeks) of web-based cognitive training performed from home. The target intervention is a process-based training program targeting working memory updating. The placebo program is a low dose short-term memory program. A battery of neuropsychological tests and questionnaires will be performed before training, directly after training, and 16 weeks after training.

DISCUSSION

We expect that the iPARK trial will provide novel and clinically useful information on whether updating training is an effective cognitive training paradigm in PD. Further, it will hopefully contribute to a better understanding of cognitive function in PD and provide answers regarding cognitive plasticity as well as determining critical factors for a responsive striatal system.

TRIAL REGISTRATION

Clinicaltrials.gov registry number: NCT03680170 , registry name: "Cognitive Training in Parkinson's Disease: the iPARK study", retrospectively registered on the 21st of September 2018. The inclusion of the first participant was the 1st of February 2017.

Cognition-Oriented Treatments for Older Adults: a Systematic Overview of Systematic Reviews

Cognition-oriented treatments - commonly categorized as cognitive training, cognitive rehabilitation and cognitive stimulation - are promising approaches for the prevention of cognitive and functional decline in older adults. We conducted a systematic overview of meta-analyses investigating the efficacy of cognition-oriented treatments on cognitive and non-cognitive outcomes in older adults with or without cognitive impairment. Review quality was assessed by A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR). We identified 51 eligible reviews, 46 of which were included in the quantitative synthesis. The confidence ratings were "moderate" for 9 (20%), "low" for 13 (28%) and "critically low" for 24 (52%) of the 46 reviews. While most reviews provided pooled effect estimates for objective cognition, non-cognitive outcomes of potential relevance were more sparsely reported. The mean effect estimate on cognition was small for cognitive training in healthy older adults (mean Hedges' g = 0.32, range 0.13-0.64, 19 reviews), mild cognitive impairment (mean Hedges' g = 0.40, range 0.32-0.60, five reviews), and dementia (mean Hedges' g = 0.38, range 0.09-1.16, seven reviews), and small for cognitive stimulation in dementia (mean Hedges' g = 0.36, range 0.26-0.44, five reviews). Meta-regression revealed that higher AMSTAR score was associated with larger effect estimates for cognitive outcomes. The available evidence supports the efficacy of cognition-oriented treatments improving cognitive performance in older adults. The extent to which such effects are of clinical value remains unclear, due to the scarcity of high-quality evidence and heterogeneity in reported findings. An important avenue for future trials is to include relevant non-cognitive outcomes in a more consistent way and, for meta-analyses in the field, there is a need for better adherence to methodological standards. PROSPERO registration number: CRD42018084490.

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).

The Beneficial Effects of Computer-Based Cognitive Training in Parkinson’s Disease: A Systematic Review

Background

Cognitive dysfunction is one of the most prevalent non-motor aspects of Parkinson’s disease (PD). The present review focuses on published studies investigating the effect of computer-based cognitive training (CT) on neuropsychological performance in PD.

Methods

A systematic search of the PubMed database and Google Scholar was carried out. Randomized controlled studies published before September 2019, investigating the effect of computer-based CT (regardless of the comparator, active or placebo) on PD patients were included. Literature search, data extraction, and Risk of Bias (RoB) evaluation (based on the RoB Cochrane tool for Randomized Trials) were performed by two authors (A.N. and M.M), independently.

Results

Among 30 full-texts assessed for eligibility, seven articles fulfilled the inclusion criteria and were involved in the qualitative analysis. The main outcomes of the retrieved studies (all studies used similar cognitive rehabilitation methodologies) were indicative of cognitive improvement in most cognitive domains, particularly memory, executive function, processing speed, and attention, that is, the domains primarily impaired in the disease.

Conclusion

Multidomain CT, which is exclusively based on computer software, leads to measurable improvements in most cognitive domains affected in patients with PD. The present review is the first to include studies assessing the effect of computer-based CT techniques without deploying CT with paper-pencil techniques. Limitations originate mainly due to the heterogeneity among included studies (differences in CT softwares, PD stages, number, and duration of training sessions.

Therapeutic noninvasive brain stimulation in Alzheimer's disease and related dementias

PURPOSE OF REVIEW

Alzheimer's disease is a progressive neurodegenerative disease without effective pharmacological treatment. Noninvasive brain stimulation (NIBS) techniques, such as repetitive transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES), are increasingly being investigated for their potential to ameliorate the symptoms of Alzheimer's disease and related dementias (ADRD).

RECENT FINDINGS

A comprehensive literature review for primary research reports that investigated the ability of TMS/tES to improve cognition in ADRD patients yielded a total of 20 reports since 2016. Eight studies used repetitive TMS and 12 used transcranial direct current stimulation, the most common form of tES. Eight of the studies combined NIBS with cognitive training. Promising results should encourage continued investigation, however there is currently insufficient evidence to support widespread adoption of NIBS-based clinical treatments for ADRD.

SUMMARY

NIBS remains an active area of investigation for treatment of ADRD, though the predominance of small, heterogeneous, proof-of-principle studies precludes definitive conclusions. We propose the establishment of a consortium to achieve the benefits of large-scale, controlled studies using biomarker-based diagnostic characterization of participants, development of neurophysiological markers to verify target engagement, and standardization of parameters.

High-Frequency Repetitive Transcranial Magnetic Stimulation Could Improve Impaired Working Memory Induced by Sleep Deprivation

Objective

To investigate whether and how the working memory impairment induced by sleep deprivation (SD) could be recovered by using repetitive transcranial magnetic stimulation (rTMS), as well as to clarify the corresponding brain activity changes.

Methods

Seventeen healthy adults received one session of 5.0 Hz rTMS over the left dorsolateral prefrontal cortex (DLPFC) following 24 hours of SD. Resting state functional magnetic resonance imaging (fMRI) and working memory test were performed during a rested waking period, after SD and rTMS. The amplitude of low-frequency fluctuations (ALFF) was used to detect the spontaneous neural activity changes after both SD and rTMS. The relationship between ALFF and the performance of working memory was also assessed by using correlation analysis.

Results

After SD, the participants exhibited lower response accuracies and longer reaction times on the working memory tests of letters and numbers. The decreased response accuracy of numbers was significantly improved after rTMS similarly to the state of the rested waking period after a normal night of sleep. ALFF values decreased from the rested waking period state to the state of SD in the brain regions involving the frontal gyrus, precuneus, angular gyrus, and parietal lobe which showed significantly increased ALFF after rTMS. Furthermore, significantly positive correlations were observed between changes of response accuracy and the changes of ALFF value of the inferior frontal gyrus and supramarginal gyrus.

Conclusion

These results indicate that high-frequency rTMS applied over left DLPFC may contribute to the recovery of the impaired working memory after SD by modulating the neural activity of related brain regions.

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

 Today, meta-analyses demonstrate that cognitive training is safe and effective to enhance vulnerable cognitive functions in patients with Parkinson’s disease (PD), so that cognitive interventions can be regarded as a promising approach to treat or even prevent cognitive dysfunction in PD. However, many research gaps exist. Thus, this article aims to identify relevant research topics with regard to cognitive interventions in PD patients for the next 20 years. The most important to do's include the development of (non-digital and digital, maybe also artificial intelligence based) standardized cognitive interventions for PD patients in different cognitive stages and the conduct of large randomized controlled trials (RCTs) in these groups, also considering different patient profiles (e.g., motor subtypes) and the living setting (inpatient versus outpatient). The impact of cognitive and combined interventions in individuals with prodromal PD is of high relevance. Studies should elucidate underlying mechanisms of cognitive and neural plasticity induced by cognitive interventions and propose prediction models on which patients profit from which intervention. Health-economic analyses are also urgently needed. More generally, increasing the awareness of the concept of cognitive reserve and possibilities for the prevention of cognitive dysfunction is an important goal.

The Effects of Computer-Based Cognitive Rehabilitation on Working Memory in Patients with Parkinson's Disease: A Systematic Review

BACKGROUND

Deterioration of working memory(WM) is a common cognitive deficit in Parkinson's disease (PD), and severely influences the ability to lead an independent life. Interventions which can delay the impact of WM deficits could positively impact the independence and quality of life of patients.

OBJECTIVE

To evaluate effects of computer-based cognitive rehabilitation (CBCR) on WM in patients with PD.

METHODS

Pubmed, Embase, Psycinfo and Cochrane Library were systematically searched. Authors of included studies were contacted to detect unpublished data or articles not found by database-search. Broad selection criteria were applied because literature was expected to be limited. Studies were eligible for inclusion if they investigated the effects of CBCR on WM in a sample consisting of at least 50% PD patients, or in which the results of PD patients could be isolated. Studies were further eligible for inclusion in a planned meta-analysis if the effects of the CBCR intervention could be isolated, the CBCR intervention was compared to active or passive control groups consisting solely of PD patients, and the WM outcome measure could be isolated.

RESULTS

Only six studies were included despite broad inclusion criteria. Study results were heterogeneous, and the risk of bias in study methodology was either unclear or high. Two studies were eligible for meta-analysis. A meta-analysis was not performed, because these studies used different measures of WM which were not rated as equally valid and reliable.

CONCLUSION

Existing literature is sparse and provides insufficient evidence to conclude if CBCR benefits WM in PD patients.

Auditory and Cognitive Training for Cognition in Adults With Hearing Loss: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis examined the efficacy of auditory training and cognitive training to improve cognitive function in adults with hearing loss. A literature search of academic databases (e.g., MEDLINE, Scopus) and gray literature (e.g., OpenGrey) identified relevant articles published up to January 25, 2018. Randomized controlled trials (RCTs) or repeated measures designs were included. Outcome effects were computed as Hedge’s g and pooled using random-effects meta-analysis (PROSPERO: CRD42017076680). Nine studies, five auditory training, and four cognitive training met the inclusion criteria. Following auditory training, the pooled effect was small and statistically significant for both working memory (g = 0.21; 95% CI [0.05, 0.36]) and overall cognition (g = 0.19; 95% CI [0.07, 0.31]). Following cognitive training, the pooled effect for working memory was small and statistically significant (g = 0.34; 95% CI [0.16, 0.53]), and the pooled effect for overall cognition was large and significant (g = 1.03; 95% CI [0.41, 1.66]). However, this was dependent on the classification of training approach. Sensitivity analyses revealed no statistical difference between the effectiveness of auditory and cognitive training for improving cognition upon removal of a study that used a combined auditory–cognitive approach, which showed a very large effect. Overall certainty in the estimation of effect was “low” for auditory training and “very low” for cognitive training. High-quality RCTs are needed to determine which training stimuli will provide optimal conditions to improve cognition in adults with hearing loss.

Cognitive Stimulation for Individuals with Parkinson's Disease Dementia Living in Long-Term Care: Preliminary Data from a Randomized Crossover Pilot Study

Background

While the efficacy of cognitive stimulation (CS) has been demonstrated in patients with dementia, no study has included patients with Parkinson's disease dementia (PDD).

Objective

For the first time, this randomized crossover pilot study examined the feasibility and potential effects of CS in PDD.

Methods

All residents of a PDD-specific long-term care unit in the Netherlands that were eligible for the study (n=12) were randomly allocated to group A (n=6) receiving CS (eight weeks, twice weekly for 60 minutes) or group B (n=6) receiving usual care (control group, CG). The CG participated in CS afterwards, resulting in an experimental group (EG), consisting of n=12. Pre- and postassessments and a six-week follow-up (FU) were conducted for cognition, neuropsychiatric symptoms, quality of life (QoL), and activities of daily living (ADL) outcomes.

Results

Between-group analysis with difference scores from pre- to posttest revealed a group difference for global cognition (CERAD total score) favoring the EG, with a moderate effect size and a p value just failing to reach statistical significance (p=0.067; r = 0.43). A further statistical trend was observed for neuropsychiatric symptoms, again with a moderate effect size (p=0.075; r = 0.42). Within-group analyses indicated improvement only in the EG with large effects also just failing to reach significance for global cognition (short term, p=0.060; r = 0.70) as well as for depression (long term, p=0.072; r = 0.61). ADL deteriorated significantly at FU in the EG (p=0.014; r = 0.71).

Conclusions

Although our data are preliminary due to the small sample size, this study shows that CS is feasible and potentially effective for cognitive and noncognitive outcomes in PDD patients. Randomized controlled trials with larger sample sizes are needed to confirm these promising results.

The impact of cognitive interventions on cognitive symptoms in idiopathic Parkinson's disease: a systematic review

This systematic review addressed efficacy of cognitive stimulation (CS), cognitive training (CT), and cognitive rehabilitation (CR) to improve cognitive functions in Parkinson's disease (PD) with (PD-MCI) and without mild cognitive impairment (PD-H). Five databases were searched. Twelve CT, four CS, and a combination of CT with CR were found. PD-H benefited from CT or CS compared to active or passive controls in 42.1% of cognitive tests, and in 33.3% of psychological and functional measures. PD-MCI alone, compared with controls, only improved in 6.9% of cognitive measures after CT. PD-H and PD-MCI, alone or together, somehow improved information processing speed, attention, working memory, executive functions, and visual episodic memory. PD-MCI improved better than PD-H in global cognition and planning abilities. The outcomes suggest some efficacy of cognitive interventions in PD. However, small samples, lack of information regarding standardization of interventions, and poor methodological quality limit results validity and prevent firm conclusions.

Cognitive effects of transcranial direct current stimulation combined with working memory training in fibromyalgia: a randomized clinical trial

Cognitive dysfunction in fibromyalgia has been reported, especially memory. Anodal transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) has been effective in enhancing this function. We tested the effects of eight sessions of tDCS and cognitive training on immediate and delayed memory, verbal fluency and working memory and its association with brain-derived neurotrophic factor (BDNF) levels. Forty females with fibromyalgia were randomized to receive eight sessions of active or sham tDCS. Anodal stimulation (2 mA) was applied over the DLPFC and online combined with a working memory training (WMT) for 20 minutes. Pre and post-treatment neurocognitive tests were administered. Data analysis on deltas considering years of education and BDNF as covariates, indicated active-tDCS + WMT significantly increased immediate memory indexed by Rey Auditory Verbal Learning Test score when compared to sham. This effect was dependent on basal BDNF levels. In addition, the model showed active stimulation increased orthographic and semantic verbal fluency scores (Controlled Oral Word Association Test) and short-term memory (Forward Digit Span). The combination of both techniques seemed to produce effects on specific cognitive functions related to short-term and long-term episodic memory and executive functions, which has clinical relevance for top-down treatment approaches in FM.

Training working memory updating in Parkinson's disease: A randomised controlled trial

Frontostriatal dysfunction in Parkinson's disease (PD) increases the risk for working memory (WM) impairment and depression, calling for counteractive measures. Computerised cognitive rehabilitation is a promising option, but targeted training protocols are lacking and lab-based training can be demanding due to the repeated visits. This study tested the feasibility and efficacy of home-based computerised training targeting mainly WM updating in PD. Fifty-two cognitively well-preserved PD patients were randomised to a WM training group and an active control group for five weeks of training (three 30-min sessions per week). WM training included three computerised adaptive WM tasks (two updating, one maintenance). The outcomes were examined pre- and post-training with trained and untrained WM tasks, tasks tapping other cognitive domains, and self-ratings of executive functioning and depression. Home-based training was feasible for the patients. The training group improved particularly on the updating training tasks, and showed posttest improvement on untrained WM tasks structurally similar to the trained ones. Moreover, their depression scores decreased compared to the controls. Our study indicates that patients with mild-to-moderate PD can self-administer home-based computerised WM training, and that they yield a similar transfer pattern to untrained WM tasks as has been observed in healthy older adults.

Neurorehabilitation in Parkinson's Disease: A Critical Review of Cognitive Rehabilitation Effects on Cognition and Brain

Background

Parkinson's disease (PD) patients experience cognitive impairment which has been related to reduced quality of life and functional disability. These symptoms usually progress until dementia occurs. Some studies have been published assessing the efficacy of cognitive treatments on improving cognition, functional outcome, and producing changes in brain activity.

Objective

A critical review was performed to present up-to-date neurorehabilitation effects of cognitive rehabilitation in PD, with special emphasis on the efficacy on cognition, quality of life aspects, brain changes, and the longitudinal maintenance of these changes.

Results

After exclusions, 13 studies were reviewed, including 6 randomized controlled trials for the efficacy on cognition, 2 randomized controlled trials regarding the brain changes after cognitive training, and 5 studies which evaluated the long-term effects of cognitive treatments.

Conclusions

Cognitive rehabilitation programs have demonstrated to be effective on improving cognitive functions, but more research is needed focusing on the efficacy on improving behavioral aspects and producing brain changes in patients with PD. Moreover, there is a need of randomized controlled trials with long-term follow-up periods.

Cognitive Training and Transcranial Direct Current Stimulation for Mild Cognitive Impairment in Parkinson's Disease: A Randomized Controlled Trial

This study examined whether standard cognitive training, tailored cognitive training, transcranial direct current stimulation (tDCS), standard cognitive training + tDCS, or tailored cognitive training + tDCS improved cognitive function and functional outcomes in participants with PD and mild cognitive impairment (PD-MCI). Forty-two participants with PD-MCI were randomized to one of six groups: (1) standard cognitive training, (2) tailored cognitive training, (3) tDCS, (4) standard cognitive training + tDCS, (5) tailored cognitive training + tDCS, or (6) a control group. Interventions lasted 4 weeks, with cognitive and functional outcomes measured at baseline, post-intervention, and follow-up. The trial was registered with the Australian New Zealand Clinical Trials Registry (ANZCTR: 12614001039673). While controlling for moderator variables, Generalized Linear Mixed Models (GLMMs) showed that when compared to the control group, the intervention groups demonstrated variable statistically significant improvements across executive function, attention/working memory, memory, language, activities of daily living (ADL), and quality of life (QOL; Hedge's g range = 0.01 to 1.75). More outcomes improved for the groups that received standard or tailored cognitive training combined with tDCS. Participants with PD-MCI receiving cognitive training (standard or tailored) or tDCS demonstrated significant improvements on cognitive and functional outcomes, and combining these interventions provided greater therapeutic effects.

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.