Challenges and promises of mixed-reality interventions in acquired brain injury rehabilitation: A scoping review

BACKGROUND

Acquired brain injury (ABI) can lead to significant impairments and difficulties in everyday life, necessitating the need for rehabilitation. Mixed-reality (MR) technologies have revolutionized the delivery of neurorehabilitation therapies. However, inconsistencies in research methodology, diverse study populations and designs, and exaggerated claims in the research, media, and private consumer sectors have impacted the knowledge base of the field, including within the context of ABI rehabilitation.

OBJECTIVE

This scoping review aims to explore MR-systems in ABI rehabilitation, while assessing the evidence base and technology readiness levels of these systems.

METHODS

Seven databases were searched for studies, which were screened and analyzed by two independent raters. The types of MR systems, levels of evidence, and technology readiness levels were extracted and analyzed using descriptive analyses.

RESULTS

Twenty-six studies were included in the review, all of which focused on ABI etiologies stemming from strokes. Across studies, upper-limb motor rehabilitation was the most common rehabilitation target of MR interventions, followed by gait, cognition, and lower-extremity functioning. At present, overall results indicate low evidence for MR-applications in ABI rehabilitation, with a median technology readiness level of 6, corresponding to system prototypes being tested in relevant environments.

CONCLUSION

Although challenges regarding system usability and design were reported, results appear promising with ongoing research. With variability across studies, technologies, and populations, determining the effectiveness of MR interventions in ABI remains a challenge, necessitating the need for ongoing innovation, research, and development of these systems.

Behavioral Treatment for Speech and Language in Primary Progressive Aphasia and Primary Progressive Apraxia of Speech: A Systematic Review

Primary progressive aphasia (PPA) and primary progressive apraxia of speech (PPAOS) are neurodegenerative syndromes characterized by progressive decline in language or speech. There is a growing number of studies investigating speech-language interventions for PPA/PPAOS. An updated systematic evaluation of the treatment evidence is warranted to inform best clinical practice and guide future treatment research. We systematically reviewed the evidence for behavioral treatment for speech and language in this population. Reviewed articles were published in peer-reviewed journals through 31 May 2021. We evaluated level of evidence, reporting quality, and risk of bias using a modified version of the American Speech-Language Hearing Association (ASHA) Levels of Evidence, an appraisal point system, additional reporting quality and internal/external validity items, and, as appropriate, the Single Case Experimental Design Scale or the Physiotherapy Evidence Database - PsycBITE Rating Scale for Randomized and Non-Randomized Controlled Trials. Results were synthesized using quantitative summaries and narrative review. A total of 103 studies reported treatment outcomes for 626 individuals with PPA; no studies used the diagnostic label PPAOS. Most studies evaluated interventions for word retrieval. The highest-quality evidence was provided by 45 experimental and quasi-experimental studies (16 controlled group studies, 29 single-subject designs). All (k = 45/45) reported improvement on a primary outcome measure; most reported generalization (k = 34/43), maintenance (k = 34/39), or social validity (k = 17/19) of treatment for at least one participant. The available evidence supports speech-language intervention for persons with PPA; however, treatment for PPAOS awaits systematic investigation. Implications and limitations of the evidence and the review are discussed.

Transcranial direct current stimulation over the right dorsolateral prefrontal cortex increases oxyhemoglobin concentration and cognitive performance dependent on cognitive load

Transcranial direct current stimulation (tDCS) has been explored as a potential method for cognitive enhancement. tDCS may induce a cascade of neurophysiological changes including alterations in cerebral oxygenation. However, the effects of tDCS on the cognitive-cerebral oxygenation interaction remains unclear. Further, oxygenation variability across individuals remains minimally controlled for. The purpose of this sham-controlled study was to test the effects of anodal tDCS over the right dorsolateral prefrontal cortex (DLPFC) on the interaction between working memory and cerebral oxygenation while controlling for individual oxygenation variability. Thirty-three adults received resting-state functional near-infrared spectroscopy (fNIRS) recordings over bilateral prefrontal cortices. Following this, working memory was tested using a Toulouse n-back task concurrently paired with fNIRS, with measurements taken before and after 20 min of anodal or sham tDCS at 1.5 mA. With individual oxygenation controlled for, anodal tDCS was found to increase the oxyhemoglobin concentration over the right DLPFC during the 2-back (q = .015) and 3-back (q = .008) conditions. Additionally, anodal tDCS was found to improve accuracy during the 3-back task by 13.4 % (p = .028) and decrease latency by 250 ms (p = .013). The increase in oxyhemoglobin was strongly correlated with increases in accuracy (p = .041) and decreases in latency during the 3-back span (p = .017). Taken together, anodal tDCS over the right DLPFC was found to regionally increase oxyhemoglobin concentrations and improve working memory performance in higher cognitive load conditions.

Task-Evoked Pupillary Response as a Potential Biomarker of Dementia and Mild Cognitive Impairment: A Scoping Review

Pupil dilation functions as a proxy for cognitive effort and can be measured through automated pupillometry. The aim of this scoping review is to examine how individuals with cognitive impairment differ in task-evoked pupillary responses relative to cognitively healthy individuals. A systematic literature search across six databases was conducted to identify studies examining changes in pupillary responses evoked by cognitive tasks comparing patients with dementia to healthy controls. Eight articles met inclusion criteria and were included for review. Differences in task-evoked pupillary response between cognitively impaired and cognitively healthy participants were observed across studies. Pupil dilation is decreased in patients with Alzheimer's Disease compared to controls, with no difference observed in patients with mild cognitive impairment. A mild, non-significant trend towards reduced pupil dilation in patients with either Parkinson's Disease or Dementia with Lewy Bodies suggests a similar but less pronounced effect than in AD patients. Further research is required to examine the utility of task-evoked pupillary responses as a potential biomarker indexing cognitive decline in individuals transitioning to mild cognitive impairment and/or dementia.

tDCS over the left prefrontal Cortex improves mental flexibility and inhibition in geriatric inpatients with symptoms of depression or anxiety: A pilot randomized controlled trial

BACKGROUND

Patients with depression and/or anxiety are commonly seen in inpatient geriatric settings. Both disorders are associated with an increased risk of cognitive impairments, notably in executive functioning. Transcranial direct current stimulation (tDCS), a type of non-invasive brain stimulation, involves the administration of a low-dose electrical current to induce neuromodulation, which ultimately may act on downstream cognitive processing.

OBJECTIVE

The purpose of this study was to determine the effects of tDCS on executive functioning in geriatric inpatients with symptoms of depression and/or anxiety.

DESIGN

Pilot Randomized Controlled Trial.

SETTING

Specialized geriatric wards in a tertiary rehabilitation hospital.

METHODS

Thirty older-aged adults were recruited, of which twenty completed ten-to-fifteen sessions of 1.5 mA anodal or sham tDCS over the left dorsolateral prefrontal cortex. Cognitive assessments were administered at baseline and following the tDCS protocol; analyses examined the effects of tDCS on cognitive performance between groups (anodal or sham tDCS).

RESULTS

tDCS was found to increase inhibitory processing and cognitive flexibility in the anodal tDCS group, with significant changes on the Stroop test and Trail Making Test-Part B. No significant changes were observed on measures of attention or working memory.

DISCUSSION

These results provide preliminary evidence that tDCS-induced neuromodulation may selectively improve cognitive processing in older adults with symptoms of depression and/or anxiety.

CLINICAL TRIALS REGISTRATION

www.clinicaltrials.gov, NCT04558177.

Does Right-Hemispheric Anodal tDCS Enhance the Impact of Script Training in Chronic Aphasia? A Single-Subject Experimental Study

Background: Script training is an aphasia treatment approach that has been demonstrated to have a positive effect on communication of individuals with aphasia; however, it is time intensive as a therapeutic modality. To augment therapy-induced neuroplasticity, transcranial direct current stimulation (tDCS) may be implemented. tDCS has been paired with other speech-language treatments, however, has not been investigated with script training.

Aims: The purpose of this study was to determine if tDCS improves communication proficiency when paired with script training, compared to script training alone.

Methods and Procedures: A single-subject experimental design was implemented with a participant with non-fluent aphasia, using two scripts across treatment conditions: script training with sham-tDCS, and script training with anodal-tDCS. Treatment sessions were 75 min long, administered three times weekly. Anodal tDCS was implemented for 20 min with a current of 1.5 mA over the right inferior frontal gyrus.

Results: Large effect sizes were obtained on script mastery for both stimulation conditions (anodal d₂ = 9.94; sham d₂ = 11.93). tDCS did not improve script accuracy, however, there was a significant improvement in the rate of change of script pace relative to baseline (3.99 seconds/day, p < 0.001) in the anodal tDCS condition.

Conclusion: Despite a null tDCS result on accuracy, the script training protocol increased script performance to a near-fluent level of communication. There is preliminary evidence to suggest that tDCS may alter the rate of script acquisition, however, further research to corroborate this finding is required. Implications for future studies are discussed.

Transcranial Brain Stimulation Improves Cognition in Older Adults With Depression and Anxiety

Older adults admitted to hospital for rehabilitation often have some degree of concomitant cognitive impairment, which may be a barrier to optimizing rehabilitation approaches. Transcranial direct current stimulation (tDCS), a type of non-invasive brain stimulation, delivers a low electrical current across the brain. The neuromodulatory effects of tDCS can be of therapeutic benefit and has been shown to augment cognitive functions in both healthy and clinical populations. This study investigated the effects of tDCS on cognition in older adult inpatients with depression or anxiety. It was hypothesized that anodal tDCS over the left dorsolateral prefrontal cortex would increase cognitive performance compared to a placebo group. Twenty adults between 65 to 86 years of age admitted to the Glenrose Rehabilitation Hospital with underlying depression or anxiety were recruited. Anodal (n=10) or sham (n=10) tDCS stimulation was administered at 1.5mA over 20 minutes, for 10-15 sessions based on participant availability. Cognitive assessments were administered before and after the tDCS protocol. Anodal tDCS stimulation resulted in significant gains on the Symbol Digit Modality Test, Trail Making Test Part A, and Forward Digit Span. This study demonstrated a tDCS-invoked cognitive enhancement in the domains of attention, information processing speed, and short-term memory processes. With the rapidly ageing population, tDCS may be a potential therapeutic option for cognitive enhancement and may be beneficial in ageing-related cognitive-disorders including mild cognitive impairment and dementia.

Effects of Transcranial Direct Current Stimulation (tDCS) on Cognitive Performance and Cerebral Oxygen Hemodynamics: A Systematic Review

Background: There is increasing evidence to support the efficacy of transcranial direct current stimulation (tDCS) applications in cognitive augmentation and rehabilitation. Neuromodulation achieved with tDCS may further regulate regional cerebral perfusion affiliated through the neurovascular unit; however, components of cerebral perfusion decrease across aging. A novel neuroimaging approach, functional near-infrared spectroscopy (fNIRS), can aid in quantifying these regional perfusional changes. To date, the interaction of the effects of tDCS on cognitive performance across the lifespan and obtained fNIRS hemodynamic responses remain unknown.

Objective: This review aims to examine the effects of tDCS on cognitive performance and fNIRS hemodynamic responses within the context of cognitive aging.

Methods: Six databases were searched for studies. Quality appraisal and data extraction were conducted by two independent reviewers. Meta-analysis was carried out to determine overall and subgroup effect sizes.

Results: Eight studies met inclusion criteria. The overall effect size demonstrates that tDCS can alter cognitive performance and fNIRS signals, with aging being a potential intermediary in tDCS efficacy.

Conclusion: From the studies included, the effects of tDCS on cognitive performance and fNIRS metrics are most prominent in young healthy adults and appear to become less robust with increasing age. Given the small number of studies included in this review further investigation is recommended.

The Impact of Aphasia Camp Participation on Quality of Life: A Primary Progressive Aphasia Perspective

Individuals with primary progressive aphasia (PPA) and their caregivers are at risk for decreased quality of life (QoL) due to their progressive condition. Aphasia camps are an intervention that can improve QoL, yet individuals with PPA are underrepresented at aphasia camps relative to those with poststroke aphasia. The purpose of this exploratory case study was to examine the effect of participation in aphasia camp on the QoL of a couple impacted by PPA. The Living with Aphasia: Framework for Outcome Measurement (A-FROM) was used to guide a semistructured interview with an individual with PPA and her spouse, both of whom had attended the Alberta Aphasia Camp for 4 years. Conventional content analysis with an inductive approach was used to analyze results. Concepts that emerged from the interview were organized into pre-camp, during, and post-camp categories. Aspects of camp that had an effect on post-camp QoL for this couple with PPA included expanding social connections and introduction to new activities. Personal characteristics exhibited by the couple had an impact on their experience of aphasia camp and how they incorporated their experiences into their everyday lives post-camp. Aphasia camps are a participation-based service approach that can benefit people with aphasia regardless of etiology. A consideration of personal factors of potential campers with PPA, and the provision of PPA-specific resources, is recommended for programs such as aphasia camps that incorporate participants with mixed etiologies.