Processing speed and attention training modifies autonomic flexibility: A mechanistic intervention study

Improving Neurological Health in Aging Via Neuroplasticity-Based Computerized Exercise: Protocol for a Randomized Controlled Trial

BACKGROUND

Our current understanding of how computerized brain training drives cognitive and functional benefits remains incomplete. This paper describes the protocol for Improving Neurological Health in Aging via Neuroplasticity-based Computerized Exercise (INHANCE), a randomized controlled trial in healthy older adults designed to evaluate whether brain training improves cholinergic signaling.

OBJECTIVE

INHANCE evaluates whether 2 computerized training programs alter acetylcholine binding using the vesicular acetylcholine transporter ligand [18F] fluoroethoxybenzovesamicol ([18F] FEOBV) and positron emission tomography (PET).

METHODS

In this phase IIb, prospective, double-blind, parallel-arm, active-controlled randomized trial, a minimum of 92 community-dwelling healthy adults aged 65 years and older are randomly assigned to a brain training program designed using the principles of neuroplasticity (BrainHQ by Posit Science) or to an active control program of computer games designed for entertainment (eg, Solitaire). Both programs consist of 30-minute sessions, 7 times per week for 10 weeks (35 total hours), completed remotely at home using either loaned or personal devices. The primary outcome is the change in FEOBV binding in the anterior cingulate cortex, assessed at baseline and posttest. Exploratory cognitive and behavioral outcomes sensitive to acetylcholine are evaluated before, immediately after, and 3 months following the intervention to assess the maintenance of observed effects.

RESULTS

The trial was funded in September 2019. The study received approval from the Western Institutional Review Board in October 2020 with Research Ethics Board of McGill University Health Centre and Health Canada approvals in June 2021. The trial is currently ongoing. The first participant was enrolled in July 2021, enrollment closed when 93 participants were randomized in December 2023, and the trial will conclude in June 2024. The study team will be unblinded to conduct analyses after the final participant exits the study. We expect to publish the results in the fourth quarter of 2024.

CONCLUSIONS

There remains a critical need to identify effective and scalable nonpharmaceutical interventions to enhance cognition in older adults. This trial contributes to our understanding of brain training by providing a potential neurochemical explanation of cognitive benefit.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04149457; https://clinicaltrials.gov/ct2/show/NCT04149457.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/59705.

Vision-based estimation of fatigue and engagement in cognitive training sessions

Computerized cognitive training (CCT) is a scalable, well-tolerated intervention that has promise for slowing cognitive decline. The effectiveness of CCT is often affected by a lack of effective engagement. Mental fatigue is a the primary factor for compromising effective engagement in CCT, particularly in older adults at risk for dementia. There is a need for scalable, automated measures that can constantly monitor and reliably detect mental fatigue during CCT. Here, we develop and validate a novel Recurrent Video Transformer (RVT) method for monitoring real-time mental fatigue in older adults with mild cognitive impairment using their video-recorded facial gestures during CCT. The RVT model achieved the highest balanced accuracy (79.58%) and precision (0.82) compared to the prior models for binary and multi-class classification of mental fatigue. We also validated our model by significantly relating to reaction time across CCT tasks (Waldχ2=5.16,p=0.023). By leveraging dynamic temporal information, the RVT model demonstrates the potential to accurately measure real-time mental fatigue, laying the foundation for future CCT research aiming to enhance effective engagement by timely prevention of mental fatigue.

The Real-World Usability, Feasibility, and Performance Distributions of Deploying a Digital Toolbox of Computerized Assessments to Remotely Evaluate Brain Health: Development and Usability Study

BACKGROUND

An ongoing global challenge is managing brain health and understanding how performance changes across the lifespan.

OBJECTIVE

We developed and deployed a set of self-administrable, computerized assessments designed to measure key indexes of brain health across the visual and auditory sensory modalities. In this pilot study, we evaluated the usability, feasibility, and performance distributions of the assessments in a home-based, real-world setting without supervision.

METHODS

Potential participants were untrained users who self-registered on an existing brain training app called BrainHQ. Participants were contacted via a recruitment email and registered remotely to complete a demographics questionnaire and 29 unique assessments on their personal devices. We examined participant engagement, descriptive and psychometric properties of the assessments, associations between performance and self-reported demographic variables, cognitive profiles, and factor loadings.

RESULTS

Of the 365,782 potential participants contacted via a recruitment email, 414 (0.11%) registered, of whom 367 (88.6%) completed at least one assessment and 104 (25.1%) completed all 29 assessments. Registered participants were, on average, aged 63.6 (SD 14.8; range 13-107) years, mostly female (265/414, 64%), educated (329/414, 79.5% with a degree), and White (349/414, 84.3% White and 48/414, 11.6% people of color). A total of 72% (21/29) of the assessments showed no ceiling or floor effects or had easily modifiable score bounds to eliminate these effects. When correlating performance with self-reported demographic variables, 72% (21/29) of the assessments were sensitive to age, 72% (21/29) of the assessments were insensitive to gender, 93% (27/29) of the assessments were insensitive to race and ethnicity, and 93% (27/29) of the assessments were insensitive to education-based differences. Assessments were brief, with a mean duration of 3 (SD 1.0) minutes per task. The pattern of performance across the assessments revealed distinctive cognitive profiles and loaded onto 4 independent factors.

CONCLUSIONS

The assessments were both usable and feasible and warrant a full normative study. A digital toolbox of scalable and self-administrable assessments that can evaluate brain health at a glance (and longitudinally) may lead to novel future applications across clinical trials, diagnostics, and performance optimization.

The effect of processing speed on verbal and visual memory of adults with a chronic acquired brain injury

OBJECTIVE

Memory problems are among the most frequently reported cognitive complaints by individuals with an acquired brain injury (ABI). Processing speed and working memory deficits are often the result of ABI. These cognitive deficits significantly impact the acquisition and retention of information necessary for memory formation. This study investigated the influence of processing speed and working memory on immediate and delayed recall for verbal and visual memory, as well as overall memory recall in adults living with a chronic ABI.

METHODS

Sixty-three participants living with a chronic ABI, who were at least one-year post-injury, were cognitively assessed with the CNS-Vital Signs (CNS-VS) computerized cognitive battery and Wechsler Test of Adult Reading.

RESULTS

The CNS-VS Processing Speed significantly predicted delayed recall for verbal memory and overall memory performance. The CNS-VS Working Memory was not a significant predictor of memory recall.

CONCLUSIONS

Processing speed deficits negatively impact memory in individuals with a chronic ABI. These findings suggest the memory recall of adults with a chronic ABI is associated with poor processing speed and poor acquisition of information. Therefore, cognitive rehabilitation that improves processing speed should be the focus for individuals with ABI to improve memory performance as well as impaired processing speed.

Positive affect disrupts neurodegeneration effects on cognitive training plasticity in older adults

Cognitive training for older adults varies in efficacy, but it is unclear why some older adults benefit more than others. Positive affective experience (PAE), referring to high positive valence and/or stable arousal states across everyday scenarios, and associated functional networks can protect plasticity mechanisms against Alzheimer's disease neurodegeneration, which may contribute to training outcome variability. The objective of this study is to investigate whether PAE explains variability in cognitive training outcomes by disrupting the adverse effect of neurodegeneration on plasticity. The study's design is a secondary analysis of a randomized control trial of cognitive training with concurrent real or sham brain stimulation (39 older adults with mild cognitive impairment; mean age, 71). Moderation analyses, with change in episodic memory or executive function as the outcome, PAE or baseline resting-state connectivity as the moderator and baseline neurodegeneration as the predictor are the methods used in the study. The result of the study is that PAE stability and baseline default mode network (DMN) connectivity disrupted the effect of neurodegeneration on plasticity in executive function but not episodic memory. The study concludes that PAE stability and degree of DMN integrity both explained cognitive training outcome variability, by reducing the adverse effect of neurodegeneration on cognitive plasticity. We highlight the need to account for PAE, brain aging factors and their interactions with plasticity in cognitive training.

Autonomic nervous system flexibility for understanding brain aging

A recent call was made for autonomic nervous system (ANS) measures as digital health markers for early detection of Alzheimer's disease and related dementia (AD/ADRD). Nevertheless, contradictory or inconclusive findings exist. To help advance understanding of ANS' role in dementia, we draw upon aging and dementia-related literature, and propose a framework that centers on the role of ANS flexibility to guide future work on application of ANS function to differentiating the degree and type of dementia-related brain pathologies. We first provide a brief review of literature within the past 10 years on ANS and dementia-related brain pathologies. Next, we present an ANS flexibility model, describing how the model can be applied to understand these brain pathologies, as well as differentiate or even be leveraged to modify typical brain aging and dementia. Lastly, we briefly discuss the implication of the model for understanding resilience and vulnerability to dementia-related outcomes.

Improving comparability across cognitive training trials for brain aging: A focus on interoperability

Cognitive training may promote healthy brain aging and prevent dementia, but results from individual studies are inconsistent. There are disagreements on how to evaluate cognitive training interventions between clinical and basic scientists. Individual labs typically create their own assessment and training materials, leading to difficulties reproducing methods. Here, we advocate for improved interoperability: the exchange and cooperative development of a consensus for cognitive training design, analysis, and result interpretation. We outline five guiding principles for improving interoperability: (i) design interoperability, developing standard design and analysis models; (ii) material interoperability, promoting sharing of materials; (iii) interoperability incentives; (iv) privacy and security norms, ensuring adherence to accepted ethical standards; and (v) interpretability prioritization, encouraging a shared focus on neurobiological mechanisms to improve clinical relevance. Improving interoperability will allow us to develop scientifically optimized, clinically useful cognitive training programs to slow/prevent brain aging.

HIGHLIGHTS

Interoperability facilitates progress via resource sharing and comparability.Better interoperability is needed in cognitive training for brain aging research.We adapt an interoperability framework to cognitive training research.We suggest five guiding principles for improved interoperability.We propose an open-source pipeline to facilitate interoperability.

Effect of simultaneous exercise and cognitive training on executive functions, baroreflex sensitivity, and pre-frontal cortex oxygenation in healthy older adults: a pilot study

Aging is characterized by cognitive decline affecting daily functioning. To manage this socio-economic challenge, several non-pharmacological methods such as physical, cognitive, and combined training are proposed. Although there is an important interest in this subject, the literature is still heterogeneous. The superiority of simultaneous training compared to passive control and physical training alone seems clear but very few studies compared simultaneous training to cognitive training alone. The aim of this pilot study was to investigate the effect of simultaneous exercise and cognitive training on several cognitive domains in healthy older adults, in comparison with either training alone. Thirty-five healthy older adults were randomized into one of three experimental groups: exercise training, cognitive training, and simultaneous exercise and cognitive training. The protocol involved two 30-min sessions per week for 24 weeks. Cognitive performance in several domains, pre-frontal cortex oxygenation, and baroreflex sensitivity were assessed before and after the intervention. All groups improved executive performance, including flexibility or working memory. We found a group by time interaction for inhibition cost (F(2,28) = 6.44; p < 0.01) and baroreflex sensitivity during controlled breathing (F(2,25) = 4.22; p = 0.01), the magnitude of improvement of each variable being associated (r = -0.39; p = 0.03). We also found a decrease in left and right pre-frontal cortex oxygenation in all groups during the trail making test B. A simultaneous exercise and cognitive training are more efficient than either training alone to improve executive function and baroreflex sensitivity. The results of this study may have important clinical repercussions by allowing to optimize the interventions designed to maintain the physical and cognitive health of older adults.

CCA identifies a neurophysiological marker of adaptation capacity that is reliably linked to internal locus of control of cognition in amnestic MCI

Locus of control (LOC) describes whether an individual thinks that they themselves (internal LOC) or external factors (external LOC) have more influence on their lives. LOC varies by domain, and a person's LOC for their intellectual capacities (LOC-Cognition) may be a marker of resilience in older adults at risk for dementia, with internal LOC-Cognition relating to better outcomes and improved treatment adherence. Vagal control, a key component of parasympathetic autonomic nervous system (ANS) regulation, may reflect a neurophysiological biomarker of internal LOC-Cognition. We used canonical correlation analysis (CCA) to identify a shared neurophysiological marker of ANS regulation from electrocardiogram (during auditory working memory) and functional connectivity (FC) data. A canonical variable from root mean square of successive differences (RMSSD) time series and between-network FC was significantly related to internal LOC-Cognition (β = 0.266, SE = 0.971, CI = [0.190, 4.073], p = 0.031) in 65 participants (mean age = 74.7, 32 female) with amnestic mild cognitive impairment (aMCI). Follow-up data from 55 of these individuals (mean age = 73.6, 22 females) was used to show reliability of this relationship (β = 0.271, SE = 0.971, CI = [0.033, 2.630], p = 0.047), and a second sample (40 participants with aMCI/healthy cognition, mean age = 72.7, 24 females) showed that the canonical vector biomarker generalized to visual working memory (β = 0.36, SE = 0.136, CI = [0.023, 0.574], p = 0.037), but not inhibition task RMSSD data (β = 0.08, SE = 1.486, CI = [- 0.354, 0.657], p = 0.685). This canonical vector may represent a biomarker of autonomic regulation that explains how some older adults maintain internal LOC-Cognition as dementia progresses. Future work should further test the causality of this relationship and the modifiability of this biomarker.

The Preventing Alzheimer's with Cognitive Training (PACT) randomized clinical trial

BACKGROUND

To address the rising prevalence of Alzheimer's disease and related dementias, effective interventions that can be widely disseminated are warranted. The Preventing Alzheimer's with Cognitive Training study (PACT) investigates a commercially available computerized cognitive training program targeting improved Useful Field of View Training (UFOVT) performance. The primary goal is to test the effectiveness of UFOVT to reduce incidence of clinically defined mild cognitive impairment (MCI) or dementia with a secondary objective to examine if effects are moderated by plasma β-amyloid level or apolipoprotein E e4 (APOE e4) allele status.

METHODS/DESIGN

This multisite study utilizes a randomized, controlled experimental design with blinded assessors and investigators. Individuals who are 65 years of age and older are recruited from the community. Eligible participants who demonstrate intact cognitive status (Montreal Cognitive Assessment score > 25) are randomized and asked to complete 45 sessions of either a commercially available computerized-cognitive training program (UFOVT) or computerized games across 2.5 years. After three years, participants are screened for cognitive decline. For those demonstrating decline or who are part of a random subsample, a comprehensive neuropsychological assessment is completed. Those who perform below a pre-specified level are asked to complete a clinical evaluation, including an MRI, to ascertain clinical diagnosis of normal cognition, MCI, or dementia. Participants are asked to provide blood samples for analyses of Alzheimer's disease related biomarkers.

DISCUSSION

The PACT study addresses the rapidly increasing prevalence of dementia. Computerized cognitive training may provide a non-pharmaceutical option for reducing incidence of MCI or dementia to improve public health.

REGISTRATION

The PACT study is registered at http://Clinicaltrials.govNCT03848312.

Unifying framework for cognitive training interventions in brain aging

Cognitive training is a promising tool for slowing or preventing cognitive decline in older adults at-risk for dementia. Its success, however, has been limited by a lack of evidence showing that it reliably causes broad training effects: improvements in cognition across a range of domains that lead to real-world benefits. Here, we propose a framework for enhancing the effect of cognitive training interventions in brain aging. The focus is on (A) developing cognitive training task paradigms that are informed by population-level cognitive characteristics and pathophysiology, and (B) personalizing how these sets are presented to participants during training via feedback loops that aim to optimize "mismatch" between participant capacity and training demands using both adaptation and random variability. In this way, cognitive training can better alter whole-brain topology in a manner that supports broad training effects in the context of brain aging.

Enhancing Cortical Network-level Participation Coefficient as a Potential Mechanism for Transfer in Cognitive Training in aMCI

Effective cognitive training must improve cognition beyond the trained domain (show a transfer effect) and be applicable to dementia-risk populations, e.g., amnesic mild cognitive impairment (aMCI). Theories suggest training should target processes that 1) show robust engagement, 2) are domain-general, and 3) reflect long-lasting changes in brain organization. Brain regions that connect to many different networks (i.e., show high participation coefficient; PC) are known to support integration. This capacity is 1) relatively preserved in aMCI, 2) required across a wide range of cognitive domains, and 3) trait-like. In 49 individuals with aMCI that completed a 6-week visual speed of processing training (VSOP) and 28 active controls, enhancement in PC was significantly more related to transfer to working memory at global and network levels in VSOP compared to controls, particularly in networks with many high-PC nodes. This suggests that enhancing brain integration may provide a target for developing effective cognitive training.

Heart rate variability in relation to cognition and behavior in neurodegenerative diseases: A systematic review and meta-analysis

Neurodegenerative diseases, which frequently present with neuropsychiatric symptoms related to prefrontal cortical dysfunction, can alter the integrity of the neural networks involved in central autonomic nervous system regulation, which is proposed to be indexed by heart rate variability (HRV). We systematically reviewed the characteristics, methodology and outcomes of 27 studies of HRV in relation to measures of cognition and behavior in neurodegenerative conditions, and assessed the strength of this relationship, cross-sectionally, across 18 studies. A significant, moderate effect was observed (r = 0.25), such that higher HRV was related to better cognitive and behavioral scores, which was not influenced by mean age or cognitive status. There was no evidence of small-study effects but we could not rule out publication bias, and other factors may have contributed to heterogeneity between studies. Our findings support the proposal that HRV may be a marker of self-regulatory processes in neurodegenerative conditions, and further research on this association is needed in relation to neuropsychiatric symptoms and alongside neuroimaging methods.

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Heart rate variability is proposed to be influenced by a neural network involved in autonomic regulation.

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Neurodegenerative processes alter the integrity of the central autonomic network.

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We reviewed studies of HRV and cognition/behavior in neurodegenerative diseases.

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We found a moderate correlation between HRV and measures of cognition/behavior.

Transcranial direct current stimulation modulates working memory and prefrontal-insula connectivity after mild-moderate traumatic brain injury

Background: Persistent posttraumatic symptoms (PPS) may manifest after a mild-moderate traumatic brain injury (mmTBI) even when standard brain imaging appears normal. Transcranial direct current stimulation (tDCS) represents a promising treatment that may ameliorate pathophysiological processes contributing to PPS. Objective/Hypothesis: We hypothesized that in a mmTBI population, active tDCS combined with training would result in greater improvement in executive functions and post-TBI cognitive symptoms and increased resting state connectivity of the stimulated region, i.e., left dorsolateral prefrontal cortex (DLPFC) compared to control tDCS. Methods: Thirty-four subjects with mmTBI underwent baseline assessments of demographics, symptoms, and cognitive function as well as resting state functional magnetic resonance imaging (rsfMRI) in a subset of patients (n = 24). Primary outcome measures included NIH EXAMINER composite scores, and the Neurobehavioral Symptom Inventory (NSI). All participants received 10 daily sessions of 30 min of executive function training coupled with active or control tDCS (2 mA, anode F3, cathode right deltoid). Imaging and assessments were re-obtained after the final training session, and assessments were repeated after 1 month. Mixed-models linear regression and repeated measures analyses of variance were calculated for main effects and interactions. Results: Both active and control groups demonstrated improvements in executive function (EXAMINER composite: p < 0.001) and posttraumatic symptoms (NSI cognitive: p = 0.01) from baseline to 1 month. Active anodal tDCS was associated with greater improvements in working memory reaction time compared to control (p = 0.007). Reaction time improvement correlated significantly with the degree of connectivity change between the right DLPFC and the left anterior insula (p = 0.02). Conclusion: Anodal tDCS improved reaction time on an online working memory task in a mmTBI population, and decreased connectivity between executive network and salience network nodes. These findings generate important hypotheses for the mechanism of recovery from PPS after mild-moderate TBI.

A Novel Explainability Approach for Technology-Driven Translational Research on Brain Aging

Brain aging leads to difficulties in functional independence. Mitigating these difficulties can benefit from technology that predicts, monitors, and modifies brain aging. Translational research prioritizes solutions that can be causally linked to specific pathophysiologies at the same time as demonstrating improvements in impactful real-world outcome measures. This poses a challenge for brain aging technology that needs to address the tension between mechanism-driven precision and clinical relevance. In the current opinion, by synthesizing emerging mechanistic, translational, and clinical research-related frameworks, and our own development of technology-driven brain aging research, we suggest incorporating the appreciation of four desiderata (causality, informativeness, transferability, and fairness) of explainability into early-stage research that designs and tests brain aging technology. We apply a series of work on electrocardiography-based "peripheral" neuroplasticity markers from our work as an illustration of our proposed approach. We believe this novel approach will promote the development and adoption of brain aging technology that links and addresses brain pathophysiology and functional independence in the field of translational research.

Targeting autonomic flexibility to enhance cognitive training outcomes in older adults with mild cognitive impairment: study protocol for a randomized controlled trial

Importance

Cognitive training with components that can further enhance the transferred and long-term effects and slow the progress of dementia is needed for preventing dementia.

Objective

The goal of the study is to test whether improving autonomic nervous system (ANS) flexibility via a resonance frequency breathing (RFB) training will strengthen the effects of a visual speed of processing (VSOP) cognitive training on cognitive and brain function, and slow the progress of dementia in older adults with mild cognitive impairment (MCI).

Design

Stage II double-blinded randomized controlled trial. The study was prospectively registered at ClinicalTrials.gov, with registration approved on 21 August 2020 (No. NCT04522791).

Setting

Study-related appointments will be conducted on-site at University of Rochester Medical Center locations. Data collection will be conducted from August 2020 to February 2025.

Participants

Older adults with MCI (n = 114) will be randomly assigned to an 8-week combined intervention (RFB+VSOP), VSOP with guided imagery relaxation (IR) control, and a IR-only control, with periodical booster training sessions at follow-ups. Mechanistic and distal outcomes include ANS flexibility, measured by heart rate variability, and multiple markers of dementia progress. Data will be collected across a 14-month period.

Discussion

This will be among the first RCTs to examine in older persons with MCI a novel, combined intervention targeting ANS flexibility, an important contributor to overall environmental adaptation, with an ultimate goal for slowing neurodegeneration.

Trial registration

ClinicalTrials.gov NCT04522791. Registered on 21 August 2020

Protocol version: STUDY00004727; IRB protocol version 2, approved on 30 July 2020.

A randomized clinical trial of plasticity-based cognitive training in mild traumatic brain injury

Clinical practice guidelines support cognitive rehabilitation for people with a history of mild traumatic brain injury (mTBI) and cognitive impairment, but no class I randomized clinical trials have evaluated the efficacy of self-administered computerized cognitive training. The goal of this study was to evaluate the efficacy of a self-administered computerized plasticity-based cognitive training programmes in primarily military/veteran participants with a history of mTBI and cognitive impairment. A multisite randomized double-blind clinical trial of a behavioural intervention with an active control was conducted from September 2013 to February 2017 including assessments at baseline, post-training, and after a 3-month follow-up period. Participants self-administered cognitive training (experimental and active control) programmes at home, remotely supervised by a healthcare coach, with an intended training schedule of 5 days per week, 1 h per day, for 13 weeks. Participants (149 contacted, 83 intent-to-treat) were confirmed to have a history of mTBI (mean of 7.2 years post-injury) through medical history/clinician interview and persistent cognitive impairment through neuropsychological testing and/or quantitative participant reported measure. The experimental intervention was a brain plasticity-based computerized cognitive training programme targeting speed/accuracy of information processing, and the active control was composed of computer games. The primary cognitive function measure was a composite of nine standardized neuropsychological assessments, and the primary directly observed functional measure a timed instrumental activities of daily living assessment. Secondary outcome measures included participant-reported assessments of cognitive and mental health. The treatment group showed an improvement in the composite cognitive measure significantly larger than that of the active control group at both the post-training [+6.9 points, confidence interval (CI) +1.0 to +12.7, P = 0.025, d = 0.555] and the follow-up visit (+7.4 points, CI +0.6 to +14.3, P = 0.039, d = 0.591). Both large and small cognitive function improvements were seen twice as frequently in the treatment group than in the active control group. No significant between-group effects were seen on other measures, including the directly-observed functional and symptom measures. Statistically equivalent improvements in both groups were seen in depressive and cognitive symptoms.

Can Reactivity of Heart Rate Variability Be a Potential Biomarker and Monitoring Tool to Promote Healthy Aging? A Systematic Review With Meta-Analyses

Background: Monitoring phasic responses of heart rate variability (HRV) in terms of HRV reactivity [i. e., the absolute change from resting state to on-task (i.e., absolute values of HRV measured during exercise)] might provide useful insights into the individual psychophysiological responses of healthy middle-aged to older adults (HOA) to cognitive and physical exercises. Objectives: To summarize the evidence of phasic HRV responses to cognitive and physical exercises, and to evaluate key moderating factors influencing these responses. Methods: A systematic review with meta-analyses was performed. Publications up to May 2020 of the databases Medline (EBSCO), Embase, Cochrane Library, CINAHL, Psycinfo, Web of Science, Scopus, and Pedro were considered. Controlled clinical trials and observational studies measuring phasic HRV responses to cognitive and/or physical exercises in HOA (≥50 years) were included. Results: The initial search identified 6,828 articles, of which 43 were included into the systematic review. Compared to resting state, vagally-mediated HRV indices were significantly reduced during all types of exercises [Hedge's g = -0.608, 95 % CI (-0.999 to -0.218), p = 0.002] indicating a significant parasympathetic withdrawal compared to rest. The key moderating variables of these responses identified included exercise intensity for physical exercises, and participant characteristics (i.e., level of cognitive functioning, physical fitness), task demands (i.e., task complexity and modality) and the individual responses to these cognitive challenges for cognitive exercises. In particular, higher task demands (task complexity and physical exercise intensity) were related to larger HRV reactivities. Better physical fitness and cognition were associated with lower HRV reactivities. Additionally, HRV reactivity appeared to be sensitive to training-induced cognitive and neural changes. Conclusion: HRV reactivity seems to be a promising biomarker for monitoring internal training load and evaluating neurobiological effects of training interventions. Further research is warranted to evaluate the potential of HRV reactivity as a monitoring parameter to guide cognitive-motor training interventions and/or as a biomarker for cognitive impairment. This may facilitate the early detection of cognitive impairment as well as allow individualized training adaptations that, in turn, support the healthy aging process by optimizing individual exercise dose and progression of cognitive-motor training.

Increased segregation of structural brain networks underpins enhanced broad cognitive abilities of cognitive training

A major challenge in the cognitive training field is inducing broad, far-transfer training effects. Thus far, little is known about the neural mechanisms underlying broad training effects. Here, we tested a set of competitive hypotheses regarding the role of brain integration versus segregation underlying the broad training effect. We retrospectively analyzed data from a randomized controlled trial comparing neurocognitive effects of vision-based speed of processing training (VSOP) and an active control consisting of mental leisure activities (MLA) in older adults with MCI. We classified a subset of participants in the VSOP as learners, who showed improvement in executive function and episodic memory. The other participants in the VSOP (i.e., VSOP non-learners) and a subset of participants in the MLA (i.e., MLA non-learners) served as controls. Structural brain networks were constructed from diffusion tensor imaging. Clustering coefficients (CCs) and characteristic path lengths were computed as measures of segregation and integration, respectively. Learners showed significantly greater global CCs after intervention than controls. Nodal CCs were selectively enhanced in cingulate cortex, parietal regions, striatum, and thalamus. Among VSOP learners, those with more severe baseline neurodegeneration had greater improvement in segregation after training. Our findings suggest broad training effects are related to enhanced segregation in selective brain networks, providing insight into cognitive training related neuroplasticity.

Mindfulness and Cognitive Training Interventions in Mild Cognitive Impairment: Impact on Cognition and Mood

With the lack of disease-modifying pharmacologic treatments for mild cognitive impairment and dementia, there has been an increasing clinical and research focus on nonpharmacological interventions for these disorders. Many treatment approaches, such as mindfulness and cognitive training, aim to mitigate or delay cognitive decline, particularly in early disease stages, while also offering potential benefits for mood and quality of life. In this review, we highlight the potential of mindfulness and cognitive training to improve cognition and mood in mild cognitive impairment. Emerging research suggests that these approaches are feasible and safe in this population, with preliminary evidence of positive effects on aspects of cognition (attention, psychomotor function, memory, executive function), depression, and anxiety, though some findings have been unclear or limited by methodological weaknesses. Even so, mindfulness and cognitive training warrant inclusion as current treatments for adults with mild cognitive impairment, even if there is need for additional research to clarify treatment outcomes and questions related to dose, mechanisms, and transfer and longevity of treatment effects.

Enhanced cardiac vagal tone in mental fatigue: Analysis of heart rate variability in Time-on-Task, recovery, and reactivity

Heart Rate Variability (HRV) has been suggested as a useful tool to assess fatigue-sensitive psychological operations. The present study uses a between and within-subject design with a cognitively demanding task and a documentary viewing condition, to examine the temporal profile of HRV during reactivity, Time-on-Task (ToT), and recovery. In the cognitive task group, participants worked on a bimodal 2-back task with a game-like character (the Gatekeeper task) for about 1.5 hours, followed by a 12-minute break, and a post-break block of performance (about 18 min). In the other group, participants watched documentaries. We hypothesized an increasing vagal-mediated HRV as a function of Time spent on the Gatekeeper task and no HRV change in the documentary viewing group. We also analyzed the trial-based post-response cardiac activity as a physiological associate of task-related motivation. Relative to the documentary-viewing, ToT was associated with an elevated level of subjective fatigue, decreased heart rate, and increased HRV, particularly in the vagal-mediated components. Based on fatigued participants' post-error cardiac slowing, and post-error reaction time analyses, we found no evidence for motivation deficits. The present findings suggest that the parasympathetic branch of the autonomous nervous system functioning as a relaxation system tends to be activated under increasing mental fatigue. In addition, the study shows that many HRV indices also seem to change when individuals are engaged in a prolonged, less fatiguing activity (e.g. documentary viewing). This finding emphasizes the relevance of comparisons/control conditions in ToT experiments.

Attitudes Toward Computers Moderate the Effect of Computerized Cognitive Trainings in Oldest-Old Senior Living Center Residents

BACKGROUND AND OBJECTIVES

Computerized cognitive interventions (CCIs) have been increasingly implemented among older adults with mild cognitive impairment (MCI). However, older individuals' attitudes toward technology may limit CCI engagement. This exploratory-developmental study examined whether a "multi-functional interactive computer system" (MICS), which provides pleasurable activities via computer, would improve attitudes toward computers and in turn increase the efficacy of a subsequent CCI.

RESEARCH DESIGN AND METHODS

A phase one double-blind trial randomized 49 seniors with MCI to a MICS + CCI condition or a CCI-only condition. Attitudes toward technology use was assessed using The Attitudes Toward Computers Questionnaire (ATCQ), and cognition was assessed using episodic memory and executive function composite scores at baseline, the ends of MICS and CCI phases, and 3-month follow-up.

RESULTS

The MICS + CCI group did not show significantly greater improvement in cognition than the CCI only group. Secondary analyses indicated that improvement in executive function from baseline occurred in both groups. Participants who did show improved attitudes toward computers, whether through MICS or simply computer exposure itself, showed improvement in executive function.

DISCUSSION AND IMPLICATION

Participants in the MICS + CCI group used MICS less than expected. A more structured and supervised approach may be needed to facilitate MICS exposure. Improved attitudes toward computers regardless of MICS exposure may benefit candidates for CCI.

Positive effects of music therapist's selected auditory stimulation on the autonomic nervous system of patients with disorder of consciousness: a randomized controlled trial

The current randomized controlled trial was performed at the China Rehabilitation Science Institute, China to test the hypothesis that musical auditory stimulation has positive effects on the autonomic nervous system of patients with disorder of consciousness. Although past studies have recommended that patients with disorder of consciousness listen to patient-preferred music, this practice is not universally accepted by researchers. Twenty patients with severe disorder of consciousness listened to either therapist-selected (n = 10, 6 males and 4 females; 43.33 ± 18.76 years old) or patient-preferred (n = 10, 5 males and 5 females, 48.83 ± 18.79 years old) musical therapy, 30 minutes/day, 5 times/week for 6 weeks. The results showed no obvious differences in heart rate variability-related parameters including heart rate, standard deviation of normal-to-normal R-R intervals, and the root-mean-square of successive heartbeat interval differences of successive heartbeat intervals between the two groups of patients. However, percentage of differences exceeding 50 ms between adjacent normal number of intervals, low-frequency power/high-frequency power, high-frequency power norm, low-frequency power norm, and total power were higher in patients receiving therapist-selected music than in patients receiving their own preferred music. In contrast, this relationship was reversed for the high-frequency power and very-low-frequency band. These results suggest that compared with preferred musical stimulation, therapist-selected musical stimulation resulted in higher interactive activity of the autonomic nervous system. Therefore, therapist-selected musical stimulation should be used to arouse the autonomic nervous system of patients with disorder of consciousness. This study was approved by the Institutional Ethics Committee of China Rehabilitation Research Center, China (approval No. 2018-022-1) on March 12, 2018 and registered with the Chinese Clinical Trial Registry (registration number ChiCTR1800017809) on August 15, 2018.

Autonomic flexibility reflects learning and associated neuroplasticity in old age

Effective learning in old age, particularly in those at risk for dementia, is essential for prolonging independent living. Individual variability in learning, however, is remarkable; that is, months of cognitive training to improve learning may be beneficial for some individuals but not others. So far, little is known about which neurophysiological mechanisms account for the observed variability in learning induced by cognitive training in older adults. By combining Lövdén et al.'s (2010, A theoretical framework for the study of adult cognitive plasticity. Psychological Bulletin, 136, 659-676) framework proposing the role of adaptation capacity in neuroplasticity and a neurovisceral integration model of the relationship between autonomic nervous system (ANS) and brain with a novel shapelet analytical approach that allows for accurate and interpretable analysis of time series data, we discovered an acute, ECG-derived ANS segment in response to cognitive training tasks at baseline that predicted learning outcomes from a 6-week cognitive training intervention. The relationship between the ANS segment and learning was robust in both cross-participant and cross-task analyses among a group of older adults with amnestic mild cognitive impairment. Furthermore, the revealed ANS shapelet significantly predicted training-induced neuroplasticity in the dorsal anterior cingulate cortex and select frontal regions during task fMRI. Across outcome measures, individuals were less likely to prospectively benefit from the cognitive training if their ECG data were more similar to this particular ANS segment at baseline. Our findings are among the first empirical evidence to confirm that adaptation capacity, indexed by ANS flexibility, predicts individual differences in learning and associated neuroplasticity beyond individual characteristics (e.g., age, education, neurodegeneration, total training).