Determinants of exercise adherence in sedentary middle-aged and older adults

Regular exercise positively impacts neurocognitive health, particularly in aging individuals. However, low adherence, particularly among older adults, hinders the adoption of exercise routines. While brain plasticity mechanisms largely support the cognitive benefits of exercise, the link between physiological and behavioral factors influencing exercise adherence remains unclear. This study aimed to explore this association in sedentary middle-aged and older adults. Thirty-one participants underwent an evaluation of cortico-motor plasticity using transcranial magnetic stimulation (TMS) to measure changes in motor-evoked potentials following intermittent theta-burst stimulation (iTBS). Health history, cardiorespiratory fitness, and exercise-related behavioral factors were also assessed. The participants engaged in a 2-month supervised aerobic exercise program, attending sessions three times a week for 60 min each, totaling 24 sessions at a moderate-to-vigorous intensity. They were divided into Completers (n = 19), who attended all sessions, and Dropouts (n = 12), who withdrew early. Completers exhibited lower smoking rates, exercise barriers, and resting heart rates compared to Dropouts. For Completers, TMS/iTBS cortico-motor plasticity was associated with better exercise adherence (r = -.53, corrected p = .019). Exploratory hypothesis-generating regression analysis suggested that post-iTBS changes (β = -7.78, p = .013) and self-efficacy (β = -.51, p = .019) may predict exercise adherence (adjusted-R2 = .44). In conclusion, this study highlights the significance of TMS/iTBS cortico-motor plasticity, self-efficacy, and cardiovascular health in exercise adherence. Given the well-established cognitive benefits of exercise, addressing sedentary behavior and enhancing self-efficacy are crucial for promoting adherence and optimizing brain health. Clinicians and researchers should prioritize assessing these variables to improve the effectiveness of exercise programs.

Estimating dementia risk in an African American population using the DCTclock

The prevalence of Alzheimer's disease (AD) and related dementias (ADRD) is increasing. African Americans are twice as likely to develop dementia than other ethnic populations. Traditional cognitive screening solutions lack the sensitivity to independently identify individuals at risk for cognitive decline. The DCTclock is a 3-min AI-enabled adaptation of the well-established clock drawing test. The DCTclock can estimate dementia risk for both general cognitive impairment and the presence of AD pathology. Here we performed a retrospective analysis to assess the performance of the DCTclock to estimate future conversion to ADRD in African American participants from the Rush Alzheimer's Disease Research Center Minority Aging Research Study (MARS) and African American Clinical Core (AACORE). We assessed baseline DCTclock scores in 646 participants (baseline median age = 78.0 ± 6.4, median years of education = 14.0 ± 3.2, 78% female) and found significantly lower baseline DCTclock scores in those who received a dementia diagnosis within 3 years. We also found that 16.4% of participants with a baseline DCTclock score less than 60 were significantly more likely to develop dementia in 5 years vs. those with the highest DCTclock scores (75-100). This research demonstrates the DCTclock's ability to estimate the 5-year risk of developing dementia in an African American population. Early detection of elevated dementia risk using the DCTclock could provide patients, caregivers, and clinicians opportunities to plan and intervene early to improve cognitive health trajectories. Early detection of dementia risk can also enhance participant selection in clinical trials while reducing screening costs.

Digital Clock and Recall is superior to the Mini-Mental State Examination for the detection of mild cognitive impairment and mild dementia

BACKGROUND

Disease-modifying treatments for Alzheimer's disease highlight the need for early detection of cognitive decline. However, at present, most primary care providers do not perform routine cognitive testing, in part due to a lack of access to practical cognitive assessments, as well as time and resources to administer and interpret the tests. Brief and sensitive digital cognitive assessments, such as the Digital Clock and Recall (DCR™), have the potential to address this need. Here, we examine the advantages of DCR over the Mini-Mental State Examination (MMSE) in detecting mild cognitive impairment (MCI) and mild dementia.

METHODS

We studied 706 participants from the multisite Bio-Hermes study (age mean ± SD = 71.5 ± 6.7; 58.9% female; years of education mean ± SD = 15.4 ± 2.7; primary language English), classified as cognitively unimpaired (CU; n = 360), mild cognitive impairment (MCI; n = 234), or probable mild Alzheimer's dementia (pAD; n = 111) based on a review of medical history with selected cognitive and imaging tests. We evaluated cognitive classifications (MCI and early dementia) based on the DCR and the MMSE against cohorts based on the results of the Rey Auditory Verbal Learning Test (RAVLT), the Trail Making Test-Part B (TMT-B), and the Functional Activities Questionnaire (FAQ). We also compared the influence of demographic variables such as race (White vs. Non-White), ethnicity (Hispanic vs. Non-Hispanic), and level of education (≥ 15 years vs. < 15 years) on the DCR and MMSE scores.

RESULTS

The DCR was superior on average to the MMSE in classifying mild cognitive impairment and early dementia, AUC = 0.70 for the DCR vs. 0.63 for the MMSE. DCR administration was also significantly faster (completed in less than 3 min regardless of cognitive status and age). Among 104 individuals who were labeled as "cognitively unimpaired" by the MMSE (score ≥ 28) but actually had verbal memory impairment as confirmed by the RAVLT, the DCR identified 84 (80.7%) as impaired. Moreover, the DCR score was significantly less biased by ethnicity than the MMSE, with no significant difference in the DCR score between Hispanic and non-Hispanic individuals.

CONCLUSIONS

DCR outperforms the MMSE in detecting and classifying cognitive impairment-in a fraction of the time-while being not influenced by a patient's ethnicity. The results support the utility of DCR as a sensitive and efficient cognitive assessment in primary care settings.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT04733989.

Electroencephalography spectral coherence analysis during cycle ergometry in low- and high-tolerant individuals

The main objective of this study was to further understanding of the patterns of spectral connectivity during exercise in low- and high-tolerant individuals. Thirty-nine healthy individuals (i.e., 17 low- and 22 high-tolerant participants) took part in the present study. A state-of-the-art portable electroencephalography system was used to measure the brain's electrical activity during an incremental exercise test performed until the point of volitional exhaustion on a cycle ergometer. Spectral coherence was used to explore the patterns of connectivity in the frontal, central, and parietal regions of the brain. Physiological, perceptual, and affective responses were assessed throughout the exercise bout. The spontaneous eyeblink rate was also calculated prior to commencement and upon completion of the exercise trial as an indirect assessment of the dopaminergic system. The present findings indicate that high-tolerant individuals reported lower levels of perceived activation, especially during the preliminary stages of the exercise test. Participants in the high-tolerance group also reported greater levels of remembered pleasure upon completion of the exercise test. The data also revealed that high-tolerant individuals exhibited increased connectivity of theta waves between frontal, central, and parietal electrode sites and increased connectivity of beta waves, primarily within the parietal cortex. Correlational analysis indicated the possibility that low- and high-tolerant individuals make use of different neural networks to process and regulate their psychophysiological state during exercise-related situations. This strategy could potentially represent a conscious decision to downregulate affective arousal and facilitate the neural control of working muscles during situations of physical stress.

Exploring the interplay between mechanisms of neuroplasticity and cardiovascular health in aging adults: A multiple linear regression analysis study

BACKGROUND

Neuroplasticity and cardiovascular health behavior are critically important factors for optimal brain health.

OBJECTIVE

To assess the association between the efficacy of the mechanisms of neuroplasticity and metrics of cardiovascular heath in sedentary aging adults.

METHODS

We included thirty sedentary individuals (age = 60.6 ± 3.8 y; 63 % female). All underwent assessments of neuroplasticity, measured by the change in amplitude of motor evoked potentials elicited by single-pulse Transcranial Magnetic Stimulation (TMS) at baseline and following intermittent Theta-Burst (iTBS) at regular intervals. Cardiovascular health measures were derived from the Incremental Shuttle Walking Test and included Heart Rate Recovery (HRR) at 1-min/2-min after test cessation. We also collected plasma levels of brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and c-reactive protein.

RESULTS

We revealed moderate but significant relationships between TMS-iTBS neuroplasticity, and the predictors of cardiovascular health (|r| = 0.38 to 0.53, p < .05). HRR1 was the best predictor of neuroplasticity (β = 0.019, p = .002). The best fit model (Likelihood ratio = 5.83, p = .016) of the association between neuroplasticity and HRR1 (β = 0.043, p = .002) was selected when controlling for demographics and health status. VEGF and BDNF plasma levels augmented the association between neuroplasticity and HRR1.

CONCLUSIONS

Our findings build on existing data demonstrating that TMS may provide insight into neuroplasticity and the role cardiovascular health have on its mechanisms. These implications serve as theoretical framework for future longitudinal and interventional studies aiming to improve cardiovascular and brain health. HRR1 is a potential prognostic measure of cardiovascular health and a surrogate marker of brain health in aging adults.

Exercise engagement drives changes in cognition and cardiorespiratory fitness after 8 weeks of aerobic training in sedentary aging adults at risk of cognitive decline

Background

With our aging population, many individuals are at risk of developing age-related cognitive decline. Physical exercise has been demonstrated to enhance cognitive performance in aging adults. This study examined the effects of 8 weeks of aerobic exercise on cognitive performance and cardiorespiratory fitness in sedentary aging adults at risk for cognitive decline.

Methods

Fifty-two participants (age 62.9 ± 6.8, 76.9% female) engaged in eight weeks of moderate-to high-intensity exercise (19 in-person, 33 remotely). Global cognition was measured by the Repeatable Battery for the Assessment of Neuropsychological Status, the Delis-Kaplan Executive Function System, and the Digit Span subtest of the Wechsler Adult Intelligence Scale (WAIS) Fourth Edition. Cardiorespiratory fitness was measured via heart rate recovery at minute 1 (HRR1) and 2 (HRR2), and exercise engagement (defined as percent of total exercise time spent in the prescribed heart rate zone). We measured pre and post changes using paired t-tests and mixed effects models, and investigated the association between cardiorespiratory and cognitive performance using multiple regression models. Cohen's d were calculated to estimate effect sizes.

Results

Overall, 63.4 % of participants demonstrated high engagement (≥ 70% total exercise time spent in the prescribed heart rate zone). There were significant pre-post improvements in verbal fluency and verbal memory, and a significant decrement in working memory, but these were associated with small effect sizes (Cohen's d <0.5). Concerning cardiorespiratory fitness, there was a pre-to-post significant improvement in HRR1 (p = 0.01, d = 0.30) and HRR2 (p < 0.001, d = 0.50). Multiple regressions revealed significant associations between cardiorespiratory and cognitive performance, but all were associated with small effect sizes (Cohen's d < 0.5). Interestingly, there were significant between-group differences in exercise engagement (all p < 0.001), with remote participants demonstrating greater exercise engagement than in-person participants.

Conclusion

Improvements in cognition and cardiorespiratory fitness were observed after 8 weeks of moderate to high-intensity exercise in aging adults. These results suggest that committing to a regular exercise regimen, even for a brief two-month period, can promote improvements in both cardiorespiratory fitness and cognitive performance, and that improvements are driven by exercise engagement.

Associations Between Cognitive Functioning and Mortality in a Population-Based Sample of Older United States Adults: Differences by Sex and Education

Objective: To determine whether cognition is associated with mortality among older US adults. Methods: We studied 5,989 National Health and Nutrition Examination Survey participants age 60+ in years 1999-2014 with mortality follow-up through 2015. Cognitive function was measured in one standard deviation decrements using the Digit Symbol Substitution Test (DSST), Animal Fluency (AnFl), and two Consortium to Establish a Registry for Alzheimer's Disease (CERAD) tests. Results: Each decrement in cognitive function was associated with increased risk of mortality overall (DSST HR: 1.36, 95% CI: 1.25, 1.48), among women only (AnFl: 1.51, 95% CI: 1.02, 2.24), and among those with less than a high school education only (AnFl HR: 1.46, 95% CI: 1.09, 1.97; CERAD-WL HR: 1.34, 95% CI: 1.07, 1.67; and CERAD-DR HR: 1.38, 95% CI: 1.05, 1.82). Discussion: Among US adults, lower cognitive functioning was associated with mortality; associations were stronger among women and those with less education.

Recommending Physical Activity to Your Aging Patients? What Clinicians Need to Know to Increase Adherence From the Older Adult Perspective

A wealth of scientific evidence supports that being physically active may prevent or delay the onset of cognitive impairment and dementia. However, a critical barrier is that while most clinicians recommend physical activity (PA) and older adults recognize its health benefits, most older adults fail to regularly practice PA. Thus, it is necessary to explore and disseminate knowledge on how to help clinicians truly partner with people and help them to change their behavior and become more active. Clinical and scientific efforts are underway to establish dose-specific PA recommendations for cognitive brain health. However, an important knowledge gap is how to develop effective strategies to increase PA adherence in aging. To better understand the perspective of older adults, we undertook a mixed-method study on sixty-five sedentary older adults at risk for cognitive decline. Participants answered a questionnaire battery related to PA engagement, and a subcohort participated in a remote focus group. Our findings revealed four main themes: First, age and aging are determinants in PA practice. Second, maintaining both an active mind and autonomy are priorities, but planned PA is not usually related as part of being “active.” Third, motivational challenges in PA engagement were noted. And fourth, they emphasized a call for tailored recommendations. Therefore, we present a multidimensional model of PA adherence to maximize brain health in older adults and suggest a tool kit and key questions to effectively screen sedentary aging adults and translate current guidelines into the needs of the individual by using behavior change strategies.

The Importance of Motivation to Older Adult Physical and Cognitive Exercise Program Development, Initiation, and Adherence

Brain health is essential to successful aging, and exercise is essential to brain health. Evidence supports the benefits of regular physical and cognitive exercise in preventing or delaying progressin of mild cognitive impairment and dementia. Despite known benefits, motivation to initiate and adhere to an exercise program can be challenging to older adults. We propose that assessment of motivation in the older adult population be part of individualized physical and cognitive exercise program initial development and ongoing precision health coaching to facilitate initiation of—and adherence to—individualized multi-modal exercise programs and sustained exercise engagement. We suggest one published, physical exercise motivation questionnaire and present a new, psychometrically supported, parallel cognitive exercise questionnaire to do so. Needs for—and implications of—continued exercise motivation research using neurophysiologic and neuropsychologic metrics are discussed.

Greater Cognitive-Motor Interference in Individuals Post-Stroke During More Complex Motor Tasks

BACKGROUND AND PURPOSE

Dual-task (DT) walking assessments allow for the simultaneous evaluation of cognitive and motor performance. During DT walking, individuals may experience interference in one or both tasks, known as cognitive-motor interference (CMI). The primary purpose of this study was to compare CMI between individuals post-stroke and healthy persons group during single- and dual-motor and cognitive tasks, using 2 distinct walking tasks.

METHODS

Motor performance was quantified as the total time for the Timed Up and Go (TUG) and gait speed for the 90-second walk (90W). Cognitive performance was measured as the correct response rate (CRR) during serial 7 subtractions. Participants performed the motor and cognitive tasks in isolation for the single-task (ST) and simultaneously for DT conditions, TUG-DT and 90W-DT. A repeated-measures analysis of variance assessed group (poststroke and healthy) by condition (ST and DT) interactions for the TUG, 90W, and CRR.

RESULTS

There were significant main effects of group and condition for both the TUG and the 90W (P < 0.05). There was also an interaction effect for the TUG, with individuals post-stroke demonstrating a larger decrement in TUG-DT performance compared with healthy persons (P < 0.05). Furthermore, a significant interaction effect was observed for the CRR, in which healthy individuals exhibited a greater decrement in performance from the ST to the 90W-DT (P < 0.05).

DISCUSSION AND CONCLUSIONS

Individuals post-stroke were susceptible to greater motor interference during the more complex motor task, the TUG-DT. However, the only decrements observed in cognitive performance from the ST to DT occurred in healthy individuals during the 90W-DT.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A367).

Harnessing Neuroplasticity to Promote Brain Health in Aging Adults: Protocol for the MOVE-Cog Intervention Study

Background

Extensive evidence supports a link between aerobic exercise and cognitive improvements in aging adults. A major limitation with existing research is the high variability in cognitive response to exercise. Our incomplete understanding of the mechanisms that influence this variability and the low adherence to exercise are critical knowledge gaps and major barriers for the systematic implementation of exercise for promoting cognitive health in aging.

Objective

We aimed to provide an in-person and remotely delivered intervention study protocol with the main goal of informing the knowledge gap on the mechanistic action of exercise on the brain by characterizing important mechanisms of neuroplasticity, cardiorespiratory fitness response, and genetics proposed to underlie cognitive response to exercise.

Methods

This is an open-label, 2-month, interventional study protocol in neurologically healthy sedentary adults. This study was delivered fully in-person and in remote options. Participants underwent a total of 30 sessions, including the screening session, 3 pretest (baseline) assessments, 24 moderate-to-vigorous aerobic exercise sessions, and 3 posttest assessments. We recruited participants aged 55 years and above, sedentary, and cognitively healthy. Primary outcomes were neuroplasticity, cognitive function, and cardiorespiratory fitness. Secondary outcomes included genetic factors, endothelium function, functional mobility and postural control, exercise questionnaires, depression, and sleep. We also explored study feasibility, exercise adherence, technology adaptability, and compliance of both in-person and remote protocols.

Results

The recruitment phase and data collection of this study have concluded. Results are expected to be published by the end of 2021 or in early 2022.

Conclusions

The data generated in these studies will introduce tangible parameters to guide the development of personalized exercise prescription models for maximal cognitive benefit in aging adults. Successful completion of the specific aims will enable researchers to acquire the appropriate expertise to design and conduct studies by testing personalized exercise interventions in person and remotely delivered, likely to be more effective at promoting cognitive health in aging adults.

Trial Registration

ClinicalTrials.gov NCT03804528; http://clinicaltrials.gov/ct2/show/NCT03804528

International Registered Report Identifier (IRRID)

RR1-10.2196/33589

Aging in the Digital Age: Using Technology to Increase the Reach of the Clinician Expert and Close the Gap Between Health Span and Life Span

Age-related cognitive impairment (ARCI) has a profound impact on individuals, families, health care systems, and societies at large. Evidence suggests that ARCI is the consequence of underlying brain pathology. Therefore, efforts to minimize the impact of ARCI and thus closing the gap between health span and life span, which has widened in recent years, requires early detection and timely deployment of targeted, personalized interventions. Access to clinical experts is limited and technology screening and assessment methods are thus appealing. However, as traditionally implemented patients were deprived of the benefit of personalized connection with a clinician, which is particularly critical for the prescription and to ensure the adherence to and ultimate success of therapeutic interventions. We present the concept of Intelligent Technology Therapy Assistant (ITA) as a scalable solution that increases the reach of clinical experts while sustaining the personal connection between each patient and their clinician. We illustrate ITA with the "Guttman Neuro Personal Trainer"®, a tele-rehabilitation platform that provides neuropsychological evaluation and care, and the Barcelona Brain Health Initiative (BBHI) multimodal intervention coaching app, a mobile-based platform that provides lifestyle coaching support in domains related to brain health. In addition, we discuss the translation of these models to a large-scale enterprise with Linus Health. To this end, we conclude with a discussion of challenges and opportunities to move the field forward.

Associations Between Cardiorespiratory Fitness, Cardiovascular Risk, and Cognition Are Mediated by Structural Brain Health in Midlife

Background

Evidence in older adults suggests that higher cardiorespiratory fitness and lower cardiovascular risk are associated with greater cognition. However, given that changes in the brain that lead to cognitive decline begin decades before the onset of symptoms, understanding the mechanisms by which modifiable cardiovascular factors are associated with brain health in midlife is critical and can lead to the development of strategies to promote and maintain brain health as we age.

Methods and Results

In 501 middle‐aged (aged 40–65 years) adult participants of the BBHI (Barcelona Brain Health Initiative), we found differential associations among cardiorespiratory fitness, cardiovascular risk, and cognition and cortical thickness. Higher cardiorespiratory fitness was significantly associated with better visuospatial abilities and frontal loading abstract problem solving (β=3.16, P=0.049) in the older middle‐aged group (aged 55–65 years). In contrast, cardiovascular risk was negatively associated with better visuospatial reasoning and problem‐solving abilities (β=−0.046, P=0.002), flexibility (β=−0.054, P<0.001), processing speed (β=−0.115, P<0.001), and memory (β=−0.120, P<0.001). Cortical thickness in frontal regions mediated the relationship between cardiorespiratory fitness and cognition, whereas cortical thickness in a disperse network spanning multiple cortical regions across both hemispheres mediated the relationship between cardiovascular risk and cognition.

Conclusions

The relationships between modifiable cardiovascular factors, cardiorespiratory fitness, and cardiovascular risk, and cognition are present in healthy middle‐aged adults. These relationships are also mediated by brain structure highlighting a potential mechanistic pathway through which higher cardiorespiratory fitness and lower cardiovascular risk can positively impact cognitive function in midlife.

Large-scale analysis of interindividual variability in single and paired-pulse TMS data

OBJECTIVE

This study brought together over 60 transcranial magnetic stimulation (TMS) researchers to create the largest known sample of individual participant single and paired-pulse TMS data to date, enabling a more comprehensive evaluation of factors driving response variability.

METHODS

Authors of previously published studies were contacted and asked to share deidentified individual TMS data. Mixed-effects regression investigated a range of individual and study level variables for their contribution to variability in response to single and paired-pulse TMS data.

RESULTS

687 healthy participant's data were pooled across 35 studies. Target muscle, pulse waveform, neuronavigation use, and TMS machine significantly predicted an individual's single-pulse TMS amplitude. Baseline motor evoked potential amplitude, motor cortex hemisphere, and motor threshold (MT) significantly predicted short-interval intracortical inhibition response. Baseline motor evoked potential amplitude, test stimulus intensity, interstimulus interval, and MT significantly predicted intracortical facilitation response. Age, hemisphere, and TMS machine significantly predicted MT.

CONCLUSIONS

This large-scale analysis has identified a number of factors influencing participants' responses to single and paired-pulse TMS. We provide specific recommendations to minimise interindividual variability in single and paired-pulse TMS data.

SIGNIFICANCE

This study has used large-scale analyses to give clarity to factors driving variance in TMS data. We hope that this ongoing collaborative approach will increase standardisation of methods and thus the utility of single and paired-pulse TMS.

Large-scale analysis of interindividual variability in theta-burst stimulation data: Results from the 'Big TMS Data Collaboration'

BACKGROUND

Many studies have attempted to identify the sources of interindividual variability in response to theta-burst stimulation (TBS). However, these studies have been limited by small sample sizes, leading to conflicting results.

OBJECTIVE/HYPOTHESIS

This study brought together over 60 TMS researchers to form the 'Big TMS Data Collaboration', and create the largest known sample of individual participant TBS data to date. The goal was to enable a more comprehensive evaluation of factors driving TBS response variability.

METHODS

118 corresponding authors of TMS studies were emailed and asked to provide deidentified individual TMS data. Mixed-effects regression investigated a range of individual and study level variables for their contribution to iTBS and cTBS response variability.

RESULTS

430 healthy participants' TBS data was pooled across 22 studies (mean age = 41.9; range = 17-82; females = 217). Baseline MEP amplitude, age, target muscle, and time of day significantly predicted iTBS-induced plasticity. Baseline MEP amplitude and timepoint after TBS significantly predicted cTBS-induced plasticity.

CONCLUSIONS

This is the largest known study of interindividual variability in TBS. Our findings indicate that a significant portion of variability can be attributed to the methods used to measure the modulatory effects of TBS. We provide specific methodological recommendations in order to control and mitigate these sources of variability.

Randomized Trial of Combined Aerobic, Resistance, and Cognitive Training to Improve Recovery From Stroke: Feasibility and Safety

Background Physical exercise and cognitive training have been recommended to improve cognitive outcomes poststroke, but a multifaceted strategy including aerobic, resistance, and cognitive training to facilitate poststroke recovery has not been investigated. We aimed to assess the feasibility, adherence, and safety of a combined aerobic, resistance, and cognitive training intervention (CARET+CTI) after stroke. Methods and Results We prospectively randomized patients presenting with recent stroke to a comparison of a supervised 12-week CARET+CTI program and a control group receiving sham CARET+CTI. Participants were scheduled for 3 weekly CARET and CTI sessions. All participants underwent pre- and postintervention assessments of strength, endurance, and cognition. The primary outcomes were feasibility and adherence, defined as the ratio of scheduled and observed visits, and safety. We enrolled 131 participants, of whom 37 withdrew from the study. There were 17 (20%) withdrawals in the CARET+CTI and 20 (44%) in the control group. The observed-over-expected visit ratio was significantly higher in the intervention than in the control group (0.74±0.30 versus 0.54±0.38; P=0.003). A total of 99 adverse events were reported by 59 participants, none of which were serious and related to the intervention. Greater gains in physical, cognitive, and mood outcomes were found in the CARET+CTI group than in the control group, but were not statistically significant after adjustments. Conclusions A CARET+CTI intervention, after stroke, is safe, feasible, and has satisfactory participant adherence over 12 weeks. REGISTRATION URL: https://www.clini​caltr​ials.gov. Unique identifier: NCT02272426.

Light aerobic exercise modulates executive function and cortical excitability

Single bouts of aerobic exercise can modulate cortical excitability and executive cognitive function, but less is known about the effect of light-intensity exercise, an intensity of exercise more achievable for certain clinical populations. Fourteen healthy adults (aged 22 to 30) completed the following study procedures twice (≥7 days apart) before and after 30 min of either light aerobic exercise (cycling) or seated rest: neurocognitive battery (multitasking performance, inhibitory control and spatial working memory), paired-pulse TMS measures of cortical excitability. Significant improvements in response times during multitasking performance and increases in intracortical facilitation (ICF) were seen following light aerobic exercise. Light aerobic exercise can modulate cortical excitability and some executive function tasks. Populations with deficits in multitasking ability may benefit from this intervention.

Exercise for Brain Health: An Investigation into the Underlying Mechanisms Guided by Dose

There is a strong link between the practice of regular physical exercise and maintenance of cognitive brain health. Animal and human studies have shown that exercise exerts positive effects on cognition through a variety of mechanisms, such as changes in brain volume and connectivity, cerebral perfusion, synaptic plasticity, neurogenesis, and regulation of trophic factors. However, much of this data has been conducted in young humans and animals, raising questions regarding the generalizability of these findings to aging adults. Furthermore, it is not clear at which doses these effects might take place, and if effects would differ with varying exercise modes (such as aerobic, resistance training, combinations, or other). The purpose of this review is to summarize the evidence on the effects of exercise interventions on various mechanisms believed to support cognitive improvements: cerebral perfusion, synaptic neuroplasticity, brain volume and connectivity, neurogenesis, and regulation of trophic factors. We synthesized the findings according to exposure to exercise (short- [1 day-16 weeks], medium- [24-40 weeks], and long-term exercise [52 weeks and beyond]) and have limited our discussion of dose effects to studies in aging adults and aged animals (when human data was not available).

Reduced motor cortex inhibition and a 'cognitive-first' prioritisation strategy for older adults during dual-tasking

It is well established that older adults are less able to perform attentionally demanding motor tasks, placing them at greater risk of accident-related injury. The primary purpose of this study was to investigate whether the interplay between prefrontal and motor cortex activity could predict such age-related performance deficits. Using a dual-task (DT) paradigm, 15 younger and 15 older adults participated in experiment 1, where brain activity was simultaneously measured using functional near infrared spectroscopy (fNIRS) and transcranial magnetic stimulation (TMS). Experiment 1 demonstrated poorer performance for the older group across a range of DTs combining visuomotor arm tracking with a secondary cognitive or motor task. Interestingly however, older adults' DT performance error was isolated to the motor component of DTs. TMS data revealed reduced motor cortex (M1) inhibition during DTs for older adults, and a trend for this correlating with poorer performance. In contrast, poorer performing younger adults showed significantly higher M1 inhibition. Experiment 2 was conducted given a high amount of movement artifact in experiment 1 fNIRS data. Using fNIRS to measure prefrontal, premotor, and motor cortex activity in an additional 15 older adults, we found no evidence of an interplay between these regions predicting DT performance. Nevertheless, performance data replicated experiment 1 in showing that DT error was isolated to motor tasks in older adults, with no significant cognitive task error. Overall, this study shows that older adults seemed to adopt a 'cognitive-first' prioritisation strategy during the DTs involved in our study, and that deficits in DT performance may be related to the modulation of M1 inhibitory mechanisms. We propose that clinicians advise older adults to allocate greater attention to motor tasks during activities where they may be at risk of accident-related injury.

Are functional mobility tests responsive to group physical therapy intervention in individuals with Parkinson's disease?

BACKGROUND

The Timed up and go test (TUG), the Five times sit-to-stand test (FTSTS) and the Bed Mobility test (BMT) are widely used in clinical practice for Parkinson Disease (PD). However, no reported studies have evaluated the responsiveness to group physical therapy intervention (GPTI).

OBJECTIVE

To verify if TUG, FTSTS and BMT were responsive to GPTI.

METHODS

Thirty individuals with PD were assessed prior to and after an 8-week evidence-based GPTI. Paired t test was used to determine statistically significant change pre-and post-intervention. Internal responsiveness (IR) was classified with the standardized response mean (SRM). A 5-point Likert scale assessed self-perceived performance by the subjects after the intervention. Analysis of the receiver operating characteristic (ROC) curve was used to determine the accuracy and cut-off scores for identifying participants who had shown improvement.

RESULTS

GPTI was efficient in improving real (p≤0.001) and self-perceived mobility performance in all measures. All tests were responsive to changes: the IR varied from medium to high (SRM = 0.7-1.5); the cut-off point for TUG test was >2.2 s, for FTSTS test was >2.5 s and for BM test >1.4 s.

CONCLUSIONS

The TUG, FTSTS and BMT were responsive to the GPTI and accurately detected meaningful clinical changes. Our results provide an important information about the clinical application of these tests in PD individuals.

Feasibility of Aerobic Exercise in the Subacute Phase of Recovery From Traumatic Brain Injury: A Case Series

BACKGROUND AND PURPOSE

Aerobic exercise is as important for individuals with traumatic brain injury (TBI) as for the general population; however, the approach to aerobic training may require some adaptation. The objective of the trial program was to examine the feasibility of introducing aerobic physical exercise programs into the subacute phase of multidisciplinary rehabilitation from moderate to severe TBI, which includes computerized cognitive training.

CASE DESCRIPTION

Five individuals undergoing inpatient rehabilitation with moderate or severe TBIs who also have concomitant physical injuries. All of these individuals were in the subacute phase of recovery from TBIs.

INTERVENTION

An 8-week progressive aerobic physical exercise program. Participants were monitored to ensure that they could both adhere to and tolerate the exercise program. In addition to the physical exercise, individuals were undergoing their standard rehabilitation procedures that included cognitive training. Neuropsychological testing was performed to gain an understanding of each individual's cognitive function.

OUTCOMES

Participants adhered to both aerobic exercise and cognitive training. Poor correlations were noted between heart rate reserve and ratings of perceived effort. Two minor adverse events were reported.

DISCUSSION

Despite concomitant physical injuries and cognitive impairments, progressive aerobic exercise programs seem feasible and well tolerated in subacute rehabilitation from moderate to severe TBI. Findings highlight the difficulty in measuring exercise intensity in this population.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A235).

Non-invasive Brain Stimulation: Probing Intracortical Circuits and Improving Cognition in the Aging Brain

The impact of cognitive aging on brain function and structure is complex, and the relationship between aging-related structural changes and cognitive function are not fully understood. Physiological and pathological changes to the aging brain are highly variable, making it difficult to estimate a cognitive trajectory with which to monitor the conversion to cognitive decline. Beyond the information on the structural and functional consequences of cognitive aging gained from brain imaging and neuropsychological studies, non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) can enable stimulation of the human brain in vivo, offering useful insights into the functional integrity of intracortical circuits using electrophysiology and neuromodulation. TMS measurements can be used to identify and monitor changes in cortical reactivity, the integrity of inhibitory and excitatory intracortical circuits, the mechanisms of long-term potentiation (LTP)/depression-like plasticity and central cholinergic function. Repetitive TMS and tDCS can be used to modulate neuronal excitability and enhance cortical function, and thus offer a potential means to slow or reverse cognitive decline. This review will summarize and critically appraise relevant literature regarding the use of TMS and tDCS to probe cortical areas affected by the aging brain, and as potential therapeutic tools to improve cognitive function in the aging population. Challenges arising from intra-individual differences, limited reproducibility, and methodological differences will be discussed.

Exercise for cognitive brain health in aging: A systematic review for an evaluation of dose

PURPOSE OF REVIEW

We systematically appraised randomized controlled trials proposing exercise to influence cognition in older adults to (1) assess the methodologic quality using Cochrane criteria; (2) describe various exercise dose measures and assess their relationship with improved cognitive performance; and (3) identify consistent patterns of reported effects on cognition.

RECENT FINDINGS

There was overall good methodologic quality in all 98 included studies. The assessment of the relationship between improved cognition and various measures of exercise dose (session duration, weekly minutes, frequency, total weeks, and total hours) revealed a significant correlation with total hours. Improvements in global cognition, processing speed/attention, and executive function were most stable and consistent.

SUMMARY

We found that exercising for at least 52 hours is associated with improved cognitive performance in older adults with and without cognitive impairment. Exercise modes supported by evidence are aerobic, resistance (strength) training, mind-body exercises, or combinations of these interventions.

Priming for Improved Hand Strength in Persons with Chronic Tetraplegia: A Comparison of Priming-Augmented Functional Task Practice, Priming Alone, and Conventional Exercise Training

Many everyday tasks cannot be accomplished without adequate grip strength, and corticomotor drive to the spinal motoneurons is a key determinant of grip strength. In persons with tetraplegia, damage to spinal pathways limits transmission of signals from motor cortex to spinal motoneurons. Corticomotor priming, which increases descending drive, should increase corticospinal transmission through the remaining spinal pathways resulting in increased grip strength. Since the motor and somatosensory cortices share reciprocal connections, corticomotor priming may also have potential to influence somatosensory function. The purpose of this study was to assess changes in grip (precision, power) force and tactile sensation associated with two different corticomotor priming approaches and a conventional training approach and to determine whether baseline values can predict responsiveness to training. Participants with chronic (≥1 year) tetraplegia (n = 49) were randomized to one of two corticomotor priming approaches: functional task practice plus peripheral nerve somatosensory stimulation (FTP + PNSS) or PNSS alone, or to conventional exercise training (CET). To assess whether baseline corticospinal excitability (CSE) is predictive of responsiveness to training, in a subset of participants, we assessed pre-intervention CSE of the thenar muscles. Participants were trained 2 h daily, 5 days/week for 4 weeks. Thirty-seven participants completed the study. Following intervention, significant improvements in precision grip force were observed in both the stronger and weaker hand in the FTP + PNSS group (effect size: 0.51, p = 0.04 and 0.54, p = 0.03, respectively), and significant improvements in weak hand precision grip force were associated with both PNSS and CET (effect size: 0.54, p = 0.03 and 0.75, p = 0.02, respectively). No significant changes were observed in power grip force or somatosensory scores in any group. Across all groups, responsiveness to training as measured by change in weak hand power grip force was correlated with baseline force. Change in precision grip strength was correlated with measures of baseline CSE. These findings indicate that corticomotor priming with FTP + PNSS had the greatest influence on precision grip strength in both the stronger and weaker hand; however, both PNSS and CET were associated with improved precision grip strength in the weaker hand. Responsiveness to training may be associated with baseline CSE.

The effects of exercise on cognitive function and brain plasticity - a feasibility trial

BACKGROUND

Exercise-mediated cognitive improvements can be at least partly attributed to neuroplastic changes in the nervous system, and may be influenced by the Val66Met polymorphism of the brain-derived neurotrophic factor (BDNF) gene. Transcranial magnetic stimulation (TMS) can be used to assess mechanisms of plasticity in humans noninvasively.

OBJECTIVES

To assess the feasibility of evaluating the effects of short-term regular exercise on cognitive performance, and to evaluate the relationship between these effects, TMS measures of plasticity, and BDNF Met carrier status in young healthy sedentary adults.

METHODS

Of the 19 participants who enrolled in the study, 14 sedentary adults (12 females, age mean±SD, 27±12.3 yr), with less than two sessions of physical exercise in the preceding 2 months, completed an aerobic exercise regimen including four 30-min daily sessions per week for 4 weeks (for a total of 16 sessions) delivered at 55-64% of age-predicted maximal heart rate. Prior to and following the exercise regimen, participants performed a neuropsychological test battery and an intermittent theta-burst TMS plasticity protocol.

RESULTS

All participants completed the various measures and adhered to the exercise regimen. There were no complications and the results obtained were reliable. The feasibility of the approach is thus well established. Between-group comparisons of pre-post change revealed trends toward increased performance on the Stroop and faster reaction times in the CPT detectability in the Val66Val subgroup (p = 0.07 and p = 0.08), and a reduction in TBS-induced modulation of TMS responses in Met carriers (p = 0.07).

CONCLUSION

Acute exercise interventions in sedentary adults can be meaningfully conducted along with cognitive and neurophysiologic measures to assess behavioral and neurobiological effects and assessment of BDNF polymorphism. TMS measures of plasticity can be used to evaluate the effects of exercise on brain plasticity, and relate them to neuropsychological measures of cognition.

Optimal number of pulses as outcome measures of neuronavigated transcranial magnetic stimulation

OBJECTIVE

Identify the optimal number of pulses necessary to achieve reliable measures of motor evoked potentials (MEPs) in transcranial magnetic stimulation (TMS) studies.

METHODS

Retrospective data was obtained from 54 healthy volunteers (30 men, mean age 61.7±13.1years) who as part of prior studies had completed three blocks of 30 consecutive TMS stimuli using neuronavigation. Data from four protocols were assessed: single-pulse TMS for measures of amplitude and latency of MEPs; paired-pulse TMS for short-interval intracortical inhibition (sICI) and intracortical facilitation (ICF); and single-pulse TMS to assess the effects of intermittent theta burst stimulation (iTBS). Two statistical methods were used: an internal consistency analysis and probability of inclusion in the 95% confidence interval (CI) around the mean MEPs amplitude.

RESULTS

For single-pulse TMS, the minimum number of pulses needed to achieve reliable amplitude and latency MEPs measures was 21 and 23, respectively. For paired-pulse TMS, the minimum number of pulses needed to achieve reliable sICI and ICF measures was 20 and 25, respectively. Finally, the minimum number of pulses needed to achieve reliable amplitude and latency MEPs measures after iTBS was 22 and 23, respectively.

CONCLUSIONS

This study provides guidelines regarding the minimum number of pulses needed to achieve reliable MEPs measurements in various study protocols using neuronavigated TMS.

SIGNIFICANCE

Results from this study have the potential to increase the reliability and quality of future neuronavigated TMS studies.

A Systematic Review of Experimental Strategies Aimed at Improving Motor Function after Acute and Chronic Spinal Cord Injury

While various approaches have been proposed in clinical trials aimed at improving motor function after spinal cord injury in humans, there is still limited information regarding the scope, methodological quality, and evidence associated with single-intervention and multi-intervention approaches. A systematic review performed using the PubMed search engine and the key words "spinal cord injury motor recovery" identified 1973 records, of which 39 were selected (18 from the search records and 21 from reference list inspection). Study phase ( clinicaltrials.org criteria) and methodological quality (Cochrane criteria) were assessed. Studies included proposed a broad range of single-intervention (encompassing cell therapies, pharmacology, electrical stimulation, rehabilitation) (encompassing cell therapies, pharmacology, electrical stimulation, rehabilitation) and multi-intervention approaches (that combined more than one strategy). The highest evidence level was for Phase III studies supporting the role of multi-intervention approaches that contained a rehabilitation component. Quality appraisal revealed that the percentage of selected studies classified with high risk of bias by Cochrane criteria was as follows: random sequence generation = 64%; allocation concealment = 77%; blinding of participants and personnel = 69%; blinding of outcome assessment = 64%; attrition = 44%; selective reporting = 44%. The current literature contains a high proportion of studies with a limited ability to measure efficacy in a valid manner because of low methodological strength in all items of the Cochrane risk of bias assessment. Recommendations to decrease bias are discussed and include increased methodological rigor in the study design and recruitment of study participants, and the use of electrophysiological and imaging measures that can assess functional integrity of the spinal cord (and may be sufficiently sensitive to detect changes that occur in response to therapeutic interventions).

Improvements in hand function in adults with chronic tetraplegia following a multiday 10-Hz repetitive transcranial magnetic stimulation intervention combined with repetitive task practice

BACKGROUND AND PURPOSE

Evidence suggests that the use of stimulation to increase corticomotor excitability improves hand function in persons with cervical spinal cord injury. We assessed effects of a multiday application of 10-Hz repetitive transcranial magnetic stimulation (rTMS) applied to the corticomotor hand area combined with repetitive task practice (RTP) in participants with tetraplegia and neurologically healthy participants.

METHODS

Using a double-blind, randomized, crossover design, 11 participants with chronic tetraplegia and 10 neurologically healthy participants received 3 sessions of 10-Hz rTMS+RTP and 3 sessions of sham-rTMS+RTP to the corticomotor hand region controlling the weaker hand. Repetitive transcranial magnetic stimulation was interleaved with RTP of a skilled motor task between pulse trains. Hand function (Jebsen-Taylor Hand Function Test, pinch, and grasp strength) and corticomotor excitability (amplitude of motor-evoked potential) were assessed before and after the rTMS+RTP and sham-rTMS+RTP phases. We assessed significance, using paired t tests on pre-post differences, and effect sizes, using the standardized response mean.

RESULTS

RTMS+RTP was associated with larger effect sizes compared with sham-rTMS+RTP for improvement in Jebsen-Taylor Hand Function Test for both the trained hand (standardized response mean = 0.85 and 0.42, respectively) and non-trained hand (0.55 and 0.31, respectively), and for grasp strength of the trained hand in the group with cervical spinal cord injury (0.67 and 0.39, respectively) alone. Effect sizes for all other measures were small and there were no statistical between-condition differences in the outcomes assessed.

DISCUSSION AND CONCLUSIONS

Repetitive transcranial magnetic stimulation may be a valuable adjunct to RTP for improving hand function in persons with tetraplegia. Higher stimulation dose (frequency, intensity, and the number of sessions) may be associated with larger effects.

VIDEO ABSTRACT AVAILABLE

(see Supplemental Digital Content 1, http://links.lww.com/JNPT/A82) for more insights from the authors.

Cortical vs. afferent stimulation as an adjunct to functional task practice training: a randomized, comparative pilot study in people with cervical spinal cord injury

OBJECTIVE

To assess single-session effects of three different types of stimuli known to increase cortical excitability when combined with functional task practice.

DESIGN

Randomized cross-over trial.

PARTICIPANTS

A total of 24 participants with chronic cervical spinal cord injury.

INTERVENTIONS

One 30-minute session of each, applied concurrently with functional task practice: transcranial direct current stimulation, vibration, and transcutaneous electrical nerve stimulation.

MEASUREMENTS

Nine-hole Peg Test, pinch force, visuomotor tracking, and cortical excitability were collected at pretest, posttest and late posttest (30 minutes after). Early effects (posttest minus pretest) and short-term persistence (late posttest minus pretest) were assessed using a general linear mixed model. Magnitude of effect size was assessed using the Cohen's d.

RESULTS

Transcutaneous electrical nerve stimulation was associated with moderate, significant early effects and short-term persistence on Nine-hole Peg Test performance (1.8 ±1.8, p = 0.003, d = 0.59; 2.0 ±2.5, p < 0.001, Cohen's d = 0.65, respectively). Transcranial direct current stimulation (1.8 ±2.5, p = 0.003, Cohen's d = 0.52) was also associated with significant short-term persistence of moderate size on Nine-hole Peg Test performance (1.8 ±2.5, p = 0.003, Cohen's d = 0.52) and visuomotor tracking performance (p = 0.05, d = 0.51). Early effects on corticomotor excitability were significant for transcutaneous electrical nerve stimulation (p = 0.003), approached significance for transcranial direct current stimulation (p = 0.07), and only vibration was associated with significant short-term persistence (p = 0.006).

CONCLUSIONS

Meaningful improvements in aspects of hand-related function that persisted at least 30 minutes after intervention were observed with transcutaneous electrical nerve stimulation and transcranial direct current stimulation, when combined with functional task practice.