Michelle Ploughman

Brain-Derived Neurotrophic Factor Contributes to Recovery of Skilled Reaching After Focal Ischemia in Rats

Background and Purpose— Brain-derived neurotrophic factor (BDNF) is involved in neuronal survival, synaptic plasticity, learning and memory, and neuroplasticity. Further, exogenous treatment with BDNF or exposing animals to enrichment and exercise regimens, which also increase BDNF, enhances behavioral recovery after brain injury. Thus, the beneficial effects of rehabilitation in promoting recovery after stroke may also depend on BDNF. We tested this hypothesis by evaluating the contribution of BDNF to motor skill relearning after endothelin-1–induced middle cerebral artery occlusion in rats. Methods— Antisense BDNF oligonucleotide, which blocks the expression of BDNF (or saline vehicle) was infused into the contralateral lateral ventricle for 28 days after ischemia. Animals received either a graduated rehabilitation program, including running exercise and skilled reaching training, which simulates clinical practice, or no rehabilitation. Functional recovery was assessed with a battery of tests that measured skilled reaching, forelimb use asymmetry, and foraging ability. Results— Rehabilitation significantly improved skilled reaching ability in the staircase task. Antisense BDNF oligonucleotide effectively blocked BDNF mRNA, and negated the beneficial effects of rehabilitation on recovery of skilled reaching. Importantly, antisense BDNF oligonucleotide did not affect reaching with the unaffected limb, body weight, infarct size, or foraging ability, indicating the treatment was specific to relearning of motor skill after ischemia. Conclusions— This study is the first to identify a critical role for BDNF in rehabilitation-induced recovery after stroke, and our results suggest that new treatments to enhance BDNF would constitute a promising therapy for promoting recovery of function after stroke.

Exercise is brain food: The effects of physical activity on cognitive function

This commentary reviews selected biomedical and clinical research examining the relationship between physical exercise and cognitive function especially in youth with disability. Youth with physical disability may not benefit from the effects of exercise on cardiovascular fitness and brain health since they are less active than their non-disabled peers. In animal models, physical activity enhances memory and learning, promotes neurogenesis and protects the nervous system from injury and neurodegenerative disease. Neurotrophins, endogenous proteins that support brain plasticity likely mediate the beneficial effects of exercise on the brain. In clinical studies, exercise increases brain volume in areas implicated in executive processing, improves cognition in children with cerebral palsy and enhances phonemic skill in school children with reading difficulty. Studies examining the intensity of exercise required to optimize neurotrophins suggest that moderation is important. Sustained increases in neurotrophin levels occur with prolonged low intensity exercise, while higher intensity exercise, in a rat model of brain injury, elevates the stress hormone, corticosterone. Clearly, moderate physical activity is important for youth whose brains are highly plastic and perhaps even more critical for young people with physical disability.

Endurance exercise regimens induce differential effects on brain-derived neurotrophic factor, synapsin-I and insulin-like growth factor I after focal ischemia

The optimal amount of endurance exercise required to elevate proteins involved in neuroplasticity during stroke rehabilitation is not known. This study compared the effects of varying intensities and durations of endurance exercise using both motorized and voluntary running wheels after endothelin-I-induced focal ischemia in rats. Hippocampal levels of brain-derived neurotrophic factor, insulin-like growth factor I and synapsin-I were elevated in the ischemic hemisphere even in sedentary animals suggesting an intrinsic restorative response 2 weeks after ischemia. In the sensorimotor cortex and the hippocampus of the intact hemisphere, one episode of moderate walking exercise, but not more intense running, resulted in the greatest increases in levels of brain-derived neurotrophic factor and synapsin-I. Exercise did not increase brain-derived neurotrophic factor, insulin-like growth factor I or synapsin-I in the ischemic hemisphere. In voluntary running animals, both brain and serum insulin-like growth factor I appeared to be intensity dependent and were associated with decreasing serum levels of insulin-like growth factor I and increasing hippocampal levels of insulin-like growth factor I in the ischemic hemisphere. This supports the notion that exercise facilitates the movement of insulin-like growth factor I across the blood-brain barrier. Serum corticosterone levels were elevated by all exercise regimens and were highest in rats exposed to motorized running of greater speed or duration. The elevation of corticosterone did not seem to alter the expression of the proteins measured, however, graduated exercise protocols may be indicated early after stroke. These findings suggest that relatively modest exercise intervention can increase proteins involved in synaptic plasticity in areas of the brain that likely subserve motor relearning after stroke.

Exercise intensity influences the temporal profile of growth factors involved in neuronal plasticity following focal ischemia.

Exercise increases brain-derived neurotrophic factor (BDNF), phosphorylated cAMP response-element binding protein (pCREB), insulin-like growth factor (IGF-I) and synapsin-I, each of which has been implicated in neuroplastic processes underlying recovery from ischemia. In this study we examined the temporal profile (0, 30, 60 and 120 min following exercise) of these proteins in the hippocampus and sensorimotor cortex following both motorized (60 min) and voluntary (12 h) running, 2 weeks after focal ischemia. Our goal was to identify the optimal training paradigms (intensity, duration and frequency) needed to integrate endurance exercise in stroke rehabilitation. Therefore we utilized telemetry to measure changes in heart rate with both exercise methods. Our findings show that although the more intense, motorized running exercise induced a rapid increase in BDNF, the elevation was more short-lived than with voluntary running. Motorized running was also associated with higher levels of synapsin-I in several brain regions but simultaneously, a more pronounced increase in the stress hormone, corticosterone. Furthermore, both forms of exercise resulted in decreased phosphorylation of CREB and downregulation of synapsin-I in hippocampus beginning 30 to 60 min after the exercise bout. This phenomenon was more robust after motorized running, the method that generated higher heart rate and serum corticosterone levels. This immediate stress response is likely specific to acute exercise and may diminish with repeated exercise exposure. The present data illustrate a complex interaction between different forms of exercise and proteins implicated in neuroplasticity. For clinical application, frequent lower intensity exercise episodes (as in voluntary running wheels), which may be safer to provide to patients with stroke, has a delayed but sustained effect on BDNF that may support brain remodeling after stroke.

Enriched environment enhances transplanted subventricular zone stem cell migration and functional recovery after stroke.

Stroke patients suffer from severe impairments and significant effort is under way to develop therapies to improve functional recovery. Stem cells provide a promising form of therapy to replace neuronal circuits lost to injury. Indeed, previous studies have shown that a variety of stem cell types can provide some functional recovery in animal models of stroke. However, it is unlikely that replacement therapy alone will be sufficient to maximize recovery. The aim of the present study was to determine if rodent stem cell transplants combined with rehabilitation resulted in enhanced functional recovery after focal ischemia in rats. Middle cerebral artery occlusion was induced by injection of the vasoconstrictive peptide endothelin-1 adjacent to the middle cerebral artery. Seven days after stroke the rats received adult neural stem cell transplants isolated from mouse subventricular zone or vehicle injection and then subsequently were housed in enriched or standard conditions. The rats in the enriched housing also had access to running wheels once a week. Enriched housing and voluntary running exercise enhanced migration of transplanted stem cells toward the region of injury after stroke and there was a trend toward increased survival of stem cells. Enrichment also increased the number of endogenous progenitor cells in the subventricular zone of transplanted animals. Finally, functional recovery measured in the cylinder test was facilitated only when the stem cell transplants were combined with enrichment and running exercise 7 days after the transplant. These results suggest that the ability of transplanted stem cells in promoting recovery can be augmented by environmental factors such as rehabilitation.

Endurance exercise facilitates relearning of forelimb motor skill after focal ischemia.

Endurance exercise (i.e. running), by up‐regulating brain‐derived neurotrophic factor (BDNF) and other modulators of synaptic plasticity, improves attention and learning, both critical components of stroke rehabilitation. We hypothesized that, following middle cerebral artery occlusion in male Sprague‐Dawley rats, endurance exercise would act synergistically with a challenging skilled forelimb task to facilitate motor recovery. Animals were randomly assigned to one of four rehabilitation conditions: no rehabilitation, running only, reach training only, and reach training preceded by running (run/reach training) for 5 weeks beginning 5 days after stroke. The behavioral outcome, morphological change and mRNA expression of proteins implicated in neuroplasticity (BDNF, synapsin I and microtubule‐associated protein 2) were compared. Endurance exercise on a motorized running wheel, prior to reach training, enhanced recovery of skilled reaching ability but did not transfer to gross motor skills such as postural support (forelimb asymmetry test) and gait (ladder rung walking test). Microtubule‐associated protein 2 staining density in the run/reach group was slightly enhanced in the contralateral motor cortex compared with the contralateral sensory and ipsilateral cingulate cortices, suggesting that running preceding reach training may have resulted in more dendritic branching within the motor cortex in this group. No significant differences in mRNA levels were detected among the training paradigms; however, there was a trend toward greater BDNF and synapsin I mRNA in the reaching groups. These findings suggest that exercise facilitates learning of subsequent challenging reaching tasks after stroke, which has the potential to optimize outcomes in patients with stroke.

Does Treadmill Exercise Improve Performance of Cognitive or Upper-Extremity Tasks in People With Chronic Stroke? A Randomized Cross-Over Trial

OBJECTIVE To determine whether acute exercise, using a body-weight-supported treadmill, improves performance on subsequent cognitive tests or an upper-extremity task in people with stroke. DESIGN The study was a within-subject, cross-over design in which 21 subjects received, randomly, 2 different testing sequences separated by an interval of 7 to 10 days. SETTING Outpatient department of a rehabilitation hospital. PARTICIPANTS Of 72 potential participants in the convenience sample, 21 people with chronic stroke completed the study. They were 0.5 to 5 years after only 1 documented stroke, were able to walk with or without a cane, were able to grasp with the affected hand, and scored more than 24 on the Mini-Mental State Examination. INTERVENTIONS One session of body-weight-supported treadmill walking for 20 minutes at 70% of estimated heart rate reserve or level 13 on the Borg rating of perceived exertion scale. The control condition consisted of a 20-minute review of a home exercise program with a physiotherapist. MAIN OUTCOME MEASURES Cognitive tests included Trail Making Tests Parts A and B, Symbol Digit Substitution Test, and Paced Auditory Serial Addition Test. The Action Research Arm Test (ARAT) measured hemiplegic upper-extremity motor skill. RESULTS Treadmill exercise improved movement of the hemiplegic upper extremity (P=.04) but not cognitive performance. The improvement in the ARAT occurred without a change in strength (measured by grip strength) and was negatively correlated with maximum treadmill speed (R(2)=.20; P=.04). CONCLUSIONS These findings suggest that acute treadmill exercise improves subsequent skilled movement of the hemiplegic upper extremity that seems unrelated to attention, visuomotor processing, or strength. The etiology and duration of this enhancing effect are worth further study. The existence of an exercise-cognition relationship in people with stroke is an intriguing area of future research.

Efficacy and safety of non-immersive virtual reality exercising in stroke rehabilitation (EVREST): a randomised, multicentre, single-blind, controlled trial

BACKGROUND Non-immersive virtual reality is an emerging strategy to enhance motor performance for stroke rehabilitation. There has been rapid adoption of non-immersive virtual reality as a rehabilitation strategy despite the limited evidence about its safety and effectiveness. Our aim was to compare the safety and efficacy of virtual reality with recreational therapy on motor recovery in patients after an acute ischaemic stroke. METHODS In this randomised, controlled, single-blind, parallel-group trial we enrolled adults (aged 18-85 years) who had a first-ever ischaemic stroke and a motor deficit of the upper extremity score of 3 or more (measured with the Chedoke-McMaster scale) within 3 months of randomisation from 14 in-patient stroke rehabilitation units from four countries (Canada [11], Argentina [1], Peru [1], and Thailand [1]). Participants were randomly allocated (1:1) by a computer-generated assignment at enrolment to receive a programme of structured, task-oriented, upper extremity sessions (ten sessions, 60 min each) of either non-immersive virtual reality using the Nintendo Wii gaming system (VRWii) or simple recreational activities (playing cards, bingo, Jenga, or ball game) as add-on therapies to conventional rehabilitation over a 2 week period. All investigators assessing outcomes were masked to treatment assignment. The primary outcome was upper extremity motor performance measured by total time to complete the Wolf Motor Function Test (WMFT) at the end of the 2 week intervention period, analysed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NTC01406912. FINDINGS The study was done between May 12, 2012, and Oct 1, 2015. We randomly assigned 141 patients: 71 received VRWii therapy and 70 received recreational activity. 121 (86%) patients (59 in the VRWii group and 62 in the recreational activity group) completed the final assessment and were included in the primary analysis. Each group improved WMFT performance time relative to baseline (decrease in median time from 43·7 s [IQR 26·1-68·0] to 29·7 s [21·4-45·2], 32·0% reduction for VRWii vs 38·0 s [IQR 28·0-64·1] to 27·1 s [21·2-45·5], 28·7% reduction for recreational activity). Mean time of conventional rehabilitation during the trial was similar between groups (VRWii, 373 min [SD 322] vs recreational activity, 397 min [345]; p=0·70) as was the total duration of study intervention (VRWii, 528 min [SD 155] vs recreational activity, 541 min [142]; p=0·60). Multivariable analysis adjusted for baseline WMFT score, age, sex, baseline Chedoke-McMaster, and stroke severity revealed no significant difference between groups in the primary outcome (adjusted mean estimate of difference in WMFT: 4·1 s, 95% CI -14·4 to 22·6). There were three serious adverse events during the trial, all deemed to be unrelated to the interventions (seizure after discharge and intracerebral haemorrhage in the recreational activity group and heart attack in the VRWii group). Overall incidences of adverse events and serious adverse events were similar between treatment groups. INTERPRETATION In patients who had a stroke within the 3 months before enrolment and had mild-to-moderate upper extremity motor impairment, non-immersive virtual reality as an add-on therapy to conventional rehabilitation was not superior to a recreational activity intervention in improving motor function, as measured by WMFT. Our study suggests that the type of task used in motor rehabilitation post-stroke might be less relevant, as long as it is intensive enough and task-specific. Simple, low-cost, and widely available recreational activities might be as effective as innovative non-immersive virtual reality technologies. FUNDING Heart and Stroke Foundation of Canada and Ontario Ministry of Health.

The Effects of Poststroke Aerobic Exercise on Neuroplasticity: A Systematic Review of Animal and Clinical Studies

Aerobic exercise may be a catalyst to promote neuroplasticity and recovery following stroke; however, the optimal methods to measure neuroplasticity and the effects of training parameters have not been fully elucidated. We conducted a systematic review and synthesis of clinical trials and studies in animal models to determine (1) the extent to which aerobic exercise influences poststroke markers of neuroplasticity, (2) the optimal parameters of exercise required to induce beneficial effects, and (3) consistent outcomes in animal models that could help inform the design of future trials. Synthesized findings show that forced exercise at moderate to high intensity increases brain-derived neurotrophic factor (BDNF), insulin-like growth factor-I (IGF-I), nerve growth factor (NGF), and synaptogenesis in multiple brain regions. Dendritic branching was most responsive to moderate rather than intense training. Disparity between clinical stroke and stroke models (timing of initiation of exercise, age, gender) and clinically viable methods to measure neuroplasticity are some of the areas that should be addressed in future research.

Factors influencing healthy aging with multiple sclerosis: A qualitative study

Purpose: The purpose of this study was to describe the factors influencing healthy aging from the perspective of the older person with multiple sclerosis (MS) in order to build curricula for MS self-management programs. Method: We sourced participants, older than 55 years with MS for more than 20 years, from a database of MS clinic and outpatient rehabilitation visits. Recruitment continued until data saturation was reached (n = 18). Semi-structured interviews explored perspectives on aging and health and lifestyle habits. Demographic, lifestyle and perceived health status information was also gathered. We analyzed the transcribed text for themes and theme relationships. Results: Work and social engagement, effective and accessible health care, healthy lifestyle habits, and maintaining independence at home were found to be critical proximal factors for healthy aging. The presence of financial flexibility, social support, cognitive and mental health, and resilience provided a supporting foundation to these critical proximal factors. These factors comprised a two-tiered model of healthy aging with MS. Conclusions: This two-tiered conceptual model of health aging, based on the perspectives of older persons with MS, provides a potential framework for the development of MS self-management program curricula aimed at optimizing quality of life. Further empirical testing may validate its utility in predicting healthy aging with MS. Implications for Rehabilitation The views of older people with Multiple Sclerosis (MS), as experts in managing the long term challenges of living with MS, should be considered in the design of self-management programs. Health care, social engagement, lifestyle and independence make critical contributions to health-related quality of life among older people with MS. This contribution depends on less-commonly addressed factors: financial flexibility, mental and cognitive health, resilience and social support. Strategies that target factors are important components of a comprehensive approach to rehabilitation and self-management of MS.