Randomized Clinical Stroke Rehabilitation Trials in 2005

No changes in corticospinal excitability, biochemical markers, and working memory after six weeks of high-intensity interval training in sedentary males

A single bout of aerobic exercise modulates corticospinal excitability, intracortical circuits, and serum biochemical markers such as brain‐derived neurotrophic factor (BDNF) and insulin‐like growth factor 1 (IGF‐1). These effects have important implications for the use of exercise in neurorehabilitation. Here, we aimed to determine whether increases in cardiorespiratory fitness (CRF) induced by 18 sessions of high‐intensity interval training (HIIT) over 6 weeks were accompanied by changes in corticospinal excitability, intracortical excitatory and inhibitory circuits, serum biochemical markers and working memory (WM) capacity in sedentary, healthy, young males. We assessed motor evoked potential (MEP) recruitment curves for the first dorsal interosseous (FDI) both at rest and during tonic contraction, intracortical facilitation (ICF), and short‐interval intracortical inhibition (SICI) using transcranial magnetic stimulation (TMS). We also examined serum levels of BDNF, IGF‐1, total and precursor (pro) cathepsin B (CTSB), as well as WM capacity. Compared to pretraining, CRF was increased and ICF reduced after the HIIT intervention, but there were no changes in corticospinal excitability, SICI, BDNF, IGF‐1, total and pro‐CTSB, and WM capacity. Further, greater CRF gains were associated with larger decreases in total and pro‐CTSB and, only in Val/Val carriers, with larger increases in SICI. Our findings confirm that HIIT is efficacious in promoting CRF and show that corticospinal excitability, biochemical markers, and WM are unchanged after 18 HIIT bouts in sedentary males. Understanding how aerobic exercise modulates M1 excitability is important in order to be able to use exercise protocols as an intervention, especially in rehabilitation following brain injuries.

Physical Activity in Older Adults With Mild Parkinsonian Signs: A Cohort Study

Background

Physical activity regimens are beneficial for older adults with Parkinson's disease; however, their beneficial effect on individuals with mild parkinsonian signs (MPS) who do not meet criteria for Parkinson's disease is not established. The current observational study aims to determine the cognitive and motor impact of physical activity in older adults with MPS over a 1-year period.

Methods

Three hundred and forty-one individuals underwent medical and neurologic assessment of MPS at baseline. MPS was diagnosed using the motor portion of the Unified Parkinson Disease Rating Scale. Physical activity frequency (days/month) were recorded at baseline and 1-year follow-up along with Repeatable Battery for Assessment of Neuropsychological Status (RBANS) score and gait velocity during normal walking (NW) and walking while talking (WWT) conditions. Associations over the 1-year period were assessed using linear regressions controlling for key covariates.

Results

One hundred and thirty (38.1%) participants met criteria for MPS. These participants demonstrated significant associations between physical activity and gait velocity at baseline (NW: p < .01; WWT: p = .03) and follow-up (NW: p < .01; WWT: p = .02). Physical activity was also associated with RBANS total score (p < .01) at follow-up. Increases in physical activity frequency over 1 year were associated with increases in NW velocity (p = .02), WWT velocity (p < .01), and RBANS total score (p < .01).

Conclusions

Among older adults with MPS, increased frequency of physical activity is associated with decreased risk of cognitive and motor decline. Our results highlight the importance of participation in physical activities on maintaining motor and cognitive functioning in older adults with MPS.

NASCIDOS PARA CORRER: A IMPORTÂNCIA DO EXERCÍCIO PARA A SAÚDE DO CÉREBRO

RESUMO A hipótese evolutiva da corrida de resistência afirma que o movimento teve um papel crucial no aparecimento de características anatômicas tipicamente humanas, assim como na modelação da estrutura e forma do cérebro humano. A íntima ligação entre exercício e evolução humana é evidenciada pelo fato de a inatividade nos tornar doentes. Efetivamente, o corpo humano, incluindo o cérebro, evoluiu para suportar períodos prolongados de estresse cardiovascular. O movimento é de tal modo essencial para o cérebro, que a atividade física regular é imprescindível para que funcione de modo adequado. Estudos vêm demonstrando que o exercício aeróbico aumenta a proliferação de neurônios, a síntese de fatores neurotróficos, gliogênese, sinaptogênese, regula sistemas de neurotransmissão e neuromodulação, além de reduzir a inflamação sistêmica. Todos esses efeitos têm impacto significativo no sentido de melhorar a saúde mental, reduzir o declínio de massa cinzenta associado à idade e melhorar as funções cognitivas. Deste modo, o objetivo deste artigo é apresentar uma atualização sobre a temática de exercício físico e saúde mental. Dados os recentes avanços apresentados neste original, sobre a neurobiologia do exercício e seu potencial terapêutico e econômico para a população em geral, espera-se que pesquisas futuras que correlacionem estudos básicos a variáveis psicológicas e estudos de imagem possam elucidar os mecanismos pelos quais o exercício melhora a saúde cerebral.

Effect of electroacupuncture on rat ischemic brain injury: importance of stimulation duration

We explored the optimal duration of electroacupuncture (EA) stimulation for protecting the brain against ischemic injury. The experiments were carried out in rats exposed to right middle cerebral artery occlusion (MCAO) for 60 min followed by 24-hr reperfusion. EA was delivered to “Shuigou” (Du 26) and “Baihui” (Du 20) acupoints with sparse-dense wave (5/20 Hz) at 1.0 mA for 5, 15, 30, and 45 min, respectively. The results showed that 30 min EA, starting at 5 minutes after the onset of MCAO (EA during MCAO) or 5 minutes after reperfusion (EA after MCAO), significantly reduced ischemic infarct volume, attenuated neurological deficits, and decreased death rate with a larger reduction of the ischemic infarction in the former group. Also in the group of EA during MCAO, this protective benefit was positively proportional to the increase in the period of stimulation, that is, increased protection in response to EA from 5- to 30-min stimulation. In all groups, EA induced a significant increase in cerebral blood flow and promoted blood flow recovery after reperfusion, and both blood flow volume and blood cell velocity returned to the preischemia level in a short period of time. Surprisingly, EA for 45 min did not show reduction in the neurological deficits or the infarct volume and instead demonstrated an increase in death rate in this group. Although EA for 45 min still increased the blood flow during MCAO, it led to a worsening of perfusion after reperfusion compared to the group subjected only to ischemia. The neuroprotection induced by an “optimal” period (30 min) of EA was completely blocked by Naltrindole, a δ-opioid receptor (DOR) antagonist (10 mg/kg, i.v.). These findings suggest that earlier EA stimulation leads to better outcomes, and that EA-induced neuroprotection against ischemia depends on an optimal EA-duration via multiple pathways including DOR signaling, while “over-length” stimulation exacerbates the ischemic injury.

Electroacupuncture and Brain Protection against Cerebral Ischemia: Specific Effects of Acupoints

Electroacupuncture (EA) has been shown to increase cerebral blood flow (CBF) and reduce ischemic infarction in the rat model of cerebral ischemia (middle cerebral artery occlusion, MCAO). Since multiple acupoints are recommended to treat cerebral ischemia, we performed this study to investigate if there is any variation in EA protection against cerebral ischemia with the stimulation of certain "acupoints" in rats. One hour of right MCAO with an 85% reduction of blood flow induced an extensive infarction (32.9% ± 3.8% of the brain), serious neurological deficits (scale = 6.0 ± 0.5, on a scale of 0-7), and a 17% (10 out of 60) mortality. EA, with a sparse-dense wave (5 Hz/20 Hz) at 1.0 mA for 30 minutes, at Du 20 and Du 26 greatly reduced the infarction to 4.5% ± 1.5% (P < 0.01), significantly improved neurological deficit (scale = 1.0 ± 0.5, P < 0.01), and decreased the death rate to 7% (2 out of 30, P < 0.01). Similarly, EA at left LI 11 & PC 6 reduced the infarct volume to 8.6% ± 3.8% (P < 0.01), improved the neurological deficit (scale = 2.0 ± 1.0, P < 0.01), and decreased the death rate to 8% (2 out of 24, P < 0.01). In sharp contrast, EA at right LI 11 & PC 6 did not lead to any significant changes in the infarct volume (33.4% ± 6.3%), neurological deficit (scale = 6.5 ± 0.5), and the death rate (20%, 5 out of 24). EA at left GB 34 & SP 6, also had an inconspicuous effect on the ischemic injury. EA at Du 20 & Du 26 or at left LI 11 & PC 6 instantaneously induced a significant increase in cerebral blood flow. Neither EA at right LI 11 & PC 6 nor at GB 34 & SP 6 increased cerebral blood flow. These results revealed that the EA protection against cerebral ischemia is relatively acupoint specific.

Exercise builds brain health: key roles of growth factor cascades and inflammation

Human and other animal studies demonstrate that exercise targets many aspects of brain function and has broad effects on overall brain health. The benefits of exercise have been best defined for learning and memory, protection from neurodegeneration and alleviation of depression, particularly in elderly populations. Exercise increases synaptic plasticity by directly affecting synaptic structure and potentiating synaptic strength, and by strengthening the underlying systems that support plasticity including neurogenesis, metabolism and vascular function. Such exercise-induced structural and functional change has been documented in various brain regions but has been best-studied in the hippocampus - the focus of this review. A key mechanism mediating these broad benefits of exercise on the brain is induction of central and peripheral growth factors and growth factor cascades, which instruct downstream structural and functional change. In addition, exercise reduces peripheral risk factors such as diabetes, hypertension and cardiovascular disease, which converge to cause brain dysfunction and neurodegeneration. A common mechanism underlying the central and peripheral effects of exercise might be related to inflammation, which can impair growth factor signaling both systemically and in the brain. Thus, through regulation of growth factors and reduction of peripheral and central risk factors, exercise ensures successful brain function.