Brain-derived neurotrophic factor (BDNF) serum basal levels is not affected by power training in mobility-limited older adults - A randomized controlled trial

The impact of resistance training on brain-derived neurotrophic factor and depression among older adults aged 60 years or older: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

This systematic review and meta-analysis aimed to investigate the impact of resistance training on brain-derived neurotrophic factor (BDNF) and depression among older adults aged 60 years or older.

METHOD

Four electronic databases were systematically searched.

RESULTS

A total of 11 randomized controlled trials, with a pooled sample of 868 participants, met our inclusion criteria. Meta-analysis demonstrated that resistance training significantly improved circulating BDNF levels (mean difference; MD: 0.73 ng/ml; 95% CI [0.04, 1.42]; p = 0.04). Additionally, resistance training was associated with significant improvements in depression (standardized mean difference; SMD: -0.38; 95% CI [- 0.62, -0.14]; p = 0.002).

DISCUSSION

These findings suggest that resistance training may be an effective intervention for improving BDNF levels and reducing depression symptoms in older adults. Further research is needed to confirm these findings and to investigate the underlying mechanisms.

Association of exercise, brain-derived neurotrophic factor, and cognition among older women: A systematic review and meta-analysis

This systematic review and meta-analysis explored the effects of structured exercise regimens on brain-derived neurotrophic factor (BDNF) levels, a proxy for cognitive function, in older women. In this study, we collated evidence from the available clinical trials that reported BDNF levels and other outcomes following structured exercise regimens. Adhering to PRISMA Statement 2020 guidelines. PubMed/MEDLINE, Scopus, CINAHL Plus, and Cochrane were systematically searched using a combination of the following keywords: brain-derived neurotrophic factor, women, exercise, older, cognition, and/or cognitive. A random-effects model was applied; the statistical analysis was conducted in RevMan 5.4 (Cochrane). The risk of bias in the included trials was assessed using the Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) tool. Across 12 trials, 994 older women were included that were enrolled in different exercise regimens globally. Exercise regimens were categorized as aerobic, resistance/power training, aquatic, taekwondo, and multimodal and ranging from 30 to 60 min, 1-5 times per week across 5-24 weeks. Moderate improvement (Cohen's d: 0.44, 95% CI: 0.04-0.84, p = 0.03) was found in BDNF levels across all trials. There was a small yet insignificant improvement in mini-mental state examination (MMSE) scores (Cohen's d: 0.17, 95% CI: -0.79-1.13, p = 0.73). Aerobic exercise, aquatic exercise, and multimodal regimens showed significant association with improved BDNF levels but the sample size for individual exercise regimens was small A main limitation was the inclusion of 114 (10.3%) males in the data, introducing gender bias. This study provides novel insight into the association between various exercise regimens and BDNF levels among older women.

Effects of Resistance Exercise on Neuroprotective Factors in Middle and Late Life: A Systematic Review and Meta-Analysis

Neuroprotective factors are involved in brain functioning. Although physical exercise has been shown to have a positive influence on these factors, the effect of resistance exercise on them is not well known. This systematic review and meta-analysis aimed to 1) estimate the efficacy of resistance exercise on major neuroprotective factors, such as insulin-like growth factor-1 (IGF-1), brain-derived neurotrophic factor (BDNF), and vascular endothelial growth factor (VEGF), in middle and late life and 2) determine whether the effect is dose dependent. A systematic search was conducted in CINAHL, Cochrane CENTRAL, MEDLINE, Scopus, PEDro, SPORTDiscus, and Web of Science up to November 2022. Random effects models were used to estimate standardized mean differences (SMDs) and their respective 95% confidence intervals (CI) for the effect of resistance exercise on peripheral IGF-1, BDNF or VEGF levels in older adults. Thirty randomized clinical trials with 1247 subjects (53.25% women, 45-92 years) were included in the systematic review, and 27 were selected for the meta-analysis. A significant effect of resistance exercise on IGF-1 levels was observed (SMD: 0.48; 95% CI: 0.27, 0.69), being more effective when performing 3 sessions/week (SMD: 0.55; 95% CI: 0.31, 0.79) but not on BDNF (SMD: 0.33; 95% CI: -0.29, 0.94). The effect on VEGF could not be determined due to the scarcity of studies. Our data support the resistance training recommendation in middle and late life, at a frequency of at least 3 sessions/week, to mitigate the neurological and cognitive consequences associated with aging, mainly through IGF-1.

Effects of different physical activities on brain-derived neurotrophic factor: A systematic review and bayesian network meta-analysis

Background

Emerging evidence suggests that exercise is a simple and effective method for maintaining brain function.

Aims

This review evaluates the effects of five physical exercises, including aerobic training (AT), high-intensity interval training (HIIT), combined training (CT), resistance training (RT), and AT+RT, on the serum level of brain-derived neurotrophic factor (BDNF) in healthy and non-healthy populations.

Methods

We searched CNKI, PubMed, Embase, Scopus, Medline, Web of Science, and Cochrane Library databases to review randomized controlled studies on exercise interventions for BDNF. Quantitative merging analysis of the resulting data using Bayesian network meta-analysis.

Results

The screening and exclusion of the searched literature resulted in the inclusion of 39 randomized controlled trials containing 5 exercise interventions with a total of 2031 subjects. The AT, RT, AT+RT, HIIT, and CT groups (intervention groups) and the CG group (conventional control group) were assigned to 451, 236, 102, 84, 293, and 865 subjects, respectively. The Bayesian network meta-analysis ranked the effect of exercise on BDNF level improvement in healthy and non-healthy subjects as follows: RT > HIIT > CT > AT+RT > AT > CG. Better outcomes were observed in all five intervention groups than in the CG group, with RT having the most significant effect [MD = 3.11 (0.33, 5.76), p < 0.05].

Conclusions

RT at moderate intensity is recommended for children and older adults in the case of exercise tolerance and is effective in maintaining or modulating BDNF levels for promoting brain health.

Systematic Review Registration

https://inplasy.com, INPLASY202250164.

The Effect of Exergame Training on Physical Functioning of Healthy Older Adults: A Meta-Analysis

Exergames have attracted increasing attention from both the public and researchers. Although previous systematic reviews provided evidence that exergame training is beneficial for improving balance or mobility in older adults, multidimensional physical function measurements, including balance, upper body strength, lower body strength, aerobic endurance, and gait, might help us achieve more robust and reliable results. This meta-analysis aims to quantify the effects of exergame training on overall and specific physical function in healthy older adults. We systematically searched exergame training studies published between January 1985 and June 2021. Forty-eight studies were included in the present meta-analysis, with a total of 1099 participants included in the training group and 1098 participants in the control group. Random-effects meta-analyses found that older adults obtained a small benefit in overall physical function performance (g = 0.43, 95% confidence interval [CI] = 0.33 to 0.53), moderate benefits in balance (g = 0.59, 95% CI = 0.46 to 0.71), upper body strength (g = 0.65, 95% CI = 0.20 to 1.10), lower body strength (g = 0.51, 95% CI = 0.37 to 0.65), and aerobic endurance (g = 0.65, 95% CI = 0.44 to 0.86), a small benefit in gait (g = 0.33, 95% CI = 0.08 to 0.59), and negligible effects on upper body flexibility (g = 0.13, 95% CI = -0.06 to 0.32) and lower body flexibility (g = 0.10, 95% CI = -0.45 to 0.67) from exergame training. The mini-mental state examination score was positively associated with the overall training efficacy (β = 0.08, P = 0.01), while body mass index and the sample size in the training group were negatively associated with the overall training efficacy (β = -0.01, P < 0.01; β = -0.004, P < 0.01). The current meta-analytic findings revealed that exergame training produced general benefits for overall physical function and different effects on specific physical function domains in older adults.

Physical Activity Intensity and Suspected Dementia in Older Japanese Adults: A Dose-Response Analysis Based on an 8-Year Longitudinal Study

Background: Moderate- to vigorous-intensity physical activity (PA) may reduce the risk of dementia; however, few studies have examined the effects of PA intensity on dementia risk. Objective: To prospectively examine the dose-response relationship of PA intensity with the incidence of suspected dementia in community-dwelling older adults. Methods: We conducted a baseline mail survey with an 8-year follow-up of 3,722 older adults in Japan. We assessed PA levels using the International Physical Activity Questionnaire short form and calculated the amount of time per week spent performing moderate- and vigorous-intensity PA (VPA). Information regarding suspected dementia was obtained from the city database during the follow-up period. Cox proportional-hazard models with age as time scale, and delayed entry and restricted cubic spline regression as variables were used to estimate risk of developing suspected dementia, excluding cases occurring <  1 year after baseline evaluation. Results: The cumulative incidence of suspected dementia during the follow-up period was 12.7% . Compared with those who did not practice moderate-intensity PA (MPA), those who practiced≥300 min (hazard ratio, 0.73; 95% confidence interval 0.56–0.95) of MPA showed a lower risk of developing suspected dementia. Furthermore, when the dose-response relationship was examined, the hazard of developing suspected dementia decreased almost linearly with MPA. A significantly lower hazard was observed from 815 minutes/week. There was no significant association between VPA and suspected dementia. Conclusion: This study suggested that MPA is often practiced in older adults and this PA intensity has a sufficiently favorable effect on dementia prevention.

State of Knowledge on Molecular Adaptations to Exercise in Humans: Historical Perspectives and Future Directions

For centuries, regular exercise has been acknowledged as a potent stimulus to promote, maintain, and restore healthy functioning of nearly every physiological system of the human body. With advancing understanding of the complexity of human physiology, continually evolving methodological possibilities, and an increasingly dire public health situation, the study of exercise as a preventative or therapeutic treatment has never been more interdisciplinary, or more impactful. During the early stages of the NIH Common Fund Molecular Transducers of Physical Activity Consortium (MoTrPAC) Initiative, the field is well-positioned to build substantially upon the existing understanding of the mechanisms underlying benefits associated with exercise. Thus, we present a comprehensive body of the knowledge detailing the current literature basis surrounding the molecular adaptations to exercise in humans to provide a view of the state of the field at this critical juncture, as well as a resource for scientists bringing external expertise to the field of exercise physiology. In reviewing current literature related to molecular and cellular processes underlying exercise-induced benefits and adaptations, we also draw attention to existing knowledge gaps warranting continued research effort. © 2021 American Physiological Society. Compr Physiol 12:3193-3279, 2022.

A Systematic Review Examining the Approaches Used to Estimate Interindividual Differences in Trainability and Classify Individual Responses to Exercise Training

Background: Many reports describe statistical approaches for estimating interindividual differences in trainability and classifying individuals as "responders" or "non-responders." The extent to which studies in the exercise training literature have adopted these statistical approaches remains unclear. Objectives: This systematic review primarily sought to determine the extent to which studies in the exercise training literature have adopted sound statistical approaches for examining individual responses to exercise training. We also (1) investigated the existence of interindividual differences in trainability, and (2) tested the hypothesis that less conservative thresholds inflate response rates compared with thresholds that consider error and a smallest worthwhile change (SWC)/minimum clinically important difference (MCID). Methods: We searched six databases: AMED, CINAHL, EMBASE, Medline, PubMed, and SportDiscus. Our search spanned the aerobic, resistance, and clinical or rehabilitation training literature. Studies were included if they used human participants, employed standardized and supervised exercise training, and either: (1) stated that their exercise training intervention resulted in heterogenous responses, (2) statistically estimated interindividual differences in trainability, and/or (3) classified individual responses. We calculated effect sizes (ES_IR) to examine the presence of interindividual differences in trainability. We also compared response rates (n = 614) across classification approaches that considered neither, one of, or both errors and an SWC or MCID. We then sorted response rates from studies that also reported mean changes and response thresholds (n = 435 response rates) into four quartiles to confirm our ancillary hypothesis that larger mean changes produce larger response rates. Results: Our search revealed 3,404 studies, and 149 were included in our systematic review. Few studies (n = 9) statistically estimated interindividual differences in trainability. The results from these few studies present a mixture of evidence for the presence of interindividual differences in trainability because several ES_IR values lay above, below, or crossed zero. Zero-based thresholds and larger mean changes significantly (both p < 0.01) inflated response rates. Conclusion: Our findings provide evidence demonstrating why future studies should statistically estimate interindividual differences in trainability and consider error and an SWC or MCID when classifying individual responses to exercise training. Systematic Review Registration: [website], identifier [registration number].

Associations between objectively measured physical activity, sedentary behaviour and time in bed among 75+ community-dwelling Danish older adults

BACKGROUND

Older adults are recommended to sleep 7-8 h/day. Time in bed (TIB) differs from sleep duration and includes also the time of lying in bed without sleeping. Long TIB (≥9 h) are associated with self-reported sedentary behavior, but the association between objectively measured physical activity, sedentary behavior and TIB is unknown.

METHODS

This study was based on cross-sectional analysis of the Healthy Ageing Network of Competence (HANC Study). Physical activity and sedentary behaviour were measured by a tri-axial accelerometer (ActiGraph) placed on the dominant wrist for 7 days. Sedentary behavior was classified as < 2303 counts per minute (cpm) in vector magnitude and physical activity intensities were categorized, as 2303-4999 and ≥ 5000 cpm in vector magnitude. TIB was recorded in self-reported diaries. Participants were categorized as UTIB (usually having TIB 7-9 h/night: ≥80% of measurement days), STIB (sometimes having TIB 7-9 h/night: 20-79% of measurement days), and RTIB (rarely having TIB 7-9 h/night: < 20% of measurement days). Multinominal regression models were used to calculate the relative risk ratios (RRR) of being RTIB and STIB by daily levels of physical activity and SB, with UTIB as the reference group. The models were adjusted for age, sex, average daily nap length and physical function.

RESULTS

Three hundred and fourty-one older adults (median age 81 (IQR 5), 62% women) were included with median TIB of 8 h 21 min (1 h 10 min)/day, physical activity level of 2054 (864) CPM with 64 (15) % of waking hours in sedentary behavior. Those with average CPM within the highest tertile had a lower RRR (0.33 (0.15-0.71), p = 0.005) for being RTIB compared to those within the lowest tertile of average CPM. Accumulating physical activity in intensities 2303-4999 and ≥ 5000 cpm/day did not affect the RRR of being RTIB. RRR of being RTIB among highly sedentary participants (≥10 h/day of sedentary behavior) more than tripled compared to those who were less sedentary (3.21 (1.50-6.88), p = 0.003).

CONCLUSIONS

For older adults, being physically active and less sedentary was associated with being in bed for 7-9 h/night for most nights (≥80%). Future longitudinal studies are warranted to explore the causal relationship sbetween physical activity and sleep duration.

Effects of high-protein diet combined with exercise to counteract frailty in pre-frail and frail community-dwelling older adults: study protocol for a three-arm randomized controlled trial

Background

The proportion of older citizens is increasing worldwide. A well-known syndrome in old age is physical frailty which is associated with a greater risk of disabilities in activities of daily living, greater reliance on in-home services, hospitalization, institutionalization, and premature mortality. The purpose of this study is to determine the effects of an intervention with high-protein diet alone or in combination with power training in pre-frail and frail old adults.

Methods

The study is a community-based assessor-blinded parallel randomized controlled trial (RCT), consisting of two phases. Phase 1 is a 1-month stabilization phase, where self-reliant community-dwelling adults + 80 years old will receive individual guidance regarding protein intake, to prevent the risk of negative protein balance prior to phase 2 and to only include participants who have reached the minimum recommended level of protein intake (1.0 g/kg/day) in the randomized controlled trial. Phase 2 is a 4-month RCT where 150 participants will be randomized into the following three arms: protein-only where participants will be provided with dairy products to increase their protein intake to 1.5 g/kg/day, protein + exercise where participants will be provided with the protein intervention in combination with power training two times a week, and recommendation group where participants will continue as in phase 1. Primary outcome is lower leg muscle power. Secondary outcomes include physical function and mobility, frailty status, muscle mechanical function, body composition, nutritional status, and health-related quality of life. The statistical analysis will include an intention-to-treat analysis of all randomized participant and per-protocol analysis of all compliant participants. The study hypothesis will be tested with mixed linear models to assess changes in the main outcomes over time and between study arms.

Discussion

The finding of this study may add to the knowledge about the beneficial effects of high-protein diet from dairy products combined with power training to counteract frailty in community-dwelling older adults. This may ultimately have an impact on the ability to live well and independent for longer.

Trial registration

ClinicalTrials.gov NCT03842579. Registered on 15 February 2019, version 1

The Impact of Different Types of Exercise Training on Peripheral Blood Brain-Derived Neurotrophic Factor Concentrations in Older Adults: A Meta-Analysis

BACKGROUND

As the prevalence of neurodegenerative diseases (such as dementia) continues to increase due to population aging, it is mandatory to understand the role of exercise for maintaining/improving brain health.

OBJECTIVES

To analyse the impact of aerobic, strength and combined aerobic/strength exercise training on peripheral brain-derived neurotrophic factor (BDNF) concentrations in older adults (minimum age 60 years).

METHODS

This meta-analysis adhered to PRISMA guidelines. Inclusion criteria were: (i) studies with subjects aged ≥ 60 years, (ii) completing a single exercise bout or an exercise programme, with (iii) measurements of blood BDNF in the periphery; (iv) with comparison between (a) an intervention and control group or (b) two intervention groups, or (c) pre- and post-measurements of an exercise intervention without control group. Studies with specific interest in known chronic co-morbidities or brain diseases affecting the peripheral and/or central nervous system, except for dementia, were excluded.

RESULTS

In general, peripheral blood BDNF concentrations increased significantly after a single aerobic/strength exercise bout (Z = 2.21, P = 0.03) as well as after an exercise programme (Z = 4.72, P < 0.001). However, when comparing the different types of exercise within these programmes, the increase in the peripheral BDNF concentrations was significant after strength training (Z = 2.94, P = 0.003) and combined aerobic/strength training (Z = 3.03, P = 0.002) but not after (low-to-moderate intense) aerobic exercise training (Z = 0.82, P = 0.41).

CONCLUSIONS

Based on current evidence, to increase the peripheral blood BDNF concentrations in older adults, strength training and combined aerobic/strength training is effective. More studies are needed to examine the impact of aerobic exercise training.

Pathophysiological Features of Obesity and its Impact on Cognition: Exercise Training as a Non-Pharmacological Approach

BACKGROUND

The number of individuals with obesity is growing worldwide and this is a worrying trend, as obesity has shown to cause pathophysiological changes, which result in the emergence of comorbidities such as cardiovascular disease, diabetes mellitus type 2 and cancer. In addition, cognitive performance may be compromised by immunometabolic deregulation of obesity. Although in more critical cases, the use of medications is recommended, a physically active lifestyle is one of the main foundations for health maintenance, making physical training an important tool to reduce the harmful effects of excessive fat accumulation.

AIM

The purpose of this review of the literature is to present the impact of immunometabolic alterations on cognitive function in individuals with obesity, and the role of exercise training as a non-pharmacological approach to improve the inflammatory profile, energy metabolism and neuroplasticity in obesity.

METHOD

An overview of the etiology and pathophysiology of obesity to establish a possible link with cognitive performance in obese individuals, with the executive function being one of the most affected cognitive components. In addition, the brain-derived neurotrophic factor (BDNF) profile and its impact on cognition in obese individuals are discussed. Lastly, studies showing regular resistance and/or aerobic training, which may be able to improve the pathophysiological condition and cognitive performance through the improvement of the inflammatory profile, decreased insulin resistance and higher BDNF production are discussed.

CONCLUSION

Exercise training is essential for reestablishment and maintenance of health by increasing energy expenditure, insulin resistance reduction, anti-inflammatory proteins and neurotrophin production corroborating to upregulation of body function.

Effects of Resistance Exercise on Cerebral Redox Regulation and Cognition: An Interplay Between Muscle and Brain

This review highlighted resistance training as an important training type for the brain. Most studies that use physical exercise for the prevention or treatment of neurodegenerative diseases have focused on aerobic physical exercise, revealing different behavioral, biochemical, and molecular effects. However, recent studies have shown that resistance training can also significantly contribute to the prevention of neurodegenerative diseases as well as to the maintenance, development, and recovery of brain activities through specific neurochemical adaptations induced by the training. In this scenario we observed the results of several studies published in different journals in the last 20 years, focusing on the effects of resistance training on three main neurological aspects: Neuroprotective mechanisms, oxidative stress, and cognition. Systematic database searches of PubMed, Web of Science, Scopus, and Medline were performed to identify peer-reviewed studies from the 2000s. Combinations of keywords related to brain disease, aerobic/resistance, or strength physical exercise were used. Other variables were not addressed in this review but should be considered for a complete understanding of the effects of training in the brain.

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).

Effect of caloric restriction on depression

Recently, most of evidence shows that caloric restriction could induce antidepressant‐like effects in animal model of depression. Based on studies of the brain–gut axis, some signal pathways were common between the control of caloric restriction and depression. However, the specific mechanism of the antidepressant‐like effects induced by caloric restriction remains unclear. Therefore, in this article, we summarized clinical and experimental studies of caloric restriction on depression. This review may provide a new therapeutic strategy for depression.