The acute response of plasma brain-derived neurotrophic factor as a result of exercise in major depressive disorder

Association of impaired cognitive function with balance confidence, static balance, dynamic balance, functional mobility, and risk of falls in older adults with depression

Objectives

Increased depression severity has been linked to cognitive impairment (CI). Importantly, CI is a known risk factor for impaired balance and falls. Therefore, this study aims to explore the relationship between CI and neuromuscular functions and secondarily it aims to find out if CI is a potential predictor for neuromuscular functions deficits in depressed elderly.

Methods

Eighty-four depressed elderly participated in the study. Assessment for CI symptoms were done using Mini Mental Status Examination (MMSE) in subjects having confirmed depression. Neuromuscular functions such as balance confidence, static and dynamic balance, functional mobility, and fall risk were subjectively assessed using Activities-specific Balance Confidence (ABC) Scale, Berg Balance Scale (BBS), Timed Up and Go (TUG) Test, and Performance Oriented Mobility Assessment (POMA), respectively.

Results

Pearson's analysis revealed that there was moderate positive linear-correlation between MMSE and BBS (R = 0.382, p = <0.001) and between MMSE and ABC (R = 0.229, p = 0.036*). Further, regression analysis (R 2) revealed that MMSE significantly predicted the neuromuscular functions using BBS [F(1, 82) = 14.013, p < 0.001, with an R 2 of 0.146] and ABC [F(1, 82) = 4.545, p= 0.036*, with an R 2 of 0.053].

Conclusion

Results of this study points to an impaired CI as a possible factor in development of neuromuscular function impairment in depressed elderly.

A 21-Day Individual Rehabilitation Exercise Training Program Changes Irisin, Chemerin, and BDNF Levels in Patients after Hip or Knee Replacement Surgery

Osteoarthritis (OA) is the most frequent worldwide cause of adult population disabilities. The study evaluated the effects of a 21-day individual rehabilitation exercise training program focused on improving patients' functional capacity. The study analyzed the changes in irisin, chemerin, and BDNF serum levels in 36 OA patients subjected to an individually-adjusted rehabilitation program 90 days after surgical hip or knee replacement. The changes in irisin, chemerin, and BDNF serum levels were measured using enzyme-linked immunosorbent assay (ELISA) kits. A 21-day individual rehabilitation exercise training program significantly increased irisin and BDNF, and decreased chemerin serum levels. The presented study indicates that individually-adjusted exercise training is an important modulator influencing serum levels of anti- and pro-inflammatory factors, leading to positive clinical outcomes in osteoarthritis therapy. Selected factors are considered potential markers of various pathophysiological conditions. The presented study brings new details to the discussion.

Physical activity may buffer against depression and promote resilience after major life stressors

As many individuals experience potentially traumatic or stressful life events, understanding factors that are likely to promote resilience is imperative. Given the demonstrated efficacy of exercise for depression treatment, we examined if exercise buffers against the risk of developing psychiatric symptoms following life stressors. 1405 participants (61% female) from a longitudinal panel cohort experienced disability onset (43%), bereavement (26%), heart attack (20%), divorce (11%), and job loss (3%). They reported time spent exercising and depressive symptoms (Center for Epidemiologic Studies Depression scale) across three time points collected in two-year intervals: T0 (pre-stressor), T1 (acutely post-stressor), and T2 (post-stressor). Participants were classified in previously identified heterogeneous depression trajectories pre- to post-life stressor: resilient (69%), emerging (11.5%), chronic (10%), and improving (9.5%). Multinomial logistic regression found that more T0 exercise predicted likelihood of classification in resilient versus other groups (all p<.02). Controlling for covariates, only the higher likelihood of classification in resilient versus improving remained (p=.03). Follow-up repeated measures general linear model (GLM) assessed whether trajectory was associated with exercise at each time, controlling for covariates. GLM indicated significant within-subjects effects for time (p=.016, partial η2=.003) and time*trajectory (p=.020, partial η2=.005) on exercise and significant between-subjects effects of trajectory (p<.001, partial η2=.016) and all covariates. The resilient group showed consistent high exercise levels. The improving group had consistent moderate exercise. The emerging and chronic groups were associated with lower exercise post-stressor. Pre-stressor exercise may buffer against depression and ongoing exercise may be associated with lower depression levels following a major life stressor.

Exercise improves depression through positive modulation of brain-derived neurotrophic factor (BDNF). A review based on 100 manuscripts over 20 years

The aim of this review was to explore the relevant neurobiology and the association between peripheral levels of brain-derived neurotrophic factor (BDNF) and acute and short to long-term exercise regimes, as well as its relation to depression and antidepressant treatment. A 20-year literature search was conducted. The screening process resulted in 100 manuscripts. Antidepressants as well as acute exercise, particularly high-intensity, elevates BDNF in healthy humans and clinical populations, as evidenced from aerobic and resistance-based studies. Although exercise is increasingly recognised in the management of depression, acute and short-term exercise studies have failed to establish a relationship between the severity of depression and changes in peripheral BDNF. The latter rapidly returns to baseline, possibly indicating a quick re-uptake by the brain, aiding its neuroplasticity functions. The timescale of administration needed for the antidepressants to stimulate biochemical changes is longer than similar increases with acute exercise.

The role of exercise in the treatment of depression: biological underpinnings and clinical outcomes

Globally, depression is a leading cause of disability and has remained so for decades. Antidepressant medications have suboptimal outcomes and are too frequently associated with side effects, highlighting the need for alternative treatment options. Although primarily known for its robust physical health benefits, exercise is increasingly recognized for its mental health and antidepressant benefits. Empirical evidence indicates that exercise is effective in treating individuals with depression; however, the mechanisms by which exercise exerts anti-depressant effects are not fully understood. Acute bouts of exercise have been shown to transiently modulate circulating levels of serotonin and norepinephrine, brain-derived neurotrophic factor, and a variety of immuno-inflammatory mechanisms in clinical cohorts with depression. However, exercise training has not been demonstrated to consistently modulate such mechanisms, and evidence linking these putative mechanisms and reductions in depression is lacking. The complexity of the biological underpinnings of depression coupled with the intricate molecular cascade induced by exercise are significant obstacles in the attempt to disentangle exercise's effects on depression. Notwithstanding our limited understanding of these effects, clinical evidence uniformly argues for the use of exercise to treat depression. Regrettably, exercise remains underutilized despite being an accessible, low-cost alternative/adjunctive intervention that can simultaneously reduce depression and improve overall health. To address the gaps in our understanding of the clinical and molecular effects of exercise on depression, we propose a model that leverages systems biology and multidisciplinary team science with a large-scale public health investment. Until the science matches the scale of complexity and burden posed by depression, our ability to advance knowledge and treatment will continue to be plagued by fragmented, irreproducible mechanistic findings and no guidelines for standards of care.

The acute affective response to physical activity in people with depression: A meta-analysis

BACKGROUND

Little is known about the acute affective response to physical activity in people with depression, which may have implications for acute symptom management and may also be a mechanism that explains the antidepressant effects of physical activity. This study aimed to quantitatively synthesize existing research on the acute affective response to physical activity in people with depression.

METHODS

Five online databases were searched to July 2021 to identify studies that examined pre-post changes in affective states following a bout of moderate-to-vigorous physical activity in people with depression. The affective response to physical activity was synthesized using a random-effects meta-analysis with a robust variance estimator.

RESULTS

A total of 18 studies were included in the meta-analysis. Results showed that people with depression experienced a favourable affective response following an acute bout of physical activity (SMD = 0.585, 95% confidence interval = [0.456, 0.714], 95% prediction interval = [-0.079, 1.249]). Moderator analysis indicated this effect was consistent across different types of affective states, exercise conditions, and participant characteristics. Additionally, results were robust to changes in the study protocol and publication bias.

LIMITATIONS

Only within-person pre-post changes in affective responses were examined. No comparisons were made with control conditions.

CONCLUSION

Acute bouts of physical activity can significantly improve affective states in people with depression. Future research should examine the effect of physical activity on affective states in non-experimental settings and examine whether the affective response to physical activity is a predictor of the long-term antidepressant effects of physical activity interventions.

Effects of Padel Competition on Brain Health-Related Myokines

Padel is becoming one of the most widespread racket sports that may have potential health benefits. Considering that several myokines mediate the cross-talk between skeletal muscles and the brain, exerting positive effects on brain health status, this study was designed to evaluate the responses of brain-derived neurotrophic factor (BDNF), leukemia inhibitory factor (LIF), and irisin (IR) to padel competition in trained players and to determine whether these responses were sex-dependent. Twenty-four trained padel players (14 women and 10 men with a mean age of 27.8 ± 6.3 years) participated voluntarily in this study. Circulating levels of BDNF, LIF, and IR were assessed before and after simulated padel competition (real playing time, 27.8 ± 8.49 min; relative intensity, 75.2 ± 7.9% maximum heart rate). Except for BDNF responses observed in female players (increasing from 1531.12 ± 269.09 to 1768.56 ± 410.75 ng/mL), no significant changes in LIF and IR concentrations were reported after padel competition. In addition, no sex-related differences were found. Moreover, significant associations between IR and BDNF were established at both pre- and post-competition. Our results suggest that while competitive padel practice stimulates BDNF response in female players, padel competition failed to boost the release of LIF and IR. Future studies are needed to further explore the role of these exercise-induced myokines in the regulation of brain functions and to identify the field sports that can contribute to myokine-mediated muscle–brain crosstalk.

Current Methodological Pitfalls and Caveats in the Assessment of Exercise-Induced Changes in Peripheral Brain-Derived Neurotrophic Factor: How Result Reproducibility Can Be Improved

Neural mechanisms, such as enhanced neuroplasticity within the motor system, underpin exercise-induced motor improvements. Being a key mediator of motor plasticity, brain-derived neurotrophic factor (BDNF) is likely to play an important role in mediating exercise positive effects on motor function. Difficulties in assessing brain BDNF levels in humans have drawn attention to quantification of blood BDNF and raise the question of whether peripheral BDNF contributes to exercise-related motor improvements. Methodological and non-methodological factors influence measurements of blood BDNF introducing a substantial variability that complicates result interpretation and leads to inconsistencies among studies. Here, we discuss methodology-related issues and approaches emerging from current findings to reduce variability and increase result reproducibility.

MTORC1 signaling as a biomarker in major depressive disorder and its pharmacological modulation by novel rapid-acting antidepressants

Major depressive disorder (MDD) is a multifactorial psychiatric disorder with obscure pathophysiology. A biomarker-based approach in combination with standardized interview-based instruments is needed to identify MDD subtypes and novel therapeutic targets. Recent findings support the impairment of the mammalian target of rapamycin complex 1 (mTORC1) in MDD. No well-established biomarkers of mTORC1 disease- and treatment-modulated activity are currently available for use in early phase antidepressant drug (AD) development. This review aims to summarize biomarkers of mTORC1 activity in MDD and to suggest how these could be implemented in future early clinical trials on mTORC1 modulating ADs. Therefore, a PubMed-based narrative literature review of the mTORC1 involvement in MDD was performed. We have summarized recent pre-clinical and clinical findings linking the MDD to the impaired activity of several key biomarkers related to mTORC1. Also, cases of restoration of these impairments by classical ADs and novel fast-acting investigational ADs are summarized. The presented biomarkers may be used to monitor pharmacological effects by novel rapid-acting mTORC1-targeting ADs. Based on findings in the peripheral blood mononuclear cells, we argue that those may serve as an ex vivo model for evaluation of mTORC1 activity and propose the use of the summarized biomarkers for this purpose. This could both facilitate the selection of a pharmacodynamically active dose and guide future early clinical efficacy studies in MDD. In conclusion, this review provides a blueprint for the rational development of rapid-acting mTORC1-targeting ADs.

The Effects and Mechanisms of Exercise on the Treatment of Depression

Background: It is necessary to seek alternative therapies for depression, because side effects of medications lead to poor adherence and some patients do not achieve a clinical treatment effect. Recently the role of exercise as a low-cost and easy-to-use treatment for depression has gained attention with a number of studies showing that exercise is effective at reducing depressive symptoms and improving body functions such as cardiorespiratory system and cognitive function. Because of the heterogeneity of exercise therapy programs, there is no standardized and unified program. Few studies have summarized the specific properties of exercise programs (type, intensity, duration, and frequency) and clinical prescriptions for exercise are not mentioned in most articles. Aims: This study aimed to investigate the feasibility and efficacy of exercise therapy for patients with depression, in order to appraise the evidence and outline accepted guidelines to direct individualized treatment plans for patients with depression based on their individual situations. Methods: A systematic review of English language literature including papers published from 2010 to present in PubMed was performed. Given the feasibility of prescribing exercise therapy for patients with depression, nearly 3 years of clinical studies on the treatments of depressive symptoms with exercise were first reviewed, comparing the exercise programs utilized. Conclusions: Exercise has therapeutic effects on depression in all age groups (mostly 18-65 years old), as a single therapy, an adjuvant therapy, or a combination therapy, and the benefits of exercise therapy are comparable to traditional treatments for depression. Moderate intensity exercise is enough to reduce depressive symptoms, but higher-dose exercise is better for overall functioning. Exercise therapy has become more widely used because of its benefits to the cardiovascular system, emotional state, and systemic functions. Recommendations: Aerobic exercise/mind-body exercise (3-5 sessions per week with moderate intensity lasting for 4-16 weeks) is recommended. Individualized protocols in the form of group exercise with supervision are effective at increasing adherence to treatment.

Acute Effects of High-Intensity Interval Training on Brain-Derived Neurotrophic Factor, Cortisol and Working Memory in Physical Education College Students

High-intensity interval training (HIIT) is considered one of the most effective methods for improving cardiorespiratory and metabolic functions. However, it is necessary to clarify their effects on neurophysiological responses and coginitive functioning. Thus, this study aimed to determine the effects of an acute bout of HIIT on neurocognitive and stress-related biomarkers and their association with working memory (WM) capacity in healthy young adults. Twenty-five male college students performed a single bout of HIIT consisting of 10 × 1 min of cycling at their VO₂ peak power output. Plasma Brain-Derived Neurotrophic Factor (BDNF) and cortisol (CORT) levels, and WM (Digit Span Test (DST)), were assessed pre-, post- and 30 min post-intervention. Significant post-exercise increases in circulating BDNF and CORT levels were observed coinciding with the highest DST performance; however, no statistical associations were found between cognitive and neurophysiological variables. Moreover, DST scores obtained 30 min after exercise remained higher than those assessed at pre-exercise. In conclusion, the stress induced by a single bout of HIIT induces a remarkable response of BDNF and CORT boosting WM capacity in healthy young males. Future research should clarify the association between cognitive and neurobiological markers during intense exercise stimulation.

Endocrine Mechanisms Connecting Exercise to Brown Adipose Tissue Metabolism: a Human Perspective

PURPOSE OF REVIEW

To summarize the state-of-the-art regarding the exercise-regulated endocrine signals that might modulate brown adipose tissue (BAT) activity and/or white adipose tissue (WAT) browning, or through which BAT communicates with other tissues, in humans.

RECENT FINDINGS

Exercise induces WAT browning in rodents by means of a variety of physiological mechanism. However, whether exercise induces WAT browning in humans is still unknown. Nonetheless, a number of protein hormones and metabolites, whose signaling can influence thermogenic adipocyte's metabolism, are secreted during and/or after exercise in humans from a variety of tissues and organs, such as the skeletal muscle, the adipose tissue, the liver, the adrenal glands, or the cardiac muscle. Overall, it seems plausible to hypothesize that, in humans, exercise secretes an endocrine cocktail that is likely to induce WAT browning, as it does in rodents. However, even if exercise elicits a pro-browning endocrine response, this might result in a negligible effect if blood flow is restricted in thermogenic adipocyte-rich areas during exercise, which is still to be determined. Future studies are needed to fully characterize the exercise-induced secretion (i.e., to determine the effect of the different exercise frequency, intensity, type, time, and volume) of endocrine signaling molecules that might modulate BAT activity and/or WAT browning or through which BAT communicates with other tissues, during exercise. The exercise effect on BAT metabolism and/or WAT browning could be one of the still unknown mechanisms by which exercise exerts beneficial health effects, and it might be pharmacologically mimicked.

Assessing BDNF as a mediator of the effects of exercise on depression

Brain-derived neurotrophic factor (BDNF) is associated with neuronal growth and reduced BDNF has been implicated in depression. A recent meta-analysis documented reliable effects of exercise on BDNF levels (Szuhany et al., 2015); although, few studies included participants with mental health conditions. In this study, we examine whether increased exercise was associated with enhanced BDNF response in depressed patients, and whether this change mediated clinical benefits. A total of 29 depressed, sedentary participants were randomized to receive either behavioral activation (BA) plus an exercise or stretching prescription. Blood was collected prior to (resting BDNF levels) and following an exercise test (pre-to post-exercise BDNF change) at four points throughout the study. Participants also completed depression and exercise assessments. BDNF increased significantly across all assessment points (p < 0.001, d = 0.83). Changes in BDNF from pre-to post-exercise were at a moderate effect for the interaction of exercise and time which did not reach significance (p = 0.13, d = 0.53), with a similar moderate, non-significant effect for resting BDNF levels (p = 0.20, d = 0.49). Contrary to hypotheses, change in resting BDNF or endpoint change in BDNF was not associated with changes in depression. In an intervention that included active treatment (BA), we could not verify an independent predictive effect for changes in BDNF across the trial. Overall, this study adds to the literature showing reliable effects of acute exercise on increasing BDNF and extends this research to the infrequently studied depressed population, but does not clarify the mechanism behind exercise benefits for depression. CLINICAL TRIALS REGISTRY (CLINICALTRIALS.GOV): NCT02176408, "Efficacy of Adjunctive Exercise for the Behavioral Treatment of Major Depression".

BDNF as a Promising Therapeutic Agent in Parkinson's Disease

Brain-derived neurotrophic factor (BDNF) promotes neuroprotection and neuroregeneration. In animal models of Parkinson’s disease (PD), BDNF enhances the survival of dopaminergic neurons, improves dopaminergic neurotransmission and motor performance. Pharmacological therapies of PD are symptom-targeting, and their effectiveness decreases with the progression of the disease; therefore, new therapeutical approaches are needed. Since, in both PD patients and animal PD models, decreased level of BDNF was found in the nigrostriatal pathway, it has been hypothesized that BDNF may serve as a therapeutic agent. Direct delivery of exogenous BDNF into the patient’s brain did not relieve the symptoms of disease, nor did attempts to enhance BDNF expression with gene therapy. Physical training was neuroprotective in animal models of PD. This effect is mediated, at least partly, by BDNF. Animal studies revealed that physical activity increases BDNF and tropomyosin receptor kinase B (TrkB) expression, leading to inhibition of neurodegeneration through induction of transcription factors and expression of genes related to neuronal proliferation, survival, and inflammatory response. This review focuses on the evidence that increasing BDNF level due to gene modulation or physical exercise has a neuroprotective effect and could be considered as adjunctive therapy in PD.

High-Intensity Aerobic Exercise Acutely Increases Brain-derived Neurotrophic Factor

Aerobic exercise (AEx) exerts antidepressant effects, although the neurobiological mechanisms underlying such effects are not well understood. Reduced brain-derived neurotrophic factor (BDNF) and elevated cortisol have been implicated in the pathophysiology of depression and appear to normalize with antidepressant treatment. Thus, BDNF and cortisol may serve as biological targets for developing AEx as an antidepressant treatment.

PURPOSE

This study examined the effects of AEx, of different intensities, on serum BDNF and cortisol in individuals with and without depression.

METHODS

Thirteen participants with depression (10 females; age = 27.2 ± 6.9 yr; Montgomery-Äsberg Depression Rating Scale = 21.7 ± 4.7) and 13 control participants (10 females; age 27.2 ± 7.2 yr; Montgomery-Äsberg Depression Rating Scale = 0.5 ± 0.9) participated. Experimental visits consisted of 15 min of low-intensity cycling (LO) at 35% heart rate reserve, high-intensity cycling (HI) at 70% heart rate reserve, or sitting (CON). During each visit, blood samples were obtained at baseline, immediately postexercise (IP), and then every 15 min postexercise for 1 h (15P, 30P, 45P, and 60P). Group, condition, and time differences in BDNF and cortisol were assessed.

RESULTS

There were no group differences in cortisol and BDNF. Secondary analysis revealed that BDNF increased in an intensity-dependent nature at IP, and cortisol was significantly elevated at 15P after HI. Changes in BDNF and cortisol showed significant linear relationships with changes in HR.

CONCLUSION

HI AEx can elicit acute, transient increases in BDNF and cortisol in young, healthy, and physically active, nondepressed and mild to moderately depressed individuals. This work suggests that AEx has potential to significantly affect the central nervous system function, and the magnitude of such effect may be directly driven by exercise intensity.

BDNF and Cortisol integrative system - Plasticity vs. degeneration: Implications of the Val66Met polymorphism

BDNF is the neurotrophin mediating pro-neuronal survival and plasticity. Cortisol (COR), in turn, is engaged in the coordination of several processes in the brain homeostasis. Stress-responsive, both factors show an integrative role through their receptor's dynamics in neurophysiology. Furthermore, the Val66Met BDNF polymorphism may play a role in this mechanism.

AIM

to investigate BDNF-COR interaction in the human neurophysiology context.

METHODS

We collected all papers containing BDNF and COR parameters or showing COR analyses in genotyped individuals in a PubMed search - full description available on PROSPERO - CRD42016050206.

DISCUSSION

BDNF and COR perform distinct roles in the physiology of the brain whose systems are integrated by glucocorticoid receptors dynamics. The BDNF polymorphism appears to have an influence on individual COR responsivity to stress. BDNF and COR play complementary roles in the nervous system where COR is a regulator of positive/negative effects. Exercise positively regulates both factors, regardless of BDNF polymorphism.

The beneficial effects of Qigong on elderly depression

Health Qigong, especially the Eight-Section Brocades (or Baduanjin), has been well established as an effective adjunct intervention to alleviate depressive symptoms of older adults. The easy to learn and safe format of health Qigong allows the promotion and employment by health care professionals to improve the physical and psychosocial wellness of older adults. The cultural relevance of Qigong practice enhances its popularity as a health maintenance practice in Chinese community. In general, the antidepressive effects of Qigong are put forward through psychosocial, physiological, and neurobiological mechanisms. More specific, the beneficial effects of Qigong can be further substantiated by findings of several research studies.

Acute high-intensity aerobic exercise affects brain-derived neurotrophic factor in mild cognitive impairment: a randomised controlled study

OBJECTIVE

To investigate the brain-derived neurotrophic factor (BDNF) and cognitive response to a short bout of high-intensity aerobic exercise in older adults with mild cognitive impairment (MCI).

METHODS

Participants were randomised to one of two testing schedules, completing either a standardised exercise test (group A) or a resting control condition (group B). Blood sampling and cognitive measures (visuospatial learning and memory, sustained attention and executive function) were collected at baseline (T1) and postintervention (T2). An additional measurement of study outcomes was collected after exercise (T3) in group B only.

RESULTS

64 participants (female 53.2%, mean age 70.5±6.3 years) with MCI were recruited. From T1 to T2, serum BDNF (sBDNF) concentration increased in group A (n=35) (median (Md) 4564.61±IQR 5737.23 pg/mL to Md 5173.27±5997.54 pg/mL) and decreased in group B (Md 4593.74±9558.29 pg/mL to Md 3974.66±3668.22 pg/mL) (between-group difference p=0.024, effect size r=0.3). The control group made fewer errors on the sustained attention task compared with the exercise group (p=0.025). Measures of visuospatial learning and memory or executive function did not change significantly between groups.

CONCLUSION

This study is the first to show that a short bout of high-intensity aerobic exercise increases peripheral sBDNF in a population with MCI. However, acute exercise did not improve cognitive performance.

Examining the Effects of Exercise on Pattern Separation and the Moderating Effects of Mood Symptoms

Aerobic exercise has broad cognitive benefits. One target of interest is enhanced memory. The present study explored pattern separation as a specific memory process that could be sensitive to acute and regular exercise and clinically significant for disorders (e.g., depression) characterized by cognitive-affective deficits and hippocampal impairment. In a within-subjects design, participants (N = 69) attended two visits during which they repeated a behavioral pattern separation task at rest and after an activity (cycling, stretching). Regular exercise habits, demographics, mood and anxiety symptoms, and recognition memory capacity were also measured. More regular exercise predicted better resting pattern separation, t(62) = 2.13, b = 1.74, p = .037. Age moderated this effect, t(61) = 2.35, b = .25, p = .02; exercise most strongly predicted performance among middle-age participants. There was no main effect of activity condition on post-activity performance, t(61) = .67, p = .51. However, with significant heterogeneity in reported mood symptoms and regular exercise habits, there was a three-way interaction between condition, regular exercise, and depression, t(55) = 2.08, b = .22, p = .04. Relative to stretching, cycling appears to have enhanced the benefit of regular exercise for pattern separation performance; however, this was evident among participants with mild to no symptoms of depression, but absent among participants with moderate to severe symptoms. Results have implications for how exercise might protect against declines in pattern separation. Future research should explore exercise's potential as a prevention tool or early intervention for pattern separation and related clinical outcomes.

Serum brain-derived neurotrophic factor (BDNF) at rest and after acute aerobic exercise in major depressive disorder

Physiological mechanisms of an anti-depressive effect of physical exercise in major depressive disorder (MDD) seem to involve alterations in brain-derived neurotrophic factor (BDNF) level. However, previous studies which investigated this effect in a single bout of exercise, did not control for confounding peripheral factors that contribute to BDNF-alterations. Therefore, the underlying cause of exercise-induced BDNF-changes remains unclear. The current study aims to investigate serum BDNF (sBDNF)-changes due to a single-bout of graded aerobic exercise in a group of 30 outpatients with MDD, suggesting a more precise analysis method by taking plasma volume shift and number of platelets into account. Results show that exercise-induced increases in sBDNF remain significant (p < .001) when adjusting for plasma volume shift and controlling for number of platelets. The interaction of sBDNF change and number of platelets was also significant (p = .001) indicating larger sBDNF-increase in participants with smaller number of platelets. Thus, findings of this study suggest an involvement of peripheral as well as additional - possibly brain-derived - mechanisms explaining exercise-related BDNF release in MDD. For future studies in the field of exercise-related BDNF research, the importance of controlling for peripheral parameters is emphasized.

Interval Training Improves Depressive Symptoms But Not Anxious Symptoms in Healthy Women

Background: Despite important advances in the relationship between exercise and mood disorders, especially regarding moderate-intensity continuous training, there is a lack of information about the chronic effects of interval training protocols. We compared the effects of two different interval training protocols [sprint interval training (SIT) and high-intensity interval training (HIIT)] on depressive and anxious symptoms in healthy women. Methods: Thirty-six women were randomly allocated to HIIT (n = 18) or SIT (n = 18) groups and performed 24 training sessions over 8 weeks (thrice a week). Levels of state-trait anxiety and depressive symptoms were evaluated using State-Trait Anxiety Inventory and Beck Depression Inventory, respectively, before and after training intervention. Results: Two-way analysis of variance (ANOVA) did not reveal a significant effect of time (p > 0.05), group intervention (p > 0.05), or time × group interaction (p > 0.05) on state-trait anxiety; however, two-way ANOVA showed a significant effect of time on depressive symptoms (p = 0.025) but not group effect (p = 0.548) or time × group interaction (p = 0.373). Depressive symptoms of the participants in both HIIT and SIT groups were reduced from baseline, (Δ_HIIT) -17.5 ± 27.9% and (Δ_SIT) -28.6 ± 47.5%, respectively. Conclusion: HIIT and SIT groups similarly improved depressive symptoms but not anxiety levels in healthy and physically active young adult women.

The effect of energy-matched exercise intensity on brain-derived neurotrophic factor and motor learning

BACKGROUND

Pairing a bout of high-intensity exercise with motor task practice can enhance motor learning beyond task practice alone, which is thought, in part, to be facilitated by an exercise-related increase in brain-derived neurotrophic factor (BDNF). The purpose of the current study was to examine the effect of different exercise intensities on BDNF levels and motor learning while controlling for exercise-related energy expenditure.

METHODS

Forty-eight young, healthy participants were assigned to one of three groups: high-intensity exercise [High], low-intensity exercise [Low], or quiet rest [Rest]. The duration of the exercise bouts were individually adjusted so that each participant expended 200 kcals regardless of exercise intensity. BDNF was measured before and after exercise or rest. After exercise or rest, all participants practiced a 3-dimensional motor learning task, which involved reach movements made to sequentially presented targets. Retention was tested after 24-h. BDNF genotype was determined for each participant to explore its effects on BDNF and motor learning.

RESULTS

All participants equally improved performance, indicated by a reduction in time to complete the task. However, the kinematic profile used to control the reach movement differed by group. The Rest group travelled the shortest distance between the targets, the High group had higher reach speed (peak velocity), and the Low group had earlier peak velocities. The rise in BDNF post-exercise was not significant, regardless of exercise intensity, and the change in BDNF was not associated with motor learning. The BDNF response to exercise did not differ by genotype. However, performance differed between those with the polymorphism (Met carriers) and those without (Val/Val). Compared to the Val/Val genotype, Met carriers had faster response times throughout task practice, which was supported by higher reach speeds and earlier peak velocities.

CONCLUSION

Results indicated that both low and high-intensity exercise can alter the kinematic approach used to complete a reach task, and these changes appear unrelated to a change in BDNF. In addition, the BDNF genotype did not influence BDNF concentration, but it did have an effect on motor performance of a sequential target reach task.

Direct and indirect evidences of BDNF and NGF as key modulators in depression: role of antidepressants treatment

PURPOSE

Depression is one of the most prevalent, recurrent and life-threatening mental illnesses. However, the precise mechanism underlying the disorder is not yet clearly understood. It is therefore, essential to identify the novel biomarkers which may help in the development of effective treatment.

METHODS

In this milieu, the profile of the brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were considered as biomarkers in the light of pathophysiology of depression and its treatment.

RESULTS

Previously, we have reported that BDNF level in the postmortem brain of suicide victims was significantly lower than those of normal controls. We also found decreased BDNF levels in the specific brain regions of the learned helplessness model of depression in rat, and was found to increase normal level following chronic fluoxetine hydrochloride treatment. NGF is another important member of neurotrophin, which is dysregulated in the pathophysiology of depression in some models of peripheral nerve damage and stress. The results shown evidences of the effect of antidepressants on modulating depression via the NGF in preclinical and clinical models of depression, but conflicted, therefore make it currently difficult to affirm the therapeutic role of antidepressants.

CONCLUSIONS

Here, we review some of the preclinical and clinical studies aimed at disclosing the role of BDNF and NGF mediated pathophysiological mechanisms of depression and the new therapeutic approaches targeting those key molecules. In addition, an important link between BDNF, NGF and depression has been discussed in the light of current existing knowledge.

A post-exercise facilitation of executive function is independent of aerobically supported metabolic costs

A single-bout of aerobic or resistance training facilitates executive function and is a benefit thought to be specific to exercise durations greater than 20 min. We sought to determine whether an executive benefit is observed for a session as brief as 10-min, and whether distinct and participant-specific exercise intensities - and associated metabolic costs - influence the magnitude of the benefit. Participants completed exercise sessions - via cycle ergometer - at moderate (80% of lactate threshold [LT]), heavy (15% of the difference between LT and VO_{2 peak}) and very-heavy (50% of the difference between LT and VO_{2 peak}) intensities determined via an incremental ramp test to volitional exhaustion. Pre- and post-exercise executive function was examined via antisaccades - an executive task requiring a saccade mirror-symmetrical to a visual stimulus. Antisaccades are an ideal tool for examining post-exercise executive changes due to the resolution of eye-tracking and because the task is mediated via the same frontoparietal networks as modified following single-bout and chronic exercise. A non-executive prosaccade task (i.e., saccade to veridical target location) was also completed to determine if the putative post-exercise benefit was specific to executive function. Results showed a 20 ms reduction in pre- to post-exercise antisaccade RTs (p < .02) and was independent of exercise intensity, whereas no such change was observed for prosaccades (p = .14). Furthermore, the antisaccade benefit occurred without concomitant changes in directional errors or endpoint accuracy; that is, participants did not decrease their post-exercise RTs at the cost of increased planning and execution errors (ps > 0.34). Accordingly, we propose that an exercise duration as brief as 10-min provides a reliable benefit to executive function and is an effect observed across the continuum of moderate to very-heavy intensities.

The effect of exercise on resting concentrations of peripheral brain-derived neurotrophic factor (BDNF) in major depressive disorder: A meta-analysis

Exercise interventions have been shown to successfully improve depression in patients with major depressive disorder (MDD), but like other forms of antidepressant treatment, exercise is not effective in all patients and its mechanisms of action have not been fully elucidated. Brain-derived neurotrophic factor (BDNF), a key mediator of neurogenesis and neuronal survival, has been shown to be decreased in individuals with MDD. One potential mechanism by which exercise alleviates depression is through an increase in BDNF. In order to evaluate this hypothesis, we conducted a meta-analysis of studies that assessed the effects of a chronic (multi-week) exercise intervention on BDNF concentrations in MDD patients. MEDLINE, Embase, PsycINFO, SPORTDiscus, Rehabilitation & Sports Medicine Source, and CINAHL databases were searched for original, peer-reviewed reports of peripheral blood BDNF concentrations before and after a chronic exercise intervention in MDD patients. Standardized mean differences (SMDs) were generated from random effects models. Potential sources of heterogeneity were explored in meta-regression analyses. In six studies that met inclusion criteria, resting blood concentrations of BDNF were not significantly higher after a chronic exercise intervention (SMD = 0.43, 95% CI: -0.06-0.92, p = 0.09) in MDD patients. This meta-analysis did not find evidence that a chronic aerobic exercise intervention increases resting concentrations of BDNF in the blood of MDD patients; however, there is a lack of studies in this area making it difficult to reach a definitive conclusion. Future studies on this topic with larger sample sizes and longer durations are needed to draw more robust conclusions.

Sprint interval training (SIT) substantially reduces depressive symptoms in major depressive disorder (MDD): A randomized controlled trial

Continuous aerobic exercise training (CAT) is considered a complementary treatment option in patients with major depressive disorder (MDD). Intermittent exercise training protocols, such as sprint interval training (SIT) have gained increasing popularity, but no studies on depressive symptoms following SIT in patients with MDD are available. Fifty-nine in-patients with MDD were randomly assigned to a SIT or CAT group. Medication was counterbalanced in both intervention arms. Both intervention groups received 3 weekly training sessions for 4-weeks (12 sessions in total). SIT comprised 25 bouts of 30 seconds at 80% of maximal power, whereas CAT consisted of 20 minutes of physical activity at 60% of maximal power. The training protocols were isocalorically designed. Maximal bicycle ergometer exercise testing yielded maximal and submaximal physical fitness parameters. The Beck-Depression-Inventory-II (BDI-II) was filled out by the patients before and after the intervention period. BDI-II scores substantially decreased in both groups with an effect size pointing towards a large effect (p < 0.001, η_p² = 0.70) while submaximal (0.07 < d < 0.89) and maximal (0.05 < d < 0.85) fitness variables improved in both groups. Short-term SIT leads to similar results as CAT in patients with MDD and can be regarded as a time-efficient and promising exercise-based treatment strategy.

Exercise Leads to Better Clinical Outcomes in Those Receiving Medication Plus Cognitive Behavioral Therapy for Major Depressive Disorder

OBJECTIVE

The aim of this study is to investigate the effects of exercise as an add-on therapy with antidepressant medication and cognitive behavioral group therapy (CBGT) on treatment outcomes in low-active major depressive disorder (MDD) patients. We also explored whether exercise reduces the residual symptoms of depression, notably cognitive impairment and poor sleep quality, and aimed to identify putative biochemical markers related to treatment response.

METHODS

Sixteen low-active MDD patients were recruited from a mental health day treatment program at a local hospital. Eight medicated patients performed an 8-week exercise intervention in addition to CBGT, and eight medicated patients attended the CBGT only. Twenty-two low-active, healthy participants with no history of mental health illness were also recruited to provide normal healthy values for comparison.

RESULTS

Results showed that exercise resulted in greater reduction in depression symptoms (p = 0.007, d = 2.06), with 75% of the patients showing either a therapeutic response or a complete remission of symptoms vs. 25% of those who did not exercise. In addition, exercise was associated with greater improvements in sleep quality (p = 0.046, d = 1.28) and cognitive function (p = 0.046, d = 1.08). The exercise group also had a significant increase in plasma brain-derived neurotrophic factor (BDNF), p = 0.003, d = 6.46, that was associated with improvements in depression scores (p = 0.002, R² = 0.50) and sleep quality (p = 0.011, R² = 0.38).

CONCLUSION

We provide evidence that exercise as an add-on to conventional antidepressant therapies improved the efficacy of standard treatment interventions. Our results suggest that plasma BDNF levels and sleep quality appear to be good indicators of treatment response and potential biomarkers associated with the clinical recovery of MDD.

Computerized cognitive training and brain derived neurotrophic factor during bed rest: mechanisms to protect individual during acute stress

Acute stress, as bed rest, was shown to increase plasma level of the neurotrophin brain-derived neurotrophic factor (BDNF) in older, but not in young adults. This increase might represent a protective mechanism towards acute insults in aging subjects. Since computerized cognitive training (CCT) is known to protect brain, herein we evaluated the effect of CCT during bed rest on BDNF, muscle mass, neuromuscular function and metabolic parameters. The subjects that underwent CCT did not show an increase of BDNF after bed rest, and showed an anti-insular modification pattern in metabolism. Neuromuscular function parameters, already shown to beneficiate from CCT, negatively correlated with BDNF in research participants undergoing CCT, while positively correlated in the control group. In conclusion, BDNF increase can be interpreted as a standardized protective mechanism taking place whenever an insult occurs; it gives low, but consistent preservation of neuromuscular function. CCT, acting as an external protective mechanism, seems to modify this standardized response, avoiding BDNF increase or possibly modifying its time course. Our results suggest the possibility of differential neuroprotective mechanisms among ill and healthy individuals, and the importance of timing in determining the effects of protective mechanisms.

Neurobiological mechanisms of exercise and psychotherapy in depression: The SPeED study-Rationale, design, and methodological issues

BACKGROUND/AIMS

Even though cognitive behavioral therapy has become a relatively effective treatment for major depressive disorder and cognitive behavioral therapy-related changes of dysfunctional neural activations were shown in recent studies, remission rates still remain at an insufficient level. Therefore, the implementation of effective augmentation strategies is needed. In recent meta-analyses, exercise therapy (especially endurance exercise) was reported to be an effective intervention in major depressive disorder. Despite these findings, underlying mechanisms of the antidepressant effect of exercise especially in combination with cognitive behavioral therapy have rarely been studied to date and an investigation of its neural underpinnings is lacking. A better understanding of the psychological and neural mechanisms of exercise and cognitive behavioral therapy would be important for developing optimal treatment strategies in depression. The SPeED study (Sport/Exercise Therapy and Psychotherapy-evaluating treatment Effects in Depressive patients) is a randomized controlled trial to investigate underlying physiological, neurobiological, and psychological mechanisms of the augmentation of cognitive behavioral therapy with endurance exercise. It is investigated if a preceding endurance exercise program will enhance the effect of a subsequent cognitive behavioral therapy.

METHODS

This study will include 105 patients diagnosed with a mild or moderate depressive episode according to the Diagnostic and Statistical Manual of Mental Disorders (4th ed.). The participants are randomized into one of three groups: a high-intensive or a low-intensive endurance exercise group or a waiting list control group. After the exercise program/waiting period, all patients receive an outpatient cognitive behavioral therapy treatment according to a standardized therapy manual. At four measurement points, major depressive disorder symptoms (Beck Depression Inventory, Hamilton Rating Scale for Depression), (neuro)biological measures (neural activations during working memory, monetary incentive delay task, and emotion regulation, as well as cortisol levels and brain-derived neurotrophic factor), neuropsychological test performance, and questionnaires (psychological needs, self-efficacy, and quality of life) are assessed.

RESULTS

In this article, we report the design of the SPeED study and refer to important methodological issues such as including both high- and low-intensity endurance exercise groups to allow the investigation of dose-response effects and physiological components of the therapy effects.

CONCLUSION

The main aims of this research project are to study effects of endurance exercise and cognitive behavioral therapy on depressive symptoms and to investigate underlying physiological and neurobiological mechanisms of these effects. Results may provide important implications for the development of effective treatment strategies in major depressive disorder, specifically concerning the augmentation of cognitive behavioral therapy by endurance exercise.

Brain-Derived Neurotrophic Factor, Depression, and Physical Activity: Making the Neuroplastic Connection

Brain-derived neurotrophic factor (BDNF) is a neurotrophin that is vital to the survival, growth, and maintenance of neurons in key brain circuits involved in emotional and cognitive function. Convergent evidence indicates that neuroplastic mechanisms involving BDNF are deleteriously altered in major depressive disorder (MDD) and animal models of stress. Herein, clinical and preclinical evidence provided that stress-induced depressive pathology contributes to altered BDNF level and function in persons with MDD and, thereby, disruptions in neuroplasticity at the regional and circuit level. Conversely, effective therapeutics that mitigate depressive-related symptoms (e.g., antidepressants and physical activity) optimize BDNF in key brain regions, promote neuronal health and recovery of function in MDD-related circuits, and enhance pharmacotherapeutic response. A greater knowledge of the interrelationship between BDNF, depression, therapeutic mechanisms of action, and neuroplasticity is important as it necessarily precedes the derivation and deployment of more efficacious treatments.

Effects of acute exercise on fear extinction in rats and exposure therapy in humans: Null findings from five experiments

BACKGROUND

Exposure therapy is an established learning-based intervention for the treatment of anxiety disorders with an average response rate of nearly 50%, leaving room for improvement. Emerging strategies to enhance exposure therapy in humans and fear extinction retention in animal models are primarily pharmacological. These approaches are limited as many patients report preferring non-pharmacological approaches in therapy. With general cognitive enhancement effects, exercise has emerged as a plausible non-pharmacological augmentation strategy. The present study tested the hypothesis that fear extinction and exposure therapy would be enhanced by a pre-training bout of exercise.

METHODS

We conducted four experiments with rats that involved a standardized conditioning and extinction paradigm and a manipulation of exercise. In a fifth experiment, we manipulated vigorous-intensity exercise prior to a standardized virtual reality exposure therapy session among adults with fear of heights.

RESULTS

In experiments 1-4, exercise did not facilitate fear extinction, long-term memory, or fear relapse tests. In experiment 5, human participants showed an overall reduction in fear of heights but exercise did not enhance symptom improvement.

CONCLUSIONS

Although acute exercise prior to fear extinction or exposure therapy, as operationalized in the present 5 studies, did not enhance outcomes, these results must be interpreted within the context of a broader literature that includes positive findings. Taken all together, this suggests that more research is necessary to identify optimal parameters and key individual differences so that exercise can be implemented successfully to treat anxiety disorders.

Exercise increases serum brain-derived neurotrophic factor in patients with major depressive disorder

BACKGROUND

Brain derived neurotrophic factor (BDNF) has been implicated in the pathogenesis of major depressive disorder (MDD). Existing data on exercise treatment in people with MDD are inconsistent concerning the effect of exercise on BDNF pointing either to increased or unaltered BDNF concentrations. However, studies in non-depressed persons demonstrated a significant effect on resting peripheral BDNF concentrations in aerobic training interventions. Given the lack of clarity mentioned above, the current study aimed at examining the effect of adjunctive exercise on serum BDNF levels in guideline based treated patients with MDD.

METHODS

42 depressed inpatients were included, and randomized either to a 6 week structured and supervised exercise intervention plus treatment as usual (EXERCISE, n=22), or to treatment as usual (TAU, n=20). BDNF serum concentrations were assessed before and after the intervention in both study groups with established immunoassays.

RESULTS

Serum BDNF slightly decreased in the TAU group, whilst there was an increase in BDNF levels in the exercise group. There was a significant time x group effect concerning sBDNF (p=0.030) with repeated ANOVA measures with age and BMI as covariates, suggesting an increase in BDNF concentrations in the EXERCISE group compared to TAU.

LIMITATIONS

Though there was no statistic difference in the antidepressant medication between EXERCISE and TAU potential interactions between exercise and medication on the effects of exercise in BDNF cannot be excluded. Gender was not considered as a covariate in ANOVA due to the small number of objects.

CONCLUSIONS

Exercise training given as adjunct to standard guideline based treatment appears to have additional effects on BDNF serum concentrations in people with MDD. Our results add further evidence to the beneficial effects of exercise in the treatment of MDD.

Physical Activity Modulates Common Neuroplasticity Substrates in Major Depressive and Bipolar Disorder

Mood disorders (MDs) are chronic, recurrent mental diseases that affect millions of individuals worldwide. Although the biogenic amine model has provided some clinical utility, a need remains to better understand the interrelated mechanisms that contribute to neuroplasticity deficits in MDs and the means by which various therapeutics mitigate them. Of those therapeutics being investigated, physical activity (PA) has shown clear and consistent promise. Accordingly, the aims of this review are to (1) explicate key modulators, processes, and interactions that impinge upon multiple susceptibility points to effectuate neuroplasticity deficits in MDs; (2) explore the putative mechanisms by which PA mitigates these features; (3) review protocols used to induce the positive effects of PA in MDs; and (4) highlight implications for clinicians and researchers.

Effects of Acute Exercise on Circulating Soluble Form of the Urokinase Receptor in Patients With Major Depressive Disorder

Inflammation has been proposed to play a role in the generation of depressive symptoms. Previously, we demonstrated that patients with major depressive disorder (MDD) have increased plasma levels of the soluble form of the urokinase receptor (suPAR), a marker for low-grade inflammation. The aim of this study was to test the hypothesis that acute exercise would induce inflammatory response characterized by increased suPAR and elucidate whether patients with MDD display altered levels of suPAR in response to acute exercise. A total of 17 patients with MDD and 17 controls were subjected to an exercise challenge. Plasma suPAR (P-suPAR) was analyzed before, during, and after exercise. There was a significantly higher baseline P-suPAR in the patients with MDD, and the dynamic changes of P-suPAR during the exercise were significantly lower in the patients with MDD, compared with the controls. This study supports the hypothesis that an activation of systemic inflammatory processes, measured as elevated P-suPAR, is involved in the pathophysiology of depression. The study concludes that P-suPAR is influenced by acute exercise, most likely due to release from activated neutrophils.

Role of brain-derived neurotrophic factor in the molecular neurobiology of major depressive disorder

Major depressive disorder (MDD) is one of the most common neuropsychiatric disorders, which affects up to 20% of people in their lifetime in the United States. The exact neurobiological mechanisms of MDD remain elusive, and the diagnostics are still uncertain. Basic and clinical research from recent years demonstrated that the etiology of MDD might be associated with genetic changes of neurotrophins, particularly brain-derived neurotrophic factor (BDNF). BDNF plays a key role in neuronal development and neurogenesis. However, the detailed mechanisms related to depression and antidepressant responses are not fully understood. This review summarizes the current knowledge of the causal relationship between BDNF and MDD, and describes the important role of BDNF in the progress of depression in animal models and patients with depressive disorders.

Effects of Endurance Exercise Modalities on Arterial Stiffness in Patients Suffering from Unipolar Depression: A Randomized Controlled Trial

BACKGROUND

Psychiatric disorders are associated with a higher prevalence of cardiovascular disease and mortality. Regular exercise has been shown to reduce depressive symptoms and improve arterial stiffness as a biomarker of cardiovascular risk. We aimed to investigate the effects of different exercise modalities on depression severity index and arterial stiffness in patients suffering from unipolar depression.

METHODS

34 patients suffering from unipolar depression [female: 25, male: 9, age: 37.8, Beck-Depression-Inventory-II (BDI-II) score: 31.0] were enrolled in this two-armed randomized controlled trial. Central hemodynamics, augmentation index at heart rate 75/min (AIx@75) and aortic pulse wave velocity (PWV) were obtained by an oscillometric monitoring device. Maximal bicycle ergometer exercise testing yielded maximal fitness parameters. Patients were assigned to either high-intensity low volume (HILV) or moderate continuous aerobic training (MCT). Both intervention groups trained three times a week during a 4-week intervention period. BDI-II were filled out by the patients before and after the intervention period.

RESULTS

We found moderate interaction effects on depression severity reduction [Formula: see text]. HILV showed a 85% beneficial effect in lowering BDI-II scores compared to MCT (HILV: pre: 28.8 (9.5), post: 15.5 (8.5), SMD = 1.48), MCT: (pre: 33.8 (8.5), post: 22.6 (7.5), SMD = 1.40). Reduction of AIx@75 was more pronounced after MCT (SMD = 0.61) compared to HILV (SMD = 0.08), showing 37% possibly beneficial effects of MCT over HILV. PWV remained unchanged in both training groups.

CONCLUSION

Both training regimes showed large effects on the reduction of depressive symptoms. While HILV was more effective in lowering depression severity, MCT was more effective in additionally lowering peripheral arterial stiffness. Exercise should be considered an important strategy for preventive as well as rehabilitative treatment in depression.

Physical Exercise for Treatment of Mood Disorders: A Critical Review

PURPOSE OF THE REVIEW

The purpose of this review is to critically assess the evidence for exercise as an adjunct intervention for major depressive disorder and bipolar disorder, chronic conditions characterized by frequent comorbid conditions as well as interepisodic symptoms with poor quality of life and impaired functioning. Individuals with these mood disorders are at higher risk of cardiovascular disease and premature death in part because of increased rates of obesity, inactivity, and diabetes mellitus compared to the general population. Exercise may not only mitigate the increased risk of cardiovascular disease, but could also potentially improve the long term outcomes of mood disorders.

RECENT FINDINGS

We conducted a literature review on the impact of exercise on mood disorders and associated comorbid conditions as well as possible biological mechanisms. We found that exercise impacts both the physical health parameters of mood disorders as well as mental health outcomes. Exercise also positively impacts conditions frequently comorbid with mood disorders (i.e. anxiety, pain, and insomnia). There are multiple candidate biomarkers for exercise, with brain-derived neurotrophic factor and oxidative stress as two main promising components of exercise's anti-depressant effect.

SUMMARY

Exercise appears to be a promising adjunct treatment for mood disorders. We conclude with recommendations for future research of exercise as an adjunct intervention for mood disorders.

Aerobic Exercise as a Tool to Improve Hippocampal Plasticity and Function in Humans: Practical Implications for Mental Health Treatment

Aerobic exercise (AE) has been widely praised for its potential benefits to cognition and overall brain and mental health. In particular, AE has a potent impact on promoting the function of the hippocampus and stimulating neuroplasticity. As the evidence-base rapidly builds, and given most of the supporting work can be readily translated from animal models to humans, the potential for AE to be applied as a therapeutic or adjunctive intervention for a range of human conditions appears ever more promising. Notably, many psychiatric and neurological disorders have been associated with hippocampal dysfunction, which may underlie the expression of certain symptoms common to these disorders, including (aspects of) cognitive dysfunction. Augmenting existing treatment approaches using AE based interventions may promote hippocampal function and alleviate cognitive deficits in various psychiatric disorders that currently remain untreated. Incorporating non-pharmacological interventions into clinical treatment may also have a number of other benefits to patient well being, such as limiting the risk of adverse side effects. This review incorporates both animal and human literature to comprehensively detail how AE is associated with cognitive enhancements and stimulates a cascade of neuroplastic mechanisms that support improvements in hippocampal functioning. Using the examples of schizophrenia and major depressive disorder, the utility and implementation of an AE intervention to the clinical domain will be proposed, aimed to reduce cognitive deficits in these, and related disorders.

Rapamycin blocks the antidepressant effect of ketamine in task-dependent manner

OBJECTIVE

The aim of our study was to test whether ketamine produces an antidepressant effect in animal model of olfactory bulbectomy and assess the role of mammalian target of rapamycin (mTOR) pathway in ketamine's antidepressant effect.

METHODS

Bulbectomized (OBX) rats and sham controls were assigned to four subgroups according to the treatment they received (ketamine, saline, ketamine + rapamycin, and saline + rapamycin). The animals were subjected to open field (OF), elevated plus maze (EPM), passive avoidance (PA), Morris water maze (MWM), and Carousel maze (CM) tests. Blood samples were collected before and after drug administration for analysis of phosphorylated mTOR level. After behavioral testing, brains were removed for evaluation of brain-derived neurotrophic factor (BDNF) in prefrontal cortex (PFC) and hippocampus.

RESULTS

Ketamine normalized hyperactivity of OBX animals in EPM and increased the time spent in open arms. Rapamycin pretreatment resulted in elimination of ketamine effect in EPM test. In CM test, ketamine + rapamycin administration led to cognitive impairment not observed in saline-, ketamine-, or saline + rapamycin-treated OBX rats. Prefrontal BDNF content was significantly decreased, and level of mTOR was significantly elevated in OBX groups.

CONCLUSIONS

OBX animals significantly differed from sham controls in most of the tests used. Treatment had more profound effect on OBX phenotype than controls. Pretreatment with rapamycin eliminated the anxiolytic and antidepressant effects of ketamine in task-dependent manner. The results indicate that ketamine + rapamycin application resulted in impaired stress responses manifested by cognitive deficits in active place avoidance (CM) test. Intensity of stressor (mild vs. severe) used in the behavioral tests had opposite effect on controls and on OBX animals.

Aerobic exercise enhances neural correlates of motor skill learning

INTRODUCTION

Repetitive, in-phase bimanual motor training tasks can expand the excitable cortical area of the trained muscles. Recent evidence suggests that an acute bout of moderate-intensity aerobic exercise can enhance the induction of rapid motor plasticity at the motor hotspot. However, these changes have not been investigated throughout the entire cortical representation. Furthermore, it is unclear how exercise-induced changes in excitability may relate to motor performance. We investigated whether aerobic exercise could enhance the neural correlates of motor learning. We hypothesized that the combination of exercise and training would increase the excitable cortical area to a greater extent than either exercise or training alone, and that the addition of exercise would enhance performance on a motor training task.

METHODS

25 young, healthy, right-handed individuals were recruited and divided into two groups and three experimental conditions. The exercise group performed exercise alone (EX) and exercise followed by training (EXTR) while the training group performed training alone (TR).

RESULTS

The combination of exercise and training increased excitability within the cortical map of the trained muscle to a greater extent than training alone. However, there was no difference in performance between the two groups. These results indicate that exercise may enhance the cortical adaptations to motor skill learning.

Neurobiological effects of exercise on major depressive disorder: A systematic review

Exercise displays promise as an efficacious treatment for people with depression. However, no systematic review has evaluated the neurobiological effects of exercise among people with major depressive disorder (MDD). The aim of this article was to systematically review the acute and chronic biological responses to exercise in people with MDD. Two authors conducted searches using Medline (PubMed), EMBASE and PsycINFO. From the searches, twenty studies were included within the review, representing 1353 people with MDD. The results demonstrate that a single bout of exercise increases atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), copepetin and growth hormone among people with MDD. Exercise also potentially promotes long-term adaptations of copeptin, thiobarbituric acid reactive species (TBARS) and total mean frequency (TMF). However, there is limited evidence that exercise promotes adaptations on neurogenesis, inflammation biomarkers and brain structure. Associations between depressive symptoms improvement and hippocampus volume and IL-1β were found. Nevertheless, the paucity of studies and limitations presented within, precludes a more definitive conclusion of the underlying neurobiological explanation for the antidepressant effect of exercise in people with MDD. Further trials should utilize appropriate assessments of neurobiological markers in order to build upon the results of our review and further clarify the potential mechanisms associated with the antidepressant effects of exercise.

Effects of a single bout of maximal aerobic exercise on BDNF in bipolar disorder: A gender-based response

Acute exercise increases brain-derived neurotrophic factor (BDNF) serum levels in majorly depressed and anxious patients. However, to the best of our knowledge, no study has evaluated the acute effects of exercise on BDNF serum levels in Bipolar Disorder (BD). The objective of the present study was to evaluate the peripheral BDNF serum response to a single maximum session of exercise in BD participants and age- and gender-matched healthy participants. BD participants (n=18) and age- and gender-matched healthy participants (n=18) were recruited to perform a single bout of maximal exercise on a cycle ergometer. Blood samples were collected prior to and immediately after the exercise protocol. There was a significant group effect and a significant group x time x gender interaction. BD participants presented significantly higher BDNF serum levels when compared to their healthy control counterparts. Exercise increases the BDNF levels of BD women, but not men.

Dose-and gender-specific effects of resistance training on circulating levels of brain derived neurotrophic factor (BDNF) in community-dwelling older adults

BACKGROUND

BDNF is known to induce neuroplasticity and low circulating levels have been related to neuronal loss in older persons. Physical exercise is thought to trigger BDNF-induced neuroplasticity, but conflicting observations have been reported regarding the effects of resistance training on circulating BDNF in the elderly. These conflicting observations might reflect dose-and gender-specific differences.

METHOD

Fifty-six apparently healthy elderly (68 ± 5 years) participants were randomized to 12 weeks of resistance training (3×/week) at either high-resistance (HIGH, 8 Males, 10 Females, 2 × 10-15 repetitions at 80% 1 RM), low-resistance (LOW, 9 Males, 10 Females, 1 × 80-100 repetitions at 20% 1 RM), or mixed low-resistance (LOW+, 9 Males, 10 Females, 1 × 60 repetitions at 20% 1 RM followed by 1 × 10-20 repetitions at 40% 1 RM). Serum was collected for BDNF assay at baseline and after 12 weeks (24 h-48 h after the last training).

RESULTS

12 weeks of LOW+ exercise significantly increased BDNF levels in male (from 34.9 ± 10.7 ng/mL to 42.9 ± 11.9 ng/mL, time × group interaction p=0.013), but not in female participants. No significant change was observed in HIGH or LOW, neither in male nor female subjects.

CONCLUSION

Our results show that only the mixed-low-resistance training program with a very high number of repetitions at a sufficiently high external resistance was able to increase circulating BDNF in older male participants. Training to volitional fatigue might be necessary to obtain optimal results. Additional studies are needed to unravel the underlying mechanisms, as well as to confirm the observed gender difference.

Brain-derived neurotrophic factor and substrate utilization following acute aerobic exercise in obese individuals

Brain-derived neurotrophic factor (BDNF) serves as a vital regulator of neuronal proliferation and survival, and has been shown to regulate energy homeostasis, glucose metabolism and body weight maintenance. Elevated concentrations of plasma BDNF have been associated with obesity and type 2 diabetes mellitus. Acute aerobic exercise transiently increases circulating BDNF, potentially correcting obesity-related metabolic impairment. The present study aimed to compare acute aerobic exercise elicited BDNF responses in obese and normal-weight subjects. Furthermore, we aimed to investigate whether acute exercise-induced plasma BDNF elevations would be associated with improved indices of insulin resistance, as well as substrate utilization [carbohydrate oxidation (CHOoxi) and fat oxidation (FAToxi)]. Twenty-two healthy, untrained subjects [11 obese (four men and seven women; age = 22.91 ± 4.44 years; body mass index = 35.72 ± 4.17 kg/m(2)) and 11 normal-weight (five men and six women; age = 23.27 ± 2.24 years; body mass index = 21.89 ± 1.63 kg/m(2))] performed 30 min of continuous submaximal aerobic exercise at 75% maximal oxygen consumption. Our analyses showed that the BDNF response to acute aerobic exercise was similar in obese and normal-weight subjects across time (time: P = 0.015; group: P = not significant) and was not associated with indices of IR. Although no differences in the rates of CHOoxi and FAToxi were found between both groups, total relative energy expenditure was significantly lower in obese subjects compared to normal-weight subjects (3.53 ± 0.25 versus 5.59 ± 0.85; P < 0.001). These findings suggest that acute exercise-elicited BDNF elevation may not be sufficient to modulate indices of IR or the utilization of either carbohydrates or fats in obese individuals.

Exercise Augmentation of Exposure Therapy for PTSD: Rationale and Pilot Efficacy Data

Brain-derived neurotrophic factor (BDNF) is associated with synaptic plasticity, which is crucial for long-term learning and memory. Some studies suggest that people suffering from anxiety disorders show reduced BDNF relative to healthy controls. Lower BDNF is associated with impaired learning, cognitive deficits, and poor exposure-based treatment outcomes. A series of studies with rats showed that exercise elevates BDNF and enhances fear extinction. However, this strategy has not been tested in humans. In this pilot study, we randomized participants (N = 9, 8 females, M(Age) = 34) with posttraumatic stress disorder (PTSD) to (a) prolonged exposure alone (PE) or (b) prolonged exposure+exercise (PE+E). Participants randomized to the PE+E condition completed a 30-minute bout of moderate-intensity treadmill exercise (70% of age-predicted HR(max)) prior to each PE session. Consistent with prediction, the PE+E group showed a greater improvement in PTSD symptoms (d = 2.65) and elevated BDNF (d = 1.08) relative to the PE only condition. This pilot study provides initial support for further investigation into exercise augmented exposure therapy.

Exercise and severe major depression: effect on symptom severity and quality of life at discharge in an inpatient cohort

BACKGROUND

Exercise is a potential treatment for depression. However, few studies have evaluated the role of adjunct exercise in the treatment of severely major depressed inpatients. The goal of this study was to evaluate the effects of add-on exercise on the usual treatment of severely depressed inpatients.

METHODS

Fifty participants were randomized to an exercise (exercise + usual treatment) or a control (usual treatment) group. Twenty-five patients were randomly allocated to each group. The participants in the exercise group performed three sessions per week throughout the hospitalization period, with a goal dose of 16.5 kcal/kg/week plus the usual pharmacological treatment. Depressive symptoms and the Quality of Life (QoL) of the participants were assessed at the baseline, the second week, and discharge.

RESULTS

A significant group × time interaction was found for depressive symptoms and the physical and psychological domains of QoL. Differences between groups occurred at the second week and discharge with respect to depressive symptoms and the physical and psychological domains of QoL. There was no difference in the remission rate at discharge (48% and 32% for the exercise and control group, respectively). An NNT of 6.25 was found. No significant baseline characteristics predict remission at discharge.

CONCLUSION

Add-on exercise is an efficacious treatment for severely depressed inpatients, improving their depressive symptoms and QoL. Initial acceptance of exercise remains a challenge.