Acute Exercise Influences Reward Processing in Highly Trained and Untrained Men

From movement to motivation: a proposed framework to understand the antidepressant effect of exercise

Depression is the leading cause of disability worldwide, exerting a profound negative impact on quality of life in those who experience it. Depression is associated with disruptions to several closely related neural and cognitive processes, including dopamine transmission, fronto-striatal brain activity and connectivity, reward processing and motivation. Physical activity, especially aerobic exercise, reduces depressive symptoms, but the mechanisms driving its antidepressant effects are poorly understood. Here we propose a novel hypothesis for understanding the antidepressant effects of exercise, centred on motivation, across different levels of explanation. There is robust evidence that aerobic exercise decreases systemic inflammation. Inflammation is known to reduce dopamine transmission, which in turn is strongly implicated in effort-based decision making for reward. Drawing on a broad range of research in humans and animals, we propose that by reducing inflammation and boosting dopamine transmission, with consequent effects on effort-based decision making for reward, exercise initially specifically improves 'interest-activity' symptoms of depression-namely anhedonia, fatigue and subjective cognitive impairment - by increasing propensity to exert effort. Extending this framework to the topic of cognitive control, we explain how cognitive impairment in depression may also be conceptualised through an effort-based decision-making framework, which may help to explain the impact of exercise on cognitive impairment. Understanding the mechanisms underlying the antidepressant effects of exercise could inform the development of novel intervention strategies, in particular personalised interventions and boost social prescribing.

Fractional amplitude of low-frequency fluctuations associated with μ-opioid and dopamine receptor distributions in the central nervous system after high-intensity exercise bouts

Introduction

Dopaminergic, opiod and endocannabinoid neurotransmission are thought to play an important role in the neurobiology of acute exercise and, in particular, in mediating positive affective responses and reward processes. Recent evidence indicates that changes in fractional amplitude of low-frequency fluctuations (zfALFF) in resting-state functional MRI (rs-fMRI) may reflect changes in specific neurotransmitter systems as tested by means of spatial correlation analyses.

Methods

Here, we investigated this relationship at different exercise intensities in twenty young healthy trained athletes performing low-intensity (LIIE), high-intensity (HIIE) interval exercises, and a control condition on three separate days. Positive And Negative Affect Schedule (PANAS) scores and rs-fMRI were acquired before and after each of the three experimental conditions. Respective zfALFF changes were analyzed using repeated measures ANOVAs. We examined the spatial correspondence of changes in zfALFF before and after training with the available neurotransmitter maps across all voxels and additionally, hypothesis-driven, for neurotransmitter maps implicated in the neurobiology of exercise (dopaminergic, opiodic and endocannabinoid) in specific brain networks associated with "reward" and "emotion."

Results

Elevated PANAS Positive Affect was observed after LIIE and HIIE but not after the control condition. HIIE compared to the control condition resulted in differential zfALFF decreases in precuneus, temporo-occipital, midcingulate and frontal regions, thalamus, and cerebellum, whereas differential zfALFF increases were identified in hypothalamus, pituitary, and periaqueductal gray. The spatial alteration patterns in zfALFF during HIIE were positively associated with dopaminergic and μ-opioidergic receptor distributions within the 'reward' network.

Discussion

These findings provide new insight into the neurobiology of exercise supporting the importance of reward-related neurotransmission at least during high-intensity physical activity.

Physical Activity Alters Functional Connectivity of Orbitofrontal Cortex Subdivisions in Healthy Young Adults: A Longitudinal fMRI Study

Physical activity (PA) plays an important role in affect processing. Studies describe the orbitofrontal cortex (OFC) as a major hub for emotion processing and the pathophysiology of affective disorders. Subregions of the OFC show diverse functional connectivity (FC) topographies, but the effect of chronic PA on subregional OFC FC still lacks scientific understanding. Therefore, we aimed at investigating the effects of regular PA on the FC topographies of OFC subregions in healthy individuals within a longitudinal randomized controlled exercise study. Participants (age: 18-35 years) were randomly assigned to either an intervention group (IG; N = 18) or a control group (CG; N = 10). Fitness assessments, mood questionnaires, and resting state functional magnetic resonance imaging (rsfMRI) were performed four times over the duration of 6 months. Using a detailed parcellation of the OFC, we created subregional FC topography maps at each time point and applied a linear mixed model to assess the effects of regular PA. The posterior-lateral right OFC showed a group and time interaction, revealing decreased FC with the left dorsolateral prefrontal cortex in the IG, while FC in the CG increased. Group and time interaction in the anterior-lateral right OFC with the right middle frontal gyrus was driven by increased FC in the IG. The posterior-lateral left OFC showed a group and time interaction based on differential change in FC to the left postcentral gyrus and the right occipital gyrus. This study emphasized regionally distinctive FC changes induced by PA within the lateral OFC territory, while providing aspects for further research.

Exercise Addiction - Status, Identification and Treatment

The term "exercise addiction" has been used in the scientific literature since the late 1970s. It is used to refer to persistent excessive exercise despite negative physical, psychological and social consequences, with unsuccessful attempts to reduce or stop the behavior. In this article, the evidence for exercise addiction as a behavioral addiction is presented. Symptoms and psychiatric comorbidities are explained, and recommendations for identification and treatment of exercise addiction are presented.

The effect of physical activity on anhedonia in individuals with depressive symptoms

The therapeutic effect of antidepressants has been demonstrated for anhedonia in patients with depression. However, antidepressants may cause side-effects, such as cardiovascular dysfunction. Although physical activity has minor side-effects, it may serve as an alternative for improving anhedonia and depression. We sought to investigate whether physical activity reduces the level of anhedonia in individuals with depression. Fifty-six university students with moderate depressive symptoms (Beck Depression Inventory total score > 16) were divided into three training groups: the Running Group (RG, n = 19), the Stretching Group (SG, n = 19), and the Control Group (n = 18). We employed the Monetary Incentive Delay (MID) task and the Temporal Experience of Pleasure Scale (TEPS) to evaluate hedonic capacity. All participants in the RG and SG received 8 weeks of jogging and stretching training, respectively. The RG experienced an increase in the level of arousal during anticipation of a future reward and recalled less negativity towards the loss condition. The SG exhibited enhanced scores on the Anticipatory and Consummatory Pleasure subscales of the TEPS after training. Moreover, in the RG, greater improvements in anticipatory arousal ratings for pleasure and remembered valence ratings for negative affect were associated with longer training duration, lower maximum heart rate, and higher consumed calories during training. To conclude, physical activity is effective in improving anticipatory anhedonia in individuals with depressive symptoms.

Transdiagnostic neuroimaging of reward system phenotypes in ADHD and comorbid disorders

ADHD is a disorder characterized by changes in the reward system and which is highly comorbid with other mental disorders, suggesting common neurobiological pathways. Transdiagnostic neuroimaging findings could help to understand whether a dysregulated reward pathway might be the actual link between ADHD and its comorbidities. We here synthesize ADHD neuroimaging findings on the reward system with findings in obesity, depression, and substance use disorder including their comorbid appearance regarding neuroanatomical features (structural MRI) and activation patterns (resting-state and functional MRI). We focus on findings from monetary-incentive-delay (MID) and delay-discounting (DD) tasks and then review data on striatal connectivity and volumetry. Next, for better understanding of comorbidity in adult ADHD, we discuss these neuroimaging features in ADHD, obesity, depression and substance use disorder and ask whether ADHD heterogeneity and comorbidity are reflected by a common dysregulation in the reward system. Finally, we highlight conceptual issues related to heterogeneous paradigms, different phenotyping, longitudinal prediction and highlight some promising future directions for using striatal reward functioning as a clinical biomarker.

The Effect of Tai Chi Chuan on Emotional Health: Potential Mechanisms and Prefrontal Cortex Hypothesis

Deep involvement in the negative mood over long periods of time likely results in emotional disturbances/disorders and poor mental health. Tai Chi Chuan (TCC) is regarded as a typical mind-body practice combining aerobic exercise and meditation to prevent and treat negative mood. Although there are an increasing number of TCC studies examining anxiety, depression, and mental stress, the mechanisms underlying these negative emotions are not fully understood. This review study examined TCC studies related to emotional health from both clinical patients and healthy individuals. Next, several potential mechanisms from physiological, psychological, and neurological perspectives were evaluated based on direct and indirect research evidence. We reviewed recent functional magnetic resonance imaging studies, which demonstrated changes in brain anatomy and function, mainly in the prefrontal cortex, following TCC practice. Finally, the effects of TCC on emotion/mental health is depicted with a prefrontal cortex hypothesis that proposed “an immune system of the mind” indicating the role of the prefrontal cortex as a flexible hub in regulating an individual's mental health. The prefrontal cortex is likely a key biomarker among the multiple complex neural correlates to help an individual manage negative emotions/mental health. Future research is needed to examine TCC effects on mental health by examining the relationship between the executive control system (mainly prefrontal cortex) and limbic network (including amygdala, insula, and hippocampal gyrus).

Basal ganglia lateralization in different types of reward

Reward processing is a fundamental human activity. The basal ganglia are recognized for their role in reward processes; however, specific roles of the different nuclei (e.g., nucleus accumbens, caudate, putamen and globus pallidus) remain unclear. Using quantitative meta-analyses we assessed whole-brain and basal ganglia specific contributions to money, erotic, and food reward processing. We analyzed data from 190 fMRI studies which reported stereotaxic coordinates of whole-brain, within-group results from healthy adult participants. Results showed concordance in overlapping and distinct cortical and sub-cortical brain regions as a function of reward type. Common to all reward types was concordance in basal ganglia nuclei, with distinct differences in hemispheric dominance and spatial extent in response to the different reward types. Food reward processing favored the right hemisphere; erotic rewards favored the right lateral globus pallidus and left caudate body. Money rewards engaged the basal ganglia bilaterally including its most anterior part, nucleus accumbens. We conclude by proposing a model of common reward processing in the basal ganglia and separate models for money, erotic, and food rewards.

The Role of Exercise in Management of Mental Health Disorders: An Integrative Review

A large and growing body of evidence suggests that physical activity (PA) may hold therapeutic promise in the management of mental health disorders. Most evidence linking PA to mental health outcomes has focused on the effects of aerobic exercise training on depression, although a growing body of work supports the efficacy of both aerobic and resistance exercise paradigms in the treatment of anxiety and post-traumatic stress disorder. Despite abundant evidence linking PA and mental health, use of exercise training as a mental health treatment remains limited due to three important sources of uncertainty: (a) large individual differences in response to exercise treatment within multiple mental health domains; (b) the critical importance of sustained PA engagement, not always achieved, for therapeutic benefit; and (c) disagreement regarding the relative importance of putative therapeutic mechanisms. Our review of treatment data on exercise interventions and mental health outcomes focuses primarily on depression and anxiety within a health neuroscience framework. Within this conceptual framework, neurobiological and behavioral mechanisms may have additiveor synergistic influences on key cognitive and behavioral processes that influence mental health outcomes. We therefore highlight sources of treatment heterogeneity by integrating the critical influences of (a) neurobiological mechanisms enhancing neuroplasticity and (b) behavioral learning of self-regulatory skills. Understanding the interrelationships between dynamic neurobiological and behavioral mechanisms may help inform personalized mental health treatments and clarify why, and for whom, exercise improves mental health outcomes. The review concludes with recommendations for future studies leveraging individual differences to refine treatment approaches to optimize mental health benefits.

The Effects of a 12-Month Weight Loss Intervention on Cognitive Outcomes in Adults with Overweight and Obesity

Obesity is associated with poorer executive functioning and reward sensitivity. Yet, we know very little about whether weight loss through diet and/or increased exercise engagement improves cognitive function. This study evaluated whether weight loss following a dietary and exercise intervention was associated with improved cognitive performance. We enrolled 125 middle-aged adults with overweight and obesity (98 female) into a 12-month behavioral weight loss intervention. Participants were assigned to one of three groups: energy-restricted diet alone, an energy-restricted diet plus 150 min of moderate intensity exercise per week or an energy restricted diet plus 250 min of exercise per week. All participants completed tests measuring executive functioning and/or reward sensitivity, including the Iowa Gambling Task (IGT). Following the intervention, weight significantly decreased in all groups. A MANCOVA controlling for age, sex and race revealed a significant multivariate effect of group on cognitive changes. Post-hoc ANCOVAs revealed a Group × Time interaction only on IGT reward sensitivity, such that the high exercise group improved their performance relative to the other two intervention groups. Post-hoc ANCOVAs also revealed a main effect of Time, independent of intervention group, on IGT net payoff score. Changes in weight were not associated with other changes in cognitive performance. Engaging in a high amount of exercise improved reward sensitivity above and beyond weight loss alone. This suggests that there is additional benefit to adding exercise into behavioral weight loss regimens on executive functioning, even without additional benefit to weight loss.

Affect Improvements and Measurement Concordance Between a Subjective and an Accelerometric Estimate of Physical Activity

Abstract. Objectives: Physical activity (PA) positively influences several aspects of mental well-being including affect improvements. Yet, the fact that subjective and objective measures of PA often diverge challenges research on the relationship of PA and affect. Methods: Subjective (ecological momentary assessment, EMA) and objective (combined heart rate and accelerometric activity tracker) measures of PA alongside repeated ratings of positive and negative affects were obtained from 37 participants over 7 consecutive days. Results: Subjective and objective PA were significantly positively correlated. Affect improvements, that is, negative affect decrease as well as positive affect increase, were predicted by both subjective (EMA) and objective (activity tracker) data. Conclusions: Measurement concordance supports the validity of both assessment strategies. Affect improvements result from both subjective representations of one’s own activity as well as from physiological mechanisms of PA that one is not aware of, suggesting two independent routes to affect improvements.

Affective Modulation after High-Intensity Exercise Is Associated with Prolonged Amygdalar-Insular Functional Connectivity Increase

Acute moderate exercise has been shown to induce prolonged changes in functional connectivity (FC) within affect and reward networks. The influence of different exercise intensities on FC has not yet been explored. Twenty-five male athletes underwent 30 min of “low”- (35% < lactate threshold (LT)) and “high”- (20% > LT) intensity exercise bouts on a treadmill. Resting-state fMRI was acquired at 3 Tesla before and after exercise, together with the Positive and Negative Affect Scale (PANAS). Data of 22 subjects (3 dropouts) were analyzed using the FSL feat pipeline and a seed-to-network-based analysis with the bilateral amygdala as the seed region for determining associated FC changes in the “emotional brain.” Data were analyzed using a repeated measures ANOVA. Comparisons between pre- and post-exercise were analyzed using a one-sample t-test, and a paired t-test was used for the comparison between “low” and “high” exercise conditions (nonparametric randomization approach, results reported at p < 0.05). Both exercise interventions induced significant increases in the PANAS positive affect scale. There was a significant interaction effect of amygdalar FC to the right anterior insula, and this amygdalar-insular FC correlated significantly with the PANAS positive affect scale (r = 0.47, p = 0.048) in the “high”-intensity exercise condition. Our findings suggest that mood changes after exercise are associated with prolonged alterations in amygdalar-insular FC and occur in an exercise intensity-dependent manner.

The Contribution of Functional Magnetic Resonance Imaging to the Understanding of the Effects of Acute Physical Exercise on Cognition

The fact that a single bout of acute physical exercise has a positive impact on cognition is well-established in the literature, but the neural correlates that underlie these cognitive improvements are not well understood. Here, the use of neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), offers great potential, which is just starting to be recognized. This review aims at providing an overview of those studies that used fMRI to investigate the effects of acute physical exercises on cerebral hemodynamics and cognition. To this end, a systematic literature survey was conducted by two independent reviewers across five electronic databases. The search returned 668 studies, of which 14 studies met the inclusion criteria and were analyzed in this systematic review. Although the findings of the reviewed studies suggest that acute physical exercise (e.g., cycling) leads to profound changes in functional brain activation, the small number of available studies and the great variability in the study protocols limits the conclusions that can be drawn with certainty. In order to overcome these limitations, new, more well-designed trials are needed that (i) use a more rigorous study design, (ii) apply more sophisticated filter methods in fMRI data analysis, (iii) describe the applied processing steps of fMRI data analysis in more detail, and (iv) provide a more precise exercise prescription.

Effects of low- and high-intensity exercise on emotional face processing: an fMRI face-matching study

Physical exercise has positive effects on mood and it reduces clinical depression and states of anxiety. While previous work mostly used subjective measures to study the effect of exercise upon emotions, this study for the first time employed blood oxygen level dependent functional magnetic resonance imaging (fMRI) to unravel associated neuronal changes of the emotional face-processing network in response to acute exercise. A total of 25 male athletes underwent fitness assessments to define two standardized 30 min exercise interventions (low and high intensity). The Positive and Negative Affect Schedule (PANAS) was completed pre- and post-exercise and neuronal responses to neutral, happy and fearful facial expressions were determined using an fMRI-based face-matching paradigm. Complete data sets were acquired in 21 participants (mean age, 27.2 ± 4.2 years). Both exercise interventions induced significant increases of the PANAS positive affect scale. Modulations of brain activation patterns following acute exercise were found only for fearful facial stimuli vs forms: reduced brain activation in posterior cingulate cortex/precuneus for the low condition and reduced activity in caudate nucleus and ventral anterior putamen for the high condition. In conclusion, this study provides first in vivo evidence that acute strenuous exercise interferes with emotional face-processing brain regions in an emotion type-specific manner.

The effect of mind-body and aerobic exercise on negative symptoms in schizophrenia: A meta-analysis

OBJECTIVE

This meta-analysis aims to evaluate the effects of different types of physical exercise (PE) on negative symptoms in schizophrenia patients. Mind-body exercise (MBE), aerobic exercise (AE) and resistance training (RT) will be investigated.

METHOD

The Cochrane Library, Medline, Embase and PsycINFO were searched from their inception until April 26, 2018. Randomized controlled trials comparing PE with any control group in patients with schizophrenia were included when negative symptoms had been assessed. This meta-analysis was conducted according to the PRISMA guidelines. The methodological quality of the included studies was assessed with the Cochrane Risk of Bias assessment tool. Moderator, sensitivity, and meta regression analyses were conducted to explore causes of heterogeneity and impact of study quality.

RESULTS

We included 22 studies (N = 1249). The overall methodological quality was poor. The meta-analysis (random effects model) showed a medium significant effect in favor of any PE intervention (Hedges' g = 0.434, 95% CI = 0.196-0.671) versus any control condition. MBE and AE respectively showed a medium significant effect (Hedges' g = 0.461) and a small significant effect (Hedges' g = 0.341) versus any control condition. The effect of RT could not be examined. The overall heterogeneity was high (I² = 76%) and could not be reduced with moderator or sensitivity analyses.

CONCLUSION

This meta-analysis demonstrated that PE could be a promising intervention in the treatment of negative symptoms. However, the quality of the included studies was low and heterogeneity was high, which makes it impossible to make a clear recommendation. Therefore, results should be interpreted with care.

Effects of an acute bout of physical exercise on reward functioning in healthy adults

Exercise has been proposed as a treatment for several psychiatric disorders. Exercise may act in part through beneficial effects on reward functioning, as it alters neurotransmitter levels in reward-related circuits. However, there has been little investigation of the effect of exercise on reward functions in humans. We hypothesized an acute bout of exercise would increase motivation for and pleasurable responses to rewards in healthy humans. In addition, we examined possible moderators of exercise's effects, including demographics, fitness and previous exercise experience. Thirty-five participants completed exercise and sedentary control sessions in randomized, counterbalanced order on separate days. Immediately after each activity, participants completed measures of motivation for and pleasurable responses to rewards, consisting of willingness to exert effort for monetary rewards and subjective responses to emotional pictures. Exercise did not increase motivation or pleasurable responses on average. However, individuals who had been running for more years showed increases in motivation for rewards after exercise, while individuals with less years running showed decreases. Further, individuals with higher resting heart rate variability reported lower arousal in response to all emotional pictures after exercise, while individuals with low heart rate variability reported increased arousal in response to all emotional pictures after exercise. General fitness did not have similar moderating effects. In conclusion, acute exercise improved reward functioning only in individuals accustomed to that type of exercise. This suggests a possible conditioned effect of exercise on reward functioning. Previous experience with the exercise used should be examined as a possible moderator in exercise treatment trials.

The Acute Effects of Aerobic Exercise on the Functional Connectivity of Human Brain Networks

Although there is promising evidence that regular physical activity could counteract age-related decline in cognitive and brain function, the mechanisms for this neuroprotection remain unclear. The acute effects of exercise can provide insight into the mechanisms by which the brain adapts to habitual exercise by reflecting transient modulations of systems that would subsequently accumulate long-term adaptations through repeated training sessions. However, methodological limitations have hindered the mechanistic insight gained from previous studies examining acute exercise effects on the human brain. In the current study, we tested the plasticity of functional brain networks in response to a single stimulus of aerobic exercise using resting-state functional connectivity analyses. In a sample of healthy younger (N = 12; age = 23.2 years; 6 females) and older adults (N = 13; age = 66.3 years; 6 females), we found that 30 minutes of moderate-intensity aerobic cycling selectively increased synchrony among brain regions associated with affect and reward processing, learning and memory, and in regions important for attention and executive control. Importantly, these changes did not occur when the same participants completed a passive, motor-driven control condition. Our results suggest that these transient increases in synchrony serve as a possible avenue for systematically investigating the effects of various exercise parameters on specific brain systems, which may accelerate mechanistic discoveries about the benefits of exercise on brain and cognitive function.

Exercise-based treatments for substance use disorders: evidence, theory, and practicality

BACKGROUND

Epidemiological studies reveal that individuals who report risky substance use are generally less likely to meet physical activity guidelines (with the exception of certain population segments, such as adolescents and athletes). A growing body of evidence suggests that individuals with substance use disorders (SUDs) are interested in exercising and that they may derive benefits from regular exercise, in terms of both general health/fitness and SUD recovery.

OBJECTIVES

The aims of this paper were to: (i) summarize the research examining the effects of exercise-based treatments for SUDs; (ii) discuss the theoretical mechanisms and practical reasons for investigating this topic; (iii) identify the outstanding relevant research questions that warrant further inquiry; and (iv) describe potential implications for practice.

METHODS

The following databases were searched for peer-reviewed original and review papers on the topic of substance use and exercise: PubMed Central, MEDLINE, EMBASE, PsycINFO, and CINAHL Plus. Reference lists of these publications were subsequently searched for any missed but relevant manuscripts. Identified papers were reviewed and summarized by both authors.

RESULTS

The limited research conducted suggests that exercise may be an effective adjunctive treatment for SUDs. In contrast to the scarce intervention trials to date, a relative abundance of literature on the theoretical and practical reasons supporting the investigation of this topic has been published.

CONCLUSIONS

Definitive conclusions are difficult to draw due to diverse study protocols and low adherence to exercise programs, among other problems. Despite the currently limited and inconsistent evidence, numerous theoretical and practical reasons support exercise-based treatments for SUDs, including psychological, behavioral, neurobiological, nearly universal safety profile, and overall positive health effects.

The stress-buffering effect of acute exercise: Evidence for HPA axis negative feedback

According to the cross-stressor adaptation hypothesis, physically trained individuals show lower physiological and psychological responses to stressors other than exercise, e.g. psychosocial stress. Reduced stress reactivity may constitute a mechanism of action for the beneficial effects of exercise in maintaining mental health. With regard to neural and psychoneuroendocrine stress responses, the acute stress-buffering effects of exercise have not been investigated yet. A sample of highly trained (HT) and sedentary (SED) young men was randomized to either exercise on a treadmill at moderate intensity (60-70% VO2max; AER) for 30 min, or to perform 30 min of "placebo" exercise (PLAC). 90 min later, an fMRI experiment was conducted using an adapted version of the Montreal Imaging Stress Task (MIST). The subjective and psychoneuroendocrine (cortisol and α-amylase) changes induced by the exercise intervention and the MIST were assessed, as well as neural activations during the MIST. Finally, associations between the different stress responses were analysed. Participants of the AER group showed a significantly reduced cortisol response to the MIST, which was inversely related to the previous exercise-induced α-amylase and cortisol fluctuations. With regard to the sustained BOLD signal, we found higher bilateral hippocampus (Hipp) activity and lower prefrontal cortex (PFC) activity in the AER group. Participants with a higher aerobic fitness showed lower cortisol responses to the MIST. As the Hipp and PFC are brain structures prominently involved in the regulation of the hypothalamus-pituitary-adrenal (HPA) axis, these findings indicate that the acute stress-buffering effect of exercise relies on negative feedback mechanisms. Positive affective changes after exercise appear as important moderators largely accounting for the effects related to physical fitness.

Increased adult hippocampal neurogenesis is not necessary for wheel running to abolish conditioned place preference for cocaine in mice

Recent evidence suggests that wheel running can abolish conditioned place preference (CPP) for cocaine in mice. Running significantly increases the number of new neurons in the hippocampus, and new neurons have been hypothesised to enhance plasticity and behavioral flexibility. Therefore, we tested the hypothesis that increased neurogenesis was necessary for exercise to abolish cocaine CPP. Male nestin-thymidine kinase transgenic mice were conditioned with cocaine, and then housed with or without running wheels for 32 days. Half of the mice were fed chow containing valganciclovir to induce apoptosis in newly divided neurons, and the other half were fed standard chow. For the first 10 days, mice received daily injections of bromodeoxyuridine (BrdU) to label dividing cells. On the last 4 days, mice were tested for CPP, and then euthanized for measurement of adult hippocampal neurogenesis by counting the number of BrdU-positive neurons in the dentate gyrus. Levels of running were similar in mice fed valganciclovir-containing chow and normal chow. Valganciclovir significantly reduced the numbers of neurons (BrdU-positive/NeuN-positive) in the dentate gyrus of both sedentary mice and runner mice. Valganciclovir-fed runner mice showed similar levels of neurogenesis as sedentary, normal-fed controls. However, valganciclovir-fed runner mice showed the same abolishment of CPP as runner mice with intact neurogenesis. The results demonstrate that elevated adult hippocampal neurogenesis resulting from running is not necessary for running to abolish cocaine CPP in mice.

Physical activity patterns and risk of depression in young adulthood: a 20-year cohort study since childhood

PURPOSE

Little is known about how physical activity patterns during childhood and adolescence are associated with risk of subsequent depression. We examined prospective and retrospective associations between leisure physical activity patterns from childhood to adulthood and risk of clinical depression in young adulthood.

METHODS

Participants (759 males, 871 females) in a national survey, aged 9-15 years, were re-interviewed approximately 20 years later. Leisure physical activity was self-reported at baseline (1985) and follow-up (2004-2006). To bridge the interval between the two time-points, historical leisure activity from age 15 years to adulthood was self-reported retrospectively at follow-up. Physical activity was categorized into groups that, from a public health perspective, compared patterns that were least beneficial (persistently inactive) with those increasingly beneficial (decreasing, increasing and persistently active). Depression (major depressive or dysthymic disorder) was assessed using the Composite International Diagnostic Interview.

RESULTS

Compared with those persistently inactive, males who were increasingly and persistently active had a 69 and 65 % reduced risk of depression in adulthood, respectively (all p < 0.05). In retrospective analyses, females who were persistently active had a 51 % reduced risk of depression in adulthood (p = 0.01). Similar but non-significant trends were observed for leisure physical activity in females and historical leisure activity in males. Results excluded those with childhood onset of depression and were adjusted for various sociodemographic and health covariates.

CONCLUSIONS

Findings from both prospective and retrospective analyses indicate a beneficial effect of habitual discretionary physical activity since childhood on risk of depression in young adulthood.

A laboratory-based evaluation of exercise plus contingency management for reducing cigarette smoking

BACKGROUND

Both contingency management (CM) and exercise have shown promise as smoking cessation treatments, but their combined effects have not been evaluated. The present study evaluated whether CM (in which motivational incentives are provided for abstinence) plus exercise reduced smoking more than either component alone.

METHOD

In a within-subjects design, 20 smokers were exposed to exercise plus CM, exercise plus CM-control (non-contingent incentives), inactivity plus CM, and inactivity plus CM-control.

RESULTS

CM increased latencies to smoke and decreased total puffs (Mdns = 39.6 min and .8 puffs, respectively) relative to CM-control (Mdns = 2.5 min and 12.8 puffs). Exercise decreased craving relative to baseline for craving based on both the pleasurable consequences of smoking (D=-10.7 on a 100-point visual analog scale) and anticipated relief from withdrawal (D=-5.9), whereas inactivity increased both components of craving (Ds=7.6 and 3.5). Exercise had no effect on smoking or a measure of temporal discounting.

CONCLUSIONS

Although exercise decreased craving, it did not affect smoking behavior. Exercise plus CM was not more effective than CM alone.