October 04, 2022 8 min read

Mental health has moved forward as a topic of discussion in the last number of years.  Depression and anxiety are topics of conversation with a stigma that has reduced over time.  The WHO has indicated that there is a worldwide increase in mental health conditions. This has become especially pertinent after three years of undergoing a global pandemic.  Up until 2017 there was a 13% increase in reported mental health conditions and substance abuse (Mental health).  It is suspected that this number has increased due to a combination of factors attributed to mental health factors including negative mood, depression, and anxiety. Approximately one in five years is lived with disability impacting all demographics. There is evidence to suggest that socioeconomic factors including those of the 12 determinants of health contribute to mental health (Social determinants of health).  Globally, anxiety and depression alone cost the United States economy around $1 trillion USD annually (Mental health).  There are multiple factors that contribute to mental health, some which are still being studied to be better understood (Geus et al., 2021).  

Youth and adolescent populations struggle with mental health, though it may not always be detected.  Mental health issues may spill into various aspects of life including socialization and academic performance for university and college students.  Exercise can help these populations buffer stress and alter physiological functions that could have chemical and mechanical changes within the body providing a reduction in stress (Grasalsoen et al. 2020). Depression and anxiety need to be addressed in youth populations as there is an increased risk of developing cardiovascular disease in later life (Philippot et al 2022).  There are factors that should be considered including an increase in sedentary behaviours that may contribute to low mood.  

 

Elderly populations are impacted by stress and anxiety far more than other demographics due to a multitude of socioeconomic factors.  Elderly populations can have increased disability, an increase in interventions, greater support from the health care system and a reduction in quality of life.  Kazemina et al. found anxiety can present as physical symptoms including insomnia, urinary, cardiovascular, GI, behavioural and sensory disorders (2020).   Depression is often more difficult to treat effectively in older populations due to being masked by comorbidities and pharmaceuticals.  Social support appears to be a decent predictor of depressive symptoms, however exercise-induced mood and exercise self-efficacy both play a role in treatment (Leaderman et al. 2018).  

 

THE BRAIN WITH ANXIETY AND DEPRESSION

There has been a certain amount of research on trying to understand how exercise influences the brain in those with mood disorders.  The amygdala is a part of the limbic system of the brain; its job is to assess and respond to situations with fear and aggression.  It provides emotional meaning to our memories, plays a role in decision making and reward processing.  The amygdala has been associated with mental health conditions including generalized anxiety disorder, PTSD, OCD and social anxiety (Hu et al. 2020).  The orbitofrontal cortex is responsible for sensory integration, modulating visceral reactions, assisting with learning, and decision making in both reward and emotional related behaviours among other functions (Ge et al. 2021; Hu et al. 2020).  The orbitofrontal cortex provides input into the amygdala.  Exercise has a positive effect on the orbitofrontal cortex, increasing the amount of input into this region of the brain, thus improving coping (Ge et al. 2021; Hu et al. 2020).  Increasing the functional connectivity of the orbitofrontal cortex with the amygdala can promote emotional flexibility, reduce repetitive negative thinking, alter emotional response and decrease depression (Ge et al 2021).  Exercise can help the body maintain the proper functioning of the hypothalamic-pituitary-adrenal axis (HPA axis)(Grasalsoen et al. 2020).  This is where the hypothalamus (above brain stem), pituitary gland (above brain stem) and adrenal glands (kidneys) interact in direct response to stress (Know your brain).  It results in the secretion of hormones from the adrenal and endocrine systems including cortisol, epinephrine (adrenaline) and norepinephrine (noradrenaline) both of which are responsible for fight and flight and rest and digest responses of the body.  Prolonged exposure to cortisol can cause issues including suppressed immunity, obesity, cardiovascular disease, diabetes mellitus type 2 and depression (Grasalsoen et al. 2021; Know your brain).

 

EXERCISE DATA

Exercise has positive outcomes for all demographics, regardless of mental health status.  However, there is variability in what the research indicates when examining the effect of exercise on mental health.  Some studies find no significant longitudinal association or the association is limited to subgroups or to symptom counts but fails to extend to clinical diagnosed depression furthermore, various studies have demonstrated the existence of simultaneous reverse causal effects. (Geus 2021).   Cochrane review rates exercise as being moderately more effective than if someone were not to undergo therapy in relation to depressive symptom changes (2013).  The sample sizes examined were indicated to be small, more research is required to provide more robust information.  Cochrane review also indicates exercise is more effective than antidepressants however, not more effective than psychological therapies in the treatment of depression (2013).  Other studies suggest that the inhibition hypothesis, where there is a report of a lack of energy, anhedonia with social withdrawal can contribute to a negative outcome regarding regular exercise participation (Geus 2021).  Though there do appear to be some barriers to exercise in those with low mood, other studies do indicate observable benefits with the implementation of exercise as an adjunct to treatment. 

Studies on exercise for disordered mood indicate behavioural, physiological and psychological changes.  An increase in general health, improvements of emotional states including that of depression and anxiety (Kazeminia et al. 2020).  Psychologically, exercise provides a positive conditional reinforcement, helps distract the brain from threatening stimuli, improves feelings of self-esteem and self-empowerment.  Biologically, exercise can improve strength and conditioning which can improve locus of control, our sense of control in daily situations.  Improvements in functionality can provide greater independence in activities of daily living (ADLs) (Kazeminia et al. 2020).  An increase in muscle strength will reduce muscle tension over time, and can lead to improved locus of control and self-efficacy.  Physiologically, exercise will improve the release of certain neurotransmitters while inhibiting others as discussed earlier.  Exercise improves the body's capacity to tolerate stress as exercise is a stressor and though it temporarily increases exercise induced cortisol, helps the body regulate stress induced cortisol (Leaderman et al. 2018).  This crosses over with the protection hypothesis, discussed by Geus et al. that found  regular exercise can reduce depressive systems including increased neuroplasticity, reduced inflammation and cortisol levels, improve self-esteem, and social support  (2021).

Geus et al. indicate that many of the prospective studies examining the association between exercise and mental health reported that regular exercise was associated with less depression and anxiety (2021).  Robust findings have been found in RCTs in those who reported low initial levels of wellbeing of the exercise program, clinically depressed or clinically anxious patients, significant improvements were reported post intervention (Chan et al. 2019).  Though some RCTs did not find antidepressant effects with exercise, these studies have been criticized for their poor design (Geus 2021).  

A meta analysis reported beneficial psychological effects of exercise e.g. depressive and bipolar disorder that match or even exceed those who received pharmacological treatment only (Hu et al. 2020). Hu et al. indicate that consistency is important to see a positive correlation between exercise and positive outcomes (2020).  Bernstein and McNally found that those who have a maladaptive response to stressors including ruminating had higher instances of relapse and onset of depression and other emotional disorders (2018). However, implementing exercise styles like moderate-to-vigorous exercise was found to alleviate symptoms, this also resulted in a reduction in sedentary behavior (Ge et al. 2021; Hu et al. 2020).   Exercises augment positive moods, there is evidence to suggest that regular exercise can decrease or even in some instances prevent negative moods (Chan et al. 2019).  

Significant benefits were found with a physical exercise intervention when compared to a control population (Philippot et al 2022).  Studies indicate that structured group-based activities including tennis, ultimate frisbee, football, basketball, table tennis or indoor wall climbing provided physical and psychological benefits in youth populations as an adjunct to pharmacological interventions (Chan et al. 2018; Philippot et al. 2022). Providing access to fun, structured, group, supervised, task-oriented exercise programs within a community setting for adolescent and youth and elderly populations was found to have positive effects (Kazemina et al. 2020; Philippot et al. 2022).  Exercise can help older individuals gain a sense of social connection in a shared experience which in turn can help individuals cope with stress and depression (Leaderman et al 2018).   The combination of movement and socialization creates a sense of community and social support which may play a role in coping.

Exercise has been shown to have a significantly positive effect on self-reported mental health in participants.  Chekroud et al. indicated that  exercising  between two and six hours per week were found to be optimal dosage in providing lasting benefit with depressive symptoms (2018).  Moderate anaerobic exercise was consistently found to have positive outcomes for mood, depressive symptoms and anxiety in a multitude of studies however, the data was not as consistent as it was with anaerobic exercise (Chan et al. 2018).  Bouts of 10 to 30 minutes of exercise were found to be sufficient to improve mood.  Yoga was found to be mildly beneficial with those participants with severe anxiety symptoms while activities like Tai Chi were found to be a good adjunct when put in combination with medical therapies (Hu et al. 2020). The adjunct of mindfulness activities including meditation were found to have positive mood effects.   

More research is needed to determine the proper dosage and style of exercise needed, however a good take away is any exercise, particularly that which you enjoy is a good addition to your ADLs. There is enough data however to see that exercise has a positive influence on the brain and behaviour.  As such it may be a good motivator to consistently participate in daily bouts of exercise on a social or individual basis as a means to improve mood, cope with stress and improve multiple aspects of wellbeing.  The data suggests that making exercise a non negotiable facet of daily life may help all demographics through all stages of life.

References

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Chekroud, S. R., Gueorguieva, R., Zheutlin, A. B., Paulus, M., Krumholz, H. M., Krystal, J. H., & Chekroud, A. M. (2018, September). Association between physical exercise and mental health in 1.2 million individuals in the USA between 2011 and 2015: a cross-sectional study. Lancet Psychiatry5, 739-746.

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