Is Exercise an Effective Treatment for Anxiety and Depression?

Although rarely promoted, exercise may be an important part of the treatment process for anxiety and depression, conditions at the forefront of New Zealand’s mental health crisis.

Before we get into the detail, I’ve got an important distinction to make.

Regarding health in general, we tend to expect treatments to cure a problem by addressing it’s cause. With conditions such as anxiety and depression it isn’t that simple. Causes are usually multi-factorial, often unclear, and vary significantly from person to person.

As such, treatments often focus on helping people to manage or minimise symptoms, in order to improve their quality of life.

This distinction will become more obvious as you read on.

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Exercise and depression

OK, let’s get the ball rolling by looking at some recent research.

A meta-analysis of 25 randomised controlled trials (RCTs) examining the effects of exercise on depression [ref 1] found that:

• Overall, exercise had a large and significant antidepressant effect in people with depression, including major depressive disorder (MDD)
• Larger effects were found for interventions; in MDD, utilising aerobic exercise, at moderate and vigorous intensities, in supervised and unsupervised formats
• In MDD, larger effects were found for interventions; utilising aerobic exercise, at moderate intensity, and supervised by exercise professionals.

This analysis is particularly relevant because it:

1. Focused on studies that isolated exercise from conventional treatment options; pharmacotherapy (drugs) and psychotherapy (talk therapies).

The authors note that previous studies tended to underestimate the effect of exercise due to their design. Rather than directly comparing exercise to conventional treatments, exercise was often included alongside such treatments. For example, exercise AND pharmacotherapy/psychotherapy were compared to pharmacotherapy or psychotherapy alone. The effect of exercise was then established by subtracting it from the pharmacotherapy/psychotherapy effect.

As you’ll find out later, this ‘subtractive’ methodology is flawed because exercise overlaps, at least in part, with the mechanisms underlying conventional treatments. I.e., you can’t assume that the mechanisms by which exercise works are different than the mechanisms by which conventional treatments work.

2. Reinforced the importance of exercise professionals.

Gaining the full benefits of exercise requires exercise behaviours to be sustained. Previous research [ref 2] found that dropout rates were lower when exercise professionals delivered exercise interventions for people with depression. This meta-analysis supported that finding, especially for people with MDD.

Overall, the analysis doesn’t suggest that exercise is more or less effective than conventional treatments. Rather, it concludes that:

• Exercise is an effective treatment independent of other treatments
• By reducing dropout, exercise professionals significantly enhance the effectiveness of exercise.

Exercise and anxiety

A meta-analysis examining the anxiolytic (anti-anxiety) effects of exercise [ref 3] found that:

• Exercise significantly decreased anxiety symptoms in people with a currently diagnosed anxiety and/or stress-related disorder
• The effect of exercise was similar in magnitude to the anxiolytic effect gained from commonly used pharmacotherapies.

Again, the analysis doesn’t claim that exercise is more or less effective than conventional treatments. Rather, it suggests that exercise might be an alternative treatment for those who are unwilling to use, or unable to access, medication or psychotherapy.

Currently, the ability to access mental health services in Aotearoa is severely constrained. Long waiting times for psychotherapy inevitably result in a poor prognosis and more entrenched symptoms. So, finding effective, alternative treatments is essential.

The authors note that (unlike conventional treatments) the benefits of exercise extend considerably beyond treating anxiety symptoms. In particular, exercise helps reduce the greatly increased risk that people with anxiety disorders have for cardiovascular disease and associated mortality.

Examining the protective effect of exercise, another meta-analysis that followed 75,000 subjects over an average of 3.5 years [ref 4] found that:

• People with higher levels of physical activity (PA) had a 27% lower risk of developing an anxiety disorder or symptoms, when compared to people with lower levels of PA
• This protective effect was evident across countries, age groups, genders, as well as BMI and smoking status.

Taken together, these studies indicate that as well as protecting people from developing anxiety, exercise is an effective treatment for those with anxiety.

Now, it’s all well and good to know that exercise can be antidepressant and anxiolytic. We need to take the next step though and develop our understanding of the mechanisms by which exercise helps. Before we do that, we need to develop our base understanding of anxiety and depression.

What is depression?

Depression is a ‘mood disorder’. It is the most common of a group of conditions associated with the elevation or lowering of a person’s mood.

It’s important to note that depression is not the same as feeling sad in response to grief or bereavement. It is normal to feel sadness or grief in response to situations such as the death of a loved one, the loss of a job, or the breakdown of a relationship. In response to such circumstances, people often describe themselves as ‘feeling depressed’, although they are not suffering from the condition or disorder ‘depression’.

Depression (often diagnosed as clinical depression or major depressive disorder (MDD)) occurs where a person’s thoughts, feelings, and actions become and remain depressed for a prolonged period of time (at least 2+ weeks). Quite often, depression doesn’t occur in response to any particular event.

The symptoms of depression can vary from mild to severe and include:

• Feeling sad, having a depressed mood
• Losing interest or pleasure in previously enjoyable activities
• Changes in appetite – eating significantly more or less than normal
• Trouble sleeping or sleeping to much
• Loss of energy or increased fatigue
• Feeling worthless or guilty
• Difficulty with thinking, concentrating, and making decisions
• Thoughts of death or suicide.

While depression can occur at any time, it tends to appear first in the late teens to mid-20s. Females tend to be more likely to suffer from depression than males. However, males are significantly more likely to suicide than females.

Far less common than depression is the other major mood disorder, bipolar disorder. Otherwise known as manic depression, bipolar disorder involves major fluctuations in mood that can last for days, weeks and sometimes months. These fluctuations are either manic (abnormally high, happy, or irritable) or depressive (abnormally sad, unhappy).

What is anxiety?

Feeling anxious in response to stressful situations is completely normal. Everyone experiences anxiety from time to time. Anxiety can manifest in feeling nervous, jittery, or having ‘butterflies in the stomach’. Such feelings normally precede an important, stressful event such as an exam, business meeting, or initial date with a relative stranger. Anxiety may also manifest in feeling overwhelmed by a variety of tasks and expectations.

For most people, the feelings associated with anxiety dissipate after the stressful event.

In contrast, a person with an anxiety disorder experiences symptoms on a persistent basis. The feelings don’t dissipate. This can prevent the affected person from taking full participation in life. Often, a persons lifestyle will be altered to accommodate the anxiety; they might avoid leaving home due to the fear or worry associated with particular stressors.

Generalised anxiety disorder (GAD) is the most common of a variety of anxiety-related disorders. A person with GAD tends to worry, constantly and excessively about many things; family, health, finances, work, school, relationships etc. This can be physically and mentally exhausting. As such, it is common for people with GAD to also suffer from depression.

GAD normally develops gradually. It can begin at any time of life. However, the risk is highest between adolescence and middle age.

The symptoms of GAD usually include:

• Expecting the worst and having constant worries running through the head
• Worrying excessively and unnecessarily about a variety of factors
• Avoiding situations that cause anxiety
• Being irritable, unable to relax and enjoy quiet time
• Struggling to concentrate
• Suffering from stomach problems, nausea, diarrhoea, poor sleep
• Needing to know what’s going to happen in the future.

Does New Zealand have a problem with anxiety and depression?

Yes, we’ve got a major problem.

For adults (aged 15+) the 2020/21 New Zealand Health Survey tells us that:

• 17% (approx. 703,000) suffered from or had suffered from depression. This was an increase from 14.2% in 2011/12
• 0.9% (approx. 38,000) suffered from or had suffered from bipolar disorder
• 12.4% (approx. 515,000) suffered from or had suffered from an anxiety disorder, more than double the prevalence of 6.1% from 2011/12.

These statistics are based on survey respondents reporting that they had been diagnosed with a mood and/or anxiety disorder, by a doctor. As such, the numbers are likely to underestimate the true scale of the problem because:

• People may not be aware that they have or might have a mood or anxiety disorder
• People may be unable or unwilling to get a diagnosis from a doctor.

Additionally, there are some other important points to note:

• The prevalence of mood and anxiety disorders is significantly higher amongst Māori, people with disabilities, and those living in the most deprived areas
• While comparatively low, the prevalence of children with a diagnosed anxiety disorder has almost doubled from 2.1% in 2011/12, to 3.7% in 2020/21.

How does exercise help to treat anxiety and depression?

Anxiety and depression are conventionally treated via pharmacology and/or forms of psychotherapy. In this section, we’ll look at how exercise compares as a treatment across three areas: lifestyle, society, and first up; neurotransmitters.

1. The neurotransmitter effect

Pharmacological treatments for anxiety and depression are oriented on treating the biological factors believed to be ‘causing’ the condition, or its distressing symptoms. ‘Psychoactive’ drugs act to alter brain function by increasing or decreasing the activity of neurotransmitters at the synapse (communication junction between neurons).

For depression, the most commonly prescribed antidepressant drugs are known as ‘selective serotonin re-uptake inhibitors (SSRIs)’. These drugs block the re-uptake of serotonin by the transmitting neuron. This increases the availability of serotonin for receptors on the receiving neuron, thus enhancing serotonin’s ‘mood stabilising’ function.

Along with SSRIs, the most commonly prescribed anxiolytic drugs are benzodiazepines (benzos) such as Valium. These drugs act to reduce the symptoms of anxiety by increasing the responsiveness of neurons to the ‘calming’ neurotransmitter ‘GABA’ (Gamma-Aminobutyric Acid).

It’s worth noting that:

• Serotonin and GABA have multiple functions across the brain
• There are over 100 other neurotransmitters that also influence brain function
• The manifestation of anxiety and depression cannot simply be attributed to a singular lack of serotonin and/or GABA.

As such, pharmacological treatments really aren’t cures. They act largely to alleviate distressing symptoms by creating an alternate, happier and calmer brain state.

Now for those who are suffering in an acute sense, alleviating the distressing symptoms of anxiety and depression is certainly very important.

Exercise increases the availability of mood enhancing neurotransmitters

As the studies mentioned earlier indicate; exercise has both an antidepressant and anxiolytic effect.

In the short-term, these effects are likely mediated by an increase in certain ‘mood enhancing’ neurotransmitters, much like the pharmacological therapies. Exercise is associated with increases in:

• Serotonin (refer to the previous section)
• Dopamine (associated with pleasure and reward)
• Endorphins (the body’s natural pain reliever)

Of particular interest is the connection between anxiety and depression, exercise, and the neurotransmitter norepinephrine.

In response to exercise, there is an increase in levels of norepinephrine in regions of the brain involved in our emotional and stress responses. It is thought that norepinephrine modulates the actions of other neurotransmitters involved in the stress response.

Let me explain.

Exercise, especially strenuous exercise, is a stressor. Exercise produces many of the stress responses that also come with anxiety. In response to exercise stress, and via the action of norepinephrine, the body learns how to effectively manage the stress response. Consequently, learning how to manage the stress response via exercise helps people to avoid being overwhelmed by stress in non-exercise situations.

Helping people to understand and learn how to manage their stress response is a major objective of the psychotherapies. Exercise may help to achieve the same objective via physical, rather than cognitive means.

2. The lifestyle effect

Our lifestyle has changed significantly over the past 40-odd years. As such, researchers are starting to pay more attention to the impact lifestyle has on mental health.

A meta-analysis of 21 RCTs investigating dietary patterns and depression across 10 countries [ref 5] found that:

• High intakes of fruit, vegetables, whole grains, fish, olive oil, low-fat dairy and antioxidants, and low intakes of animal foods, were associated with a low risk of depression
• High consumption of red and/or processed meat, refined grains, sweets, high-fat dairy products, and low intakes of fruit and vegetables, were associated with an increased risk of depression.

Research also tells that mentally and physically active individuals are less likely to contract neurological disorders, and if they do, their symptoms tend to be less severe and their recovery better [ref 6]. While the majority of such research has focused on disorders such as Alzheimer’s, there are strong associations with depression and anxiety, and neural degeneration.

The mantra of ‘use it or lose it’ applies to the brain as much as it applies to our muscles. However, our modern lifestyle appears to err strongly towards the ‘lose it’.

The 2020/21 New Zealand Health Survey tells us that of the adult population (15 years +):

• 53% were ‘physically active’ (did at least 2.5 hours of physical activity over the past week)
• 12.8% did little or no physical activity over the past week
• 34.2% did more than 30mins of physical activity but not enough to be considered ‘physically active’
• 30.1% ate the recommended daily serves of vegetables (3+) and fruit (2+). This was down from 44.4% in 2011/12.

Exercise enhances our physical and mental abilities

For the majority of human history, 2.5 hours of physical activity would constitute a ‘light’ activity day.

Consider the environments that have dominated human history. We’ve tended to be very active; physically and mentally. We’d spend our days hunting, gathering, and foraging for food. We needed to be constantly alert to dangers in our environment. We needed to work together to plan, problem solve and protect each other.

Physical activity appears to benefit our mental health in the longer-term as well as the short-term.  Studies on rodents (you can’t do such studies on humans) [ref 7] have found that regular exercise:

• Increases neurogenesis (development of new neurons) in the hippocampus (region of the brain associated with learning and memory)
• Reduces the age-related decline in neurons in the hippocampus
• Improves performance on tests of memory, learning and navigation (getting from A to B).

As depression and anxiety are associated with neural degeneration, such studies suggest that exercise protects from, as well as alleviates the symptoms of these conditions.

Additionally, exercise can provide people with a sense of accomplishment, and by prioritising self-care practices like exercise; other healthy behaviours often follow such as eating nutritiously, socialising, and getting a good nights sleep. All of which can alleviate the symptoms of depression.

Quite simply, physical activity and healthy eating are key to our physical and mental wellbeing. We need to move, frequently, and where possible, with vigor. Why else would we release neurotransmitters that make us feel good and relieve pain when we exercise?

Encouraging people to be more physically active is an objective of many psychotherapies. For good reason.

3. The societal effect

According to health researchers, Picket and Wilkinson [ref 8] sufficient evidence exists of a causal relationship between income inequality and mental health. They argue that a much higher percentage of the population suffer from mental illness in more unequal countries, such as New Zealand.

Amongst other things, Picket and Wilkinson argue that greater inequality:

• Makes social status more important
• Creates feelings of superiority and inferiority in relation to others
• Highlights status differences which create a social stressor that impacts negatively on the quality of social relationships.

Additionally, we can’t escape the reality that climate change and the threat of nuclear war pose an existential threat to us. We’ve also been living through a global pandemic where we’ve been:

• Required to isolate ourselves from others
• Encouraged to consider others as potential threats to our health, or the health of our loved ones
• Fed doom and gloom on a daily basis via Covid-19 death and infection rates.

Quite simply, there’s a lot to be anxious, unhappy, and concerned about. For those struggling with personal issues, the divisions in society, and concerns for the future certainly don’t help.

Exercise provides a valuable break

Just like the conventional treatments for anxiety and depression, exercise can’t cure societies ills.

Exercise can provide an important, albeit temporary, break from the stress of reality. Removing oneself from the source(s) of stress can help to alleviate the distressing symptoms of anxiety and depression. Especially if it allows those mood enhancing and stress moderating neurotransmitters to work their magic.

Anxiety is controlled by the deeper, darker regions of the brain. It’s a physiological response to perceived threat(s), real or not. When these regions of the brain are in control, the more rational, higher-level regions struggle. Hence, a person with an anxiety disorder often appears to be thinking and behaving irrationally. When the exercise setting suits the individual, exercise can be physically demanding, yet mentally relaxing. It can provide an opportunity for those deeper, darker regions to ‘chill out’.

For people with depression, who might feel sad, worthless, and disconnected, exercise provides a vehicle to build connections.

The older readers might remember the sitcom ‘Cheers’, based at a bar in Boston, USA. The catchphrase of the bar was ‘where everybody knows your name and they’re always glad you came’.

When we get it right in fitness, we help to build social connections where people feel valued, noticed, and important. From a mental health perspective, this is an important antidote to the problems of society.

How do we help people gain the benefits of exercise?

In our article ‘Exercise behaviour is more important than working out’ we explained that exercise behaviours need to be built by making exercise easy and enjoyable to repeat. For fitness professionals, helping people to build an exercise behaviour involves:

• Identifying and catering to the individuals preferences with regard to the exercise:
  • Setting – indoors, outdoors, club or home
  • Type – aerobic, resistance, machine-based or bodyweight
  • Intensity – easy, moderate, or hard
  • Frequency and duration – whatever suits the persons schedule
• Identifying and removing barriers to exercise repetition
• Setting process goals, monitoring progress, and celebrating success
• Always making the people who use our services feel welcome, valued, and important
• Building and maintaining social connections where people can provide and receive support and encouragement from others.

A word of caution…

It’s important to note that the information in this article does not constitute professional medical or psychological advice. The article relies on population-based data to help improve the readers understanding of anxiety and depression, and the potential benefits that exercise offers.

Population-based data doesn’t always apply to individuals. Hence, an individual diagnosis from a suitably qualified mental health professional is critical to identify what is causing a problem and how best to treat it.

If you’re worried that you, or someone close to you might be suffering from depression or anxiety, the priority will be an initial discussion with your doctor/GP.

Valuable information is also available via:

• The Mental Health Foundation of New Zealand
• The Health Promotion Agency ‘Te Hiringa Hauora’ (depression.org.nz).

References

[1] Schuch et al. (2016). Exercise as a treatment for depression: A meta-analysis adjusting for publication bias. Journal of Psychiatric Research, 77, 42-51.

[2] Stubbs et al. (2016). Dropout from exercise randomised controlled trials among people with depression: A meta-analysis and meta-regression. Journal of Affective Disorders, 190, 457-466.

[3] Stubbs et al. (2017). An examination of the anxiolytic effects of exercise for people with anxiety and stress-related disorders: A meta-analysis. Psychiatry Research, 249, 102-108.

[4] Schuch et al. (2019). Physical activity protects from incident anxiety: A meta-analysis of prospective cohort studies. Depression & Anxiety, 36(9), 846-858.

[5] Ye Li et al. (2017). Dietary patterns and depression risk: A meta-analysis. Psychiatry Research, 253, 373-382.

[6] van Praag, H. (2009). Exercise and the brain: Something to chew on. Trends in Neurosciences (Regular Ed.), 32(5), 283-290.

[7] Cotman et al. (2007). Exercise builds brain health: Key roles of growth factor cascades and inflammation. Trends in Neurosciences (Regular Ed.), 30(9), 464-472.

[8] Picket & Wilkinson. (2014). Income inequality and health: A causal review. Social Science & Medicine, 128, 316-326.