- Exercise can help manage weight, reduce the risk of disease, strengthen bones and muscles, and even improve brain health.
- Evidence is growing that it can also alleviate the symptoms of depression, the leading cause of mental health-related disease.
- However, advice varies about how much exercise is needed for a beneficial effect.
- Now, a 10-year study in Ireland has found that even small amounts of exercise, such as a 20-minute walk most days, can help reduce the risk of depression in older adults.
Depression — a chronic feeling of emptiness, sadness, or inability to feel pleasure — is one of the most common mental health conditions. According to the World Health Organization (WHO), it affects around 5% of adults worldwide.
In the United States, in 2020, 21 million adults (8.4% of all adults), had at least one major depressive episode, with higher rates in women than men.
In the United Kingdom, government statistics show that one in six people experienced depressive symptoms in 2021–2022.
Treatments for depression depend on the type of depression a person is experiencing but may include antidepressants, psychotherapy, such as cognitive behavioral therapy (CBT), or a combination of therapy and medication. They are effective for many people, but depression can return once treatment is stopped.
A little exercise can go a long way
There is increasing evidence that lifestyle changes can reduce depressive symptoms. A 2014 analysis of 21 studies found that a diet high in fruit, vegetables, fish, and whole grains may be associated with a reduced depression risk. And a 2022 review of studies found that exercise alleviated depressive symptoms.
However, few studies have looked at how much exercise is needed to have a positive impact on depression.
Now, a 10-year study has found that even small amounts of exercise can reduce depression among older adults — people aged 50 years and older.
The study, which was funded by the Health Research Board (HRB) Ireland, and appears in JAMA Network Open, found that a 20-minute brisk walk, 5 times a week significantly reduced the risk of depression.
Study author Dr. Eamon Laird, a postdoctoral research fellow at the University of Limerick, Ireland, told Medical News Today why the team carried out the study:
“Depression is unfortunately increasingly prevalent in the older adult population and is associated with increased risk of chronic conditions including cardiovascular disease (CVD), cognitive decline, mortality, and suicide. […] Physical activity has been previously shown to be associated with reduced risk of depression; however, no one has yet investigated what is the bare minimal dose of physical activity that might provide benefits.”
The researchers included 4,016 participants from The Irish Longitudinal Study on Ageing (TILDA), a large-scale, longitudinal study that aims to improve the aging experience of people in Ireland. They collected data at five time points between October 2009 to December 2018.
At each time point, the researchers collected detailed information on demographic, health, lifestyle, and social factors through either a self-completed questionnaire, nurse health assessment, or interview.
They assessed depressive symptoms using the short form of the Center for Epidemiological Studies Depression (CES-D). From this, they classified major depression as either a CES-D score greater than or equal to nine and/ or a major depressive episode at any of the data collection time points.
At each data point, participants self-reported their physical activity for the previous 7 days. They had to record on how many days and for how long they undertook vigorous, moderate, and walking activities.
The researchers then estimated the total number of metabolic equivalent of task (MET) minutes per week for each individual, and categorized them into low, moderate, or high physical activity.
“We found that older adults performing as little as 20 minutes a day (for 5 days a week) of moderate to vigorous physical activity (MVPA) had a 16% lower risk of depressive symptoms and a 43% lower odds of depression [than those undertaking no exercise],” Dr. Laird told us.
In the three exercise categories, the researchers saw an increase in benefit as their exercise level increased. Individuals taking the most exercise were 20% less likely to experience depression than those in the low exercise category.
Even people taking only a minimal amount of exercise were 16% less likely to experience depression than those who took no exercise.
“Twenty minutes was the minimal dose but we also observed that the greater the level of activity the greater the mental health benefits.”
– Dr. Eamon Laird