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ATLANTA — As little as 20 minutes of moderate activity a day for five days a week can significantly lower the risk of depressive symptoms for people over 50 who have conditions often linked to depression, such as diabetes, heart disease and chronic pain, a new study found.
People with diabetes have twice the risk for depression, according to Diabetes U.K., and a 2017 study found heart disease patients are twice as likely to die if they develop depression after their diagnosis. Up to 85% of people with chronic pain experience severe depression, according to a different 2017 study.
People without chronic disease in the study, however, needed to do moderate to vigorous exercise two hours a day to see improvement in depressive symptoms, according to lead study author Eamon Laird, a researcher at the Physical Activity for Health Research Centre at the University of Limerick in Ireland.
Moderate physical activity is typically defined as an activity that "takes your breath" so that it is hard to speak while doing it. Examples include brisk walking, bicycling, dancing, playing tennis, or running up and down stairs. If the exercise level is increased to vigorous — such as jogging or running, during which breathing is fast and the heart rate rises — the time spent exercising can be reduced, according to the U.S. Centers for Disease Control and Prevention.
"What is unique (about this study is) that it is the first and largest investigation of a longitudinal cohort — with and without chronic disease — to try and work out what was the lowest minimal dose to observe a difference in depression," Laird said.
"We do not advocate for reduced activity levels in any population, but these findings suggest that even doses lower than recommended may well protect mental health over time in older adults," he added. "These doses may be more achievable as many older adults may find it difficult to undertake physical activity for a large number of reasons."
A 10-year study
The study, published Monday in the journal JAMA Network Open, followed more than 4,000 Irish adults with an average age of 61 for 10 years. The participants, who were part of the Irish Longitudinal Study on Aging, were evaluated every two years. They were asked about their physical activity and exercise levels and given tests to determine the number of depressive symptoms they displayed — if the symptoms were excessive, they were classified as having major depression.
"Examples of symptoms from the questionnaire included: I had trouble keeping my mind on what I was doing; my sleep was restless; I felt I could not shake off the blues even with the help from my family and friends; etc," Laird said in an email.
People who had suffered a major depressive episode during the past 12 months were also put into the major depression group. An episode is defined as a period of two weeks or longer in which the person experienced fatigue, feelings of sadness and hopelessness, a loss of interest in activities or sleeping problems, weight gain or loss, or thoughts of suicide.
The study found that the more time people spent exercising, the better. People who moderately exercised for 20 minutes a day, five days a week, had a 16% lower rate of depressive symptoms and a 43% lower risk of major depression compared with those who did not exercise, the study said.
Those who exercised two hours a day benefited the most, with a 23% reduction in depressive symptoms and a 49% lower risk of major depression, according to the study.
"The higher the physical activity dose, the greater the mental health benefits for depression," Larid said.
Unfortunately, the overall rate of depression for the entire group rose over the 10 years, from an average of 8% to 12%, while antidepressant use increased from about 6% to 10%. However, rates of exercise also declined about 10% for the group over the study's duration.
Physical activity is just absolutely magnificent. If you blend that with eating a more plant-based diet, de-stressing, sleeping enough and connecting with others — that's your magic recipe. It's the fountain of youth, if you will.
– Dr. Andrew Freeman
Lowering the risk for depression
The study's finding were not surprising, Larid said, noting extensive past research that shows a strong link between exercise and reducing depression. A systematic review and meta-analysis published in 2022 found brisk walking for just 2.5 hours a week cut depressive symptoms by 25%. The same study also found that doing half that amount lowered the risk of depression by 18%.
Another large review published in February found that getting physical is 1.5 times more effective at reducing stress, anxiety and mild-to-moderate symptoms of depression than antidepressant medications or cognitive behavior therapy, which is considered a gold standard treatment.
Exercise does more for a person's health than just ease depression. It keeps the body in tip-top shape, allowing it to function efficiently and do a better job at warding off disease of all kinds.
"Physical activity is just absolutely magnificent," Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver, Colorado, told CNN in a prior interview.
"If you blend that with eating a more plant-based diet, de-stressing, sleeping enough and connecting with others — that's your magic recipe," he added. "It's the fountain of youth, if you will."
