Study on Sedentary Behavior and Depression in Teens

Researchers have found that teens who become more sedentary as they age are more likely to develop depressive symptoms. The study found that an additional 60 minutes of light activity (such as walking or doing chores) daily at age 12 was associated with a 10% reduction in depressive symptoms at age 18.

The study has been published in The Lancet Psychiatry.

The research team used data from 4,257 adolescents, who have been participating in longitudinal research from birth as part of the University of Bristol's Children of the 90s cohort study. The children wore accelerometers to track their movement for at least 10 hours over at least three days, at ages 12, 14, and 16.

The accelerometers reported whether the child was engaging in:

• Light activity (which could include walking or hobbies such as playing an instrument or painting)
• Moderate-to-physical activity (such as running or cycling)
• Sedentary behavior

The use of accelerometers provided more reliable data than previous studies which have relied on people self-reporting their activity, which have yielded inconsistent results.

Roughly 2,500 young people wore accelerometers to measure their activity levels up to three times — at ages 12, 14, and 16. At age 18, they were assessed for depressive symptoms.

Sedentary behavior increased and light activity (e.g., slow walking) decreased throughout adolescence. Each additional hour of sedentary behavior per day at age 12, 16, or 18 was associated with significantly higher depression scores at age 18. Conversely, each additional 60 minutes of light activity at each time point was associated with significantly lower depression scores later.

"Our findings show that young people who are inactive for large proportions of the day throughout adolescence face a greater risk of depression by age 18. We found that it's not just more intense forms of activity that are good for our mental health, but any degree of physical activity that can reduce the time we spend sitting down is likely to be beneficial," said the study's lead author, PhD student Aaron Kandola (UCL Psychiatry).

"We should be encouraging people of all ages to move more, and to sit less, as it's good for both our physical and mental health."

The researchers concluded that "The displacement of sedentary behaviour with light activity in young people warrants more direct and specific consideration in physical activity guidelines and public health interventions aimed at reducing the prevalence of depression."

For further reference log on to:

• Aaron Kandola, Gemma Lewis, David P J Osborn, Brendon Stubbs, Joseph F Hayes. Depressive symptoms and objectively measured physical activity and sedentary behaviour throughout adolescence: a prospective cohort study. The Lancet Psychiatry, 2020; DOI: 10.1016/S2215-0366(20)30034-1