Sitting still linked to increased risk of depression in adolescents
February 11, 2020
Science Daily/University College London
Too much time sitting still -- sedentary behaviour -- is linked to an increased risk of depressive symptoms in adolescents, finds a new UCL-led study.
The Lancet Psychiatry 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.
"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 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), engaging in moderate-to-physical activity (such as running or cycling), or if they were sedentary. 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.
Depressive symptoms, such as low mood, loss of pleasure and poor concentration, were measured with a clinical questionnaire. The questionnaire measures depressive symptoms and their severity on a spectrum, rather than providing a clinical diagnosis.
Between the ages of 12 and 16, total physical activity declined across the cohort, which was mainly due to a decrease in light activity (from an average of five hours, 26 minutes to four hours, five minutes) and an increase in sedentary behaviour (from an average of seven hours and 10 minutes to eight hours and 43 minutes).
The researchers found that every additional 60 minutes of sedentary behaviour per day at age 12, 14 and 16 was associated with an increase in depression score of 11.1%, 8% or 10.5%, respectively, by age 18. Those with consistently high amounts of time spent sedentary at all three ages had 28.2% higher depression scores by age 18.
Every additional hour of light physical activity per day at age 12, 14 and 16 was associated with depression scores at age 18 that were 9.6%, 7.8% and 11.1% lower, respectively.
The researchers found some associations between moderate-to-vigorous activity at earlier ages and reduced depressive symptoms, although they caution that their data was weaker due to low levels of activity of such intensity in the cohort (averaging around 20 minutes per day), so the findings do not clarify whether moderate-to-vigorous activity is any less beneficial than light activity.
While the researchers cannot confirm that the activity levels caused changes to depressive symptoms, the researchers accounted for potentially confounding factors such as socioeconomic status, parental history of mental health, and length of time wearing the accelerometer, and avoided the possibility of reverse causation by adjusting their analysis to account for people with depressive symptoms at the study outset.
"Worryingly, the amount of time that young people spend inactive has been steadily rising for years, but there has been a surprising lack of high quality research into how this could affect mental health. The number of young people with depression also appears to be growing and our study suggests that these two trends may be linked," Kandola added.
The study's senior author, Dr Joseph Hayes (UCL Psychiatry and Camden and Islington NHS Foundation Trust), said: "A lot of initiatives promote exercise in young people, but our findings suggest that light activity should be given more attention as well."
"Light activity could be particularly useful because it doesn't require much effort and it's easy to fit into the daily routines of most young people. Schools could integrate light activity into their pupils' days, such as with standing or active lessons. Small changes to our environments could make it easier for all of us to be a little bit less sedentary," he added.
https://www.sciencedaily.com/releases/2020/02/200211193051.htm
Heart risk raised by sitting in front of the TV, not by sitting at work
June 26, 2019
Science Daily/Columbia University Irving Medical Center
Sitting for long periods of time has been linked to increased risk of cardiovascular disease and early death, but a new study suggests that not all types of sitting are equally unhealthy.
The study, led by researchers at Columbia University Vagelos College of Physicians and Surgeons, found that leisure-time sitting (while watching TV) -- but not sitting at work -- was associated with a greater risk of heart disease and death among the study's more than 3,500 participants. The study also found that moderate-to-vigorous exercise may reduce or eliminate the harmful effects of sedentary television watching.
"Our findings show that how you spend your time outside of work may matter more when it comes to heart health," study author Keith M. Diaz, PhD, assistant professor of behavioral medicine at Columbia University Vagelos College of Physicians and Surgeons and a certified exercise physiologist. "Even if you have a job that requires you to sit for long periods of time, replacing the time you spend sitting at home with strenuous exercise could reduce your risk of heart disease and death."
The study was published online today in the Journal of the American Heart Association.
Background
A growing body of research shows that people who are sedentary -- especially those who sit for long, uninterrupted periods of time -- have a higher risk of cardiovascular disease and death.
But most previous studies did not follow people over time, making it difficult to draw conclusions about the relationship between sedentary behavior and health risk. These studies have included mainly people of European descent rather than African Americans, a group that has a higher risk of heart disease compared with whites. Previous studies also measured physical activity using an activity monitor, which is unable to distinguish between different types of sedentary behavior.
What the Study Found
The new study followed 3,592 people, all African Americans, living in Jackson, Miss., for almost 8.5 years. The participants reported how much time they typically spent sitting while watching TV and during work. They also reported how much time they spent exercising in their down time.
The participants who had logged the most TV-viewing hours (4 or more hours a day) had a 50% greater risk of cardiovascular events and death compared to those who watched the least amount of TV (less than 2 hours a day).
In contrast, those who sat the most at work had the same health risks as those who sat the least.
Even for the most dedicated TV watchers, moderate to vigorous physical activity -- such as walking briskly or doing aerobic exercise -- reduced the risk of heart attacks, stroke, or death. No increased risk of heart attack, stroke, or death was seen in people who watched TV for 4 or more hours a day and engaged in 150 minutes or more of exercise a week.
Why Does the Type of Sitting Matter?
In a previous study, Diaz found that excessive sitting is linked to worse health outcomes, and even more so when sitting occurs in lengthy, uninterrupted bouts.
"It may be that most people tend to watch television for hours without moving, while most workers get up from their desk frequently," Diaz says. "The combination of eating a large meal such as dinner and then sitting for hours could also be particularly harmful."
"More research is needed, but it's possible that just taking a short break from your TV time and going for a walk may be enough to offset the harm of leisure-time sitting," adds Diaz. "Almost any type of exercise that gets you breathing harder and your heart beating faster may be beneficial."
And although occupational sitting was less problematic, Diaz notes that the same approach to movement applies at work. "We recognize that it isn't easy for some workers, like truck drivers, to take breaks from sitting, but everyone else should make a regular habit of getting up from their desks. For those who can't, our findings show that what you do outside of work may be what really counts."
The researchers suspect that the study's findings may be applicable to anyone who is sedentary, even though the study focused on African Americans.
What's Next
In future studies, Diaz will examine why TV watching may be the most harmful sedentary behavior and whether the timing of sedentary behavior around dinner time could be a contributing factor.
https://www.sciencedaily.com/releases/2019/06/190626125045.htm