Too much time sitting still – sedentary behavior – 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.
Depressive symptoms, such as low mood, loss of pleasure and poor concentration, were measured with a clinical questionnaire.
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.
Funding: The study also involved King’s College London and South London and Maudsley NHS Foundation Trust, and was supported by the Economic and Social Research Council (ESRC), Health Education England, Wellcome, Medical Research Council and the National Institute for Health Research.
Regular physical activity reduces the progression of atherosclerosis, and consequently optimizes the cardiovascular risk profile, and thereby decreases the incidence of cardiovascular events [1].
Exercise capacity is mentioned as one of the strongest modifiable predictors of mortality among patients at risk for developing a cardiovascular disease (CVD) [2].
Despite this well-documented effect, exercise activity is limited among many patients at high cardiovascular risk [3, 4].
Stimulating physical activity is therefore a core component of cardiovascular risk management (CVRM) in primary care [5].
However, to tailor CVRM interventions to individual patients’ needs it is critical to identify patient characteristics that are associated with physical inactivity.
Patient characteristics such as depressive symptomatology [6–8], female gender [9, 10], and suffering a CVD [11] have been found to deteriorate physical activity levels.
Depressive symptomatology may impede the successful stimulation of physical activity and patients’ efforts to improve lifestyle in CVD [6–8].
On the other hand, symptoms of depression can be reduced by increasing physical activity levels among CVD patients [12–14].
Depressive symptomatology predicts the incidence of CVD, worsens its prognosis, and is mentioned as an independent risk factor for mortality in CVD patients [15–17].
The prevalence of depressive symptomatology increases with age [11, 18], smoking status [18, 19], and is more prevalent in women compared to men [9, 10].
Female gender is, independent from experiencing symptoms of depression, also associated with lower activity levels [20, 21].
This might, for instance, be caused by lower perceived self-efficacy and self-management levels in women [22].
Additionally, women experience a CVD at an older age than men, and consequently suffer comorbidity more frequently, resulting in lower activity levels [23–25].
More attention for female gender during CVRM in clinical practice is therefore advocated in the literature [9, 10].
Symptoms of depression and consequently lower activity levels are also more frequently reported after a cardiovascular event [20, 26, 27].
Research demonstrating this relationship between depression and inactivity is predominantly conducted during or after (cardiac) rehabilitation in patients with an established CVD (secondary prevention patients) [20].
It may be assumed that this relationship also exists in primary prevention patients (patients at high cardiovascular risk without an established CVD), but data to support this hypothesis are lacking.
Yet, insight into possible differences in the association between symptoms of depression and physical inactivity among primary and secondary prevention population might be important for tailoring CVRM to these respective populations [28].
To further explore the association between symptoms of depression and physical inactivity we used baseline data from a large clustered randomized clinical trial (RCT) conducted in primary care patients in the Netherlands [28].
The present study aims to investigate
(1) the association between symptoms of depression and physical inactivity, and
(2) whether this association is different between primary and secondary prevention patients, and between men and women.
These analyses should contribute to our understanding about how to tailor patient-specific lifestyle interventions aiming at a healthy and physically active lifestyle, offered during CVRM in primary care.
Conclusion
Symptoms of depression are associated with physical inactivity. This association was not modified by gender and the presence of a CVD.
Future research should focus on lifestyle interventions aiming at the increase of physical activity levels while simultaneously improving symptoms of depression, despite gender difference and the presence of a CVD. Longitudinal research should be performed to re-confirm the present findings.
Source:
UCL
