30 Aug Depression: Association with Low Physical Activity, Prolonged Sitting
MedicalResearch.com Interview with:
Jannique van Uffelen, PhD, MSc (epidemiology),
MSc (human movement sciences), BHealth
Senior Research Fellow Active Ageing
INSTITUTE OF SPORT, EXERCISE & ACTIVE LIVING (ISEAL)
MedicalResearch.com: What are the main findings of the study?
Answer: We examined the link between sitting-time and physical activity with current and future depressive symptoms in 8,950 mid aged women, who participated in the Australian Longitudinal Study on Women’s Health.
Both high sitting-time and low physical activity levels were associated with higher risk of current depressive symptoms, and in combination, the risk further increased. Compared with women sitting ≤4 hours/day and meeting the physical activity recommendations of at least 150 minutes of moderate intensity activity per week, women who sat >7 hrs/day and who did no physical activity were three times as likely to have depressive symptoms. However, only lack of physical activity was associated with increased risk of future depressive symptoms, irrespective of sitting-time. Women who did no physical activity were 26% more likely to have future depressive symptoms than women meeting physical activity recommendations.
Depressive symptoms did not predict changes in sitting-time. However, compared with women without symptoms, women with depressive symptoms were 20% less likely to increase their physical activity levels over time. This suggests a vicious circle whereby inactive women are more likely to have future depressive symptoms and those with depressive symptoms are less likely to increase their activity levels.
MedicalResearch.com: Were any of the findings unexpected?
Answer: An interesting finding in our study was that sitting-time was associated with current depressive symptoms, but not with future symptoms. There are several potential explanations for this, which are described in more detail in the article. A particularly interesting explanation is the potential of reverse causality. Fatigue and loss of energy are common depressive symptoms and it could therefore be the case that, instead of high sitting-time causing depressive symptoms, depressive symptoms cause high sitting-time. Although this seems to be a logical explanation, we did not find evidence for reverse causation in our study.
MedicalResearch.com: What should clinicians and patients take away from your report?
Answer: Based on the findings of our study, lifestyle interventions to alleviate current depressive symptoms and prevent future symptoms should include strategies to increase activity levels commensurate with meeting the physical activity recommendations for public health. These recommendations indicate that , to promote and maintain health, adults should do a minimum of 30 minutes of moderate intensity aerobic activity on 5 days per week, or 20 minutes of vigorous intensity aerobic activity on 3 days per week, or any combination of moderate and vigorous intensity activity to meet the minimum activity level. Lifestyle interventions could also include strategies to reduce sitting-time to alleviate current symptoms, which is in line with common practice to reduce behavioural inactivity in the treatment of depression.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Answer: More prospective studies are needed to clarify the association between sitting-time and depressive symptoms over time and to further examine the direction of the association. Furthermore, as there are indications that the association between sedentary behaviour and mental health differs by domain, such as occupational sitting or leisure time sitting, the link between domain specific sitting time and depressive symptoms is a direction for future research.
For a 6 minute video cast of the paper, please see: http://www.scivee.tv/node/60419
Jannique G.Z. van Uffelen, Yolanda R. van Gellecum, Nicola W. Burton, Geeske Peeters, Kristiann C. Heesch, Wendy J. Brown
American Journal of Preventive Medicine – September 2013 (Vol. 45, Issue 3, Pages 276-281, DOI: 10.1016/j.amepre.2013.04.009