Int.J. Behav. Med. DOI 10.1007/s12529-015-9484-0
Independent and Combined Associations of Physical Activity and Sedentary Behavior with Depressive Symptoms Among Japanese Adults Yung Liao 1 & Ai Shibata 2 & Kaori Ishii 3 & Koichiro Oka 3
# International Society of Behavioral Medicine 2015
Abstract Background Associations between levels of sedentary behavior and depressive symptoms independently and in combination with different levels of physical activity remain unclear. Purpose This study aimed to examine independent and combined associations of physical activity (PA) and sedentary behavior (SB) with depressive symptoms among Japanese adults. Method An Internet-based survey collected data on depression levels (Center for Epidemiologic Studies Depression Scale), self-reported time spent in PA and SB (Japanese short version of the International Physical Activity Questionnaire), and sociodemographic variables from 2,914 adults in 2009. Binary logistic regression analyses were conducted to examine the odds ratios (ORs) for being depressed (depression scores ≥16) according to independent PA levels (none, insufficient, sufficient), SB levels (low, moderate, high), and nine combinations of PA and SB categories. Results After adjusting for potential confounders, sufficient PA level was found to be related to lower risk of depressive symptoms independently (OR=0.61), whereas no significant associations were observed between SB levels and depression. In the combined associations, adults in the sufficient PA/high SB (OR=0.44), sufficient PA/moderate SB (OR=0.56), and sufficient PA/low SB (OR=0.57) categories were significantly
* Yung Liao [email protected]
Department of Health Promotion and Health Education, National Taiwan Normal University, 162, Heping East Road Section 1, Taipei, Taiwan
Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
Faculty of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan
less likely to have depressive symptoms in comparison with the no PA/high SB category. Conclusion Meeting physical activity recommendations is associated with a lower risk of depressive symptoms, regardless of time spent in total sedentary behavior. These results suggest that promoting physical activity may be an effective strategy against depressive symptoms among Japanese adults. Keywords Physical activity . Sedentary behavior . Depression . Japanese
Introduction Depression, a common mental illness in developed countries, is associated with an increased prevalence of chronic diseases, such as cardiovascular diseases, diabetes, obesity, and cancer [1, 2]. In Japan, the prevalence of major depression in adults was 1–2 % for previous 12 months and 3–7 % for lifetime according to the Diagnostic and Statistical Manual of Mental Disorders-IV criteria . Previous studies have provided relatively consistent evidence for the protective effects of physical activity (PA) against depression [4–6]. Also, recent literature has shown that high level of overall and specific sedentary behavior (SB) such as TV viewing and computer use can be associated with an increased risk of depression, even after accounting for the influence of moderate-to-vigorous intensity of PA [7–9]. Although the independent associations between the risk of depression and PA or SB are well observed in Western countries [4–9], limited studies have examined association of sedentary time with depressive risks in Japan, which had the highest prevalence of overall self-reported sedentary time in a 20-country survey . A preliminary understanding of the associations between levels of overall self-reported sedentary time and depressive risks would be critical for
Int.J. Behav. Med.
depression prevention in Japanese population in the first place. Moreover, limited studies have compared the relative effect of both PA and SB behaviors on depressive symptoms. To better understand how combinations of engagement in PA and spending in SB lead to certain epidemics, recent studies have examined the joint associations of PA and SB with obesity. These studies found that combinations of PA/SB categories contributed to assorted influences on the likelihood of obesity in different age populations [11–13]. However, in considering the strong connections between physical and mental health , fewer studies have addressed the combined associations of PA and SB with mental health, especially in Japanese adults, who show an increasing trend of having mental disorders . It would be of value to know how high levels of SB might influence depressive symptoms in combination with different PA levels. This information could be important in determining intervention strategies for the treatment and prevention of these symptoms. It was hypothesized that (1) no PA and/or high SB category may contribute the highest odds of being depressed, and (2) positive associations exist between levels of SB and depressive symptoms independently and in combination with different levels of PA. Therefore, this study aimed to examine both independent and combined associations of PA and SB with depressive symptoms among Japanese adults.
Methods Participants An Internet-based cross-sectional survey was conducted in 2009 by a Japanese Internet research service organization, which listed approximately 290,000 voluntarily registered subjects across Japan with their detailed personal attributes. Thus, the organization could access data from the targeted group on the basis of the requirements of each survey. In this study, the sample size and sociodemographic attributes of the targeted group were set as follows: (1) approximately a total of 3,000 adults including 1,500 samples of each gender and (2) 750 adults in each age group (aged 20–29, 30–39, 40–49, and 50–59 years). A total of 12,435 potential respondents were randomly selected from the database and invited to attend this Internet-based survey via email. The email invitations included the URL for access to this survey, and the potential respondents could log in using their own ID and password to answer the questionnaire voluntarily. The final respondents were 3, 000 Japanese adults (response rate=24.1 %). Compared with data from the Ministry of Health, Labour and Welfare and Ministry of Internal Affairs and Communications of Japan [16, 17], the present study may have more married and unemployed individuals than the general Japanese population . Thus, the respondents of the present study may not be
representative of the general adult population of Japan. All respondents before participating in the study clicked on the agree button at the online informed consent form. This study received prior approval from the Ethics Committee of Waseda University. Outcome Variable The outcome variable in this study was depressive symptoms. This was assessed using the Japanese version of the Center for Epidemiologic Studies Depression Scale (CES-D) with a confirmed reliability coefficient (α=0.89)  and dichotomized as Bpresence of depressive symptoms (scores ≥16)^ or Babsence of depressive symptoms (scores