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] 1
Department of Health Promotion and Health Education, National Taiwan Normal University, 162, Heping East Road Section 1, Taipei, Taiwan
2
Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
3
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 [3]. 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 [10]. A preliminary understanding of the associations between levels of overall self-reported sedentary time and depressive risks would be critical for
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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 [14], 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 [15]. 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 [15]. 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) [15] and dichotomized as Bpresence of depressive symptoms (scores ≥16)^ or Babsence of depressive symptoms (scores <16)^ [18]. Exposure Variable The exposure variable was calculated from levels of PA and SB that were assessed using the short version of the International Physical Activity Questionnaire (IPAQ-SV). Since the distribution of time spent in PA and SB was skewed, based on the recommendation of IPAQ scoring protocol [19], exposure variables were categorized in tertiles according to public health guidelines [20] and a previous study [21]. For PA, total time spent in vigorous-intensity PA, moderateintensity PA, and walking was calculated and divided into Bsufficient PA^ (≥150 min/week), Binsufficient PA^ (1– 149 min/week), or Binactivity^ (0 min/week), based on public health guidelines [20]. For SB, respondents reported their time spent sitting on a weekday and weekend. The sum of the time spent in SB per day ((SB time weekday×5+SB weekend×2)/ 7) was classified by tertiles: Blow SB^ (<3 h/day), Bmoderate SB^ (3–6 h/day), or Bhigh SB^ (≥6 h/day) because these cutoff points have been reported as health risks in a previous study [21]. Test–retest reliability and criterion validity of the Japanese version of the IPAQ-SV have been confirmed [22]. According to the levels of PA and SB, nine categories were classified. Sociodemographic Variables Data on respondents’ sex, age, marital status, living conditions, educational level, employment status, household income, and body mass index (BMI) were obtained from the research company. Statistical Analyses Data for 2,914 adults who provided complete information for the study variables were analyzed. Chi-square test analyses were utilized to identify the proportional differences for the study variables among PA levels, SB levels, and combined nine PA/SB categories. Binary logistic regression analyses
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were performed to examine the independent associations of PA and SB with depressive symptom. Then, likelihood ratio test was utilized to identify the interaction between PA and SB (PA × SB) for depressive sym ptoms. Furthermore, binary logistic regression analyses were performed to estimate the odds ratios (ORs) for being depressed by PA/SB categories. The inactivity/high SB category was the reference for these analyses. In all analyses, sociodemographic variables and BMI status were controlled. Statistical analyses were conducted using SPSS 24.0; the level of significance was set at p<0.05.
Results Table 1 shows the characteristics of the total sample. The sample was well balanced by gender and age. Overall, 61.4 % of the respondents were married and 85.4 % were living with others. Of the total respondents, 51.7 % of the respondents had graduated from college or graduate school, 18.9 % were overweight, 94.4 % were employed, and 41.6 % had 5–10 million yen income. The proportion of those with depressive symptoms was 35.2 % for the total sample. In Table 2, chi-square test revealed the proportional differences in educational level, employment status, household income, and depressive symptoms among PA levels. Among SB levels, proportional differences were found for all study variables except for the BMI status. Table 3 shows that across PA/SB category, proportional differences were also observed for all study variables except for the BMI status. Table 4 presents independent associations of PA and SB levels with odds of being depressive symptoms. The results indicated that only adults who engaged in sufficient PA were less like to have depressive symptoms (OR=0.61, 95 % confidence interval (CI)=0.51–0.74; p<0.001). No significantly independent association between SB levels and depressive symptoms were observed. Interaction term between PA and SB levels for depression was not statistically significant (p= 0.33). Table 5 shows ORs for depression by combined categories of PA and SB for the total sample, adjusting for sociodemographic variables and BMI status. In the total sample, adults who engaged in sufficient PA/high SB (OR =0.44, 95% CI= 0.30–0.64), sufficient PA/moderate SB (OR =0.56, 95% CI= 0.38–0.82), and sufficient PA/ low SB (OR=0.57, 95% CI=0.35–0.94) were less likely to be depressed compared with those who had no PA/high SB. The combinations of insufficient/no PA and high/moderate/low SB categories were not significantly different from the reference category. These main results are also shown in Fig. 1.
Table 1
Characteristics of respondents for the total sample Total (%)
No. (%) Gender Men Women Age group 20s 30s 40s 50s Marital status Unmarried Married Living conditions Living with others Living alone Educational level Junior high/high school 2-year college or equivalent 4-year college/graduate school Employment status Employed Not employed Household income (yen p.a.) <5 million 5 to 10 million ≥10 million Depression Yes (≥16) No (<16) Body mass index Normal weight (<25 kg/m2)
2,914 40.9 50.1 25.0 25.0 24.9 25.1 38.6 61.4 85.4 14.6 23.5 24.8 51.7 94.4 5.6 44.9 41.6 13.5 35.2 64.8 81.1 18.9
Overweight (≥25 kg/m2) Physical activity Inactivity (0 min/week) Insufficient PA (1–149 min/week) Sufficient PA (≥150 min/week)
25.4 20.0 54.6
Sedentary behavior Low SB (>3 h/day) Moderate SB (3–6 h/day) High SB (≥6 h/day)
15.9 30.0 54.1
PA physical activity, SB sedentary behavior, p.a. per annum *p<0.05
Discussion This study found that adults who met PA recommendations (150 min/week) were less likely to have depressive symptoms, regardless of time spent in SB. This suggests that even adults
*p<0.05
Overweight (≥25 kg/m2)
Yes (≥16) No (<16) Body mass index Normal weight (<25 kg/m2)
p value
19.2 21.1 19.6
28.6 23.8 19.6
20.2 19.3
20.0 20.7
24.9 32.9
24.9 27.6
16.6 21.4 20.9
30.7 25.4 23.0
22.6 18.7
20.6 16.7
25.4 25.6
30.4 22.7
18.3 21.1
21.0 20.6 19.3 19.3
26.1 27.7 25.2 22.6 27.1 24.3
18.3 21.8
26.0 24.7
54.9 53.1
47.0 58.7
52.3 55.0 60.8
55.1 46.3
52.7 53.2 56.1
54.0 57.6
54.5 54.6
52.9 51.6 55.6 58.1
55.7 53.5
0.40
0.000*
0.002*
0.048*
0.002*
0.16
0.09
0.23
0.06
15.9 16.2
15.5 16.2
13.4 19.0 14.8
16.7 2.4
15.8 15.5 16.2
17.1 8.9
10.4 19.4
10.0 16.2 18.3 19.2
17.7 14.2
30.6 27.1
26.8 31.7
29.5 30.5 29.8
30.3 24.4
33.0 34.9 26.2
30.7 25.9
25.3 32.9
26.7 28.8 29.4 34.8
27.4 32.5
Moderate SB (%)
Low SB (%)
Sufficient PA (%)
Inactivity (%)
Insufficient PA (%)
Sedentary behavior level
Physical activity level
Characteristics of respondents by independent physical activity and sedentary behavior level
Marital status Unmarried Married Living conditions Living with others Living alone Educational level Junior high/high school 2-year college or equivalent 4-year college/graduate school Employment status Employed Not employed Household income (yen p.a.) <5 million 5 to 10 million ≥10 million Depression
Gender Men Women Age group 20s 30s 40s 50s
Table 2
53.5 56.7
57.7 52.1
57.1 50.5 55.5
53.0 73.2
51.2 49.6 57.6
52.2 65.2
64.3 47.7
63.2 54.9 52.3 46.0
54.9 53.3
High SB (%)
0.25
0.009*
0.001*
<0.001*
<0.001*
<0.001*
<0.001*
<0.001*
0.02*
p value
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15.9 %
15.0 % 12.2 %
30s
40s 50s
*p<0.05
Normal weight (<25 kg/m2) Overweight (≥25 kg/m2)
Body mass index
No (<16) Yes (≥16)
14.3 % 16.9 %
12.6 % 18.9 %
11.7 %
≥10 million
Depression
17.5 % 13.0 %
<5 million 5 to 10 million
Household income (yen p.a.)
Employed Not employed
14.1 % 26.2 %
14.9 % 13.6 %
2-year college or equivalent 4-year college/graduate school
Employment status
17.4 %
14.5 %
16.7 %
Junior high/high school
Living with others Educational level
Living alone
Living conditions
Not married Married
17.4 % 13.2 %
16.2 %
Marital status
6.9 %
14.9 %
Women
Age group 20s
6.9 % 5.6 %
6.6 % 6.6 %
4.1 %
7.4 % 6.6 %
6.6 % 6.7 %
6.4 % 5.5 %
9.3 %
6.7 %
5.9 %
6.3 % 6.8 %
6.2 % 6.0 %
7.7 %
6.6 %
6.4 %
14.8 %
Men
193 (6.6)
Inactivity/ moderate SB
115 (3.9)
Inactivity/ high SB
PA/SB category
3.7 % 5.1 %
3.4 % 4.9 %
3.8 %
3.7 % 4.3 %
4.2 % 0.0 %
4.1 % 3.9 %
3.9 %
4.1 %
3.1 %
3.4 % 4.3 %
4.0 % 4.4 %
4.1 %
3.3 %
3.0 %
4.9 %
432 (14.8)
Inactivity/ low SB
11.5 % 12.4 %
10.2 % 14.5 %
11.7 %
11.9 % 11.5 %
11.4 % 16.5 %
11.2 % 12.6 %
10.2 %
11.6 %
12.2 %
13.8 % 10.4 %
10.3 % 9.3 %
12.4 %
14.8 %
13.2 %
10.2 %
79 (2.7)
Insufficient PA/ high SB
5.9 % 4.4 %
5.8 % 5.4 %
4.8 %
4.9 % 6.7 %
5.7 % 3.7 %
7.9 % 5.3 %
3.9 %
6.1 %
2.8 %
3.3 % 7.1 %
5.6 % 5.8 %
6.3 %
4.8 %
6.3 %
4.9 %
164 (5.6)
Insufficient PA/ moderate SB
Characteristics of respondents by combined physical activity and sedentary behavior category
No. (%) Gender
Table 3
2.7 % 2.5 %
2.7 % 2.7 %
3.1 %
2.4 % 3.0 %
2.8 % 0.6 %
2.3 % 3.0 %
2.5 %
2.9 %
1.6 %
1.2 % 3.6 %
3.3 % 4.2 %
1.9 %
1.4 %
2.3 %
3.2 %
341 (11.7)
Insufficient PA/ low SB
27.6 % 27.5 %
29.4 % 24.3 %
32.1 %
27.7 % 26.1 %
27.4 % 30.5 %
23.5 % 31.4 %
23.6 %
26.1 %
36.2 %
33.1 % 24.1 %
27.0 % 24.5 %
26.6 %
32.2 %
25.2 %
30.0 %
270 (9.3)
Sufficient PA/ high SB
17.9 % 17.1 %
19.3 % 14.8 %
20.9 %
17.2 % 17.2 %
17.9 % 14.0 %
20.7 % 15.3 %
19.7 %
17.8 %
17.2 %
15.7 % 19.0 %
17.6 % 23.0 %
14.8 %
15.4 %
19.3 %
16.1 %
516 (17.7)
Sufficient PA/ moderate SB
9.4 % 8.5 %
10.0 % 7.9 %
7.9 %
7.4 % 11.7 %
9.7 % 1.8 %
9.0 % 9.4 %
9.3 %
10.1 %
4.2 %
5.8 % 11.5 %
11.0 % 10.5 %
10.2 %
5.3 %
8.9 %
9.6 %
804 (27.6)
Sufficient PA/ low SB
0.432
<0.001*
<0.001*
<0.001*
<0.001*
<0.001*
<0.001*
<0.001*
0.001*
p value
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Int.J. Behav. Med. Table 4 Independent associations of physical activity and sedentary behavior levels with odds of depressive symptoms among Japanese adults (n=2,914)
Physical activity level Inactivity (PA=0 min/week) Insufficient PA (0–149 min/week) Sufficient PA (150+ min/week) Sedentary behavior level High (≥6 h/day) Moderate (3–6 h/day) Low (<3 h/day) Interaction PA×SB level
OR (95 % CI)
p value
1.00 0.96 (0.76–1.21) 0.61 (0.51–0.74)
0.77 <0.001
1.00 0.92 (0.73–1.16) 0.80 (0.62–1.06) 0.94 (0.83–1.06)
0.50 0.07 0.33
Adjusted for gender, age, marital status, living conditions, educational level, employment status, household income, and body mass index PA physical activity, SB sedentary behavior, p.a. per annum, OR odds ratio, CI confidence interval
who spend greater time in SB but are sufficiently physically active may have a lower likelihood of depression. This finding was comparable with that for adults who had low SB and sufficient PA. Therefore, these findings suggest that promoting PA rather than reducing SB may be beneficial to mental health in adults. To our knowledge, this study is the first to examine independent associations between levels of overall self-reported sedentary time and depressive risks in Japan, which had increasing trend of having mental disorders and high overall self-reported sedentary time [10, 15]. The results of present study were inconsistent with previous findings which have demonstrated that reducing time spent in overall objectively measured sedentary time or specific types of SB such as TV viewing, computer use, and Internet use could decrease the risk of depressive symptoms in Western countries [7–9, 23]. In Table 5 Combined associations of physical activity and sedentary behavior with depressive symptoms among Japanese adults (n=2,914) N (%)
OR (95 % CI)
p value
Inactivity/ high SB Inactivity/moderate SB
115 (3.9) 193 (6.6)
1.00 (ref.) 0.72 (0.43–1.20)
– 0.21
Inactivity/low SB Insufficient PA/high SB Insufficient PA/moderate SB Insufficient PA/low SB Sufficient PA/high SB Sufficient PA/moderate SB Sufficient PA/low SB
432 (14.8) 79 (2.7) 164 (5.6) 341 (11.7) 270 (9.3) 516 (17.7) 804 (27.6)
1.16 (0.59–2.30) 0.88 (0.58–1.33) 0.79 (0.47–1.35) 1.30 (0.61–2.79) 0.44 (0.30–0.64) 0.56 (0.38–0.82) 0.57 (0.35–0.94)
0.66 0.53 0.40 0.49 <0.001 0.003 0.03
Adjusted for gender, age, marital status, living conditions, educational level, employment status, household income, and body mass index CI confidence interval, PA physical activity, SB sedentary behavior
Fig. 1 Adjusted odds of being depressed according to PA/SB category. PA physical activity, SB sedentary behavior
the combination with PA levels, the present results also showed that in no PA, insufficient PA, and sufficient PA levels, no trends of decreasing odds with reduced SB levels for depressive symptoms were observed. The possible reason for these inconsistencies could be that time spent in SB of the present study was measured by the overall SB but not measured in different domains and purposes such as occupational SB, leisure-time SB, or transported-related SB. Domainspecific SB has been found to lead to different associations for the risk of mental health [9, 24, 25]. For example, TV viewing, computer use, or non-occupational sitting were found to be adversely related to mental well-being but not found in socializing and transported SB [26], and this could be explained by the different nature of these SB activities [27]. Thus, more evidence on the associations between domainspecific SB and depression in Japanese population is warranted. Evidence shows that attaining recommended levels of PA is beneficial in protecting against depressive symptoms and involves psychological (distraction, self-efficacy), social (social support, social interaction), and physiological (endorphin increase) benefits [5, 6]. Consistent with previous crosssectional and prospective studies, meeting recommended levels of PA was associated with lower risks of depressive symptoms [4–6, 23]. Moreover, in combination with SB levels, despite the decreasing odds of depression were not found with increasing PA levels, sufficient PA is significantly associated with lower odds of depressive symptoms in low SB, moderate SB, and high SB level. Therefore, this study suggests that PA may play a protective role against depressive symptoms in adults even they spent higher time in SB. Several limitations of this study should be considered. First, the study used a cross-sectional design; thus, it is not possible to make causal inferences from these results. Second, the use of the IPAQ-SV may have overestimated time spent in PA [28, 29] and SB [30] because of recall bias. Third, the potentially confounding factors such as light-intensity activity, smoking, and health status were not assessed in the study.
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Fourth, the response rate was relatively low and could result in that more depressed and sedentary participants might have been more likely to decline answering this survey [15]. This low response rate could lead to a self-selection bias and the prevalence of having depressive symptoms in PA and SB category may be underestimated. Finally, the study sample was extracted from a list held by an Internet survey company, which might be more likely to have selection bias due to nonrepresentative nature of Internet population and volunteer effect [31]. Previous studies have indicated that respondents to Internet-based surveys are generally younger, better educated, have a higher income, and may have greater access to the Internet than respondents to traditional surveys [32, 33]. As a result, the behavior pattern of the respondents tended to have higher levels of screen-based sedentary behavior and lower levels of physical activity [34]. Moreover, in comparison with the national data of Japan [16, 17], the present study may have more married and unemployed adults than the general population. Thus, for considering these limitations, the findings obtained from our sample may not be representative of the entire adult population of Japan.
7.
8.
9. 10.
11.
12.
13.
14.
Conclusion These results suggest that promoting PA may be an effective strategy against depressive symptoms in Japanese adults. Examining the relationship of the domain-specific sedentary behaviors and physical activity with depressive symptoms should be considered for future studies.
15.
16.
17. Acknowledgments This study was supported by the Grant-in-Aid for Scientific Research (No. 26242070) from Japan Society for the Promotion of Science and the 29th Research Grant in Medical and Health Science of Meiji Yasuda Life Foundation of Health and Welfare.
18. 19.
Conflict of Interest Statement Yung Liao, Ai Shibata, Kaori Ishii, and Koichiro Oka declare that they have no conflict of interest.
20.
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