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ScienceDirect Comprehensive Psychiatry 56 (2015) 272 – 278 www.elsevier.com/locate/comppsych
Age and gender differences in the factor structure of the Center for Epidemiological Studies Depression Scale among Japanese working individuals Norio Sugawara a, b,⁎, Norio Yasui-Furukori a , Ippei Takahashi c , Masashi Matsuzaka c , Shigeyuki Nakaji b, c a
Department of Neuropsychiatry, Hirosaki University School of Medicine, Hirosaki, Japan b Aomori Occupational Health Promotion Center, Aomori, Japan c Department of Social Medicine, Hirosaki University School of Medicine, Hirosaki, Japan
Abstract Objectives: Depression is a serious mental illness with a high rate of prevalence. Depressive sympotomatology is heterogeneous and is expressed as a combination of emotional, physical, cognitive, and social symptoms. The objective of this study was to examine differences in the factor structure of the Center for Epidemiologic Studies Depression Scale (CES-D) among Japanese working individuals of differing age and gender using exploratory factor analysis (EFA). Methods: This study examined the factor structure of the CES-D in a sample of 6696 Japanese working individuals aged 20 and older. To examine within-group differences in the structural characteristics of the CES-D, the participants were stratified by age subgroup. Results: The EFA with promax rotation identified three factors among the participants. These factors were labeled “depressed and negative complaints” (DEP), “somatic and apathetic complaints” (SOM), and “positive affect” (POS). Although the three factors were comparable for males in their 20–50s and females in their 20s and 30s, the content of these factors varied for other subgroups. For females in their 40s and 50s, items 15 and 19 (belonging to Radloff’s original interpersonal problem factor) constituted an independent factor. For all individuals in their 60s, items that were not included in the SOM and POS factors constituted new factors that were not observed for participants in their 20s–50s. Conclusion: These findings indicate that age and gender could affect the factor structure of the CES-D among Japanese working individuals. Psychosocial or biological factors might contribute to the age- and gender-related differences in the factor structure of the CES-D. © 2014 Elsevier Inc. All rights reserved.
1. Introduction Depression is a serious mental illness with high rates of prevalence. In Japan, major depressive disorder has a lifetime prevalence of 6.7% and a 12-month prevalence of 2.9%, is twice as common in females as in males, and causes a significant public health burden [1,2]. The age of onset for depression is typically young adulthood, and its prevalence remains elevated throughout the entire lifespan [3].
⁎ Corresponding author at: Department of Neuropsychiatry, Hirosaki University School of Medicine, 5 Zaifu-cho, Hirosaki city, Aomori, 0368562, Japan. Tel.: +81 172 39 5066; fax: +81 172 34 5067. E-mail address: [email protected] (N. Sugawara). http://dx.doi.org/10.1016/j.comppsych.2014.09.004 0010-440X/© 2014 Elsevier Inc. All rights reserved.
Depressive symptomatology is heterogeneous and is expressed as a combination of emotional, physical, cognitive, and social symptoms. The Center for Epidemiologic Studies Depression Scale (CES-D), which was developed to identify people with depressive symptoms, is a widely used screening tool that is simple and quick to implement. The CES-D consists of 20 items that measure depressive symptoms across four domains: depressed affect (DA), somatic symptoms (SS), (lack of) positive affect (PA), and interpersonal problems (IP) [4]. However, these factors were originally identified based on responses from Caucasian participants. Previous studies have shown great variety and many inconsistencies in the symptoms of depression across different ethnic groups [5–7]. Cultural and social differences among populations may result in disagreement regarding the conceptualization of depressive symptoms.
N. Sugawara et al. / Comprehensive Psychiatry 56 (2015) 272–278
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Table 1 Mean scores on the Center for Epidemiologic Studies Depression Scale (CES-D) by age subgroup. Age (years)
Total
20s* 30s 40s 50s 60s Total*
18.6 16.2 16.1 14.7 13.7 16.3
± ± ± ± ± ±
9.9 (n 9.4 (n 9.5 (n 8.4 (n 7.3 (n 9.4 (n
Male = = = = = =
1485) 1919) 1678) 1375) 239) 6696)
17.6 15.9 15.7 14.4 13.9 15.8
± ± ± ± ± ±
9.7 9.3 9.3 8.2 7.4 9.2
(n (n (n (n (n (n
Female = = = = = =
868) 1207) 1025) 885) 186) 4171)
20.0 ± 10.1 (n 16.7 ± 9.5 (n 16.6 ± 9.7 (n 15.2 ± 8.7 (n 12.8 ± 6.6 (n 17.1 ± 9.6 (n
= = = = = =
617) 712) 653) 490) 53) 2525)
Mean ± SD. *: p b 0.001 comparison between gender.
The majority of studies using the CES-D in Japan have examined only total CES-D scores [8–10]. A previous study that examined the factor structure of the CES-D in different Japanese age groups extracted four factors using principal component analysis (PCA) [11]. However, an imbalanced gender ratio in that study (male: n = 1870, female: n = 142) may have influenced the CES-D factor structure. The objective of this study was to examine differences in the factor structure of the CES-D among Japanese working individuals of differing age and gender using exploratory factor analysis (EFA).
participants consisted of 6696 workers (4171 males and 2525 females) aged 20 and older who completed the anonymous questionnaires. The participants reported their age by choosing 1 of 5 age groups (20–29, 30–39, 40–49, 50–59, and 60+). The characteristics of the study population have been reported previously [12]. This study was approved by the Ethics Committee of Hirosaki University. Informed consent was collected from all subjects prior to the questionnaire distribution, and the participants were allowed to refuse to answer the questions if desired.
2. Methods
2.2. Measures
2.1. Participants
The Japanese version of the CES-D scale was administered to all participants to measure their depressive status [13]. This questionnaire has been widely used to measure depressive symptoms in community populations and is also used as a screening tool for depression. The CES-D is a 20-item self-report measure that focuses on depressive symptoms within the week prior to the administration of the questionnaire. The maximum score is 60, with higher scores indicating increased severity of depression. The traditional cut-off score of 16 overestimates the prevalence of depression in Japan (44.9% of the current participants) compared with the results of samples from Western countries. Therefore, the present study used a higher cut-off score of 19 to define probable depression (CES-D-19 depression). This score was chosen based on a recent validation study [14].
The present study was part of a survey conducted by the Occupational Health Promotion Centers in the Hokkaido and Tohoku regions between November 2010 and December 2010. Anonymous questionnaires on demographics and occupational stress were distributed to subjects from 103 randomly selected workplaces (with N50 workers each). The Table 2 The Center for Epidemiologic Studies Depression Scale (CES-D) items and item-total correlations. Items
Entire sample
Subgroups
Item 6 Item 7 Item 3 Item 18 Item 10 Item 1 Item 20 Item 15 Item 5 Item 19 Item 13 Item 14 Item 9 Item 11 Item 2 Item 16 Item 17 Item 12 Item 8 Item 4
0.72 0.65 0.64 0.63 0.60 0.59 0.58 0.58 0.57 0.57 0.55 0.53 0.50 0.47 0.46 0.45 0.40 0.24 0.18 0.07
0.64–0.73 0.54–0.71 0.57–0.68 0.42–0.66 0.50–0.64 0.44–0.62 0.49–0.64 0.33–0.63 0.46–0.62 0.33–0.62 0.39–0.60 0.29–0.61 0.36–0.54 0.24–0.52 0.35–0.60 0.26–0.50 0.29–0.54 0.09–0.37 0.11–0.26 −0.14 to 0.16
2.3. Data analysis An EFA was conducted using the maximum likelihood method with promax rotation to analyze the underlying structure of the CES-D. Because previous studies showed interfactor correlations in the factor structure of the CES-D [11,15], we used the promax rotation which allows the factors to be correlated. To determine the number of factors, the eigenvalues N1.0 rule was employed. The data were analyzed using PASW Statistics-PCsoftware for Windows, Version 18.0.0, and Amos-PC-software for Windows, Version 17.0.
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Table 3 Factor structure by gender in the Center for Epidemiologic Studies Depression Scale (CES-D) items after promax rotation. Total
Item 1 Item 2 Item 3 Item 4 Item 5 Item 6 Item 7 Item 8 Item 9 Item 10 Item 11 Item 12 Item 13 Item 14 Item 15 Item 16 Item 17 Item 18 Item 19 Item 20
Male
Female
F1
F2
F3
F1
F2
F3
F1
F2
F3
0.01 0.18 0.19 0.10 −0.07 0.06 −0.07 −0.10 0.39 0.53 0.29 0.00 0.34 0.63 0.69 0.03 0.54 0.70 0.70 0.27
0.69 0.37 0.54 −0.24 0.76 0.76 0.81 0.00 0.25 0.19 0.28 0.04 0.31 0.00 −0.02 0.22 −0.04 0.05 −0.05 0.42
−0.03 −0.06 0.01 0.44 −0.05 0.05 0.03 0.61 −0.10 −0.02 −0.04 0.48 0.00 0.00 0.05 0.51 −0.03 0.00 0.08 −0.03
0.70 0.39 0.57 −0.25 0.77 0.80 0.84 0.00 0.33 0.21 0.29 0.03 0.35 0.03 0.03 0.26 −0.10 0.06 −0.01 0.46
0.01 0.18 0.15 0.12 −0.08 0.01 −0.09 −0.08 0.32 0.52 0.29 −0.01 0.31 0.61 0.69 0.01 0.54 0.68 0.67 0.25
−0.04 −0.03 −0.01 0.47 −0.04 0.04 0.02 0.61 −0.12 −0.01 −0.02 0.51 0.00 0.01 0.04 0.49 −0.03 0.00 0.07 0.00
−0.02 0.20 0.21 0.08 −0.07 0.11 −0.05 −0.12 0.47 0.53 0.27 0.00 0.34 0.63 0.65 0.04 0.63 0.74 0.69 0.31
0.69 0.37 0.52 −0.20 0.77 0.70 0.79 −0.02 0.16 0.18 0.28 0.04 0.29 −0.01 −0.07 0.18 −0.01 0.04 −0.09 0.37
0.00 −0.11 0.05 0.37 −0.08 0.07 0.03 0.59 −0.06 −0.03 −0.07 0.43 0.02 0.00 0.11 0.56 −0.09 −0.01 0.13 −0.07
1.00
1.00 0.73 0.25
1.00 0.18
1.00
1.00 0.72 0.41
1.00 0.46
1.00
Interfactor correlations F1 1.00 F2 0.73 F3 0.27
1.00 0.32
Figures are rounded to two decimal places. The loadings of 0.30 or above are boldfaced.
3. Results 3.1. Reliability of the CES-D The mean CES-D score was 16.3 ± 9.4 (median 14.0). Table 1 shows the mean CES-D scores by age and gender subgroup [12]. The prevalence of depression (CES-D-19 depression) was 33.6% (31.7% for males and 36.6% for females). The overall reliability of the scale was good (alpha = 0.88). Corrected item-total correlations for individual items ranged from 0.07 (item 4, “good”) to 0.72 (item 6, “depressed”) (Table 2). 3.2. The factor structure of the CES-D in Japanese working individuals The EFA yielded three factors among all participants. The factors were tentatively labeled as “depressed and negative complaints” (DEP), “somatic and apathetic complaints” (SOM), and “positive affect” (POS) for F1 through F3, respectively. As shown in Table 3, the first DEP factor comprised 8 items belonging to the original DA (five items: 9, 10, 14, 17, and 18), SS (one item: 13), and IP (two items: 15, 19) factors. The second SOM factor comprised 9 items belonging to the original DA (three items: 3, 6, and 10) and SS (six items: 1, 2, 5, 7, 13, and 20) factors. The last POS factor corresponded to the original PA
items. The three factors were approximately equivalent between genders. Table 4 shows the factor structure of the CES-D by age group in males. The three factors were approximately the same for males in their 20s–50s. However, the content varied for males in their 60s. Although the SOM and POS factors were approximately the same for these individuals, the remaining items constituted three factors (F3, F4, and F5) that were not observed in males in their 20s to 50s. Table 5 shows the factor structure of the CES-D by age group in females. The three factors were approximately the same for females in their 20s and 30s. However, the content varied for females in their 40s and older. For women in their 40s and 50s, items 15 and 19 (original IP factors) constituted an independent factor (F3). Furthermore, items that were not included in the SOM and POS factors for women in their 60s constituted four factors (F1, F3, F4, and F6) that were not observed for females in their 20–50s.
4. Discussion The aim of the present study was to examine the factor structure of the CES-D among Japanese working individuals. In our sample, the good internal consistency of the overall CES-D (alpha = 0.88) indicated that this scale can be used as
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N. Sugawara et al. / Comprehensive Psychiatry 56 (2015) 272–278 Table 4 Factor structure by age group in the Center for Epidemiologic Studies Depression Scale (CES-D) items after promax rotation in males. 20s
Item 1 Item 2 Item 3 Item 4 Item 5 Item 6 Item 7 Item 8 Item 9 Item 10 Item 11 Item 12 Item 13 Item 14 Item 15 Item 16 Item 17 Item 18 Item 19 Item 20
30s
40s
50s
60s
F1
F2
F3
F1
F2
F3
F1
F2
F3
F1
F2
F3
F1
F2
F3
F4
F5
0.10 0.20 0.14 0.15 −0.06 0.06 −0.05 −0.09 0.31 0.54 0.30 −0.07 0.34 0.60 0.77 −0.06 0.56 0.66 0.71 0.34
0.57 0.32 0.57 −0.20 0.69 0.76 0.72 −0.01 0.32 0.18 0.22 0.17 0.30 0.05 −0.09 0.35 −0.06 0.14 −0.04 0.37
0.00 0.00 0.01 0.51 −0.04 −0.01 0.09 0.57 −0.19 −0.05 −0.04 0.40 0.00 −0.08 0.12 0.44 −0.05 −0.05 0.18 0.01
0.80 0.50 0.69 −0.23 0.69 0.83 0.80 −0.06 0.38 0.35 0.33 0.00 0.41 0.06 0.05 0.28 −0.09 0.15 −0.07 0.41
−0.05 0.04 0.02 0.10 −0.01 −0.05 −0.08 −0.06 0.29 0.40 0.28 0.02 0.29 0.58 0.69 −0.04 0.48 0.62 0.74 0.29
−0.08 −0.08 −0.07 0.42 0.01 0.07 0.05 0.66 −0.10 0.01 −0.02 0.54 0.00 0.06 0.02 0.53 −0.04 0.01 0.05 0.00
−0.02 0.26 0.18 0.13 −0.03 0.03 −0.05 −0.12 0.42 0.61 0.36 −0.04 0.34 0.68 0.71 0.02 0.50 0.72 0.65 0.16
0.75 0.36 0.55 −0.31 0.79 0.76 0.86 0.03 0.23 0.14 0.24 0.04 0.33 −0.03 0.03 0.20 −0.05 −0.01 0.00 0.55
−0.03 −0.03 0.01 0.46 −0.06 0.08 −0.02 0.59 −0.09 −0.04 0.02 0.53 0.08 0.02 0.05 0.55 −0.05 −0.03 0.04 −0.04
0.66 0.37 0.53 −0.23 0.86 0.78 0.91 0.00 0.36 0.23 0.43 0.04 0.40 0.06 0.03 0.19 −0.17 0.06 0.10 0.51
0.00 0.17 0.21 0.03 −0.17 0.02 −0.18 −0.06 0.25 0.48 0.18 −0.04 0.27 0.64 0.68 0.10 0.60 0.60 0.57 0.24
−0.04 −0.03 0.03 0.46 −0.02 0.05 0.02 0.61 −0.13 −0.03 −0.01 0.45 −0.03 0.01 0.04 0.44 −0.04 0.00 0.04 0.02
0.69 0.65 0.54 −0.12 0.65 0.88 0.87 0.09 0.33 −0.06 0.16 −0.07 0.35 −0.07 0.47 0.11 0.10 −0.01 0.12 0.46
−0.05 0.05 −0.04 0.50 −0.07 0.07 0.06 0.75 −0.04 0.08 −0.02 0.70 0.00 −0.01 −0.06 0.46 −0.02 0.03 −0.04 0.02
−0.17 −0.03 0.23 −0.05 −0.18 0.01 0.06 −0.04 −0.06 0.10 0.00 0.10 0.33 0.74 0.32 −0.10 −0.09 0.32 0.28 0.14
−0.08 0.15 0.10 −0.03 0.13 −0.13 0.06 0.11 −0.07 0.14 0.32 −0.13 −0.24 −0.05 0.02 0.04 0.82 0.37 0.10 0.10
0.22 −0.06 −0.07 −0.09 0.07 0.12 −0.11 −0.16 0.51 0.72 0.22 0.14 0.10 0.01 −0.13 0.20 0.01 0.24 0.14 −0.04
1.00
1.00 0.73 0.28
1.00 0.20
1.00
1.00 0.72 0.24
1.00 0.35
1.00
1.00 0.72 0.13
1.00 0.16
1.00
1.00 −0.11 0.55 0.58 0.60
1.00 −0.17 0.05 −0.13
1.00 0.47 0.43
1.00 0.43
1.00
Interfactor correlations F1 1.00 F2 0.70 1.00 F3 0.22 0.28 F4 F5
Figures are rounded to two decimal places. The loadings of 0.30 or above are boldfaced.
a reliable screening tool [16]. Among all participants, we demonstrated that the CES-D consists of three factors, which we labeled as DEP, SOM, and POS. Although the three factors were approximately the same for individuals in their 20s and 30s, the content varied for other age subgroups. The EFA model that we identified was similar to another three-factor model that arose from studies using ChineseAmerican or Mainland Chinese samples, in which the original DA and SS factors merged and then constituted two factors [17–19]. In those studies, the merged model could reflect traditional Chinese medicine concepts of mind-body holism [18]. In Japan, traditional religions such as Shintoism, Buddhism, and Qi also advocate the unity of mind and body [20]. Traditional concepts could thus affect the factor structure of depressive symptoms. Our results showed that CES-D items belonging to the original PA factor constituted the same POS factor among all subgroups. Previous studies showed that individuals of Asian descent reported lower levels of positive affect than other populations [6,21]. In a study conducted in US, the amount and experience of life stress showed association to positive affect in Native Hawaiians and European Americans but not in Japanese Americans [7]. Among Asians, including Japanese, lower positive affect might be linked to cultural values more than actual mental health status. In this study CES-D items belonging to the original IP factor constituted the independent factor only among females
in their 40s and 50s. In Japan, the ratio of the workforce to the total female population shows a characteristic M-shaped curve with two peaks. The first peak occurs in approximately the early 20s for unmarried women. The second peak is observed in the late 40s, when women have finished child-rearing and are ready to begin working again [22]. There is a wide wage gap between males and females in Japan. Females earn only two-thirds of the wages that males earn because of significant differences in occupational standing, such as promotion (few women are assigned to managerial positions), segregation, and forms of employment (more women are assigned to part-time jobs). Ogiwara and colleagues have shown that the most significant factor related to depression in females is interpersonal conflict, but that the most significant factor for males is professional matters [23]. The above-mentioned occupational gender gap may contribute to gender-specific interpersonal problems. Individuals in their 60s exhibited more extracted factors from the CES-D than those in their 20s to 50s. Although the interpretation of our results was hampered by the relatively small sample of individuals in their 60s, the factor structure observed among these older individuals could be related to distinct etiologies. Depression among the elderly could have different etiological pathways: (1) early onset with longstanding psychobiological vulnerability, (2) late onset as a reaction to severe life stress, and (3) late onset with vascular risk factors [24,25].
276
Table 5 Factor structure by age group in the Center for Epidemiologic Studies Depression Scale (CES-D) items after promax rotation in females. 20s
40s
50s
60s
F1
F2
F3
F1
F2
F3
F1
F2
F3
F4
F1
F2
F3
F4
F1
F2
F3
F4
F5
F6
0.04 0.25 0.25 0.05 −0.15 0.09 0.01 −0.09 0.45 0.48 0.22 −0.02 0.34 0.60 0.62 −0.04 0.58 0.72 0.71 0.24
0.62 0.26 0.48 −0.18 0.83 0.67 0.72 −0.08 0.12 0.17 0.31 0.14 0.25 0.00 −0.13 0.20 0.08 0.15 −0.20 0.42
−0.07 −0.10 0.04 0.39 −0.12 0.12 0.04 0.55 −0.07 0.06 −0.01 0.43 0.03 −0.08 0.14 0.63 −0.15 −0.10 0.20 0.00
0.05 0.12 0.33 −0.01 −0.05 0.14 −0.19 −0.16 0.52 0.42 0.29 0.12 0.28 0.60 0.67 0.12 0.60 0.73 0.72 0.10
0.64 0.45 0.41 −0.16 0.74 0.67 0.89 0.01 0.08 0.22 0.30 −0.04 0.35 0.00 −0.07 0.12 0.04 0.03 −0.06 0.54
0.01 −0.15 0.07 0.40 −0.06 0.08 0.07 0.71 −0.01 0.00 −0.11 0.47 0.01 −0.01 0.07 0.51 −0.13 0.01 0.08 −0.10
0.79 0.54 0.72 −0.19 0.84 0.71 0.72 −0.02 0.30 0.30 0.45 −0.01 0.42 0.08 −0.05 0.19 −0.02 −0.08 0.05 0.38
−0.13 0.16 −0.01 0.10 −0.11 0.14 −0.03 −0.06 0.36 0.46 0.21 −0.03 0.18 0.43 −0.07 0.00 0.65 0.98 0.25 0.26
0.02 −0.08 0.04 −0.03 −0.05 −0.06 0.00 −0.07 0.01 0.01 −0.06 0.04 0.13 0.26 1.08 0.05 0.02 −0.13 0.42 0.08
0.01 −0.09 0.04 0.37 −0.10 0.09 0.06 0.58 −0.04 −0.07 −0.07 0.36 0.01 0.05 −0.04 0.55 −0.03 0.08 0.06 −0.10
−0.16 0.00 0.04 0.07 0.03 0.18 0.04 −0.02 0.52 0.60 0.21 −0.04 0.06 0.38 0.23 −0.06 0.55 0.80 0.35 0.39
0.67 0.26 0.52 −0.24 0.70 0.74 0.80 0.05 0.19 0.15 0.18 0.10 0.22 0.02 −0.12 0.23 −0.12 −0.06 −0.02 0.19
0.21 0.24 0.21 0.05 −0.08 −0.07 −0.09 −0.15 −0.04 0.05 0.18 −0.03 0.44 0.22 0.74 0.14 0.06 −0.09 0.41 0.15
0.01 −0.10 0.00 0.39 0.01 0.05 −0.02 0.52 −0.11 −0.04 −0.08 0.41 −0.07 0.02 0.01 0.51 −0.01 0.14 0.09 −0.06
0.08 0.62 0.35 0.11 0.07 −0.18 0.07 −0.09 0.06 0.67 0.24 −0.02 0.07 −0.09 0.08 0.05 0.98 0.67 −0.03 0.92
0.61 0.05 0.49 −0.24 0.16 0.78 0.77 −0.17 0.26 0.09 0.16 0.15 0.07 0.15 −0.01 0.39 −0.06 0.25 −0.10 −0.19
−0.16 −0.08 −0.01 0.10 −0.09 0.04 0.36 0.14 −0.03 0.14 −0.23 −0.19 0.17 0.74 0.90 0.04 0.02 −0.07 0.22 0.04
0.08 −0.04 0.04 −0.05 0.97 0.33 0.01 0.12 0.44 0.00 −0.16 0.04 −0.14 −0.06 −0.06 −0.13 0.08 −0.10 0.32 0.16
−0.12 0.03 −0.01 0.63 0.06 0.13 −0.13 0.67 −0.07 −0.01 0.07 0.66 0.02 0.01 0.06 0.52 0.00 −0.05 −0.08 0.04
0.10 0.20 0.05 −0.10 −0.07 0.05 −0.10 0.06 −0.05 −0.03 0.25 0.15 0.92 0.13 0.06 −0.16 −0.10 −0.03 0.47 0.04
1.00
1.00 0.71 0.39
1.00 0.45
1.00 0.70 0.61 0.43
1.00 0.58 0.33
1.00
1.00 0.64 0.66 0.32
1.00 0.55 0.43
1.00 0.44 −0.02 0.16 −0.02 0.18
1.00 0.14 0.23 0.03 0.32
1.00 0.27 −0.03 0.32
1.00 0.04 0.26
1.00 0.10
1.00
Interfactor correlations F1 1.00 F2 0.70 1.00 F3 0.49 0.51 F4 F5 F6
1.00
Figures are rounded to two decimal places. The loadings of 0.30 or above are boldfaced.
1.00 0.39
1.00 0.30
1.00
N. Sugawara et al. / Comprehensive Psychiatry 56 (2015) 272–278
Item 1 Item 2 Item 3 Item 4 Item 5 Item 6 Item 7 Item 8 Item 9 Item 10 Item 11 Item 12 Item 13 Item 14 Item 15 Item 16 Item 17 Item 18 Item 19 Item 20
30s
N. Sugawara et al. / Comprehensive Psychiatry 56 (2015) 272–278
A previous study conducted among working individuals in Japan showed that the interpersonal problem factor was combined with other depressed and retarded activity items, composing a large “general dysphoria” factor for those aged 50–63 [11]. These results may indicate that the conceptualization of depression becomes more unified for this older Japanese generation. However, our results did not show this large factor for participants in their 50s and 60s. Most of the participants were born after World War II; hence, those between 50–63 years of age in Iwata's study may have experienced differences in social norms and the degree of westernization relative to most of the participants in our study. The current study has some limitations. First, subject recruitment was restricted to working individuals, and we could not generalize our findings to all individuals who receive a clinical diagnosis of depression. Second, as all of the participants were volunteers who were interested in their mental health, they may have been healthier than non-participants. Thus, working individuals who were not included in the study may have differing depressive symptoms. 5. Conclusion Our findings indicate that differences in age and gender could affect the factor structure of the CES-D among Japanese working individuals. Psychosocial or biological factors might contribute to the age- and gender-related differences in the factor structure of the CES-D. Acknowledgment The authors are grateful to Dr. Hirotsugu Miyake for his courtesy and assistance in our work. The authors declare that they have no competing interests.
Appendix A
Table 1 Center for Epidemiologic Studies Depression Scale (CES-D) items and Radloff's original four factors. Items Factor 1: Depressed Affect Item 3 I felt that I could not shake off the blues even with help from my family or friends. Item 6 I felt depressed. Item 9 I thought my life had been a failure. Item 10 I felt fearful. Item 14 I felt lonely. Item 17 I had crying spells. Item 18 I felt sad. Factor 2: Somatic symptoms Item 1 I was bothered by things that usually do not bother me. Item 2 I did not feel like eating; my appetite was poor.
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Table 1 (continued) Items Item 5 Item 7 Item 11 Item 13 Item 20
I had trouble keeping my mind on what I was doing. I felt that everything I did was an effort. My sleep was restless. I talked less than usual. I could not get going.
Factor 3: (Lack of) positive affect Item 4 I felt that I was just as good as other people. Item 8 I felt hopeful about the future. Item 12 I was happy. Item 16 I enjoyed life. Factor 4: Interpersonal problems Item 15 People were unfriendly. Item 19 I felt that people disliked me. Table 2 Fit indices for confirmatory factor analysis models*.
Total Male Female
GFI
AGFI
NFI
CFI
RMSEA
0.92 0.92 0.92
0.90 0.89 0.90
0.89 0.89 0.89
0.90 0.90 0.90
0.07 0.07 0.07
GFI goodness of fit index; AGFI adjusted goodness of fit index; NFI normed fit index; approximation. CFI comparative fit index; RMSEA root mean square error of approximation.
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ScienceDirect Comprehensive Psychiatry 56 (2015) 272 – 278 www.elsevier.com/locate/comppsych
Age and gender differences in the factor structure of the Center for Epidemiological Studies Depression Scale among Japanese working individuals Norio Sugawara a, b,⁎, Norio Yasui-Furukori a , Ippei Takahashi c , Masashi Matsuzaka c , Shigeyuki Nakaji b, c a
Department of Neuropsychiatry, Hirosaki University School of Medicine, Hirosaki, Japan b Aomori Occupational Health Promotion Center, Aomori, Japan c Department of Social Medicine, Hirosaki University School of Medicine, Hirosaki, Japan
Abstract Objectives: Depression is a serious mental illness with a high rate of prevalence. Depressive sympotomatology is heterogeneous and is expressed as a combination of emotional, physical, cognitive, and social symptoms. The objective of this study was to examine differences in the factor structure of the Center for Epidemiologic Studies Depression Scale (CES-D) among Japanese working individuals of differing age and gender using exploratory factor analysis (EFA). Methods: This study examined the factor structure of the CES-D in a sample of 6696 Japanese working individuals aged 20 and older. To examine within-group differences in the structural characteristics of the CES-D, the participants were stratified by age subgroup. Results: The EFA with promax rotation identified three factors among the participants. These factors were labeled “depressed and negative complaints” (DEP), “somatic and apathetic complaints” (SOM), and “positive affect” (POS). Although the three factors were comparable for males in their 20–50s and females in their 20s and 30s, the content of these factors varied for other subgroups. For females in their 40s and 50s, items 15 and 19 (belonging to Radloff’s original interpersonal problem factor) constituted an independent factor. For all individuals in their 60s, items that were not included in the SOM and POS factors constituted new factors that were not observed for participants in their 20s–50s. Conclusion: These findings indicate that age and gender could affect the factor structure of the CES-D among Japanese working individuals. Psychosocial or biological factors might contribute to the age- and gender-related differences in the factor structure of the CES-D. © 2014 Elsevier Inc. All rights reserved.
1. Introduction Depression is a serious mental illness with high rates of prevalence. In Japan, major depressive disorder has a lifetime prevalence of 6.7% and a 12-month prevalence of 2.9%, is twice as common in females as in males, and causes a significant public health burden [1,2]. The age of onset for depression is typically young adulthood, and its prevalence remains elevated throughout the entire lifespan [3].
⁎ Corresponding author at: Department of Neuropsychiatry, Hirosaki University School of Medicine, 5 Zaifu-cho, Hirosaki city, Aomori, 0368562, Japan. Tel.: +81 172 39 5066; fax: +81 172 34 5067. E-mail address: [email protected] (N. Sugawara). http://dx.doi.org/10.1016/j.comppsych.2014.09.004 0010-440X/© 2014 Elsevier Inc. All rights reserved.
Depressive symptomatology is heterogeneous and is expressed as a combination of emotional, physical, cognitive, and social symptoms. The Center for Epidemiologic Studies Depression Scale (CES-D), which was developed to identify people with depressive symptoms, is a widely used screening tool that is simple and quick to implement. The CES-D consists of 20 items that measure depressive symptoms across four domains: depressed affect (DA), somatic symptoms (SS), (lack of) positive affect (PA), and interpersonal problems (IP) [4]. However, these factors were originally identified based on responses from Caucasian participants. Previous studies have shown great variety and many inconsistencies in the symptoms of depression across different ethnic groups [5–7]. Cultural and social differences among populations may result in disagreement regarding the conceptualization of depressive symptoms.
N. Sugawara et al. / Comprehensive Psychiatry 56 (2015) 272–278
273
Table 1 Mean scores on the Center for Epidemiologic Studies Depression Scale (CES-D) by age subgroup. Age (years)
Total
20s* 30s 40s 50s 60s Total*
18.6 16.2 16.1 14.7 13.7 16.3
± ± ± ± ± ±
9.9 (n 9.4 (n 9.5 (n 8.4 (n 7.3 (n 9.4 (n
Male = = = = = =
1485) 1919) 1678) 1375) 239) 6696)
17.6 15.9 15.7 14.4 13.9 15.8
± ± ± ± ± ±
9.7 9.3 9.3 8.2 7.4 9.2
(n (n (n (n (n (n
Female = = = = = =
868) 1207) 1025) 885) 186) 4171)
20.0 ± 10.1 (n 16.7 ± 9.5 (n 16.6 ± 9.7 (n 15.2 ± 8.7 (n 12.8 ± 6.6 (n 17.1 ± 9.6 (n
= = = = = =
617) 712) 653) 490) 53) 2525)
Mean ± SD. *: p b 0.001 comparison between gender.
The majority of studies using the CES-D in Japan have examined only total CES-D scores [8–10]. A previous study that examined the factor structure of the CES-D in different Japanese age groups extracted four factors using principal component analysis (PCA) [11]. However, an imbalanced gender ratio in that study (male: n = 1870, female: n = 142) may have influenced the CES-D factor structure. The objective of this study was to examine differences in the factor structure of the CES-D among Japanese working individuals of differing age and gender using exploratory factor analysis (EFA).
participants consisted of 6696 workers (4171 males and 2525 females) aged 20 and older who completed the anonymous questionnaires. The participants reported their age by choosing 1 of 5 age groups (20–29, 30–39, 40–49, 50–59, and 60+). The characteristics of the study population have been reported previously [12]. This study was approved by the Ethics Committee of Hirosaki University. Informed consent was collected from all subjects prior to the questionnaire distribution, and the participants were allowed to refuse to answer the questions if desired.
2. Methods
2.2. Measures
2.1. Participants
The Japanese version of the CES-D scale was administered to all participants to measure their depressive status [13]. This questionnaire has been widely used to measure depressive symptoms in community populations and is also used as a screening tool for depression. The CES-D is a 20-item self-report measure that focuses on depressive symptoms within the week prior to the administration of the questionnaire. The maximum score is 60, with higher scores indicating increased severity of depression. The traditional cut-off score of 16 overestimates the prevalence of depression in Japan (44.9% of the current participants) compared with the results of samples from Western countries. Therefore, the present study used a higher cut-off score of 19 to define probable depression (CES-D-19 depression). This score was chosen based on a recent validation study [14].
The present study was part of a survey conducted by the Occupational Health Promotion Centers in the Hokkaido and Tohoku regions between November 2010 and December 2010. Anonymous questionnaires on demographics and occupational stress were distributed to subjects from 103 randomly selected workplaces (with N50 workers each). The Table 2 The Center for Epidemiologic Studies Depression Scale (CES-D) items and item-total correlations. Items
Entire sample
Subgroups
Item 6 Item 7 Item 3 Item 18 Item 10 Item 1 Item 20 Item 15 Item 5 Item 19 Item 13 Item 14 Item 9 Item 11 Item 2 Item 16 Item 17 Item 12 Item 8 Item 4
0.72 0.65 0.64 0.63 0.60 0.59 0.58 0.58 0.57 0.57 0.55 0.53 0.50 0.47 0.46 0.45 0.40 0.24 0.18 0.07
0.64–0.73 0.54–0.71 0.57–0.68 0.42–0.66 0.50–0.64 0.44–0.62 0.49–0.64 0.33–0.63 0.46–0.62 0.33–0.62 0.39–0.60 0.29–0.61 0.36–0.54 0.24–0.52 0.35–0.60 0.26–0.50 0.29–0.54 0.09–0.37 0.11–0.26 −0.14 to 0.16
2.3. Data analysis An EFA was conducted using the maximum likelihood method with promax rotation to analyze the underlying structure of the CES-D. Because previous studies showed interfactor correlations in the factor structure of the CES-D [11,15], we used the promax rotation which allows the factors to be correlated. To determine the number of factors, the eigenvalues N1.0 rule was employed. The data were analyzed using PASW Statistics-PCsoftware for Windows, Version 18.0.0, and Amos-PC-software for Windows, Version 17.0.
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Table 3 Factor structure by gender in the Center for Epidemiologic Studies Depression Scale (CES-D) items after promax rotation. Total
Item 1 Item 2 Item 3 Item 4 Item 5 Item 6 Item 7 Item 8 Item 9 Item 10 Item 11 Item 12 Item 13 Item 14 Item 15 Item 16 Item 17 Item 18 Item 19 Item 20
Male
Female
F1
F2
F3
F1
F2
F3
F1
F2
F3
0.01 0.18 0.19 0.10 −0.07 0.06 −0.07 −0.10 0.39 0.53 0.29 0.00 0.34 0.63 0.69 0.03 0.54 0.70 0.70 0.27
0.69 0.37 0.54 −0.24 0.76 0.76 0.81 0.00 0.25 0.19 0.28 0.04 0.31 0.00 −0.02 0.22 −0.04 0.05 −0.05 0.42
−0.03 −0.06 0.01 0.44 −0.05 0.05 0.03 0.61 −0.10 −0.02 −0.04 0.48 0.00 0.00 0.05 0.51 −0.03 0.00 0.08 −0.03
0.70 0.39 0.57 −0.25 0.77 0.80 0.84 0.00 0.33 0.21 0.29 0.03 0.35 0.03 0.03 0.26 −0.10 0.06 −0.01 0.46
0.01 0.18 0.15 0.12 −0.08 0.01 −0.09 −0.08 0.32 0.52 0.29 −0.01 0.31 0.61 0.69 0.01 0.54 0.68 0.67 0.25
−0.04 −0.03 −0.01 0.47 −0.04 0.04 0.02 0.61 −0.12 −0.01 −0.02 0.51 0.00 0.01 0.04 0.49 −0.03 0.00 0.07 0.00
−0.02 0.20 0.21 0.08 −0.07 0.11 −0.05 −0.12 0.47 0.53 0.27 0.00 0.34 0.63 0.65 0.04 0.63 0.74 0.69 0.31
0.69 0.37 0.52 −0.20 0.77 0.70 0.79 −0.02 0.16 0.18 0.28 0.04 0.29 −0.01 −0.07 0.18 −0.01 0.04 −0.09 0.37
0.00 −0.11 0.05 0.37 −0.08 0.07 0.03 0.59 −0.06 −0.03 −0.07 0.43 0.02 0.00 0.11 0.56 −0.09 −0.01 0.13 −0.07
1.00
1.00 0.73 0.25
1.00 0.18
1.00
1.00 0.72 0.41
1.00 0.46
1.00
Interfactor correlations F1 1.00 F2 0.73 F3 0.27
1.00 0.32
Figures are rounded to two decimal places. The loadings of 0.30 or above are boldfaced.
3. Results 3.1. Reliability of the CES-D The mean CES-D score was 16.3 ± 9.4 (median 14.0). Table 1 shows the mean CES-D scores by age and gender subgroup [12]. The prevalence of depression (CES-D-19 depression) was 33.6% (31.7% for males and 36.6% for females). The overall reliability of the scale was good (alpha = 0.88). Corrected item-total correlations for individual items ranged from 0.07 (item 4, “good”) to 0.72 (item 6, “depressed”) (Table 2). 3.2. The factor structure of the CES-D in Japanese working individuals The EFA yielded three factors among all participants. The factors were tentatively labeled as “depressed and negative complaints” (DEP), “somatic and apathetic complaints” (SOM), and “positive affect” (POS) for F1 through F3, respectively. As shown in Table 3, the first DEP factor comprised 8 items belonging to the original DA (five items: 9, 10, 14, 17, and 18), SS (one item: 13), and IP (two items: 15, 19) factors. The second SOM factor comprised 9 items belonging to the original DA (three items: 3, 6, and 10) and SS (six items: 1, 2, 5, 7, 13, and 20) factors. The last POS factor corresponded to the original PA
items. The three factors were approximately equivalent between genders. Table 4 shows the factor structure of the CES-D by age group in males. The three factors were approximately the same for males in their 20s–50s. However, the content varied for males in their 60s. Although the SOM and POS factors were approximately the same for these individuals, the remaining items constituted three factors (F3, F4, and F5) that were not observed in males in their 20s to 50s. Table 5 shows the factor structure of the CES-D by age group in females. The three factors were approximately the same for females in their 20s and 30s. However, the content varied for females in their 40s and older. For women in their 40s and 50s, items 15 and 19 (original IP factors) constituted an independent factor (F3). Furthermore, items that were not included in the SOM and POS factors for women in their 60s constituted four factors (F1, F3, F4, and F6) that were not observed for females in their 20–50s.
4. Discussion The aim of the present study was to examine the factor structure of the CES-D among Japanese working individuals. In our sample, the good internal consistency of the overall CES-D (alpha = 0.88) indicated that this scale can be used as
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N. Sugawara et al. / Comprehensive Psychiatry 56 (2015) 272–278 Table 4 Factor structure by age group in the Center for Epidemiologic Studies Depression Scale (CES-D) items after promax rotation in males. 20s
Item 1 Item 2 Item 3 Item 4 Item 5 Item 6 Item 7 Item 8 Item 9 Item 10 Item 11 Item 12 Item 13 Item 14 Item 15 Item 16 Item 17 Item 18 Item 19 Item 20
30s
40s
50s
60s
F1
F2
F3
F1
F2
F3
F1
F2
F3
F1
F2
F3
F1
F2
F3
F4
F5
0.10 0.20 0.14 0.15 −0.06 0.06 −0.05 −0.09 0.31 0.54 0.30 −0.07 0.34 0.60 0.77 −0.06 0.56 0.66 0.71 0.34
0.57 0.32 0.57 −0.20 0.69 0.76 0.72 −0.01 0.32 0.18 0.22 0.17 0.30 0.05 −0.09 0.35 −0.06 0.14 −0.04 0.37
0.00 0.00 0.01 0.51 −0.04 −0.01 0.09 0.57 −0.19 −0.05 −0.04 0.40 0.00 −0.08 0.12 0.44 −0.05 −0.05 0.18 0.01
0.80 0.50 0.69 −0.23 0.69 0.83 0.80 −0.06 0.38 0.35 0.33 0.00 0.41 0.06 0.05 0.28 −0.09 0.15 −0.07 0.41
−0.05 0.04 0.02 0.10 −0.01 −0.05 −0.08 −0.06 0.29 0.40 0.28 0.02 0.29 0.58 0.69 −0.04 0.48 0.62 0.74 0.29
−0.08 −0.08 −0.07 0.42 0.01 0.07 0.05 0.66 −0.10 0.01 −0.02 0.54 0.00 0.06 0.02 0.53 −0.04 0.01 0.05 0.00
−0.02 0.26 0.18 0.13 −0.03 0.03 −0.05 −0.12 0.42 0.61 0.36 −0.04 0.34 0.68 0.71 0.02 0.50 0.72 0.65 0.16
0.75 0.36 0.55 −0.31 0.79 0.76 0.86 0.03 0.23 0.14 0.24 0.04 0.33 −0.03 0.03 0.20 −0.05 −0.01 0.00 0.55
−0.03 −0.03 0.01 0.46 −0.06 0.08 −0.02 0.59 −0.09 −0.04 0.02 0.53 0.08 0.02 0.05 0.55 −0.05 −0.03 0.04 −0.04
0.66 0.37 0.53 −0.23 0.86 0.78 0.91 0.00 0.36 0.23 0.43 0.04 0.40 0.06 0.03 0.19 −0.17 0.06 0.10 0.51
0.00 0.17 0.21 0.03 −0.17 0.02 −0.18 −0.06 0.25 0.48 0.18 −0.04 0.27 0.64 0.68 0.10 0.60 0.60 0.57 0.24
−0.04 −0.03 0.03 0.46 −0.02 0.05 0.02 0.61 −0.13 −0.03 −0.01 0.45 −0.03 0.01 0.04 0.44 −0.04 0.00 0.04 0.02
0.69 0.65 0.54 −0.12 0.65 0.88 0.87 0.09 0.33 −0.06 0.16 −0.07 0.35 −0.07 0.47 0.11 0.10 −0.01 0.12 0.46
−0.05 0.05 −0.04 0.50 −0.07 0.07 0.06 0.75 −0.04 0.08 −0.02 0.70 0.00 −0.01 −0.06 0.46 −0.02 0.03 −0.04 0.02
−0.17 −0.03 0.23 −0.05 −0.18 0.01 0.06 −0.04 −0.06 0.10 0.00 0.10 0.33 0.74 0.32 −0.10 −0.09 0.32 0.28 0.14
−0.08 0.15 0.10 −0.03 0.13 −0.13 0.06 0.11 −0.07 0.14 0.32 −0.13 −0.24 −0.05 0.02 0.04 0.82 0.37 0.10 0.10
0.22 −0.06 −0.07 −0.09 0.07 0.12 −0.11 −0.16 0.51 0.72 0.22 0.14 0.10 0.01 −0.13 0.20 0.01 0.24 0.14 −0.04
1.00
1.00 0.73 0.28
1.00 0.20
1.00
1.00 0.72 0.24
1.00 0.35
1.00
1.00 0.72 0.13
1.00 0.16
1.00
1.00 −0.11 0.55 0.58 0.60
1.00 −0.17 0.05 −0.13
1.00 0.47 0.43
1.00 0.43
1.00
Interfactor correlations F1 1.00 F2 0.70 1.00 F3 0.22 0.28 F4 F5
Figures are rounded to two decimal places. The loadings of 0.30 or above are boldfaced.
a reliable screening tool [16]. Among all participants, we demonstrated that the CES-D consists of three factors, which we labeled as DEP, SOM, and POS. Although the three factors were approximately the same for individuals in their 20s and 30s, the content varied for other age subgroups. The EFA model that we identified was similar to another three-factor model that arose from studies using ChineseAmerican or Mainland Chinese samples, in which the original DA and SS factors merged and then constituted two factors [17–19]. In those studies, the merged model could reflect traditional Chinese medicine concepts of mind-body holism [18]. In Japan, traditional religions such as Shintoism, Buddhism, and Qi also advocate the unity of mind and body [20]. Traditional concepts could thus affect the factor structure of depressive symptoms. Our results showed that CES-D items belonging to the original PA factor constituted the same POS factor among all subgroups. Previous studies showed that individuals of Asian descent reported lower levels of positive affect than other populations [6,21]. In a study conducted in US, the amount and experience of life stress showed association to positive affect in Native Hawaiians and European Americans but not in Japanese Americans [7]. Among Asians, including Japanese, lower positive affect might be linked to cultural values more than actual mental health status. In this study CES-D items belonging to the original IP factor constituted the independent factor only among females
in their 40s and 50s. In Japan, the ratio of the workforce to the total female population shows a characteristic M-shaped curve with two peaks. The first peak occurs in approximately the early 20s for unmarried women. The second peak is observed in the late 40s, when women have finished child-rearing and are ready to begin working again [22]. There is a wide wage gap between males and females in Japan. Females earn only two-thirds of the wages that males earn because of significant differences in occupational standing, such as promotion (few women are assigned to managerial positions), segregation, and forms of employment (more women are assigned to part-time jobs). Ogiwara and colleagues have shown that the most significant factor related to depression in females is interpersonal conflict, but that the most significant factor for males is professional matters [23]. The above-mentioned occupational gender gap may contribute to gender-specific interpersonal problems. Individuals in their 60s exhibited more extracted factors from the CES-D than those in their 20s to 50s. Although the interpretation of our results was hampered by the relatively small sample of individuals in their 60s, the factor structure observed among these older individuals could be related to distinct etiologies. Depression among the elderly could have different etiological pathways: (1) early onset with longstanding psychobiological vulnerability, (2) late onset as a reaction to severe life stress, and (3) late onset with vascular risk factors [24,25].
276
Table 5 Factor structure by age group in the Center for Epidemiologic Studies Depression Scale (CES-D) items after promax rotation in females. 20s
40s
50s
60s
F1
F2
F3
F1
F2
F3
F1
F2
F3
F4
F1
F2
F3
F4
F1
F2
F3
F4
F5
F6
0.04 0.25 0.25 0.05 −0.15 0.09 0.01 −0.09 0.45 0.48 0.22 −0.02 0.34 0.60 0.62 −0.04 0.58 0.72 0.71 0.24
0.62 0.26 0.48 −0.18 0.83 0.67 0.72 −0.08 0.12 0.17 0.31 0.14 0.25 0.00 −0.13 0.20 0.08 0.15 −0.20 0.42
−0.07 −0.10 0.04 0.39 −0.12 0.12 0.04 0.55 −0.07 0.06 −0.01 0.43 0.03 −0.08 0.14 0.63 −0.15 −0.10 0.20 0.00
0.05 0.12 0.33 −0.01 −0.05 0.14 −0.19 −0.16 0.52 0.42 0.29 0.12 0.28 0.60 0.67 0.12 0.60 0.73 0.72 0.10
0.64 0.45 0.41 −0.16 0.74 0.67 0.89 0.01 0.08 0.22 0.30 −0.04 0.35 0.00 −0.07 0.12 0.04 0.03 −0.06 0.54
0.01 −0.15 0.07 0.40 −0.06 0.08 0.07 0.71 −0.01 0.00 −0.11 0.47 0.01 −0.01 0.07 0.51 −0.13 0.01 0.08 −0.10
0.79 0.54 0.72 −0.19 0.84 0.71 0.72 −0.02 0.30 0.30 0.45 −0.01 0.42 0.08 −0.05 0.19 −0.02 −0.08 0.05 0.38
−0.13 0.16 −0.01 0.10 −0.11 0.14 −0.03 −0.06 0.36 0.46 0.21 −0.03 0.18 0.43 −0.07 0.00 0.65 0.98 0.25 0.26
0.02 −0.08 0.04 −0.03 −0.05 −0.06 0.00 −0.07 0.01 0.01 −0.06 0.04 0.13 0.26 1.08 0.05 0.02 −0.13 0.42 0.08
0.01 −0.09 0.04 0.37 −0.10 0.09 0.06 0.58 −0.04 −0.07 −0.07 0.36 0.01 0.05 −0.04 0.55 −0.03 0.08 0.06 −0.10
−0.16 0.00 0.04 0.07 0.03 0.18 0.04 −0.02 0.52 0.60 0.21 −0.04 0.06 0.38 0.23 −0.06 0.55 0.80 0.35 0.39
0.67 0.26 0.52 −0.24 0.70 0.74 0.80 0.05 0.19 0.15 0.18 0.10 0.22 0.02 −0.12 0.23 −0.12 −0.06 −0.02 0.19
0.21 0.24 0.21 0.05 −0.08 −0.07 −0.09 −0.15 −0.04 0.05 0.18 −0.03 0.44 0.22 0.74 0.14 0.06 −0.09 0.41 0.15
0.01 −0.10 0.00 0.39 0.01 0.05 −0.02 0.52 −0.11 −0.04 −0.08 0.41 −0.07 0.02 0.01 0.51 −0.01 0.14 0.09 −0.06
0.08 0.62 0.35 0.11 0.07 −0.18 0.07 −0.09 0.06 0.67 0.24 −0.02 0.07 −0.09 0.08 0.05 0.98 0.67 −0.03 0.92
0.61 0.05 0.49 −0.24 0.16 0.78 0.77 −0.17 0.26 0.09 0.16 0.15 0.07 0.15 −0.01 0.39 −0.06 0.25 −0.10 −0.19
−0.16 −0.08 −0.01 0.10 −0.09 0.04 0.36 0.14 −0.03 0.14 −0.23 −0.19 0.17 0.74 0.90 0.04 0.02 −0.07 0.22 0.04
0.08 −0.04 0.04 −0.05 0.97 0.33 0.01 0.12 0.44 0.00 −0.16 0.04 −0.14 −0.06 −0.06 −0.13 0.08 −0.10 0.32 0.16
−0.12 0.03 −0.01 0.63 0.06 0.13 −0.13 0.67 −0.07 −0.01 0.07 0.66 0.02 0.01 0.06 0.52 0.00 −0.05 −0.08 0.04
0.10 0.20 0.05 −0.10 −0.07 0.05 −0.10 0.06 −0.05 −0.03 0.25 0.15 0.92 0.13 0.06 −0.16 −0.10 −0.03 0.47 0.04
1.00
1.00 0.71 0.39
1.00 0.45
1.00 0.70 0.61 0.43
1.00 0.58 0.33
1.00
1.00 0.64 0.66 0.32
1.00 0.55 0.43
1.00 0.44 −0.02 0.16 −0.02 0.18
1.00 0.14 0.23 0.03 0.32
1.00 0.27 −0.03 0.32
1.00 0.04 0.26
1.00 0.10
1.00
Interfactor correlations F1 1.00 F2 0.70 1.00 F3 0.49 0.51 F4 F5 F6
1.00
Figures are rounded to two decimal places. The loadings of 0.30 or above are boldfaced.
1.00 0.39
1.00 0.30
1.00
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Item 1 Item 2 Item 3 Item 4 Item 5 Item 6 Item 7 Item 8 Item 9 Item 10 Item 11 Item 12 Item 13 Item 14 Item 15 Item 16 Item 17 Item 18 Item 19 Item 20
30s
N. Sugawara et al. / Comprehensive Psychiatry 56 (2015) 272–278
A previous study conducted among working individuals in Japan showed that the interpersonal problem factor was combined with other depressed and retarded activity items, composing a large “general dysphoria” factor for those aged 50–63 [11]. These results may indicate that the conceptualization of depression becomes more unified for this older Japanese generation. However, our results did not show this large factor for participants in their 50s and 60s. Most of the participants were born after World War II; hence, those between 50–63 years of age in Iwata's study may have experienced differences in social norms and the degree of westernization relative to most of the participants in our study. The current study has some limitations. First, subject recruitment was restricted to working individuals, and we could not generalize our findings to all individuals who receive a clinical diagnosis of depression. Second, as all of the participants were volunteers who were interested in their mental health, they may have been healthier than non-participants. Thus, working individuals who were not included in the study may have differing depressive symptoms. 5. Conclusion Our findings indicate that differences in age and gender could affect the factor structure of the CES-D among Japanese working individuals. Psychosocial or biological factors might contribute to the age- and gender-related differences in the factor structure of the CES-D. Acknowledgment The authors are grateful to Dr. Hirotsugu Miyake for his courtesy and assistance in our work. The authors declare that they have no competing interests.
Appendix A
Table 1 Center for Epidemiologic Studies Depression Scale (CES-D) items and Radloff's original four factors. Items Factor 1: Depressed Affect Item 3 I felt that I could not shake off the blues even with help from my family or friends. Item 6 I felt depressed. Item 9 I thought my life had been a failure. Item 10 I felt fearful. Item 14 I felt lonely. Item 17 I had crying spells. Item 18 I felt sad. Factor 2: Somatic symptoms Item 1 I was bothered by things that usually do not bother me. Item 2 I did not feel like eating; my appetite was poor.
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Table 1 (continued) Items Item 5 Item 7 Item 11 Item 13 Item 20
I had trouble keeping my mind on what I was doing. I felt that everything I did was an effort. My sleep was restless. I talked less than usual. I could not get going.
Factor 3: (Lack of) positive affect Item 4 I felt that I was just as good as other people. Item 8 I felt hopeful about the future. Item 12 I was happy. Item 16 I enjoyed life. Factor 4: Interpersonal problems Item 15 People were unfriendly. Item 19 I felt that people disliked me. Table 2 Fit indices for confirmatory factor analysis models*.
Total Male Female
GFI
AGFI
NFI
CFI
RMSEA
0.92 0.92 0.92
0.90 0.89 0.90
0.89 0.89 0.89
0.90 0.90 0.90
0.07 0.07 0.07
GFI goodness of fit index; AGFI adjusted goodness of fit index; NFI normed fit index; approximation. CFI comparative fit index; RMSEA root mean square error of approximation.
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