The construct validity of two depression measures, Zung’s Self-rating Depression Scale (SDS) and the Asian Adolescents Depression Scale (AADS), was investigated. Three studies were conducted using two samples collected in two stages, and the results were used to construct the Asian Depression Scale (ADS). Participants responded to the SDS and AADS in random order of presentation during stage 1; two months later, validation variables were collected. Study 1 found that the SDS is a reliable and valid measure of depression for Singaporean Chinese, but it does not cover the interpersonal dimension found in the AADS. Study 2 combined the two measures and found six factors. One of these factors, negative social self, which was a unique Asian depressive symptom cluster, consisted only of AADS items, while the affective manifestation and psychosomatic symptoms factor primarily consisted of items from the SDS. Study 3 selected high-loading items from the identified factors to construct the ADS, which showed excellent internal reliability, and good convergent and discriminant validity. Incremental predictive validity found on criterion data collected in stage 2, supported the nonspuriousness of the Asian Depression Scale.
Depression is a common human condition. Subjective experiences and symptom presentation; however, vary from culture to culture [
Epidemiological studies of depression in Asians are rare and have used a variety of instruments, most of which were developed in non-Asian populations [
Earlier studies of depressive symptoms in Asian populations, especially the Chinese, have found that the Chinese tend to de-emphasize affective symptoms; instead, they present somatized complaints (e.g., [
We have explored the depressive symptomatology of Asians living in Asian communities. We used in-depth interviews, followed by focus group discussions with children and adolescents. The reported depressive symptoms were factor analyzed to identify the symptom groups and to construct an Asian Adolescents Depression Scale (AADS) [
The above review suggested the following features in the depressive symptoms of Asian populations: a relative de-emphasis of affective manifestations, and a strong emphasis on the somatic and interpersonal symptoms. The AADS is high on interpersonal symptoms, while SDS has a considerable portion of somatized symptoms, with considerable overlap between them. Three empirical studies were conducted to develop a comprehensive measure of depression by amalgamating these two measures.
The current study aims to establish a valid and comprehensive instrument of depression to be used mainly for screening and survey of community level screening. We have chosen the AADS and the SDS for which extensive empirical data have been collected to support each instrument’s internal reliability and easy interpretability for use in Asian community samples across a wide age range. We have also considered World Health Organization’s International Statistical Classification of Diseases and Related Health Problems (ICD-10) [
Two samples were used to investigate the internal structure and the ecological validity of the SDS. The exploration sample consisted of 160 participants (39 males and 121 females, mean age 20.82, SD = 1.78 years). The validation sample consisted of 166 participants (46 males and 120 females, mean age 20.40, SD = 1.31 years). Participants were recruited from a major university in Singapore and were given course credit for their participation.
This 20-item self-rating depression scale was developed by Zung [
For convergent and discriminant validity: measures of positive affects (PA) [
The Positive and Negative Affect Scale was developed by Watson, Watson et al. [
The Asian Subjective Wellbeing Scale was developed by Chang and Chu [
The 20-item test anxiety scale has been widely used to assess anxiety related to being evaluated. For the present sample, the internal reliability was found to be .912.
The Hope Scale constructed by Snyder et al. [
The Life Orientation (LOT): The Life Orientation Scale [
Data were collected in two stages. In the first stage, data were collected on the SDS, the AADS, and demographic variables of the exploration sample. In the second stage, data were collected from the validation sample on a set of validation variables, including positive and negative affects such as optimism, hope, test anxiety, life satisfaction, and Asian subjective wellbeing.
Data analysis was guided by our objective to identify underlying dimensions that are meaningful and parsimonious. To achieve this objective, we employed a series of exploratory factor analysis and conceptual grouping of items into meaningful categories to construct a hypothesized factor structural model to be subject to confirmatory factor analysis.
First, a principal components analysis with Promax rotation was conducted on the items in the Self-rating Depression Scale. We chose Promax rotation for two reasons: (1) we hypothesized that the factors were correlated, however, (2) we did not have a apriori hypothesis as to the magnitude of factor correlation, therefore we did not use Oblimin rotation but chose Promax rotation as suggested by Gorsuch [
Factor two was labeled “loss of self-efficacy” and included items such as “I find it easy to make decisions (reversed coded)” and “I find it easy to do the things I used to do (reversed coded).” Factor three was labeled “physical symptoms” and included items such as “I eat as much as I used to (reverse coded)” and “I have trouble with constipation.”
Additional factor analysis was conducted on Factor one, which initially included conceptually mixed items. Two conceptually coherent factors emerged: loss of life directions and affective manifestations.
Finally, by reviewing factor loadings and sorting items into meaningful categories, four factors were identified for the SDS: loss of life direction (existentialist factor) (four items), loss of self-efficacy (five items), affective manifestations (two items), and physical symptoms (nine items).
Table
Factor structure and factor loading of self-rating depression scale.
Item number | Item | LLD | LSE | AM | PS |
---|---|---|---|---|---|
S 14 | I feel hopeful about the future | 0.57 | |||
S 17 | I feel that I am useful and needed | 0.8 | |||
S 18 | My life is pretty full | 0.71 | |||
S 19 | I feel that others would be better off if I were dead | 0.54 | |||
S 11 | My mind is as clear as it used to be | 0.69 | |||
S 12 | I find it easy to do the things I used to do | 0.7 | |||
S 16 | I find it easy to make decisions | 0.43 | |||
S 2 | Morning is when I feel the best | 0.17 | |||
S 20 | I still enjoy the things I used to do | 0.45 | |||
S 1 | I feel sad | 0.71 | |||
S 3 | I have crying spells or feel like it | 0.87 | |||
S 4 | I have trouble sleeping at night | 0.47 | |||
S 5 | I eat as much as I used to | 0.26 | |||
S 6 | I enjoy sex | 0.24 | |||
S 7 | I notice that I am losing weight | 0.22 | |||
S 8 | I have trouble with constipation | 0.45 | |||
S 9 | My heart beats faster than normal | 0.65 | |||
S 10 | I get tried for no reason | 0.55 | |||
S 13 | I am restless and cannot keep still | 0.08 | |||
S 15 | I am more irritable than usual | 0.42 |
Note. “S” refers to items in the Self-rating Depression Scale; LLD is loss of life direction; LSE is loss of self-efficacy; AM is affective manifestations; PS is physical symptoms.
The four-factor structure was tested. Each of the factors, except affective manifestations (which only has two items), was parceled. The four-factor structure had a reasonably good fit, specifically
Internal reliability of the SDS was .801 and .803 for the exploratory sample and the validation sample, respectively. Both were acceptable, but were considerably lower than the internal reliability of .945 of AADS in the validation sample.
As a depression measure, the SDS should correlate substantially with other depression measures
As a depression measure, the SDS should correlate positively with negative emotions, anxiety, and negative affects and correlate negatively with positive emotions and positive cognitions. SDS correlated positively with negative emotions (test anxiety
As a depression measure the SDS should predict such positive outcomes as subjective wellbeing. SDS negatively predicted subjective wellbeing measured in stage 2 (Asian Subjective Wellbeing,
The SDS correlates strongly with the AADS suggesting that it successfully assesses depression in these Asian adult samples. The EFA and CFA produced four coherent factors: Loss of life direction, loss of self-efficacy, affective manifestations, and physical symptoms. However, there were no factors that included negative social self or negative social relationships. Therefore, the SDS alone is not sufficient to assess depressive symptoms in Asian populations.
Participants in both subsamples were administered the SDS and AADS in random order. The items in the Self-rating Depression Scale and the Asian Adolescent Scale were combined for analyses, resulting in a total of 40 items. A series of EFA and CFA were conducted to test for the best fit for the underlying factors and the internal structure.
A principal components analysis with Promax rotation was conducted on the 40 items. The scree plot suggested a three factor solution, with eigenvalues and variance accounted for values of 13.15 and 32.88% for factor one (16 items), 2.29 and 5.72% for factor two (15 items), and 2.15 and 5.37% for factor three (nine items), respectively.
Factor three was conceptually coherent, with items such as “I get tried for no reason,” “my heart beats faster than normal,” and “I have trouble sleeping at night.” This factor was labeled “physical symptoms.” factor one and factor two contained conceptually mixed items, so further factor analyses were conducted.
After analysis of the 15 items in Factor One, two facets were identified: “Loss of Life Direction (existentialist factor),” which included items such as “my life is pretty full (reversed coded)” and “I feel hopeful about the future (reversed coded),” and “negative self and relationship,” which included items such as “I do not like going out with friends or meeting people” and “I feel that others would be better off if I were dead.” The remaining items consisted of symptoms of affective manifestations and were combined with factor three.
Further analysis of factor two yielded additional facets. The first and third facetswith items such as “I take a long time to decide on things” and “my mind is as clear as it used to be (reversed coded)”—were grouped into one factor, that was labeled “loss of cognitive efficacy.” The second facet included items such as “I feel that have no energy to do things most of the time” and “I do not feel like doing anything,” and was labeled “loss of motivation.”
In the final analysis, six factors were identified: loss of life direction (existentialist factor) (five items), negative self and relationship esteem (five items), loss of cognitive efficacy (eight items), loss of motivation (seven items), affective manifestations (five items) and physical symptoms (ten items). This six-factor solution formed the hypothesized factor model to be tested by confirmatory factor analysis. Table
Factor structure and factor loading of Self-Rating Depression Scale and Asian Adolescent Depression Scale.
Item number | Item | LLD | NSS | LCE | LOM | AM | PS |
---|---|---|---|---|---|---|---|
S 14 | I feel hopeful about the future | 0.6 | |||||
S 17 | I feel that I am useful and needed | 0.71 | |||||
S 18 | My life is pretty full | 0.66 | |||||
A 3 | I feel that I am not wanted | 0.71 | |||||
A 5 | I feel hopeless | 0.66 | |||||
S 19 | I feel that others would be better off if I were dead | 0.61 | |||||
A13 | I do not like going out with friends or meeting people | 0.53 | |||||
A 16 | I have thought about dying | 0.54 | |||||
A 19 | I feel that I am not as good as others | 0.77 | |||||
A 20 | Nothing works out right for me | 0.75 | |||||
S 11 | My mind is as clear as it used to be | 0.49 | |||||
S 12 | I find it easy to do the things I used to do | 0.43 | |||||
S 16 | I find it easy to make decisions | 0.66 | |||||
A 4 | I take a long time to get things done | 0.76 | |||||
A 8 | I cannot think well | 0.73 | |||||
A 11 | I cannot concentrate on my studies as much as I used to | 0.6 | |||||
A 12 | I take a long time to decide on things | 0.76 | |||||
A 18 | I am confused about what kind of person I am | 0.67 | |||||
S 2 | Morning is when I feel the best | 0.3 | |||||
S 20 | I still enjoy the things I used to do | 0.16 | |||||
A 6 | I feel tired most of the time | 0.73 | |||||
A 9 | I do not feel like doing anything | 0.77 | |||||
A 14 | I feel that I have no energy to do things most of the time | 0.7 | |||||
A 15 | I do not get satisfaction from what I do | 0.72 | |||||
A 17 | I feel that I have no control over what happens | 0.63 | |||||
S 1 | I feel sad | 0.61 | |||||
S 3 | I have crying spells or feel like it | 0.6 | |||||
A 1 | I feel sad most of the time | 0.76 | |||||
A 2 | My heart feels heavy | 0.74 | |||||
A 10 | I often feel like crying | 0.6 | |||||
S 4 | I have trouble sleeping at night | 0.45 | |||||
S 5 | I eat as much as I used to | 0.18 | |||||
S 6 | I enjoy sex | 0.29 | |||||
S 7 | I notice that I am losing weight | 0.12 | |||||
S 8 | I have trouble with constipation | 0.35 | |||||
S 9 | My heart beats faster than normal | 0.53 | |||||
S 10 | I get tried for no reason | 0.65 | |||||
S 13 | I am restless and can’t keep still | 0.11 | |||||
S 15 | I am more irritable than usual | 0.53 | |||||
A 7 | I am more bad tempered than before | 0.55 |
Note. “S” refers to items in the Self-rating Depression Scale; “A” refers to items in the Asian Adolescent Depression Scale. LLD: loss of life direction; NSS: negative social self; LCE: loss of cognitive efficacy; LOM: loss of motivation; AM: affective manifestations; PS: physical symptoms.
Finally, the six-factor structure was tested. Each of the factors was parceled. The six-factor structure had a reasonably good fit; specifically,
As mentioned earlier, we aimed at identifying the best fit internal structure that was meaningful and parsimonious. We hypothesized that some of the factors identified may be empirically grouped into higher order factors.
Table
Correlations, reliabilities, and descriptive statistics of the six factors for the Subsample one (English) and Subsample two.
Factors | LLD | NSS | LCF | LOM | AM | PS |
---|---|---|---|---|---|---|
Subsample one | ||||||
| ||||||
LLD | 1.00 | |||||
NSS | .68** | 1.00 | ||||
LCF | .67** | .56** | 1.00 | |||
LOM | .66** | .61** | .72** | 1.00 | ||
AM | .65** | .62** | .52** | .51** | 1.00 | |
PS | .60** | .44** | .59** | .64** | .52** | 1.00 |
|
.87 | .76 | .84 | .78 | .88 | .66 |
M | 2.39 | 2.14 | 2.78 | 2.70 | 2.43 | 2.54 |
SD | .77 | .70 | .68 | .63 | .80 | .52 |
| ||||||
Subsample two | ||||||
| ||||||
LLD | 1.00 | |||||
NSS | .74** | 1.00 | ||||
LCF | .74** | .68** | 1.00 | |||
LOM | .73** | .42** | .78** | 1.00 | ||
AM | .65** | .69** | .64** | .65** | 1.00 | |
PS | .55** | .56** | .49** | .56** | .61** | 1.00 |
|
.81 | .77 | .85 | .78 | .84 | .62 |
M | 2.24 | 2.14 | 2.81 | 2.54 | 2.39 | 2.54 |
SD | .59 | .70 | .71 | .64 | .74 | .45 |
Note. LLD: loss of life direction; NSS: negative social self; LCF: loss of cognitive efficacy; LOM: loss of motivation; AM: affective manifestations; PS: physical symptoms.
**
Confirmatory factor analyses were then conducted to test and confirm the conceptual appropriateness of the three-factor structure of depression.
Using the item mean of each factor as a manifested indicator, with two indicators for each of the three latent factors, a reasonably good fit was found for the higher order structure (
Using the item mean of each factor as an indicator, with two indicators for each of the three latent factors, a good fit was found for the higher order structure (
Of the six factors that emerged from the joint item pool, the negative social self factor, which consists mainly of AADS items, appears to be a specifically Asian depressive manifestation. The loss of self-efficacy factor, which includes loss of cognitive efficacy and loss of motivation symptoms, corresponds with young Asian’s worries about achievement and failure. The SDS’s factor of affective and somatic symptoms confirms the earlier findings on Asian depressive complaints. The integrated symptomatology of AADS and SDS is a more comprehensive reflection of the contemporary Asian experience of depression [
Using the integrated symptomatology of depression derived in Study 2, we constructed the Asian Depression Scale (ADS) and assessed its internal reliability, construct validity, and incremental validity.
Data from the validation sample were used to construct and validate the ADS. Materials used were as described above.
We examined the individual item loadings in all three factors and chose the higher loading items and deleted redundant items. The resultant scale maintained the comprehensive factor structure of the integrated symptomatology.
We explored the internal reliability, the convergent and predictive validity of the newly constructed ADS. We conducted exploratory factor analysis followed by confirmatory factor analysis (EFA and CFA) for the ADS. Finally, using validating data collected at stage 2, we tested whether the incremental validity of the ADS was a spurious measure over SDS or AADS.
Table
The Asian Depression Scale.
Factor one: loss of meaning of life | |
---|---|
18 | I feel that I am not wanted |
5 | I feel hopeless |
15 | I feel that others would be better off if I were dead |
4 | I do not like going out with friends or meeting people |
17 | Nothing works out right for me |
| |
Factor two: loss of self-efficacy | |
| |
22 | My mind is as clear as it used to be |
23 | I find it easy to do the things I used to do |
19 | I find it easy to make decisions |
7 | I cannot think well |
9 | I cannot concentrate on my studies as much as I used to |
20 | I take a long time to decide on things |
3 | I am confused about what kind of person I am |
2 | I feel tired most of the time |
13 | I do not feel like doing anything |
8 | I feel that I have no energy to do things most of the time |
6 | I do not get satisfaction from what I do |
16 | I feel that I have no control over what happens |
| |
Factor three: Affective-somatic symptoms | |
| |
21 | I feel sad |
11 | I have crying spells or feel like it |
14 | My heart feels heavy |
1 | I often feel like crying |
24 | My heart beats faster than normal |
10 | I get tried for no reason |
12 | I am more bad tempered than before |
Note: Numbers refer to item numbering in the Asian Depression Scale.
The ADS had excellent psychometric properties. Cronbach’s alpha was .964.
The intercorrelation between the ADS with the AADS were
The ADS was negatively correlated with positive affects and cognitions. It was negatively correlated with positive affect (
The SDS predicted subjective wellbeing, as measured in stage 2. The SDS negatively predicted both life satisfaction (
We assessed the incremental validity of the ADS for each criterion measure, including Asian subjective wellbeing, life satisfaction, positive affect, negative affect, and test anxiety compared to the SDS and AADS. When the AADS was parceled out, the ADS made a marginally significant contribution to Asian subjective wellbeing (
When the SDS was controlled for, ADS independently contributed to Asian subjective wellbeing, (
The ADS demonstrates excellent internal reliability and is highly correlated with the ADS and the SDS. Furthermore, the ADS correlates with both positive and negative affects, subjective wellbeing and hope, and life satisfaction in the theoretically correct directions. This pattern of correlations supports the conclusion that the ADS is a measure of depression. Most importantly, the ADS demonstrates significant incremental validity over the AADS and SDS in predicting positive and negative outcomes, suggesting that it is not a spurious measure of depression for the Asian population.
The amalgamated items from the SDS and the AADS have excellent internal coherence and culturally meaningful factors, suggesting that the combined list provides a more accurate assessment of depression for Singaporean adults than either measure alone.
The ADS yields incremental validity on the positive and negative criteria over its source measures, suggesting that it is not a spurious measure of depression over the AADS or the SDS.
These empirical studies were conducted with Singaporean Chinese samples; however, this should not greatly limit the application of the ADS. The social dimension identified here reflects a shared Asian cultural emphasis on the interdependence of self-construal. The ADS is more suitable for other collectivist Asian cultures than the standardized Western measures.
Cross-cultural comparisons with non-Asian populations should also be conducted to test the boundary of cultural limitations of the instrument. Furthermore, as the ADS was developed on community samples, studies should be conducted to test the utility of the scale in clinical settings.