Abstract
Background:
Previous studies have identified the significant role of stressful life events in the onset of depressive episodes. However, there is a paucity of cross-national studies on stressful life events that precede depression.
Aims:
We aimed to compare types of stressful life events associated with the onset of depressive episodes in patients with major depressive disorder (MDD) in five Asian countries.
Method:
A total of 507 outpatients with MDD were recruited in China (n = 114), South Korea (n = 101), Malaysia (n = 90), Thailand (n = 103) and Taiwan (n = 99). All patients were assessed with the Mini-International Neuropsychiatric Interview and the List of Threatening Experiences. The prevalence of each type of stressful life events was calculated and compared between each country.
Results:
The type of stressful life event that preceded the onset of a depressive episode differed between patients in China and Taiwan and those in South Korea, Malaysia and Thailand. Patients in China and Taiwan were less likely to report interpersonal relationship problems and occupational/financial problems than patients in South Korea, Malaysia and Thailand.
Conclusion:
Understanding the nature and basis of culturally determined susceptibilities to specific stressful life events is critical for establishing a policy of depression prevention and providing effective counseling services for depressed patients.
Introduction
Depressive disorder is one of the most common psychiatric disorders, with a lifetime prevalence of about 15% (Sadock & Sadock, 2007), and one of the leading causes of disease burden and disabilities worldwide (Lopez, Mathers, Ezzati, Jamison, & Murray, 2006). Although genetic factors play a role in the development of depression, social factors also have an impact (Kendler et al., 1995; Sadock & Sadock, 2007). It is well established that stressful life events play an important role in the onset of depressive episode (Hammen, 2005; Kendler et al., 1995). The diathesis-stress model of depression etiology posits that a major depressive episode emerges in vulnerable persons as an abnormal reaction to stressful life events (Hammen, Henry, & Daley, 2000; Patten, 2013). Strength of the stress–depression relationship reportedly declines across the course of the recurrent depression (Post, Susan, & Weiss, 1992). On the contrary, recent study by Roca et al. (2013) found that severe stressful life events showed no differences between first and recurrent episodes, and moderate and minor stressful life events were more present in recurrent than in first episodes, suggesting a need for management of stressful life events during long-term periods and not just in the initial recurrences of the disease.
Depression may follow any undesirable events that have personal meaning and significance for an individual, and researchers have explored whether some classes of events are especially likely to provoke depressive reactions. The most extensive line of research has focused on the unique significance of interpersonal loss, which may include bereavement, separations or threats of separation (Asselmann, Wittchen, Lieb, Höfler, & Beesdo-Baum, 2014; Hammen, 2003; Kendler et al., 1995; Paykel, 2003; Tennant, 2002). The concept of loss has sometimes been expanded beyond interpersonal loss events to include loss of self-esteem or role loss (Brown, Harris, & Hepworth, 1995; Mandal, Ayyagari, & Gallo, 2011). However, the characteristics of stress and stressful life events that precede the onset of a depressive episode are influenced by the socio-cultural context. For example, Kendler and colleagues (1995) reported that the stressful life events predicting the onset of major depression in female–female Caucasian twin pairs in Virginia, United States, were death of a close relative, assault, serious marital problems and divorce or breakup. By contrast, Lueboonthavatchai (2009) reported that sexual difficulties with spouse, job loss and absence of recreation had a particularly strong association with the onset of depression in Thai patients.
Given the paucity of cross-national studies on stressful life events that precede depression, the present study aimed to compare types of stressful life events associated with the onset of depressive episodes in patients with major depressive disorder (MDD) in five Asian countries. It is important to identify the preceding factors of depressive episodes so that prevention and intervention strategies can be implemented in each Asian country.
Methods
Study design and settings
The subjects were participants in the Study on the Aspects of Asian Depression – a multi-country, cross-sectional, observational study of depression in clinical settings carried out between 2008 and 2011 (Jeon et al., 2013). We used data from 12 study sites across five Asian countries: China, South Korea, Malaysia, Taiwan and Thailand. The study sites were the Beijing Anding Hospital (Beijing, China), Institute of Mental Health (Beijing, China), Shanghai Mental Health Center (Shanghai, China), Samsung Medical Center (Seoul, Korea), Asan Medical Center (Seoul, Korea), Kyungpook National University Hospital (Daegu, Korea), Inha University Hospital (Incheon, Korea), University of Malaya Medical Center (Kuala Lumpur, Malaysia), Chung Gang Memorial Hospital (Taoyan County, Taiwan), Mackay Memorial Hospital (Taipei City, Taiwan), Maharaj Nakorn Chiang Mai Hospital (Chiang Mai, Thailand) and the Prince of Songkla University (Songkla, Thailand). All sites provide tertiary psychiatric care for the public or private sector in each district.
Mental health care system in these countries is underdeveloped. Mental health spending is no more than 2% of the health budget appropriated to mental hospitals (Maramis, Van Tuan, & Minas, 2011). All five countries provide public health care, but insurance coverage varies widely regionally in these countries. Reimbursement for psychiatric care is covered in Korea, Singapore and Taiwan, but only partly covered in China, Thailand and Malaysia (Hu, 2004).
The study was approved by the Institutional Review Board of Asan Medical Center and the relevant review board of each study site.
Participants
Participants were recruited from patients who visited psychiatric outpatient clinic for psychiatric treatment at a study site. Written informed consent was obtained from each participant after the study details had been fully explained. The inclusion criteria were as follows: (1) age 18–65 years, (2) a positive response (‘yes’) to the Mini-International Neuropsychiatric Interview (MINI) (Sheehan et al., 1998) question A1 (depressed mood) and/or A2 (loss of interest) and (3) a diagnosis of MDD according to the Diagnostic and Statistical Manual of Mental Disorders–Fourth Edition (DSM-IV; American Psychiatric Association, 1994), as assessed using the MINI. The exclusion criteria were as follows: (1) unstable medical condition, (2) mood disorder due to medical condition and/or substance abuse, (3) psychotic or bipolar disorder, (4) clinically significant cognitive impairment, (5) treatment with psychotropic medication within the previous month, (6) treatment with a benzodiazepine drug within the previous week and (7) treatment with a long-acting antipsychotic medication within the previous 3 months. All other psychiatric and comorbid conditions were permitted.
A total of 1777 outpatients were screened for eligibility, of whom 590 (33.2%) were eligible. The reasons for screen failure were as follows: use of psychotropic medication (28.9%), failure to meet the MINI criteria (24.1%), presence of psychotic or bipolar disorder (17.7%), age > 65 years (9.9%), presence of mood disorders due to medical conditions or substance abuse (7.6%), age < 18 years (5.4%), refusal to provide informed consent (4.4%) or presence of an unstable medical condition (2.1%). Of the 590 eligible patients, 507 were enrolled. The remaining patients were not enrolled for one of the following reasons: refusal/unwillingness to cooperate (56 patients), lack of patience to be interviewed (14 patients) or lack of time to participate in the study (9 patients).
Participants completed several self-report questionnaires in the presence of the study coordinator. A face-to-face diagnostic evaluation was then conducted with the site investigator before the participant met their treating clinician.
Measurements
Recent stressful life events were evaluated using the List of Threatening Experiences (LTE) questionnaire (Brugha & Cragg, 1990). This 12-item instrument evaluates common life events that tend to be threatening. Participants were asked to select life events that had occurred within the 12 months prior to the onset of their current depressive symptoms, with each life event scored dichotomously (yes/no). The level of distress associated with the event was assessed for all ‘yes’ responses. Distress level was rated on a 4-point Likert scale (not at all, mildly, moderately or severely distressed). Events rated as moderately or severely distressing were considered to be stressful life events that preceded the onset of the depressive episode. Additional self-report questionnaires were used to obtain information on gender, age, marital status, occupation and education. Past major depressive episodes were assessed using the MINI.
Statistical analysis
Participants were classified into five groups according to their countries. Group differences in the demographic and clinical characteristics were tested using a one-way analysis of variance for continuous variables and a chi-square test for categorical variables. A principal component analysis with varimax rotation was performed to reduce the number of variables and to aggregate the 12 stressful life events into reliable indices that reflected the main domains of stressful life events experienced by each patient. We selected the number of factors with eigenvalues of ⩾1.00. Items that were loaded at ⩾0.5 were included in each factor, and cross-loading items (i.e. those correlating with more than one factor) were excluded. Participants were defined as exposed to each factor of stressful life events if they had ⩾1 life events rated as moderately or severely distressing in that factor. The prevalence of each factor of stressful life events was calculated and compared between each country. Logistic regression analyses derived odds ratios and 95% confidence intervals using the presence of each factor of stressful life events (⩾1 stressful life events in that factor) as the main outcome variable and country as the principal predictor, after controlling for age, marital status, occupation, educational level and the presence of past major depressive episodes. SPSS software (version 21.0; SPSS Inc., Chicago, IL) was used to perform all statistical analyses, and a p-value < .05 was considered to be significant.
Results
Table 1 shows socio-demographic characteristics of patients in each of the five countries. Gender profile was similar across countries, but age, marital status, occupation, educational level and the prevalence of past MDDs were significantly different.
Demographic and clinical characteristics of participants.
SD: standard deviation.
Missing data were excluded from the analysis.
Table 2 showed the prevalence of the different stressful life events that occurred in the year prior to the development of the current depressive episode in each country. Patients in China and Taiwan were less likely to report a stressful life event (an event rated as moderately or severely distressing on the LTE) in the year prior to the development of the current depressive episode than patients in Malaysia, Thailand and South Korea. The most common stressful life event differed across countries, with serious illness or injury the most common among patients in China, South Korea and Taiwan, and major financial crisis the most common among patients in Malaysia and Thailand.
The prevalence of each item of the List of Threatening Experiences rated as moderately or severely distressing in the year preceding the onset of the current episode of major depressive disorder.
Data are n (%).
Post hoc comparison: China, Taiwan < South Korea, Thailand, Malaysia.
The five-factor solution to the principal component analysis accounted for 53.7% of the variance in LTE scores. The first factor, interpersonal relationship problems (eigenvalue 1.98), accounted for 16.5% of the variance in LTE scores and was composed of 3 LTE items, including ‘Broke off a steady relationship’, ‘Separation due to marital difficulties’ and ‘Serious problem with a close friend, neighbor or relative’. The second factor, occupational or financial problems (eigenvalue 1.30), accounted for 10.8% of the variance in LTE scores and was composed of 3 LTE items including ‘Sacked from job’, ‘Unemployed or seeking work for more than one month’ and ‘Major financial crisis’. The third factor, serious illness to subject or death of a close relative (eigenvalue 1.15), accounted for 9.6% of the variance in LTE scores and was composed of 2 LTE items including ‘Serious illness or injury’ and ‘Death of a close relative’. The fourth factor, material loss or legal problem (eigenvalue 1.08), accounted for 9.0% of the variance in LTE scores and was composed of 2 LTE items including ‘Something valuable lost or stolen’ and ‘Problems with police and court appearance’. The fifth factor (eigenvalue 1.05), accounted for 8.8% of the variance and was composed of a single item, change of residence (Table 3).
The item-to-factor loading for each item on the List of Threatening Experiences.
Table 4 showed the odds ratio for each factor of stressful life events for each country relative to China and Taiwan, after adjusting for age, marital status, occupation, educational level and the presence of past major depressive episodes. Patients in South Korea, Malaysia and Thailand were more likely to report interpersonal relationship problems and occupational/financial problems than patients in China, and patients in Thailand were more likely to report material loss or legal problems than patients in China (Table 4, Figure 1). Patients in South Korea, Malaysia and Thailand were more likely to report interpersonal relationship problems and serious illness to subjects or death of a close relative than patients in Taiwan, and patients in Malaysia were more likely to report occupational/financial problems than patients in Taiwan (Table 4, Figure 1). There were no significant differences in the frequency of each factor of stressful life events between South Korea, Malaysia and Thailand (Figure 1).
Odds ratios (ORs) for each type of stressful life event in participants with major depressive disorder in five Asian countries.
CI: confidence interval; OR: odds ratio.
Adjusted for age, marital status, occupation, educational level and the presence of past major depressive episode.
Prevalence (%) of each type of stressful life event in participants with major depressive disorder in five Asian countries (n = 507).
Discussion
Consistent with previous studies in Western countries (Asselmann et al., 2014; Hammen, 2003; Kendler et al., 1995; Paykel, 2003; Tennant, 2002), we found that relationship stressors, including loss or threatened loss events, were the most common stressful life events preceding the onset of a depressive episode in patients in Asian countries. Loss of a source of self-esteem such as work, finances or health was also a common preceding event, in line with previous studies (Brown et al., 1995; Mandal et al., 2011).
We found that patients in China and Taiwan were less likely to report preceding stressful life events than patients in South Korea, Malaysia and Thailand. This may indicate that patients in China and Taiwan are more likely to conceal negative experiences such as marital or financial difficulties. The reporting of stressful life events may also be affected by the social atmosphere of the collectivistic, group-oriented society that exists in China and Taiwan in which expression of individual difficulties is considered an admission of weakness, as well as an assault on social harmony (Kleinman et al., 2011; Yoo, 2001). Another possible explanation for the lower prevalence of preceding stressful life events in patients in China and Taiwan is that there are differences in treatment-seeking behaviors across the five countries that resulted in different selection bias. Even in modernized urban China, the majority of patients with mental illnesses seek alternatives to direct mental health professional treatments, possibly due to stigma and/or lack of knowledge (Zhang et al., 2013). In Chinese culture, mental illnesses are considered as independent conditions, not psychological states that could be caused by social stressors or that could exacerbate the negative effect of social stressors (Phillips, Liu, & Zhang, 1999). This is partly because the folk conception of mental illness in Chinese culture is still largely restricted to patients with severely disturbed thinking or behavior and does not include those with emotional disturbances related to psychological stress (Lin, 1982). Because of such a narrow conception of mental illness, a lot of depressed patients with obvious precipitating factors in China and Taiwan may not perceive their affective status as a disease and not seek treatment. Therefore, recruitment from psychiatric outpatient clinic in tertiary care hospitals could be biased toward patients with endogenous depression that has no obvious cause, particularly in China.
Our results showed that the type of stressful life event that preceded the onset of a depressive episode differed between patients in China and Taiwan and those in South Korea, Malaysia and Thailand. Patients in China were less likely to report interpersonal relationship problems and occupational/financial problems than patients in South Korea, Malaysia and Thailand. South Korea has experienced an extremely rapid rate of economic development and structural change, rebuilding quickly after the Korean War and becoming one of the top global economic powers in less than 40 years (Chung, 2006). This rapid modernization dramatically improved the population’s quality of life, but also exposed them to the unsettling effects of disruption, family disintegration and social isolation that are associated with modernization and industrialization (Jiloha, 2009; Yazaki & Takahashi, 1988). In rapidly developing societies such as South Korea, the discrepancy between rich and poor is a common problem and often gives rise to a sense of relative deprivation. Although Taiwan experienced a similarly rapid economic development, its rapid economic growth has not undermined stability and income equity (Chan & Clark, 1992). Compared with socialist China, job loss or major financial crisis is relatively common in South Korea. In addition, the spread of individualist culture in Korea may promote depressive dysphoria in response to negative achievement-related events such as job loss or financial crisis (Tafarodi & Smith, 2001). Another consideration is the differences in mental health care systems across the countries. Unlike other countries where there is no discrimination against coverage for mental health services, China does not have a national health insurance system in which mental health services are available to all (Ng & Li, 2010). The coverage of insurance is limited to inpatient services, and many types of mental disorders are not covered by these insurance programs in many areas. Because of this limited insurance coverage for psychiatric care, patients with occupational/financial problem in China are less likely to use health care institutions for psychiatric care.
Our study had several limitations. We assessed stressful life events using the LTE, which is not a complete list of stressful life events. Thus, we may have underestimated the prevalence of preceding stressful life events. In addition, it is possible that the depressive state of participants at the time of the study may have biased the reporting of stressful life events via mood-congruent recall, the possible reconstructive nature of memory and the instability of retrospective reports over time, which may reduce the validity and reliability of our results. Finally, the study sample from each of the five countries may not have been drawn from the same population. Recruitment was biased toward MDD patients who used health care institutions, and there may have been differences in the health care systems (e.g. different health insurance possibilities) across the five countries that resulted in different selection bias. Despite these limitations, our study has clinical and policy implications for depressed patients. Serious illness to subject or death of relative is a highly prevalent stressful life event preceding the onset of depression in all five Asian countries. Therefore, psychiatric service and social intervention for seriously ill patients and the bereaved are commonly required to prevent depression in all five countries. In addition, in countries with relatively high prevalence of interpersonal relationship problem (i.e. Korea, Malaysia and Thailand), problem-solving methods and specialized counseling services for marital difficulties, divorce and intergenerational conflicts could be useful for preventing depression. In countries with high prevalence of occupational/financial problems (i.e. South Korea, Malaysia and Thailand), government should foster social policies that focus on sustaining the quality of life for the unemployed and low-income group.
Conclusion
This was the first study to compare stressful life events that precede the development of a depressive episode between Asian countries, and highlights the common and unique features of preceding stressful life events between the five studied countries. Understanding the nature and basis of culturally determined susceptibilities to specific stressful life events is critical for establishing a policy of depression prevention and providing effective counseling services for depressed patients.
Footnotes
Acknowledgements
This study is the work of the Mood Disorders Research: Asian & Australian Network (MD RAN), which comprises the following members (in alphabetical order of family name (in capital letters)): Jae Nam BAE (Korea), Dianne BAUTISTA (Singapore), Edwin CHAN (Singapore), Sung-man CHANG (Korea), Chia-hui CHEN (Taiwan), CHUA Hong Choon (Singapore), Yiru FANG (China), Tom GEORGE (Australia), Ahmad HATIM (Malaysia), Yanling HE (China), Jin Pyo HONG (Korea), Hong Jin JEON (Korea), Augustus John RUSH (Singapore), Tian-Mei SI (China), Manit SRISURAPANONT (Thailand), Pichet UDOMRATN (Thailand) and Gang WANG (China).
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by an unrestricted research grant from H. Lundbeck A/S and from the Duke-National University of Singapore Office of Clinical Research. This study was also supported by the Basic Science Program through the National Research Foundation (NRF) of Korea funded by the Korean government (NRF-2014R1A1A3049818).