Lifetime and Twelve-Month Prevalence Rates of Major Depressive Episodes and Dysthymia Among Chinese Americans in Los Angeles

This paper reports the prevalence rates for major depressive episode and dysthymia. The occurrence of at least one major depressive episode is an essential feature for a diagnosis for major depressive disorder. Lifetime rates refer to the proportion of respondents who reported having experienced the problem ever in their lifetime, and 12-month prevalence rates are the proportion of respondents who experienced the problem sometime during the 12 months before the interview. The lifetime rate of major depression episode was 6.9%; 3.4% of the respondents had an episode in the past 12 months. Approximately 5.2% of the respondents experienced dysthymia in their lifetime; 0.9% had experienced it within 12 months of the interview. The National Comorbidity Survey (2), using the Composite International Diagnostic Interview, reported much higher rates of depressive episodes: a lifetime rate of 17.1% and a 12-month rate of 10.3%. However, the National Comorbidity Survey rates for lifetime (6.4%) and current (2.5%) dysthymia were relatively closer to the estimates found in this study, which suggests that the experience of sadness may be more chronic than episodic for Chinese Americans, many of whom are immigrants.

Table 1 displays the odds ratios for the lifetime occurrence of a depressive episode and dysthymia. Among the sociodemographic variables, marital status has the strongest and most consistent association with the lifetime occurrence of a major depressive episode. Age shows some association with depression and dysthymia in that respondents in the younger age groups (ages 18–29 and 30–49) are less likely to have experienced mood disorders than the oldest age group in our sample (ages 50–65). Since many of the respondents were immigrants, the age variable is confounded with age at immigration. Table 1 shows that age at immigration is associated with depressive episodes and dysthymia. Accordingly, there may be strong cohort differences based on the timing of immigration rather than simply an age effect.

The most perplexing of the results in table 1 is the absence of an association between sex and depressive episodes and dysthymia. In most community studies, women have consistently higher rates of mood disorders than men. In the National Comorbidity Survey (2), for example, women were 1.8 times more likely to have a lifetime mood disorder than men. To explore this anomaly further, we examined sex differences among respondents at different acculturation levels. We used an acculturation scale that included items on language use, ethnicity of the workplace, and types of foods eaten (29). A high score indicated a greater exposure to American life styles and a low score indicated a greater exposure to Chinese culture. To explore how acculturation and sex intersect to explain the rates of mood disorders among Chinese men and women, we divided the sample into two groups based on a midpoint on the acculturation scale score. Although the selection of the midpoint is somewhat arbitrary, it did create two groups that differed in acculturation levels. The mean score of the group on the top half of the scale (mean=3.00, SD=0.42) was significantly higher than the mean score of the group on the bottom half (mean=1.76, SD=0.30) (F=1735.36, df=1, 1642, p=0.0001). We examined the association between sex and depression and dysthymia in these two groups. Since women are expected to have a higher rate of depression, we used a one-tailed test of the odds ratios. Within the high-acculturation-score group, women were 3.1 times more likely than men to have dysthymia in their lifetime (Wald F=1.76, df=1, 401, p=0.10) and 2.16 times more likely than men to have a lifetime depressive episode (Wald F=1.15, df=1, 401, p=0.14). In the low-acculturation-score group, women did not differ significantly from men in lifetime depressive episodes (odds ratio=0.99, Wald F=0.00, df=1, 401, p=0.97) and dysthymia (odds ratio=0.91, Wald F=0.09, df=1, 401, p=0.76). Two explanations are plausible. First, it is possible that women who have low acculturation levels may be protected against the onset of depressive episodes. Second, it is also likely that sex differences may become pronounced as Chinese immigrants become acculturated. Although these explanations are not mutually exclusive, our data do not allow us to examine this issue extensively.

The socioeconomic status variables are associated with either lifetime depression or dysthymia. Between the two immigration variables, only language use is associated with depressive episodes and dysthymia. Among all correlates listed in table 1, negative life events has one of the strongest and most consistent associations with the lifetime occurrence of major depressive episode and dysthymia. The life events measure is an inventory of 10 traumatic events (combat experience; life-threatening accident; involvement in a natural disaster; witnessing someone being badly injured or killed, raped, sexually molested, physically attacked, or assaulted; physical abuse as a child; neglect as a child; and threat with a weapon). The experience of at least one negative life event is associated with an elevated risk for depressive episode and dysthymia.

Table 2 displays the association of the sociodemographic, socioeconomic status, immigration, and life event variables with 12-month major depressive episode and dysthymia. Age and sex do not show an association with 12-month depressive episode and dysthymia. Marital status is associated with dysthymia but not with depressive episode.

Among the socioeconomic status variables, income and employment status are associated with current depressive episode and dysthymia. Language and length of time in the United States are not associated with either disorder. Recent negative life events (e.g., breakup of a close friendship, separation from a loved one, having been robbed or burglarized, having one’s driver’s license suspended, suing someone, being sued by someone, experiencing serious trouble with police or law, death of close friends or relatives) has a strong association with both disorders.

Two divergent hypotheses are presented when predictions are made about the prevalence of psychiatric problems among Asian Americans. The first hypothesis suggests that rates will be high because a large proportion of Asian Americans are immigrants who will undergo difficult transitions in their adjustment to American society. Indeed, studies have found that some Asian American ethnic groups have higher symptom scores than whites (4). The second hypothesis argues that the rates of mood disorders will be low because Asian Americans, like their counterparts in other countries, are likely to express their problems in behavioral or somatic terms rather than as emotional ones. Available evidence suggests that the rates of mood disorders are quite low in Taiwan, Hong Kong, and China (30).

Findings from the Chinese American Psychiatric Epidemiological Study suggest that, when DSM-III-R criteria are used, the prevalence estimates of depressive episodes and dysthymia are more complex than the hypotheses that have been advanced. When compared with a national estimate, the National Comorbidity Survey (2), which used the same diagnostic measure (the Composite International Diagnostic Interview), Chinese Americans have a much lower rate of major depressive episode. However, it is equally evident that Chinese Americans are not adverse to expressing problems in emotional idioms. This is supported by the finding of similar rates of lifetime and current dysthymia in our study and the National Comorbidity Survey.

Except for marital status and employement status, none of the sociodemographic and socioeconomic variables shows a strong and consistent association with both lifetime and current major depressive episode and dysthymia. The lack of an association with sex, household income, and education warrants some comment. Education and income may not be consistently associated with depression and dysthymia in our sample for two reasons. First, past empirical studies do not actually show a stable association between socioeconomic status and depression. Although the inverse association between socioeconomic status and mental illness is widely known, socioeconomic status has unique associations with discrete disorders. The Epidemiologic Catchment Area (ECA) study (31), for example, found that socioeconomic status was not associated with depression but had an inverse association with lifetime rates of alcohol abuse. The National Comorbidity Survey (2) demonstrated that people in the lowest income levels (compared with those in the highest) were most at risk for affective disorders and that socioeconomic status was more strongly linked to anxiety disorders than to affective disorders. The inverse association between socioeconomic status and depression has not been found consistently for all ethnic groups (32). Second, commonly used measures of socioeconomic status, such as income and education, may not fully capture the important dimensions of status among immigrant groups. Although some Chinese immigrants may have high levels of education when they arrive in the United States, it may not lead to high-paying jobs because employers may not value education gained in another country as much as education gained in the United States. Moreover, language difficulties and discrimination against immigrants may prevent them from accruing the benefits of higher education. Finally, although income typically measures the annual resources available to a person, it does not fully capture other economic resources that people can rely on (e.g., savings, home ownership) (33). Some immigrants in low-income brackets may be quite wealthy, and some who have high annual incomes may use most of their resources to accommodate their entry into the United States.

The absence of an association between sex and depressive episodes and dysthymia is striking. Most studies tend to show that women have significantly higher rates of depression than men. Although the precise reason for sex differences is open for debate, women tend to show a 2-to-1 margin in depression across a number of countries and studies. However, some exceptions to this pattern can be found. Brown and associates (34) found no association between sex and 12-month rates of depression among African Americans in Maryland. No sex association was found among Southeast Asian refugees in Canada (35) and among Korean Americans living in Chicago (36). The Taiwan study (30) found that women had slightly elevated rates of depression and dysthymia but that the rates for both men and women were low and that the differences did not appear statistically significant. In a reanalysis of the ECA data (37), Jewish men had a similar rate of major depression as Jewish women, although other religious groups (e.g., Catholics, Protestants, and non-Jews) had the expected 2:1 female-male ratio for depression. Some of our preliminary analyses suggest that acculturation may partly explain the absence of an overall sex difference. Sex differences seem to appear as Chinese immigrants acculturate to life in the United States. Another explanation is that when the rate of alcohol consumption is low, as it is among Chinese Americans (38), sex differences in mood disorders may be diminished (37).

There are some similarities and differences between our findings and those of previous studies regarding the rates and correlates of major depressive episode and dysthymia. Although the Chinese American Psychiatric Epidemiological Study focuses exclusively on Chinese Americans, much diversity exists within this ethnic category. For example, Chinese Americans who immigrate to the United States come from countries that are different in their sociopolitical environment—such as China, Taiwan, and Hong Kong. Moreover, large numbers of Chinese sought refuge from Vietnam during and after the Vietnam conflict. The Chinese American Psychiatric Epidemiological Study provides a rare opportunity to investigate the heterogeneity among Chinese Americans and to identify subgroups who may be most at risk for mental health problems.

Received July 7, 1997; revisions received Sept. 30 and Dec. 22, 1997, and March 9, 1998; accepted April 2, 1998. From the Neuropsychiatric Institute and the Department of Psychology, University of California, Los Angeles. Address reprint requests to Dr. Takeuchi, 10920 Wilshire Blvd., Los Angeles, CA 90024-6505; [email protected] (e-mail). Supported by NIMH grants MH-47460, MH-47193, and MH-44331.