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 Prevalence rates of psychiatric disorders among late adolescent or young adult populations have been reported in only a few studies, with estimates ranging from 10% to 40% (1–4). Rates of mental disorders have been shown to increase from childhood through adolescence, peaking in young adulthood (3), and recent epidemiologic surveys show that young people (that is, those aged 15 to 24 years) have higher prevalence rates of mental disorders than do other age groups (5,6). Depressive disorders and anxiety disorders among youths aged between 15 and 24 years in Canada represent a particular challenge for prevention in public health, since little information exists concerning the beginning and the evolution of these disorders in this population. While depressive and anxiety symptoms have often been investigated as separate mental health entities, few studies examine and compare both disorders in regard to potential risk factors among youths. Even though they are very different psychiatric disorders according to the DSM-IV criteria (7), we do know from community and clinical studies that measures of anxiety disorders correlate well with measures of depressive disorders (8,9). Various sociodemographic characteristics (for example, sex, level of education, and income) are associated with depressive and anxiety disorders. Most studies indicate that sex and socioeconomic status are the most important predictors of these disorders (10–11). Moreover, studies have shown that the rates of mental disorders, particularly depression, are associated with various environmental stressors, including family discord (divorce or marital conflict), economic hardship, and stressful life events (12–14), whereas others have suggested that the etiologic model of mental disorder is not generically linked to adverse events but is, rather, associated with a greater stress induced by a high number and recurrence of adversities (15). Data on the frequency and characteristics of depressive and anxiety disorders among young people are necessary for both scientific purposes and service planning. Thus the aims of this study were to use data from the CCHS 1.2 to investigate the prevalence of depressive and anxiety disorders in the Canadian population aged 15 to 24 years and to analyze and compare the relation of these disorders with different sociodemographic indicators and with the general level of stress in daily life. MethodsStudy Population This study is based on the CCHS 1.2 data, a population-based, cross-sectional study designed to monitor the mental health of the general population and to evaluate the use of and need for health services. The design was a multistage cluster sampling. The response rate for CCHS 1.2 was 77%. In total, 36 984 Canadians were interviewed in 2002, and this sample is representative of the population both at the national and provincial levels. The aims, design, and methods have been described in greater detail elsewhere in this issue (16). For this particular study on depressive and anxiety disorders among young Canadians, the target population was Canadian inhabitants aged 15 to 24 years. The final sample comprised 5673 young Canadians (2884 male and 2779 female subjects). Most subjects lived in urban areas (83.9%), reported ongoing education (62.4%), and were considered single (77.8%). Instruments Measures: Depressive and Anxiety Disorder Diagnoses. We measured depressive and anxiety disorders, using the WMH-CIDI, an instrument that generates a profile of people with a disorder according to the DSM-IV definitions. Included in the definition of a depressive disorder was a diagnosis of a major depressive disorder, whereas anxiety dis- orders included social phobia, panic disorder, and agoraphobia. The depressive or anxiety disorders were categorized as being present or absent and were assessed according to a lifetime or 12-month reference period. Measures: Sociodemographic Variables Potentially Associated With Depressive and Anxiety Disorders. Sociodemographic data included sex, age group (late adolescence and young adulthood), province of residence (10 provinces grouped in 5 categories because of small numbers of cases in some provinces), urban or rural municipality, occupation (student only or student with employment, or not in school, with or without employment) and living arrangements (with parents, without parents, or other such as other family members or roommates). Marital status was categorized in 2 groups: presence of a partner (married or common law) and absence of a partner (single or divorced). This variable was not considered for the group aged 15 to 19 years, because 98% of youth in this category reported the absence of a partner. The level of education was treated differently, depending on the age group, to properly reflect its possible influence. Education level was dichotomized for the group aged 15 to 19 years as either having obtained a secondary school diploma or not, whereas for the group aged 20 to 24 years, 4 categories were made, including having no secondary school diploma, having only a secondary school diploma, having some postsecondary education, and having a postsecondary diploma. Respondent’s current household financial situation was used as an indicator of income and was grouped in 4 categories (inferior-average, average, superior-average, and superior). Finally, we also evaluated general stress level in daily life (in 3 categories), taking into account the associations found in the literature (17,18). Statistical AnalysisWe used cross-tabulations to calculate lifetime and 12-month prevalence of depressive and anxiety disorders according to each correlate. ORs were measured with logistic regressions to study associations between the disorders and the various independent indices. Because the CCHS 1.2 uses a multistage survey design, no simple formula could be used to calculate variance estimates. Therefore, we estimated 95%CIs using the bootstrapping method, a good approximate offered by Statistics Canada. We computed all analyses using the WesVar 4.2 (19), a software package for the variance estimation analyses of complex samples. Reported differences were significant at the 0.05 level or less. ResultsPrevalence of Depressive and Anxiety Disorders Among Canadian youth, 10.2% had suffered from depressive disorders during their lifetime, while 12.1% had suffered from anxiety disorders. Comorbidity between both disorders was assessed at 3.7%. Among those who suffered from an anxiety disorder during their lifetime, 78.7% suffered from social phobia, 23.9% from a panic disorder, and 11.5% from agoraphobia. The 12-month prevalence rates were 6.4% and 6.5%, respectively, 6.4% and 6.5% for depressive and anxiety disorders and 1.8% for both disorders. For the purpose of this study, we did not examine the 3 subtypes of anxiety disorders individually, because of the small number of individuals with agoraphobia or panic disorder. Sociodemographic Correlates Tables 1 and 2 present the prevalence rates of depressive and anxiety disorders against various potential predictors. Unless otherwise specified, the associations found were the same on a lifetime and 12-month basis.
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