BackgroundMajor depression is one of the leading causes of disability worldwide, yet epidemiologic data are not available for many countries, particularly low- to middle-income countries. In this paper, we present data on the prevalence, impairment and demographic correlates of depression from 18 high and low- to middle-income countries in the World Mental Health Survey Initiative.MethodsMajor depressive episodes (MDE) as defined by the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DMS-IV) were evaluated in face-to-face interviews using the World Health Organization Composite International Diagnostic Interview (CIDI). Data from 18 countries were analyzed in this report (n = 89,037). All countries surveyed representative, population-based samples of adults.ResultsThe average lifetime and 12-month prevalence estimates of DSM-IV MDE were 14.6% and 5.5% in the ten high-income and 11.1% and 5.9% in the eight low- to middle-income countries. The average age of onset ascertained retrospectively was 25.7 in the high-income and 24.0 in low- to middle-income countries. Functional impairment was associated with recency of MDE. The female: male ratio was about 2:1. In high-income countries, younger age was associated with higher 12-month prevalence; by contrast, in several low- to middle-income countries, older age was associated with greater likelihood of MDE. The strongest demographic correlate in high-income countries was being separated from a partner, and in low- to middle-income countries, was being divorced or widowed.ConclusionsMDE is a significant public-health concern across all regions of the world and is strongly linked to social conditions. Future research is needed to investigate the combination of demographic risk factors that are most strongly associated with MDE in the specific countries included in the WMH.

Background Although depression appears to decrease in late life, this could be due to misattribution of depressive symptoms to physical disorders that increase in late life. Methods We investigated this issue by studying age differences in comorbidity of DSM-IV major depressive episodes (MDE) with chronic physical conditions in the WHO World Mental Health (WMH) surveys, a series of community epidemiological surveys carried out in 10 developed countries (n = 51,771) and 8 developing countries (n = 37,265). MDE and other mental disorders were assessed with the Composite International Diagnostic Interview (CIDI). Organic exclusion rules were not used to avoid inappropriate exclusion of cases with physical comorbidity. Physical conditions were assessed with a standard chronic conditions checklist. Results Twelve-month DSM-IV/CIDI MDE was significantly less prevalent among respondents ages 65+ than younger respondents in developed but not developing countries. Prevalence of comorbid mental disorders generally either decreased or remained stable with age, while comorbidity of MDE with mental disorders generally increased with age. Prevalence of physical conditions, in comparison, generally increased with age, while comorbidity of MDE with physical conditions generally decreased with age. Depression treatment was lowest among the elderly in developed and developing countries. Conclusions The weakening associations between MDE and physical conditions with increasing age argue against the suggestion that the low estimated prevalence of MDE among the elderly is due to increased confounding with physical disorders. Future study is needed to investigate processes that might lead to a decreasing impact of physical illness on depression among the elderly.

Objective While it is now recognized that psychotic experiences (PEs) are associated with an increased risk of later mental disorders, we lack a detailed understanding of the reciprocal time-lagged relationships between first onsets of PEs and mental disorders. Methods The WHO World Mental Health (WMH) surveys assessed lifetime prevalence and age-of-onset of PEs and 21 common DSM-IV mental disorders among 31,261 adult respondents from 18 countries. Results Temporally primary PEs were significantly associated with subsequent first onset of 8 of the 21 mental disorders (major depressive disorder, bipolar disorder, generalized anxiety disorder, social phobia, post-traumatic stress disorder, adult separation anxiety disorder, bulimia nervosa, alcohol abuse), with ORs (95%CI) ranging from 1.3 (1.2–1.5; major depressive disorder) to 2.0 (1.5–2.6; bipolar disorder). In contrast, 18 of 21 primary mental disorders were significantly associated with subsequent first onset of PEs, with ORs (95% CI) ranging from 1.5 (1.0–2.1; childhood separation anxiety disorder) to 2.8 (1.0–7.8; anorexia nervosa). Conclusions While temporally primary PEs are associated with an elevated risk of several subsequent mental disorders, we found that most mental disorder are associated with an elevated risk of subsequent PEs. Further investigation of the underlying factors accounting for these time-order relationships might shed light on the etiology of PEs.

It is unclear whether differences exist in the prevalence of mood, anxiety and alcohol use disorders among persons with multiple pain conditions compared with those with single pain problems. We conducted population surveys in 17 countries in Europe, the Americas, the Middle East, Africa, Asia, and the South Pacific. Participants were community-dwelling adults (N = 85,088). Mental disorders were assessed with the Composite International Diagnostic Interview. Pain was assessed by self-report. Both multiple and single site pain problems were associated with mood and anxiety disorders, but not with alcohol abuse or dependence. In general, the prevalence of specific mood and anxiety disorders followed a linear pattern with the lowest rates found among persons with no pain, intermediate rates among those with one pain, and highest rates among those with multi-site pain problems. Relative to persons not reporting pain, the pooled estimates of the age-sex adjusted odds ratios were 1.8 (1.7-2.0) for mood disorders and 1.9 (1.8-2.1) for anxiety disorders for persons with single site pain; 3.7 (3.3-4.1) for mood disorders and 3.6 (3.3-4.0) for anxiety disorders among those with multi-site pain. Our results indicate that the presence of multiple pain conditions was strongly and comparably associated with mood and anxiety disorders in diverse cultures. This consistent pattern of associations suggests that diffuse pain and psychiatric disorders are generally associated, rather than diffuse pain representing an idiom for expressing distress that is specific to particular cultural settings or diffuse pain solely representing a form of masked depression. Ó

This first cross-national study of the joint effect of mental and physical conditions on the probability of severe disability finds that co-morbidity exerts modest synergistic effects. Clinicians need to accord both mental and physical conditions equal priority, in order for co-morbidity to be adequately managed and disability reduced.