Epidemiology of Mental Disorders

This review describes the contribution of psychiatric epidemiology to our understanding of the distribution and determinants of psychiatric disorders. First, it describes basic concepts within epidemiology, such as prevalence, incidence, case definition, bias, and confounding, and their specific meaning within psychiatric research. The two basic study designs in epidemiology, cohort and case-control, are then reviewed. This discussion includes a tutorial on how to calculate key measures of association: risk ratio and odds ratio. Major community-based studies in psychiatric epidemiology are then reviewed, focusing on the Epidemiologic Catchment Area Study, the National Comorbidity Study and the National Comorbidity Study Replication, the National Survey of American Life, the National Latino and Asian American Study of Mental Health, and the National Epidemiologic Survey on Alcohol and Related Conditions. The review concludes with a discussion of pharmacoepidemiology and how it is critical to our understanding of the full impact of psychiatric medications postmarketing. In the future, epidemiology will be revolutionized with “big data” collection in both institutional and community settings. Nonetheless, the basic concepts presented in this review will continue to be relevant and critical to drawing sound, evidence-based conclusions about the true nature, correlates, and causes of psychiatric disorders. This review contains 6 tables, and 63 references. Key words: case-control study, cohort study, community-based studies, measures of association, pharmacoepidemiology, psychiatric epidemiology

Introduction:Cardiovascular Disease and Metabolic Risk Factors in Patients with Mental Illness

According to the National Comorbidity Study Replication, >25% of people in the United States have some type of mental illness. The prevalence of serious mental illness has been estimated at 6.2%. Patients with severe and persistent mental illness have significantly reduced life expectancy relative to the general population. On average, pooled populations of public sector inpatients and outpatients die 25–30 years earlier than unaffected individuals in the general population, according to recent data from multiple states in the US. Schizophrenia and bipolar disorder together account for ∼23,000 deaths and >20 million life-years of disability worldwide each year. The most common cause of mortality in these individuals is cardiovascular disease (CVD), not, as might be assumed, suicide (Figure 1). Heart disease and stroke are the most common causes of death in patients with serious mental illness, accounting for ∼40% of deaths, underlying the dramatically decreased life expectancy in these patients.

Alcoolisme, anxiété et dépression

Résumé Dans cet article, les auteurs examinent les liens entre l'alcoolisme et les troubles psychiatriques. Ils estiment que la dépendance à l'alcool est rarement une pathologie qui survient de manière isolée. Les recherches nord-américaines menées en population générale (Epidemiological Catchment Area (ECA), National Comorbidity Study) ont confirmé l'association fréquente des troubles psychiatriques et des conduites alcooliques (Regier et al., 1990). Les auteurs concluent que la dépression et l'anxiété sont les deux principales comorbidités psychiatriques de l'alcoolisme. Ils suggèrent que le traitement de l'anxiété et de la dépression soit intégré à celui de l'alcoolisme.

Is the female preponderance in major depression secondary to a gender difference in specific anxiety disorders?

Background. While a female preponderance in unipolar depression is a consistent finding in community-based studies, determinants remain speculative. This study aimed to examine whether a female preponderance in certain anxiety disorders drives a gender difference in depression.Method. The relevant data from the National Comorbidity Study (NCS) are analysed.Results. We observed a biphasic pattern in the emergence of a female preponderance in the depressive and anxiety disorders, with an initial pre-pubertal or early adolescent onset, and after attenuation in early to middle adulthood, re-emergence in mid- to late-adulthood. Analyses focused on determinants of the initial female preponderance. Female gender, presence of an anxiety disorder and variable ages of onset in the anxiety disorder all contributed to the increased chance of an initial depressive episode. Some specificity in linking the onset of depressive temporally in early adolescence with two anxiety disorders was demonstrated, specifically generalized anxiety disorder and panic disorder.Conclusions. The separate anxiety disorders and their age of onset had variable links with depression, but female gender remained a significant predictor of depression after accounting for the effects of prior anxiety.