An Epidemiological Contribution to Clinical Understanding of Anxiety

The study by Derrick Silove, M.D., Ph.D., et al. (1), in this issue of the Journal, on pediatric- and adult-onset separation anxiety disorder across countries in the World Mental Health Survey, an epidemiologic report of separation anxiety disorder in a sample of 38,993 adults in 18 countries, is an eye-opening study that will contribute to a better appreciation of anxiety disorders across the lifespan. Methods in this extraordinary study are clearly articulated and exemplary. The data reported are divided sensibly by income of country.

The most arresting finding is that 43% of patients with separation anxiety disorder report adult onset. As the DSM diagnostic system has only just acknowledged the presence of separation anxiety disorder in adulthood (2), this study highlights a very recent and persistent oversight in our understanding of adult anxiety. Another important finding is that separation anxiety disorder prevalence rates vary more widely across countries than do those of other psychiatric disorders. This observation bears consideration, likely hinting at varying definitions of what it means to be so overly anxiously attached as to warrant the label of “illness” across cultures and the economic spectrum, as the authors note. Surprisingly, the prevalence found in the U.S. general population by Silove et al.’s epidemiological survey is 9.2%, second highest in the world after Colombia. Are clinicians aware of rates of separation anxiety disorder of this magnitude in their patients? I doubt it (3).

The effects of separation anxiety disorder and directionality of psychiatric comorbidities are noteworthy. Previous observations are here borne out: that separation anxiety is a common precursor to other anxiety disorders, particularly panic disorder and agoraphobia (4), and that anxious attachments may constitute a vulnerability for development of posttraumatic stress disorder (PTSD) in the presence of severe stressors (5). In this study, looking at time-lagged associations (odds ratios) between onset of separation anxiety disorder and other psychiatric disorders, presence of separation anxiety disorder elevates the odds ratios of developing other mood and anxiety disorders, yet presence of major depression, bipolar disorder, and other anxiety disorders presages development of separation anxiety disorder as well. Notably, Separation anxiety disorder elevates the odds ratios of developing attention deficit hyperactivity disorder and PTSD in nonreciprocal relationships. Risks for development of separation anxiety disorder include childhood adversity and “maladaptive family functioning in childhood” (both of which have increasing cumulative risks for development of separation anxiety disorder), as well as lifetime traumatic exposure: parsed here as war, violence, sexual violence, family death, “network events,” and “other.” Another article featured in this issue of the Journal, by Thalia C. Eley, Ph.D., et al. (6), on genetic study of anxiety transmission, highlights the central role of environmental contributions to development of anxiety between generations, looking at a widely divergent domain: a twin-study genetic data set.

Severe role impairment resulting from separation anxiety disorder is worst in high-income countries, where it is nonignorable (71% severe role impairment among adolescents in the presence of psychiatric comorbidity). Yet meaningful role impairment from separation anxiety disorder occurs across age groups and income categories, with or without comorbidity.