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Does the relationship between recent past-year stressful life events and prevalence of psychiatric disorder vary according to exposure to childhood adversity (CA)?
34 653 civilian, non-institutionalised adults aged 18 years or older. Participants were taking part in the second wave of the National Epidemiologic Study of Alcohol and Related Conditions.
General population, USA; 2004–2005.
The Alcohol Use Disorder and Associated Disabilities Interview Schedule – DSM-IV Version (AUDADIS-IV) was used to assess stressful life events and psychiatric diagnoses in the past 12 months. Experience of CA before the age of 17 was assessed retrospectively using various questionnaires, and included physical, emotional or sexual abuse; neglect or parental dysfunction (domestic violence, serious mental illness, criminality or substance abuse).
Major depression, post-traumatic stress disorder (PTSD) and anxiety disorders (including generalised anxiety disorder, panic disorder with or without agoraphobia, and social phobia).
Cross-sectional analysis of a single wave of data collection from a cohort study.
About half of respondents (49.4%) reported some degree of CA, with 19.3% reporting exposure to three or more events. The most common adversities were exposure to parental substance abuse (23.0%) and emotional abuse (22.5%). As adults, the prevalence of past-year minor stressors was 63.6%, and 39.6% had experienced major stressors. The prevalence of past-year psychiatric disorders was 8.3% for major depressive episode (MDE), 6.5% for PTSD and 7.1% for other anxiety disorders. The prevalence of these disorders was higher in individuals who reported greater exposure to past-year stressful events and to CA. The extent of the increase associated with past-year stressful events was related to exposure to CAs, with greater exposure to CAs associated with a greater increase in prevalence. There was significant interaction between major stressors and degree of CA for all outcomes in both men and women (p<0.05 for all outcomes). For example, the difference in prevalence of MDE in women with three or more major stressful past events in the past year and those with no such events was 27.3% in women with three or more CA events compared with 16.6% in women with one to two CAs (p=0.012 for difference), and 14.8% in women with no CA events (p=0.002). The difference in prevalence of MDE in men with three or more major stressful past events in the past year and those with no such events was 22.7% in men with three or more CA events compared with 10.2% in men with one to two CAs (p=0.005 for difference), and 9.7% in men with no CA events (p<0.001). There was interaction between minor stressors and CA for all outcomes in men (p<0.05 for all outcomes), but not women.
Past-year prevalence of major depressive events, anxiety disorders and PTSD is higher among people with past-year major stressful life events, with the increase in prevalence being greatest among those with greater exposure to childhood adverse events.
The temporal sequence of the past-year stressors and onset of past-year psychiatric disorders was not established; therefore, reverse causality cannot be ruled out. Retrospective assessment of CAs may be affected by recall bias.
Children's exposure to significant stress, adverse conditions and trauma is a well-known predictor of psychopathology persisting into adulthood. This association has powerful treatment/intervention implications, and also stimulates important hypotheses about how early stressors and disorders are linked. Yet, major questions remain that need to be addressed in order to maximise the potential yield of the association.
McLaughlin and colleagues tackled several of these issues in their paper. First, they tested a mechanism previously proposed by Hammen and colleagues1 that exposure to significant stressors during childhood renders individuals more sensitive to the effects of stress (higher probability of depression following stress, or depression in response to less stress, among those with early adversity). Second, the authors used the largest US epidemiological sample of diverse respondents to date (the National Epidemiological Survey of Alcohol and Related Conditions) to test the question for both men and women, and in reference to several different forms of disorders compared to most studies' focus on depression. Their findings established that exposure to early adversity does promote sensitivity to recent acute stressors in both men and women, extending to onset of post-traumatic stress disorder, and anxiety disorders, as well as major depression. Sensitisation was most apparent for those with exposure to multiple childhood adversities – which often ‘cluster’ together.
Many questions remain to be tested (how early the exposure, how chronic and severe, what changes underlie processes of sensitisation). Nevertheless, this study is compelling in clinical applications; the effects of harsh environments on children are devastating and persist over lifetimes, affecting adults and likely their own children as well. Unfortunately, scientific evidence continues to surpass efforts to address the environmental and family-level interventions that are indicated. Clinical interventions need to teach, bolster and support individuals' efforts to deal with, if not sidestep, major stressors where possible. Clearly, many of the very common and costly disorders of anxiety and depression require multifaceted and early interventions to break the cycle of stress occurrence and emotional disorders.
Sources of funding Robert Wood Johnson Foundation and the National Institutes of Health.
Competing interests None.
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