Childhood adversity and psychiatric disorder in young adulthood: An analysis of 107,704 Swedes

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Abstract

Childhood adversity (CA) is associated with increased risks of psychiatric disorder in young adulthood, but details in this association are less known. We aimed to explore the association of a range of CA indicators with psychiatric disorder in young adulthood, and the impact of age at exposure, disorder type and accumulation of indicators. We capitalized on Sweden's extensive and high-quality registers and analyzed a cohort of all Swedes (N = 107,704) born in Stockholm County 1987–1991. Adversities included familial death, parental substance misuse and psychiatric disorder, parental criminality, parental separation, public assistance recipiency and residential instability. Age at exposure was categorized as: 0–6.9 years (infancy and early childhood), 7–11.9 years (middle childhood), and 12–14 years (early adolescence). Psychiatric disorders after age 15 were defined from ICD codes through registers. Risks were calculated as Hazard Ratios (HR) with 95% confidence intervals (CI).

Results showed that exposure to at least one CA was associated with an increased risk of psychiatric disorder (HR 1.4, 95% CI: 1.3–1.4). Risks were increased for mood, anxiety, and psychotic disorders and ADHD but not for eating disorders. The risk varied with type of disorder but was similar for all exposure periods. Individuals with multiple (3+) CAs had a two-fold risk of psychiatric disorder (HR 2.0, 95% CI: 1.9–2.1). In conclusion, our findings support the long-term negative impact of CA on mental health, regardless of developmental period of exposure. Given that experience of CA is common, efforts should be put to alleviate the burden of childhood adversities for children, particularly among the most disadvantaged.

Introduction

There is accumulating evidence that childhood adversities (CAs) are associated with an increased risk of mental disorders in young adulthood, including substance misuse (Anda, 2008, Bellis et al., 2014, Dube et al., 2003, Kessler et al., 2010, McLaughlin et al., 2010a, Mersky et al., 2013), psychosis (Trauelsen et al., 2015), mood disorder (Anda, 2008, Björkenstam et al., 2015, Chapman et al., 2004, Kessler et al., 2010, McLaughlin et al., 2010a, Mersky et al., 2013, Sareen et al., 2013), and anxiety (Kessler et al., 2010, McLaughlin et al., 2010a, Mersky et al., 2013, Sareen et al., 2013). CAs may shape mental health through early life influences on neurodevelopment and psychosocial functioning.

Studies investigating adverse childhood experiences (ACE) as risk factors for psychiatric disorders have generally included adversities such as childhood abuse, neglect, and growing up in a dysfunctional household (Anda, 2008, Chapman et al., 2004, Felitti et al., 1998), the latter being characterized by substance misuse in the home, mentally ill family members, incarcerated parents etc. (Anda, 2008). CAs have been positively associated with the risk of psychiatric disorder in young adulthood in a number of recent studies. However, few studies have focused on to what extent the timing of exposure to CA affect subsequent onset of psychiatric disorder (Andersen and Teicher, 2008, Dunn et al., 2013, Heim and Binder, 2012, Kaplow and Widom, 2007, Khan et al., 2015) and whether the strength of the association depends on type of disorder and adversity. Furthermore, most previous studies have used retrospectively self-reported adversities and are, thus, limited by recall bias (Anda, 2008, Dube et al., 2003, Kessler et al., 2010, Mersky et al., 2013).

The results from the landmark ACE-study in San Diego (US) have suggested a framework for a new paradigm for medical, public health and social services (Felitti and Anda, 2010). The strong links between accumulations of childhood adversity, hypothesized to be indications of childhood traumas, and later psychiatric disorders have challenged a biological model of the etiology of psychiatric disorders (Skehan et al., 2012), but European replications based on the ACE-construct are still relatively few and far-in-between. Given that childhood adversities are common, any long-term detrimental effects on mental health would have an immense effect on both individuals and societies. Shedding light on the details of the CA and mental health relationship might inform the timing and targeting of public health interventions aiming to alleviate the burden of CA upon exposed children.

In the present study we capitalize on Sweden's extensive and high quality registers, by using a large sample of all individuals born between 1987 and 1991 in Stockholm County, Sweden. Our aim is to explore:

  • 1.

    the association between different indicators of CA and the risk of psychiatric disorder in young adulthood, and whether the association differs by age at exposure and type of psychiatric disorder; and

  • 2.

    the effects of cumulative exposure to multiple indicators of CA on the risk of psychiatric disorder

Section snippets

Study population

In total nine registers were merged to conduct the current analyses. The study population was defined as all individuals born in Stockholm County, Sweden between 1987 and 1991 (n = 116,087), recorded in the Medical Birth Register (Cnattingius et al., 1990). Stockholm County, with 11 municipalities, spans over an area of 2517 square miles. It has approximately 2.2 million people living in the metropolitan area. The Swedish health care system is publicly funded and there is universal access to

Prevalence of indicators of CA and psychiatric disorders

42% of the study participants (N = 107,704, 49% women and 51% men) were exposed to at least one indicator of CA (Table 1). Parental separation was the most common exposure (22%), followed by household public assistance (20%). Having a mother born outside Sweden, and low parental SEP were more common in children exposed to CA.

One in every five study participants received a diagnosis of psychiatric disorder during the follow-up period. The most common disorder types were anxiety spectrum

Key results

In this large cohort study of 107,704 young adults in Sweden, we found a significantly elevated risk of psychiatric disorder related to exposure to childhood adversity. All studied CA indicators appeared to increase the risk of psychiatric disorder regardless of timing for the exposure and the association persisted across different types of psychiatric disorders, including mood, anxiety, substance misuse and psychotic disorders and ADHD. By contrast, CA appeared unrelated to the risk of eating

Conclusion

In conclusion, our findings support the long-term negative impact of childhood adversity on mental health, particularly when accumulating. It also demonstrates that, regardless of when in childhood exposure to CA occurs it is detrimental for the child's subsequent health. Given that experience of CA is common, early and efficient detection of CA is of importance for preventing interventions targeted to improve long term mental health outcomes among disadvantaged children.

Ethical considerations

This study is approved by the ethical committee in Stockholm, Sweden (dnrs: 2010/1185-31/1 and 2013/1118-32).

Role of funding source

This study was supported by a grant from the Swedish Council for Working Life and Social Research (grant number 2013-2729). Professor Vinnerljung's work was supported by a grant from Bank of Sweden Tercentenary Foundation. The funders had no role in the analyses interpretation of results or the writing of this manuscript.

Conflicts of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.

Contributors

Emma Björkenstam, and Kyriaki Kosidou originated the idea. Emma Björkenstam analyzed the data and wrote the manuscript draft. All authors contributed to the interpretation of the results and to the writing of the final article.

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