Childhood social environment, emotional reactivity to stress, and mood and anxiety disorders across the life course

Exposure to adverse childhood experiences including maltreatment, family instability, and economic hardship are well-documented risk factors for psychopathology (Gilman et al. 2003; Green et al. 2010; Kessler et al. 1997). The finding that such adversities are associated with elevated risk for disorder onset not only in childhood, but also in adulthood (Green et al. 2010; Kessler et al. 1997), suggests that exposure to childhood adversity creates a generalized diathesis to psychopathology that persists across the life-course. One possible explanation for this increased liability to psychopathology is that exposure to stressors early in life impacts the development of the physiological stress response system (Heim and Nemeroff 2001; Heim et al. 2008; Loman and Gunnar 2010). Indeed, dysregulation in physiological systems has been documented among both children (Chen and Matthews 2001; Ellis et al. 2005; Essex et al. 2002) and adults (Carpenter et al. 2007; Heim et al. 2000; van der Vegt et al. 2009) exposed to psychosocial adversity in childhood. Childhood adversity is also associated with heightened emotional reactivity to stress. Elevated emotional reactivity to daily events has been documented among individuals exposed to maltreatment and other trauma (Glaser et al. 2006; Wichers et al. 2009). Although elevated physiological and emotional reactivity also have been found among children and adults with mood and anxiety disorders (Boyce et al. 2001; Goldin et al. 2009; Heim and Nemeroff 2001; Yehuda 2000), the extent to which such reactivity mediates the association between childhood adversity and adult psychopathology has, to our knowledge, not been examined directly. Importantly, the particular aspects of childhood environments that lead to maladaptive stress reactivity are poorly characterized. The term childhood adversity is used to describe a wide variety of adverse childhood experiences ranging from poverty to parental instability to maltreatment (Green et al. 2010). It may be that only severe adverse events, like abuse, lead to alterations in stress reactivity. Indeed, the preponderance of studies on childhood contributors to stress reactivity have focused on these relatively severe experiences (Carpenter et al. 2007; Glaser et al. 2006; Harkness et al. 2006; Heim and Nemeroff 2001; Kendler et al. 2004; Wichers et al. 2009). On the other hand, some evidence suggests that environments characterized by chronic adversity, such as low socio-economic status (SES) and high family conflict, are associated with elevated physiological reactivity (Chen and Matthews 2001; Ellis et al. 2005; Essex et al. 2002; Kapaku et al. 2002). The strength of the association between such environments and maladaptive patterns of stress reactivity may not be as strong as the associations with more severe experiences like abuse. However, the ubiquity of such exposures suggests their role in determining the population-level distribution of psychiatric disorders could be substantial. Extant evidence on the links between childhood adversity, stress reactivity, and psychiatric disorders has come primarily from cross-sectional studies that examine emotional and physiological responses to laboratory-based stressors (Boyce et al. 2001; Heim et al. 2000; Steptoe and Marmot 2006). Thus, it remains unclear whether emotional reactivity to stress represents a risk factor for psychopathology or simply a concomitant of current distress. Recent work has attempted to overcome this problem by demonstrating longitudinally that liability to mood and anxiety disorders following stressful life events in adulthood is heightened among individuals who have experienced childhood adversities (Hammen et al. 2000; Harkness et al. 2006; Kendler et al. 2004). These studies have assumed that a stronger association between adult stress and psychopathology is indicative of greater emotional and physiological reactivity, though reactivity was not measured directly. We are unaware of prospective research directly examining the association between emotional reactivity and the later onset of psychopathology. The current study examines the associations between the childhood social environment, adolescent emotional reactivity to stress, and the subsequent onset of mood and anxiety disorders in adulthood using prospective data from a cohort of healthy young men followed into late life. We first examine the associations between aspects of the childhood environment and emotional reactivity in late adolescence. Second, we examine the association between emotional reactivity and the onset of mood and anxiety disorders in adulthood. Finally, we evaluate whether emotional reactivity is a mechanism underlying the association between adverse childhood environments and the onset of adult psychiatric disorders. Because the sample includes men from relatively privileged backgrounds, we provide a stringent test of the relationship between the childhood social environment and emotional reactivity. If variation in the childhood environment is associated with reactivity in this sample, then the effect of the childhood environment on stress reactivity would be expected to be much greater in the general population.