Vagal Tone Moderates the Association Between Child Maltreatment and Young Adult Suicide Ideation: A Test of the Biological Sensitivity to Context Hypothesis

Introduction: Childhood maltreatment is associated with increased risk for suicide ideation (SI) in young adulthood (Miller, Esposito-Smythers, Weismoore, & Renshaw, 2013; Thompson et al., 2012). Developmental theory suggests that child abuse disrupts the development of the self-concept and can result in weaker emotion regulation capacities. Accordingly, regulation of emotion may be an important risk and protective factor in the link between child abuse and SI in young adulthood. Thus, a possible moderator of this association is respiratory sinus arrhythmia (RSA), a physiological index of parasympathetic nervous system activity, which is suggested to reflect emotion regulation capabilities (Porges, 1992).

Studies of RSA and childhood adversity have found support for the biological sensitivity to context hypothesis (Boyce & Ellis, 2005), in which high physiological reactivity is beneficial in positive contexts, but a risk factor in adverse environments (i.e. maltreating households; Sturge-Apple et al., 2016). The present study tests this hypothesis by examining the relationship between types of child adversity (physical neglect, emotional neglect, emotional abuse, and physical abuse) and SI in young adulthood, moderated by vagal tone.

Methods: The data were from a diverse community sample of 106 young adults (M_age=21.17, SD_age=2.37, 44% racial/ethnic minority, 55% female). Suicide ideation was measured using the Suicide Ideation Scale (Rudd, 1989; α = .93). Maltreatment types (i.e. physical neglect [α = .79], emotional abuse, [α = .89], physical abuse [α = .87], and emotional neglect [α = .89]) were measured via the Childhood Trauma Questionnaire (Bernstein & Fink, 1998).

RSA was obtained with an electrocardiogram and analyzed with BioLab software. A mental math task (Berntson, Cacciopo, & Fieldstone, 1996) was used to elicit emotional stress. Moderation effects were tested using interaction terms for maltreatment types and measures of RSA. Hypotheses were tested with Mplus version 7.4 (Muthén & Muthén, 1998-2010).

Results: Baseline RSA moderated the relationship between suicide ideation in young adulthood and childhood experiences of physical neglect (β = -.275, p < .01), emotional abuse (β = -.285, p < .01), and physical abuse (β = -.244, p< .01). Higher vagal tone (i.e. RSA) was protective in adverse contexts. Low vagal tone was related to higher suicide ideation in adverse contexts, and to less suicide ideation for those who reported positive rearing environments.

Conclusions: The present study showed that vagal tone moderates the association between three types of childhood maltreatment and young adult suicide ideation. Furthermore, the biological sensitivity to context hypothesis was supported: high vagal tone can be a protective or a risk factor, depending on the family context. Young adults who experience child maltreatment are at significant risk for suicide ideation. Identifying risk and protective factors can enhance the development of prevention programs for suicide.