Resting heart rate associations with violence exposure and posttraumatic stress symptoms: sex differences in children

Abstract

Traumatic events experienced in childhood can lead to increased risk of cardiovascular disorders in adulthood. Black Americans are disproportionately affected, as they are at increased risk for experiencing childhood trauma and cardiovascular diseases in adulthood. One of the hypothesized mechanisms of this association is through long-lasting dysregulation of the autonomic nervous system, a hallmark physiological biomarker of posttraumatic stress disorder (PTSD), which is twice as prevalent in women compared to men. Ninety-one, majority Black American children, aged 9 were recruited to be a part of our longitudinal study of child development at research centers in Atlanta, GA and Detroit, MI. Resting HR was measured through a electrocardiogram (ECG) recording using the Biopac MP150. Self-report measures of violence exposure and PTSD symptoms were administered by research staff. Children with more violence exposure reported increased PTSS as well as lower resting HR. Regression analysis showed evidence of sex modifying this relationship, (B = -0.64, p < 0.05), such that the association between resting HR and PTSS was stronger in girls than in boys. In our exploratory analysis with standard clinical cutoffs of resting HR, the normative HR group was found to significantly moderate the relationship between violence exposure and PTSS in boys, (B = -2.14, p < 0.01), but not girls (B = -0.94, p = 0.27). In our sample of primarily Black urban children, we found that violence exposure was associated with slower, more adult-like HR, that girls showed greater PTSS associated with slower HR while boys did not, and that girls with lower than normative HR showed significantly higher PTSS compared to girls with normative HR. Our sample’s demonstration of psychological consequences in addition to the physiological implications could provide new information about a psychobiological sequelae of violence exposure. Experiencing traumatic events in childhood can lead to increased risk of heart disease in adulthood. One of the ways this might happen is through long-lasting changes of the autonomic nervous system. This system is dysregulated in posttraumatic stress disorder (PTSD), which is twice as common in women compared to men. We explored whether resting heart rate (HR), a measure of autonomic functioning was associated with violence exposure in children, and whether this relationship was different in boys and girls. We also explored whether categorizing our sample into resting HR groups based off standardized norms for HR predicted differing relationships between violence exposure and posttraumatic stress symptoms (PTSS). Because childhood trauma and heart disease impact Black Americans at greater rates, we recruited our sample of 92 nine-year-old children from research centers in Atlanta, GA and Detroit, MI. We measured their resting HR, exposure to violence, and PTSS. We found that violence exposure was associated with lower HR overall, that girls showed greater PTSS associated with lower HR when compared to boys, and that boys with lower than normative HR showed a stronger association between violence exposure and PTSS compared to boys with normative HR. Future studies should examine potential mechanisms underlying this sex difference to best understand the long-term cardiovascular consequences for sex-related health disparities. Specifically, longitudinal studies may be able to help researchers understand how reduced HR during adolescents might lead to future cardiovascular disease and psychopathology.