A multilevel examination of lifetime aggression: integrating cortical thickness, personality pathology and trauma exposure

Aggression represents a significant public health concern, causing serious physical and psychological harm. Although many studies have sought to characterize the etiology of aggression, research on the contributions of risk factors that span multiple levels of analysis for explaining aggressive behavior is lacking. To address this gap, we investigated the direct and unique contributions of cortical thickness (level 1), pathological personality traits (level 2) and trauma exposure (level 3) for explaining lifetime physical aggression in a high-risk sample of community adults (N = 129, 47.3% men). First, the frequency of lifetime aggression was inversely associated with cortical thickness in regions of prefrontal and temporal cortices that have been implicated in executive functioning, inhibitory mechanisms and socio-emotional processing. Further, aggression was positively associated with pathological personality traits (antagonism and disinhibition) and exposure to assaultive trauma. Notably, all three levels of analysis (cortical thickness, pathological personality traits and assaultive trauma exposure) explained non-overlapping variance in aggressive behavior when examined simultaneously in integrative models. Together, the findings provide a multilevel assessment of the biopsychosocial factors associated with the frequency of aggression. They also indicate that cortical thickness explains novel variance in these harmful behaviors not captured by well-established personality and environmental risk factors for aggression.

Severe Sexual Abuse Reduces Frontoparietal Network Activity during Model-Based Reinforcement Learning Updates

Trauma and trauma-related disorders are characterized by altered learning styles. Two learning processes that have been delineated using computational modeling are model-free and model-based reinforcement learning (RL), characterized by trial and error and goal-driven, rule-based learning, respectively. Prior research suggests that model-free RL is disrupted among individuals with a history of assaultive trauma and may contribute to altered fear responding. Currently, it is unclear whether model-based RL, which involves building abstract and nuanced representations of stimulus-outcome relationships to prospectively predict action-related outcomes, is also impaired among individuals who have experienced trauma. The present study sought to test the hypothesis of impaired model-based RL among adolescent females exposed to assaultive trauma. Participants (n=60) completed a three-arm bandit RL task during fMRI acquisition. Two computational models compared the degree to which each participant’s task behavior fit the use of a model-free versus model-based RL strategy. Overall, a greater portion of participants’ behavior was better captured by the model-based than model-free RL model. Although assaultive trauma did not predict learning strategy use, greater sexual abuse severity predicted less use of model-based compared to model-free RL. Additionally, severe sexual abuse predicted less left frontoparietal network encoding of model-based RL updates, which was not accounted for by PTSD. Given the significant impact that sexual trauma has on mental health and other aspects of functioning, it is plausible that altered model-based RL is an important route through which clinical impairment emerges.

Clustering of Trauma and Associations with Single and Co-Occurring Depression and Panic Attack over Twenty Years

Individuals who experience one type of trauma often experience other types, yet few studies have examined the clustering of trauma. This study examines the clustering of traumatic events and associations of trauma with risk for single and co-occurring major depressive disorder (MDD) and panic attack for 20 years after first trauma. Lifetime histories of MDD, panic attack, and traumatic events were obtained from participants in an Australian twin sample. Latent class analysis was used to derive trauma classes based on each respondent's trauma history. Associations of the resulting classes and of parental alcohol problems and familial effects with risk for a first onset of single and co-occurring MDD and panic attack were examined from the year of first trauma to 20 years later. Traumatic events clustered into three distinct classes characterized by endorsement of little or no trauma, primarily nonassaultive, and primarily assaultive events. Individuals in the assaultive class were characterized by a younger age at first trauma, a greater number of traumatic events, and high rates of parental alcohol problems. Members of the assaultive trauma class had the strongest and most enduring risk for single and co-occurring lifetime MDD and panic attack. Assaultive trauma outweighed associations of familial effects and nonassaultive trauma with risk for 10 years following first trauma.

Accumulation of trauma over time and risk for depression in a twin sample

BackgroundFew genetically informative studies have examined the effects of different types of trauma on risk for depression over time. The aim of the present study was to examine the relative contributions over time of assaultive trauma, non-assaultive trauma, and familial effects to risk for depression.MethodHistories of depression and trauma were obtained during structured diagnostic interviews with 5266 (mean age 29.9 years, s.d.=2.4) members of a volunteer Australian twin panel from the general population. Age at first onset of a DSM-IV major depressive episode was the dependent variable. Associations of depression with traumatic events were examined while accounting for the temporal sequence of trauma and depression and familial effects.ResultsAssaultive traumatic events that occurred during childhood had the strongest association with immediate and long-term risk for depression, and outweighed familial effects on childhood-onset depression for most twins. Although men and women endorsed equal rates of assaultive trauma, women reported a greater accumulation of assaultive events at earlier ages than men, whereas men reported a greater accumulation of non-assaultive events at all ages.ConclusionsEarly exposure to assaultive trauma can influence risk for depression into adulthood. Concordance for early trauma is a significant contributor to the familiality of early-onset depression.

Trauma Exposure and Stress Response: Exploration of Mechanisms of Cause and Effect

People differ markedly in their risk for developing posttraumatic stress symptoms (PTSS) after exposure to traumatic events. Twin studies suggest that the trauma-PTSS relationship is moderated by genetic and environmental influences. The present study tested for specific types of genetic and environmental interaction effects on PTSS. A sample of 222 monozygotic and 184 dizygotic twin pairs reported on lifetime frequency of assaultive and nonassaultive trauma and associated PTSS. Biometric analyses indicated that in the case of nonassaultive trauma, PTSS were directly affected by environmental factors that also influence exposure to nonassaultive trauma. For assaultive trauma both genetic and non-shared environmental influences jointly affected PTSS, and the number of traumatic events moderated the severity of PTSS. Genetic factors were found to become less important beyond some threshold (e.g., 3 or 4 types of serious trauma) suggesting that genetic factors — which may confer either risk or resilience to PTSS — modify these symptoms within a range of human experience, beyond which environmental effects supervene.