Sympathetic Nervous System Predominance in Intimate Partner Violence Perpetrators After Coping With Acute Stress

The contribution of brain volume to explain autonomous imbalance during recovery from acute stress in batterers

AIM

Many authors have suggested that intimate partner violence (IPV) perpetrators present an imbalance between both branches of the autonomous nervous system when coping with acute stress. Concretely, there is a predominance of the sympathetic branches over the parasympathetic ones when recovering from stress. This imbalance can be explained by their tendency toward anger rumination, and more concretely, by their focus on thoughts of revenge during this period. Unfortunately, there is a gap in the scientific literature in terms of using magnetic resonance imaging (MRI) techniques to assess which brain structures would explain this tendency of IPV perpetrators when coping with acute stress.

METHOD

The main objective of this study was to assess whether the gray matter volume (GMV) of relevant brain structures, signaled in previous scientific literature, moderates the association between thoughts of revenge and sympathetic activation during the recovery period, based on skin conductance levels (SCL) after being exposed to stress, in a group of IPV perpetrators (n = 58) and non-violent men (n = 61).

RESULTS

This study highlighted that the GMV of the left nucleus accumbens, right lobules of the cerebellum, and inferior temporal gyrus in IPV perpetrators moderated the association between thoughts of revenge and SCL during the recovery period. Accordingly, the higher the thoughts of revenge, the higher the sympathetic predominance (or higher SCL levels), especially among IPV perpetrators with the lowest GMV of these brain structures. Nonetheless, those variables were unrelated in the control group.

CONCLUSIONS

Our study highlights the involvement of certain brain structures and how they explain the tendency of some IPV perpetrators to ruminate anger or, more precisely, to focus on thoughts of revenge when they recover from acute stress. These results reinforce the need to incorporate neuroimaging techniques during screening processes to properly understand how IPV perpetrators deal with stress, which in turn helps target their needs and design concrete intervention modules.

Weakened sympathetic response and lower parasympathetic activity in intimate partner violence perpetrators when empathizing: Influence of autonomous activation in affective approach and prosocial behavior

The autonomic nervous system (ANS) functioning has been proposed as a relevant method to characterize the therapeutic needs of intimate partner violence (IPV) perpetrators. Nevertheless, research has neglected the influence of the ANS on socio-affective functions in this population. The aim of the present study was to analyze the psychophysiological activity of IPV perpetrators (n = 52) compared to controls (n = 46) following an empathic induction task, performed through negative emotion-eliciting videos. We employed two general ANS markers (heart rate [HR] and respiratory rate [RR]), two sympathetic-related indexes (pre-ejection period [PEP] and skin conductance level [SCL]) and a parasympathetic biomarker (respiratory sinus arrhythmia [RSA]). Additionally, we explored the impact of psychophysiological activity on prosocial behavior using Hare's donation procedure. Compared to controls, IPV perpetrators reported lower HR and SCL following the task, as well as longer PEP, suggesting an attenuated sympathetic response to others' distress. No differences in the RSA response pattern were found, however, IPV perpetrators displayed lower overall RSA levels throughout the protocol, indicative of reduced parasympathetic activity. Besides, while no differences in prosocial performance were observed, greater sympathetic responses and overall parasympathetic activity predicted increased donations across the sample. Thus, a high sympathetic and parasympathetic activity might influence the occurrence of prosocial behavior. The present study provides further evidence supporting that IPV perpetrators cope differently with others' negative emotions. In line with this biopsychosocial perspective, insights are gained on the emotional processing of IPV perpetrators which, in turn, could contribute to improve IPV psychotherapeutic programs.

Reduced vagal tone in intimate partner violence perpetrators is partly explained by anger rumination

Polyvagal theory proposed that an autonomous nervous system imbalance might be characteristic of violent individuals, especially reduced parasympathetic or vagal tone. Accordingly, some studies concluded that when intimate partner violence (IPV) perpetrators deal with acute stress, they tend to present a sympathetic predominance over the parasympathetic nervous system once the stress has ended. However, less is known about cognitive mechanisms that explain this phenomenon. In fact, this functioning might be explained by inner speech and/or angry thoughts (anger rumination) in reactive aggressors. Nonetheless, there is a gap in the scientific literature assessing whether this psychophysiological functioning in IPV perpetrators is explained by anger rumination. For this reason, the first aim of this study was to assess the cardiorespiratory (heart rate (HR), pre-ejection period (PEP), and respiratory sinus arrhythmia (RSA)) and electrodermal (skin conductance level (SCL)) changes, as well as the anger state, when coping with an acute laboratory stressor, comparing a group of reactive IPV perpetrators (n = 47) and a group of non-violent men (n = 36). The second aim was two-fold. After checking whether the groups differed on their anger rumination and manifestation of aggression (reactive and/or proactive) scores, we studied whether these variables explained psychophysiological and psychological responses to a laboratory task (changes and levels during the recovery period) in each group. Our results demonstrated that, compared to the control group, IPV perpetrators presented lower RSA levels (vagal tone). Even though the groups did not differ on their anger rumination or manifestation of aggression scores (except for proactive aggression), only in the IPV perpetrators, high anger rumination and reactive aggression partly explained the lower vagal tone (RSA levels) and high levels of anger state at post-task. Consequently, this study contributes to understanding the psychobiological basis for violence proneness in IPV perpetrators, making it possible to explore new therapeutic strategies.

Exposure to intimate partner aggression during childhood is associated with blunted skin conductance recovery following stress in early adulthood

This study examines skin conductance level (SCL) trajectories and childhood exposure to intimate partner aggression (IPA) committed between parents in a sample of college students. Although IPA among parents does not directly involve children, children frequently see or are exposed to IPA first-hand when it occurs. This exposure to IPA increases risks for psychopathology and emotional or behavioral difficulties for children or adolescents later in life. However, research has not yet examined the stress response patterns of individuals exposed to IPA, nor how reactivity to stress may be altered based on this exposure. Participants included 161 college students who completed questionnaires assessing demographics, mental health, and exposure to IPA, and also reported on family functioning and parental drinking habits. Additionally, participants completed a three-minute mirror tracing task followed by a three-minute recovery period while SCL was monitored. Multilevel modeling was used to assess whether frequency or level of exposure to IPA was related to trajectories of SCL. Neither variable was related to SCL trajectories during the mirror-tracing task. However, both frequency and level of exposure were related to SCL trajectories during the recovery period, such that for participants reporting higher levels of either IPA exposure variable, SCL trajectories during recovery declined less rapidly and did not decline to as low of a level compared to participants reporting lower levels of IPA exposure. This blunted SCL recovery may be due to wear and tear from repeated innervation, or a calibrating of the SCL response to adapt to a volatile home environment.

Hormonal Differences in Intimate Partner Violence Perpetrators When They Cope with Acute Stress: A Pilot Study

BACKGROUND

Only a few studies have paid attention to the ability of perpetrators of intimate partner violence (IPVAW) against women to cope with acute stress, including hormonal parameters. In fact, previous studies assessed how salivary testosterone (Tsal) and cortisol (Csal) changed after coping with an acute emotional stressor (directly related to IPVAW), and they concluded that an imbalance between the two hormones might be characteristic of these men. Nevertheless, they neglected to examine the role of other hormones, such as salivary oxytocin (OXsal), which also seemed to play an important role in behavioral regulation, and whether this response could be generalized to other types of stress not directly related to IPVAW.

METHODS

This study aims to assess whether IPVAW perpetrators (n = 19) present differential hormonal (Tsal, Csal, OXsal and their ratios) and psychological state (anxiety, anger, and general affect) responses when coping with an acute cognitive laboratory stressor (a set of neuropsychological tests performed in front of an expert committee) in comparison with non-violent men (n = 16). This quasi-experimental study also assessed whether the psychological state variables drive this different hormonal response.

RESULTS

Our results revealed that IPVAW perpetrators had lower Csal and higher Tsal/Csal ratio levels during the post-task period, as well as higher total levels (average) of OXsal than controls. We also found that, only in IPVAW perpetrators, high levels of baseline anxiety and negative affect were related to high rises in Csal during the stress task.

CONCLUSIONS

These data present a background showing that IPVAW perpetrators and non-violent men cope differently with stress. These findings might help to identify idiosyncratic profiles of IPVAW perpetrators that can then be employed to establish their therapeutic needs. Moreover, we reinforced the importance of combining biological markers with self-reports, thus increasing the reliability of these forensic assessments.