The link between trauma and violence in bipolar disorder
Childhood trauma history has been found to correlate with increased aggression in adults with and without affective disorders.1,2,13 In addition, there is an overlap between the neurochemical changes found in adults with histories of traumatic stress and those found in adults with increased impulsive aggression-in particular, increased functioning of both the catecholamine system and the hypothalamic-pituitary-adrenal axis.14
The prevalence of childhood trauma in persons with bipolar disorder combined with the risks that arise from the symptoms of the disorder itself renders bipolar patients at increased risk for violent behavior. Because childhood trauma has been associated with earlier onset and a greater number of episodes, there is more cumulative time when aggressive behavior is most likely to manifest. In addition, a history of trauma is associated with an increase in rates of substance abuse, which itself is associated with significant violence risk. Aggressiveness is often shown in different clinical settings, including bipolar, borderline, and antisocial personality disorders. Comorbidity with borderline personality disorder is associated with a higher risk of aggression in bipolar disorder during periods of euthymia.
Violence and aggression
Persons with bipolar disorder are at significantly increased risk for violence, with some history of violent behavior ranging from 9.4% to just under 50%, often in the presence of comorbid diagnoses.15-18 Bipolar patients are prone to agitation that can result in impulsive aggression during manic and mixed episodes. However, depressed states can involve intense dysphoria with agitation and irritability, which can also increase the risk of violent behavior. Bipolar patients may have chronic impulsivity during euthymia, predisposing them to aggression. This is especially true with comorbid features of borderline personality disorder. In fact, particularly high levels of impulsivity and aggression in a bipolar patient could be a strong indicator of comorbidity with borderline personality disorder.19
Impulsive aggression (as opposed to premeditated aggression) is most commonly associated with bipolar and other affective disorders. In animal models, premeditated aggression corresponds to predatory behavior, while impulsive aggression is a response to perceived threat (the fight in fight-or-flight). As either a state or trait, increased impulsive aggression is driven by an increase in the strength of aggressive impulses or a decrease in the ability to control these impulses. Neurochemically, impulsive aggression has been associated with low serotonin levels, high catecholamine levels, and a predominance of glutamatergic activity relative to γ-amino-butyric acid (GABA)ergic activity.20