Borderline personality disorder is characterized by particular patterns of behavior, including instability of affect, interpersonal relationships, impulse control and self-image. This results in impairments in self-management and the achievement of goals, as well as deficits in social interactions.
Approximately 15-20 percent of clinical patients have BPD, 10 percent of outpatients, and 2 percent of the general population. Due to the high prevalence of the disorder and the sociocultural factors associated with it, many theories have been suggested to explain the possible causes of BPD.
Trauma in childhood can cause devastating psychological issues later in life. Interpersonal challenges and psychiatric disorders both can result from trauma. Major depression, panic disorder, substance abuse, post-traumatic stress disorder and eating disorders are all common outcomes associated with trauma during childhood.
Trauma can be caused by family violence, such as emotional or physical abuse, disease and the experience of war. Personality disorders such as borderline, avoidant, paranoid, antisocial and schizotypal may also be outcomes of trauma. Because of the severe consequences of childhood trauma, it is sometimes called “soul murder.”
Parental rejection or verbal assaults, devaluation and being ignored all impact a child’s identity. Parental maltreatment can also influence the development of a secure attachment. Attachment avoidance and attachment anxiety both may be the result of childhood maltreatment. Fearful attachment styles are characterized by a desire for intimacy combined with a fear of hurt and rejection. Someone with an unresolved or preoccupied attachment style may want an intimate relationship but has a tendency to view their partner as dependent.
Studies have demonstrated that people diagnosed with BPD have a high prevalence of childhood sexual abuse. In addition, childhood sexual abuse is associated with attachment avoidance. Some estimate a 75 percent rate of childhood sexual abuse in BPD patients. Furthermore, childhood sexual abuse was found to distinguish BPD patients from depressed, non-BPD adolescents.
Due to these factors, researchers believe that childhood sexual abuse may be an etiological factor for the development of borderline personality. In some studies, sexual abuse predicted BPD symptoms better than family environment, although instability in the family environment was a partial mediator.
Childhood sexual abuse is not the only form of maltreatment that has been linked with BPD. Physical abuse, emotional abuse and neglect are all associated with the development of the disorder. In some studies, the rates of maltreatment were as high as 90 percent in BPD patients.
Because severe dissociation is included in the diagnostic criteria for BPD, some researchers believe that it may also be related to the emotional neglect experienced by so many of those suffering with BPD. Dissociation is a state in which one becomes removed from reality. This may take the form of daydreaming, running on auto-pilot or a general disconnection from actions. One study found four risk factors for dissociation: inconsistent treatment by a caretaker, sexual abuse, witnessing sexual violence as a child and adult rape history.
Dissociation and BPD may both share the etiological factor of childhood trauma. This means that, for some, the disorder is a defense mechanism against the childhood trauma. Its purpose is to prevent dangerous information from entering consciousness. Researchers also posit that the degree of betrayal that is linked with the childhood trauma may influence subsequent memory encoding and accessibility.
Memory and dissociation in BPD are now topics of intense focus for researchers. One study required patients with the disorder to take the Autobiographical Memory Test. During this test, participants recall specific events in their lives when given negative, positive or neutral word prompts. Those with BPD remembered far more general events and had more non-responses than the control group. In addition, the BPD patients responded to negative cues with significantly more general memories. The researchers found a correlation between the amount of general memories and the severity of dissociation in the patients with borderline personality.
Additionally, those with BPD believe less in the benevolence of others and the world in general compared to patients with other personality disorders. More women than men report high-betrayal trauma, which may serve to explain why more women, approximately 75 percent, are diagnosed with BPD.
Some researchers note that this gender difference may also be related to power. Those in a less powerful position may view and respond to betrayal violations more intensely than those with more power in a situation. Others point to the “just world” construct, which is the belief that the world is just, and thus people are rewarded or punished based on their actions. Men, in particular European Americans and older Americans, tend to have higher just world beliefs than women, younger generations and African-Americans. This belief gives one a sense of invulnerability, which is altered after trauma. Gender aside, it is clear that betrayal traumas are strongly associated with BPD.
Because trauma is frequently associated with posttraumatic stress disorder (PTSD), this condition has been examined in relationship with BPD. Studies have demonstrated size reductions of the left amygdala and hippocampus that vary with the severity of PTSD. A recent study found both amygdala and hippocampus size reduction in patients with both BPD and PTSD. Interestingly, further research verified that a 12 percent hippocampus size reduction was present in those with BPD and PTSD, whereas an 11 percent reduction was found in those just with BPD.
Studies have found 10-20 percent hippocampus size reduction in individuals with BPD compared to control groups without the disorder. What this means is that trauma-exposed individuals with BPD, who do not have PTSD, still demonstrate size differences in this region of the brain. A 22 percent amygdala size reduction has been found in patients with BPD as well. Severity of traumatic exposure and severity of hippocampus size reduction have also been found to be related. What is evidenced by the current data is that BPD has a negative effect on the brains of those suffering with the disorder.