It is well-known among psychological researchers that individuals with borderline personality disorder are much more likely than the general population to have experienced some form of childhood sexual abuse, with a childhood sexual abuse rate of about 75 percent among such patients, suggesting that this source of trauma is extremely important in explaining the genesis of BPD. Indeed, that borderline personality disorder shares significant aetiological overlap with PTSD is quite well-known. Other forms of abuse have also been found to be correlated with borderline personality disorder. These include emotional and physical abuse, as well as neglect. Abuse of some sort during childhood figures to about 90 percent in individuals with borderline personality disorder.
Some researchers believe that the quasi-psychotic symptom of dissociation associated with BPD may be related to the emotional neglect experienced by the borderline. The four primary risk factors involved in the experience of dissociation are: “inconsistent treatment by a caretaker, sexual abuse, witnessing sexual violence as a child and adult rape history”(“Borderline Personality Disorder and Trauma”). There thus seems to be clinically significant mutual overlap between borderline personality disorder, dissociation and different forms of childhood abuse, especially sexual abuse(“Borderline Personality Disorder and Trauma”).
“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”(“Borderline Personality Disorder and Trauma”)
Further evidence for the importance of the overlap between dissociation, borderline personality disorder and trauma has been found thanks to the use of the Autobiographical Memory Test in experimenting with such patients.
“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”(“Borderline Personality Disorder and Trauma”)
Indeed, individuals with borderline personality disorder are less likely to believe in the so-called “just world construct.” This fact may shed important light on certain gender, sex and race-related asymmetries involved in borderline personality disorde(“Borderline Personality Disorder and Trauma”). The just world construct is a mentality people have in which good individuals are rewarded for their actions and bad individuals are punished. Unsurprisingly, European and American men are more likely to adhere to this, whereas women and African-Americans are less likely to believe in it. Since these groups are more prone to oppression, it is unsurprising that they would reject this construct(“Borderline Personality Disorder and Trauma”).
But what does this have to do with borderline personality disorder? A particular form of trauma known as high-betrayal trauma is much more common among women, along with the diagnosis of borderline personality disorder(“Borderline Personality Disorder and Trauma”).
“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…Gender aside, it is clear that betrayal traumas are strongly associated with BPD”(“Borderline Personality Disorder and Trauma”)
Neurobiological findings on the relation of PTSD to borderline personality disorder have also shed some light on the impact of trauma. Those with borderline personality disorder and PTSD both exhibit reductions in certain parts of the brain important in memory and emotion. Patints diagnosed with both BPD and PTSD both exhibit unusual reduction in the volume in those diagnosed with both BPD and PTSD(“Borderline Personality Disorder and Trauma”). Furthermore, reduction in the size of the left amygdala and hippocampus are directly proportionate to the severity of an individual’s PTSD(“Borderline Personality Disorder and Trauma”).
In another study, 12 percent reduction in hippocampus size was found in those with both PTSD and BPD, with an 11 percent reduction in individuals who had only been diagnosed with borderline personality disorder(“Borderline Personality Disorder and Trauma”). Other studies indicate that those with borderline personality disorder present with a hippocampus reduction 10 to 20 percent greater healthy control subjects, as well as a 22 percent reduction in the size of the amygdala(“Borderline Personality Disorder and Trauma”). Thus, it is clear that BPD and PTSD both have clinically significant ramifications on similar brain regions, especially where the individual exhibits comorbidity(“Borderline Personality Disorder and Trauma”).
Some have suggested that borderline personality disorder be understood as a trauma-spectrum disorder. However, while there is a great deal of aetiological overlap between PTSD and BPD, other researchers insist that they remain distinct diagnoses:
The associations of personality disorder with early trauma and PTSD were evident, but modest, in borderline personality disorder and were not unique to this type of personality disorder. The results do not appear substantial or distinct enough to support singling out borderline personality disorder from the other personality disorders as a trauma-spectrum disorder or variant of PTSD.