Since traumatic events can increase cortisol production and HPA axis activity, one possibility is that the prevalence of higher than average activity in the HPA axis of people with BPD may simply be a reflection of the higher than average prevalence of traumatic childhood and maturational events among people with BPD. Estrogen
Individual differences in womens estrogen cycles may be related to the expression of BPD symptoms in female patients. A 2003 study found that womens BPD symptoms were predicted by changes in estrogen levels throughout their menstrual cycles, an effect that remained significant when the results were controlled for a general increase in negative affect. Developmental factors
Childhood trauma
There is a strong correlation between child abuse, especially child sexual abuse, and development of BPD. Many individuals with BPD report a history of abuse and neglect as young children, but causation is still debated. Patients with BPD have been found to be significantly more likely to report having been verbally, emotionally, physically, or sexually abused by caregivers of either sex. They also report a high incidence of incest and loss of caregivers in early childhood. Individuals with BPD were also likely to report having caregivers of both sexes deny the validity of their thoughts and feelings. Caregivers were also reported to have failed to provide needed protection and to have neglected their childs physical care. Parents of both sexes were typically reported to have withdrawn from the child emotionally and to have treated the child inconsistently.
Sexual abuse can be a particular trigger for suicidal behavior in adolescents with BPD tendencies. Sense of self
People with BPD tend to have trouble seeing their identity clearly. In particular, they tend to have difficulty knowing what they value, believe, prefer, and enjoy. They are often unsure about their long-term goals for relationships and jobs. This can cause people with BPD to feel "empty" and "lost". Self-image can also change rapidly from healthy to unhealthy. People with BPD may base their identity on others, leading to chameleon-like changes in identity. Cognitions
The often intense emotions people with BPD experience may make it difficult for them to concentrate. They may also tend to dissociate, which can be thought of as an intense form of "zoning out". Others can sometimes tell when someone with BPD is dissociating because their facial or vocal expressions may become flat or expressionless, or they may appear distracted and "numb" to emotional stimuli.Dissociation most often occurs in response to a painful event (or something that triggers the memory of a painful event). It involves the mind automatically redirecting attention away from the current event or situation or blocking it out entirely. This is done presumably to protect against - based on similar or related past experiences - what the mind perceives and forecasts as arousing intense negative emotions and unwanted behavioral impulses that the present emotive event might trigger.