There are many theories as to what causes and influences the occurrence of Borderline Personality Disorder. No one factor has been recognised as the ‘true’ cause of BPD.
Developmental
In people with BPD there is often a history of childhood sexual abuse, physical abuse, witnessing violence in the home, emotional abuse and neglect. BPD patients often come from a background of dysfunctional family relationships. This suggests that trauma and suffering of this ilk could be a key factor in why people may go on to develop BPD.
This cannot be considered the sole reason as to why BPD occurs. However, this cannot be ignored because such a high percentage of sufferers report the aforementioned types of childhood experience. It has been suggested that BPD may be a form of, or similar to post traumatic stress disorder.
Biological
Another accepted theory is that BPD may be a result of biological and genetic factors.
According to research, there is evidence to suggest a genetic component. Parents with BPD have an increased likelihood of having children who are prone to BPD and other psychiatric disorders. Genetic factors may cause a slight susceptibility to a person developing BPD. This susceptibility may only result in a disorder when nurtured in a triggering environment i.e. that of abuse or neglect.
Some medical professionals also believe that physical problems in the brain may be a contributing factor or cause of BPD. It has been suggested that BPD can be attributed to brain damage caused to a baby in the womb or during or after birth. There is also some evidence of organic lesions in the brains of people with BPD. Brain imaging has reportedly seen abnormalities in the brains of BPD sufferers.
Other than physical damage to the brain, it has been theorised that there may be a chemical dysfunction in the brains of BPD patients. Hormonal and chemical imbalances found in some BPD subjects may explain some of the BPD symptoms. Investigations have shown BPD patients to have imbalances of several chemicals including serotonin, dopamine, norepinephrine (noradrenaline) and acetylcholine monoamine oxidase.
Both theories are largely indefinite as there is a lack of evidence to conclusively prove either theory. However both genetic and environmental theories are held to be credible, particularly the developmental theories (i.e. childhood experiences) and it is likely that a combination of these increases the chances of developing BPD.