As with most mental disorders, the causes of borderline personality disorder (BPD) are not completely understood.
It is probably caused by a combination of genes and life experiences. Having a mental health condition, being very sensitive, or suffering abuse or neglect during childhood may make some people more likely to develop BPD. But not everyone with these factors will experience BPD and not everyone with these experiences will develop a BPD.
In some people, a stressful event or relationship breakup may cause BPD to develop. During times of stress, many people with BPD experience post-traumatic stress symptoms, such as flashbacks, nightmares, feelings of unreality and panic attacks.
Sometimes negative experiences from the past return as voices or punishing self-talk that feel real and are difficult to ignore.
Last reviewed: December 2018