Abuse, trauma and neglect in childhood are the most common cause of BPD. Occasionally it can be caused by trauma in adulthood. There are some neurological factors and it has been considered that there could also but some genetic attributes.
Often this is thought of as not serious but in some ways it is worse then physical abuse because of this misconception. Just because there are no bruises on the outside, does not mean there are none on the inside. If a child grows up living in fear then it becomes set behaviour causing problems in adulthood. Emotional abuse often can take place in school as well as at home. Remember bullying counts as abuse.
This commonly goes hand in hand with emotional abuse. This can vary in severity, it may happen occasionally or regularly. It is basically any abuse that can cause physical harm. Like emotional abuse this can often happen at school. Often people who in adult life suffer from physical abuse develop BPD symptoms or Post-Traumatic Stress Disorder (which is closely related to BPD).
This is probably the most traumatic type of abuse. Emotional and physical abuse play major factors in sexual abuse. This can take place in a number of situations especially at home, homes of trusted adults, church, and sometimes school. Often adults who suffer rape or sexual assault go on to develop PTSD.
A dysfunctional childhood is one that is more stressful then a conventional one. This can include children who grow up in care, or have major problems with other family members such as abuse or neglect.
Lose of a close relative or friend at an early age:
Children do not understand death in the same way an adult does, the earlier it happens the worse it is.
This could be any situation that involves emotional or physical trauma.
It is considered that genetics can influence the development of BPD. Often the caregiver of a child has psychological issues as it is in their genes. If there is a genetic factor then it will be in combination with neglect or abuse from a close relative.
Many people with BPD take anti-depressants, it is thought that they have a lower level of a neurotransmitter call serotonin. Serotonin is the chemical in our brains which basically helps control our moods. If you have low serotonin then you will feel depressed. If you think of a bath, the water will run down the drain if you don't put the plug in. This is how anti-depressants work, they work like the plug in a bath does, by helping the brain to not be drained too much of serotonin.