Borderline Personality Disorder (BPD)

There is no known cause of BPD, but it is thought that both genetics and environment play a role in its development.  For example, childhood trauma or neglect are thought to be risk factors.

Although there is no gene for BPD, studies have shown that certain inherited genes can make someone more vulnerable.

Impairment with brain chemicals, particularly the neurotransmitter serotonin which regulates mood, is a risk factor.

Brain studies reveal that in people with BPD, the amygdala, hippocampus, and orbitofrontal cortex are smaller or show unusual activity level.  These brain areas regulate emotions and mood, behaviour and self-control, and decision making and planning, respectively.  Early upbringing impacts the brain development of these areas.

Early relationships impact how individuals perceive themselves, their world, and others.  When unresolved feelings like distress, anger, and fear persist, these can lead to cognitive distortions as an adult.  For example, behaving like you’re not an adult, expecting others to either parent or bully you, or idealising others.

Other environmental risk factors that people with BPD seem to have in common include: neglect by one or both parents, experiencing distress or fear for prolonged periods as a child, growing up around someone who had a serious mental health condition (for example, BPD, or addiction), or having experienced physical, emotional, or sexual abuse.