The development of borderline personality disorder (BPD) is complex; there are likely a variety of borderline personality disorder causes. Most experts believe that BPD develops as a result of biological, genetic and environmental factors. The factors that may cause BPD are discussed below. However, it is important to keep in mind that the exact causes of BPD are not known yet. Right now these are theories that have some research support but are by no means conclusive. More research is needed to determine how and why the factors discussed below are related to BPD.
Environmental Borderline Personality Disorder Causes
There is strong evidence to support a link between distressing childhood experiences, particularly involving caregivers, and BPD. The types of experiences that may be associated with BPD include, but are not limited to, physical and sexual abuse, early separation from caregivers, emotional or physical neglect, emotional abuse, and parental insensitivity. Marsha Linehan, the developer of Dialectical Behavior Therapy (DBT) for BPD, believes that BPD is caused by an interaction between biological factors and an "emotionally invalidating" childhood environment (or an environment where the child's emotional needs are not met).
It is important to remember, however, that not everyone who has BPD has had these types of childhood experiences (although a large number have). Further, even if a person does have these types of experiences, it does not mean that they will have BPD.
Genetic and Biological Borderline Personality Disorder Causes
While early studies showed that BPD does tend to run in families, for some time it was not known whether this was because of environmental influences or because of genetics. There is now some evidence that in addition to environment, genetics plays a significant role.
In particular, studies have shown that a variation in a gene which controls the way the brain uses serotonin (a natural chemical in the brain) may be related to BPD. It appears that individuals who have this specific variation of the serotonin gene may be more likely to develop BPD if they also experience difficult childhood events (e.g., separation from supportive caregivers). One study found that monkeys with the serotonin gene variation developed symptoms that looked similar to BPD, but only when they were taken from their mothers and raised in less nurturing environments. Monkeys with the gene variation who were raised by nurturing mothers were much less likely to develop BPD-like symptoms.
In addition, a number of studies have shown that people with BPD have differences in both the structure of their brain and in brain function. BPD has been associated with excessive activity in parts of the brain that control the experience and expression of emotion. For example, people with BPD have more activation of the limbic system, an area in the brain that controls fear, anger, and aggression, than people without BPD. This may be related to the emotional instability symptoms of BPD.
Linehan MM. Cognitive Behavioral Therapy for Borderline Personality Disorder. New York: Guilford, 1993.
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