Causes of Borderline Personality Disorder

same woman showing different moods / Stock Photo / KatarzynaBialasiewisz

If you or a loved one has a borderline personality disorder (BPD), you may be wondering what caused it or if you are to blame. The development of this disorder is complex, and there are likely a variety of borderline personality disorder causes, and you should rest assured that no one person or thing is at fault.

Most experts believe that BPD develops as a result of biological, genetic, and environmental factors. However, it is essential to keep in mind that the exact causes of BPD are not known yet. Right now, these are theories that have some support in 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 Influences

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:

  • Early separation from caregivers
  • Emotional or physical neglect
  • Parental insensitivity
  • Physical and sexual abuse

It is thought that interaction between biological factors (discussed below) and an invalidating childhood environment may work together in predisposing a person to develop BPD. An emotionally invalidating environment is one in which a child's emotional needs are not met.

An invalidating environment is not always evident to those who have experienced it or to others around them. These painful experiences can be hidden and even disguised as praise.

Not everyone who has BPD has had these types of childhood experiences (although a large number have). And not everyone who has these types of experiences will have BPD. It is likely that a combination of factors, rather than a single cause, is responsible for most cases of borderline personality disorder.


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 the environment, genetic factors play a significant role.

In particular, studies have shown that a variation in a gene that 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 (for example, 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.

Biological Factors

Several 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 of the brain that controls fear, anger, and aggression, than people without BPD. This may be related to the emotional instability symptoms of BPD. Newer studies are also findings associations with the hormone oxytocin and the development of BPD.

A Word From Verywell

There is much to be learned about the causes of BPD, and it's likely that it is a combination of factors rather than any one specific finding which can lead to the disorder. Research is in progress and hopefully we will learn more in the coming years.

Understanding the causes may help prevent the onset of the disorder, especially in those who have a genetic or biological predisposition to the disorder. As it is, an invalidating environment is harmful to a child whether or not it raises the likelihood of BPD in the future, and it is crucial for therapists to be alert for this setting in children.

Although it can be challenging to be optimally validating to children who have the underlying biological vulnerabilities that may contribute to BPD. Sometimes an invalidating environment can be hidden, with many comments appearing to be comments of praise on the surface, emotions can easily be mistaken as just an oversensitivity on the part of the child.

It's important for adults who experienced emotional invalidation as a child to learn to recognize the difference between validating and invalidating remarks from others to better protect themselves from further hurt and navigate these interpersonal interactions more effectively.

Was this page helpful?
Article Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institute of Mental Health. Borderline personality disorder. Updated December 2017.

  2. Cattane N, Rossi R, Lanfredi M, Cattaneo A. Borderline personality disorder and childhood trauma: exploring the affected biological systems and mechanisms. BMC Psychiatry. 2017;17(1):221. Published 2017 Jun 15. doi:10.1186/s12888-017-1383-2

  3. Reeves M, James L, Pizzarello S, Taylor J. Support for Linehan’s biosocial theory from a nonclinical sampleJournal of Personality Disorders. 2010;24(3):312-26. doi:10.1521/pedi.2010.24.3.312

  4. Maurex L, Zaboli G, Ohman A, Asberg M, Leopardi R. The serotonin transporter gene polymorphism (5-HTTLPR) and affective symptoms among women diagnosed with borderline personality disorder. Eur Psychiatry. 2010;25(1):19-25. doi:10.1016/j.eurpsy.2009.05.001

  5. Bennett AJ, Lesch KP, Heils A, et al. Early experience and serotonin transporter gene variation interact to influence primate CNS function. Mol Psychiatry. 2002;7(1):118-22. doi:10.1038/

  6. Ruocco AC, Carcone D. A neurobiological model of borderline personality disorder: systematic and integrative review. Harv Rev Psychiatry. 2016;24(5):311-29. doi:10.1097/HRP.0000000000000123

  7. Brüne M. On the role of oxytocin in borderline personality disorder. Br J Clin Psychol. 2016;55(3):287-304. doi:10.1111/bjc.12100