Causes of Borderline Personality Disorder

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If you or a loved one has 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 potential causes, so it's unlikely that one person or thing is at fault.

The exact causes of BPD are not yet known, but most experts believe that BPD develops as a result of biological, genetic, and environmental factors. The following 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 the development of BPD. The types of childhood 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 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 people who have this specific genetic variation 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 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 difference may be related to the emotional instability symptoms of BPD. Newer studies have also found associations between 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 potential causes may help prevent the onset of the disorder, especially in those who have a genetic or biological predisposition to it. As it is, an invalidating environment is harmful to a child whether or not it raises the likelihood of BPD in the future.

7 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.
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By Kristalyn Salters-Pedneault, PhD
 Kristalyn Salters-Pedneault, PhD, is a clinical psychologist and associate professor of psychology at Eastern Connecticut State University.