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What Causes Borderline Personality Disorder in Teens?

Written by Evolve's Behavioral Health Content Team​:

Alyson Orcena, LMFT, Melissa Vallas, MD, Shikha Verma, MD, Ellen Bloch, LCSW, Lianne Tendler, LMFT, Megan Johnston, LMFT Meet The Team >

Borderline personality disorder in teens is marked by high levels of impulsivity, repeated self-harming and suicidal attempts, conflicted relationships with others, and high emotional sensitivity and reactivity.

But what causes this disorder?

Experts can’t point to one single cause of borderline personality disorder (BPD) in adolescents. Mental health professionals believe it is caused by several factors, including genetics and environmental issues. This is what DBT’s Biosocial Theory suggests. Some adolescents are simply born with a predisposition to emotional reactivity. When they are placed in an environment that is invalidating (the “social” aspect), the combination of factors produces BPD.

Let’s go through these two aspects of the biosocial theory in more detail.


Evidence shows that genetics plays a factor in borderline personality disorder. In fact, twin studies have shown that one has a higher risk of developing borderline personality disorder if other family members also have it.

“Some teens are just born highly emotionally sensitive, highly emotionally reactive, and with a slow return to baseline,” says Alyson Orcena, LMFT, Executive Clinical Director of Evolve Treatment Centers.

What does it mean to be emotionally sensitive?

“When teens with BPD feel emotions, they experience them strongly, more than others… they kind of take over the body,” explains Orcena. “Emotionally reactive means: are you going to make things worse? Are we gonna throw our partner’s things out of the window when we experience a breakup?”

Many teens with BPD engage in unhealthy coping mechanisms when they feel such emotions: attempting suicide, engaging in self-injury, threatening someone else, or physically attacking others. And when someone has a slow return to baseline, they have a hard time letting the emotion pass.

“Instead of experiencing the emotion and letting it pass, they keep reigniting it. The moment they think about the trigger, their distress peaks back up, so they stay emotionally activated,” says Orcena.

Of course, this predisposition to emotional reactivity does not mean every teen who has a more sensitive or reactive temperament will develop BPD. It just means that they’re more likely to develop BPD if they’re brought up in a certain environment. More on that below.

An Invalidating Environment

Evidence shows that adolescents with BPD were raised in an invalidating environment when they were children. This could mean that they experienced one of the following situations:

  • Emotional, physical or sexual abuse
  • Childhood marked by instability and/or family conflict
  • Emotional neglect from a parent or caregiver
  • Parent had mental health or substance abuse issues
  • Parent chronically invalidated their emotions

When a parent invalidates a child, they do not affirm their emotional needs. Such parents would, for example, tell a child to “stop crying” if the child is upset. Or they might ignore the child and retreat into themselves because they cannot handle the child’s neediness.

“But asking a child or adolescent ‘Why are you sensitive? Why do you cry about everything?’ not only dismisses a child’s sadness, it invokes shame,” says Orcena.  Instead of communicating to the child that their emotions are valid, a parent teaches the child not to trust their instincts.

After being invalidated by a parent numerous times, a child learns not to trust himself or herself. They stop expressing their feelings and instead learn to bury and repress their emotions.

“However, just like what happens when you try to stand on a kickboard, instead of letting our emotions come and go naturally, by trying to bury them they come up even harder,” explains Orcena. This is why borderline personality disorder, marked by extreme displays of emotional reactivity and sensitivity, is a natural consequence of such an invalidating childhood.

Note: The role of a mental health professional should never be to blame a parent; rather, to provide explanation as to how parenting can affect a teen. Often, such parents were raised by parents who were emotionally unavailable themselves.  

Biology + Environment

While having a biological predisposition to highly emotional behavior rarely produces BPD by itself, its combination with an invalidating environment can.

Even if a child is born with a sensitive temperament, a person’s relationship with their parents and family has a very strong influence on their perspective of the world and their role in it. “In fact, certain environments are so invalidating and distressing that a biological predisposition is not even necessary for BPD to develop,” says Orcena.

How DBT Helps

Dialectical Behavior Therapy is accepted as the primary treatment for borderline personality disorder. DBT teaches teens with BPD the skills they’re lacking to engage in emotion regulation and manage their extreme, polarizing reactions. Through direct practice and application of DBT in their day-to-day life, these teens can compensate for their biological predispositions and/or lack of an affirming childhood. Eventually, their symptoms can be reduced drastically.

Our Behavioral Health Content Team

We are an expert team of behavioral health professionals who are united in our commitment to adolescent recovery and well-being.

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