Borderline personality disorder (BPD): Signs and treatment

Reviewed by Brooks Baer, LCPC, CMHP

Written by

therapist.com team

Last updated: 06/26/2024

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What is borderline personality disorder (BPD)?

Borderline personality disorder (BPD) is a mental health disorder featuring frequent, intense changes in mood. It can be difficult for people with borderline personality disorder to manage their feelings, actions, and thoughts and have stable relationships.

Types of borderline personality disorder

The four types of borderline personality disorder come from Theodore Millon’s evolutionary model of personality.¹ His model describes variations of each of the typical personality disorders. Each subtype shares the main features of BPD but also has additional characteristics.

1. Impulsive BPD: Characterized by impulsive behaviors.
2. Discouraged BPD: A person may exhibit clingy or codependent behavior, often feeling unworthy or insecure.
3. Petulant BPD: Marked by unpredictability and anger, coupled with stubbornness and a compulsion to have control.
4. Self-destructive BPD: Where a person may engage in self-harming behaviors and act out in a self-destructive way.

Signs of borderline personality disorder

Symptoms of borderline personality disorder and their intensity can be different from person to person. They can include:²

• Having strong feelings and moods that change abruptly
• Worrying about being abandoned by loved ones
• Having intense, “rocky” relationships
• Acting impulsively or taking risks
• Feeling uncertain about your identity, or like it’s constantly changing
• Feeling paranoid when you’re stressed out
• Feeling empty or disconnected from reality
• Frequently getting angry  or starting fights
• Self-destructive behavior or self-harm
• Thinking about or threatening suicide

People with BPD often have other mental health conditions. The most common conditions that cooccur alongside BPD include depression, anxiety, substance use disorders, and bipolar disorder.³

Borderline personality disorder can present differently depending on the person. It’s important to seek out a mental health professional if you have concerns, rather than trying to self-diagnose.

Borderline personality disorder vs. bipolar disorder

Borderline personality disorder and bipolar disorder have some of the same symptoms, such as impulsiveness and mood shifts. BPD, however, is a personality disorder whereas bipolar disorder is a mood disorder.

Bipolar disorder can involve long periods, or “episodes,” of depression (“low lows”) and mania (“high highs”). A depressive episode might involve low energy, extreme sadness, worry, and loss of interest in once-enjoyable activities. A manic episode might look like high energy levels, impulsive actions, risk-taking, and unrealistic plans. The length of an episode can vary greatly.

Meanwhile, BPD’s intense moods tend to be shorter, lasting from a few minutes to a few days, and they can shift quickly. Internal or external conflict, often around relationships and interactions, can trigger the shifts.

BPD splitting

In BPD, “splitting” is a defense mechanism in which a person sees things in unrealistic extremes—either all good or all bad, with no middle ground.⁴ This can lead to quick shifts in their opinions of others, from idealizing someone one moment to devaluing them the next.

Splitting is a way to cope with the complexity and nuances of relationships and emotions, which they might find overwhelming or difficult to integrate. The concept of splitting helps to explain the intense and unstable relationships often experienced by those with BPD.

Causes of borderline personality disorder

We don’t know the exact cause of BPD, but certain risk factors can increase a person’s chance of developing the disorder.⁵ These factors include:

• Genetics: Having a family member with borderline personality disorder.
• Brain differences: Certain differences in your brain’s functioning or structure.
• Childhood trauma or stress: Traumatic childhood events including abuse, separation from a parent or caregiver, or unstable family relationships.

Getting a borderline personality disorder diagnosis

Borderline personality disorder symptoms can overlap with symptoms of other mental health disorders, so you should avoid self-diagnosing. If you notice symptoms in yourself, it’s important to speak with a therapist.

While there’s no one test that can tell you if you have the disorder, a therapist is the most qualified to assess your symptoms. They’ll ask you questions about your mental health history and current mental state, offer you a diagnosis, and begin a treatment plan.

Borderline personality disorder treatment

The right treatment plan can help people manage their symptoms and begin living happier, more fulfilling lives. There are many different treatment options, depending on a person’s symptoms and how severe they are.

Some of the most effective borderline personality disorder treatments include:

• Cognitive behavioral therapy (CBT)
• Dialectical behavior therapy (DBT)
• Medication

Browse our provider directory for CBT and DBT therapists in your area.

If you or a loved one are in crisis, help is available now. For free, confidential 24/7 support, please call the 988 Suicide & Crisis Lifeline at 988, or text HOME to 741741. 

Borderline personality disorder and relationships

BPD can make relationships challenging. Someone with BPD may be loving and affectionate one moment, then overwhelmed and distant if they’re distressed. They may idealize the person they’re with, then devalue them when that person doesn’t meet their expectations.⁶

People with BPD may feel greater joy when something exciting happens, and more intense sadness when something bad happens. It can be hard for them to recover from relationship difficulties. At the same time, people with BPD tend to have rejection sensitivity. This sensitivity can cause them to overthink a partner’s words or actions, or feel their loved ones don’t care about them enough.

When a loved one has borderline personality disorder, the ups and downs of the relationship can feel chaotic. However, despite these difficulties, people with the disorder can still maintain long-lasting friendships and romantic partnerships. Treatment, support, and hard work can help them manage their symptoms and have healthy, meaningful bonds with their loved ones.

How to support a loved one with BPD

If you’re in a relationship with someone who has BPD, there are some things you can do to understand what they’re going through and support them. 

It’s important to be prepared for their emotional needs and mood changes, and to be aware of potential triggers. People with BPD may find it helpful to talk openly about the disorder with their partners, friends, or family members. They may need to explain what they struggle with and how they’d like loved ones to respond during arguments and other challenges. Someone with BPD may also need more reassurance due to their fear of abandonment. 

While BPD can make a relationship more challenging, having a support system can have a positive impact on a person’s symptoms. Visit our directory to find a therapist who can help you and your loved one navigate BPD together.