Borderline Personality Disorder

borderline personality disorder

Borderline personality disorder (BPD) is a mental disorder marked by persistent difficulty regulating emotions, maintaining a stable sense of self, and navigating close relationships. These patterns are long-lasting (not just a “phase”), tend to begin by early adulthood, and can lead to serious distress and impairment in daily life.

Core features of BPD

BPD commonly involves a cycle of intense emotional reactions and rapid shifts in mood, often in response to interpersonal stress (for example, feeling suddenly rejected, criticized, or abandoned). Other common features include:

• Unstable relationships: Relationships may feel “all-or-nothing”—someone can be idealized in one moment and then viewed as uncaring or hostile after a disappointment or conflict.
• Unstable self-image or identity: Self-concept may shift quickly (values, goals, friendships, plans), leading to feeling unsure about who one is or what matters most.
• Fear of abandonment: Strong sensitivity to separation—whether real or perceived—can lead to frantic efforts to avoid being alone or left out.
• Impulsivity: Risky, self-defeating behaviors may occur in areas like spending, substance use, unsafe sex, reckless driving, or binge eating—especially during intense emotions.
• Self-harm and suicidal behavior: Some cases include suicidal ideation, suicidal behavior, or non-suicidal self-injury, often linked to emotion regulation difficulties and crisis-level distress.
• Intense anger or difficulty controlling anger: Anger may feel sudden, overwhelming, or hard to manage, sometimes followed by guilt or shame.
• Stress-related changes in thinking or perceptio: Under high stress, brief dissociation (feeling unreal, detached, “not in your body”) or short-lived paranoid thoughts can occur.

How common is it?

National estimates vary depending on how BPD is measured and which samples are studied. In U.S. adults, commonly cited estimates cluster around about 1–2% in the general population, while rates are much higher in clinical settings (especially inpatient care). 

Why does BPD develop?

BPD does not have a single cause. Research supports a biopsychosocial explanation—meaning risk increases through the interaction of temperament, biology, and environment.

Common risk factors include:

• Temperament and emotion sensitivity (for example, strong emotional reactivity, difficulty returning to baseline after stress)
• Genetic influences on traits like impulsivity and negative emotionality
• Chronic invalidation or unstable environments (repeated experiences of being dismissed, ignored, or punished for emotions)
• Trauma and adversity, including higher rates of childhood neglect or abuse among those diagnosed (though trauma is not required for the diagnosis)

A helpful way to think about BPD is that the disorder often reflects emotion regulation difficulties in a context of high stress and vulnerability, where impulsive behaviors or relationship conflicts can become short-term “solutions” that accidentally make long-term functioning worse.

Psychotherapy is the first-line treatment for BPD, and improvement is common with effective care and support.

Evidence-based approaches for treatment include:

• Dialectical behavior therapy (DBT): focuses on skills for mindfulness, distress tolerance, emotion regulation, and interpersonal effectiveness. A systematic review of randomized controlled trials found DBT improved outcomes such as suicidality and related symptoms (often with small-to-moderate effects), and it may reduce emergency visits and hospitalization. 

• Other structured therapies with evidence include mentalization-based therapy (MBT), schema therapy, and transference-focused psychotherapy (TFP). 

Medication is not considered a primary treatment for BPD itself, but it may be used to address co-occurring conditions (like major depression, anxiety disorders, PTSD, or substance use disorders) when appropriate. 

A hopeful note

BPD is often portrayed as “unchangeable,” but that is not accurate. With consistent, skills-based treatment and supportive relationships, many symptoms can lessen substantially over time, and functioning can improve.