Borderline personality disorder is a type of personality disorder in which the affected person experiences periods of intense, unstable mood and behavior, and an altered sense of self.¹ This can result in impulsive actions and relationship problems with friends and family, affecting a person’s ability to cope with everyday life.^1,2

Borderline personality disorder is a serious condition, associated with self-harm and suicide attempts.² Up to one in ten people with the disorder will complete suicide.²

People with borderline personality disorder are very sensitive to changes in their environment, and can react severely and inappropriately to these changes. They may, for example, be afraid of being abandoned by someone close to them.² If someone they are expecting arrives a few minutes late, their feelings toward the person may very quickly shift from affection to dislike or anger.^1,2 This reflects a person with borderline personality disorder’s extreme view of the world, seeing things and people – including themselves – as being either all good or all bad.^1,2

A person with borderline personality disorder will frequently be unsure how they feel about themselves, suddenly changing their goals in life and opinions about their career, values, and friends.² They may engage in impulsive and often dangerous behaviors such as spending sprees, reckless driving, and substance abuse.² They may feel intense and inappropriate anger, or feelings of emptiness, and self-harm is common.² People with borderline personality disorder may also experience feelings of depression and anxiety.^1,2

Estimates of the proportion of people who have borderline personality disorder vary from less than 1% to around 6%.^2-4 Borderline personality disorder affects a roughly equal number of men and women, but appears to be more disabling in women.³

Symptoms of borderline personality disorder most commonly emerge in adolescence.⁴ The disorder is most problematic and harmful in young adults, and tends to improve as people get older.² Symptoms can exist for a person’s whole life, but most people with borderline personality disorder have stable work and home lives by the time they reach their 30s and 40s.²

People with borderline personality disorder are emotionally and functionally disabled, which puts a significant burden on their families.⁵ Mood swings are a source of stress for both the person with the disorder and their loved ones, who may ultimately develop mental health problems of their own.^1,5

Borderline personality disorder is diagnosed by a mental health professional using interviews and discussions about symptoms and medical history.¹

Psychotherapy can help people with borderline personality disorder by, for example, teaching them how to interact with others and to express their thoughts and feelings more clearly.¹ It may also be beneficial for caregivers and family members of those affected to receive therapy and guidance on how best to care for a person with borderline personality disorder.¹ There is currently no cure, but one study showed that, after 10 years, 50% of people with borderline personality disorder had recovered, being able to function at work and maintain personal relationships.⁶