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Borderline personality disorder (BPD)

Explains borderline personality disorder (BPD), also known as emotionally unstable personality disorder (EUPD). Includes what it feels like, causes, treatment, support and self-care, as well as tips for friends and family.

Mae'r dudalen hon hefyd ar gael yn Gymraeg. This link will take you to a Welsh translation of this page.

What causes BPD?

There's no clear reason why some people experience difficulties associated with BPD. Women are given this diagnosis more often than men – more research needs to be done to understand why this is. But it can affect people of all genders and backgrounds.

Researchers think that BPD is caused by a combination of factors, including:

One of the things I struggled with was a feeling of 'why me' – I felt others had experienced far worse and could deal with it so why couldn't I. Over time I've realised that lots of low level issues are as valid a reason for struggling as a few bigger traumas.

Stressful or traumatic life events

If you get a BPD diagnosis you're more likely than most people to have had difficult or traumatic experiences growing up, such as:

  • Often having felt afraid, upset, unsupported or invalidated
  • Family difficulties or instability, such as living with a parent or carer who experienced an addiction
  • Sexual, physical or emotional abuse or neglect
  • Losing a parent

Difficult childhood experiences may cause you to develop particular coping strategies, or beliefs about yourself and other people. These can become less helpful in time and cause you distress. You might also be struggling with feelings of anger, anxiety and depression.

You might also experience BPD without having any history of traumatic or stressful life events. Or you might have had other types of difficult experiences.

If you already experience some of these difficulties, then experiencing stress or trauma as an adult could make things worse. Our pages on how to manage stress and post-traumatic stress disorder have some tips on how to cope.

Because I don't have many memories of healthy emotional behaviour or relationships I feel totally at sea dealing with these things. When I get let down, it just reinforces my belief that the world is full of bad people who won't be kind – like my parents.

Genetic factors

You're more likely to get a diagnosis of BPD if someone in your close family also has one. This suggests that genetic factors could contribute to BPD. But we also know that the environment we grow up in and our early relationships can impact the way we think, feel and behave as adults. So it's difficult for researchers to know exactly how much of a role genes play.

It's possible that a combination of factors could be involved. Genetics might make you more vulnerable to developing BPD. Whereas stressful, difficult or traumatic life experiences could then trigger these vulnerabilities. More research is needed to understand this area.

I saw my parents and family members regularly behave in out-of-control ways and I thought that was normal.

Can children and young people be diagnosed with BPD?

It's very hard to diagnose BPD in children and young people because you go through so many changes as you grow up. But you might be given the diagnosis as a teenager if your difficulties have lasted for long enough and BPD is the diagnosis that best matches what you're experiencing.

You may also hear the term ‘emerging borderline personality disorder’. YoungMinds has more information about BPD and emerging BPD for young people.

This information was published in September 2022. We'll revise it in 2025.

References and bibliography available on request.

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