Most experts agree there is not one single cause of borderline personality disorder (BPD). It is likely the condition is caused by a combination of factors.

These include:

• genetics – genes you inherit from your parents may make you more vulnerable to developing BPD, given certain environmental factors (see below)
• neurotransmitters – these are ‘messenger chemicals’ used by your brain to transmit signals between brain cells. Certain neurotransmitters can have a significant effect on mood and behaviour
• neurobiology – this term describes the structure and function of your brain and nervous system. It appears some people with BPD have a number of regions in the brain with abnormal structure and function
• environmental factors – events that happened in your past, such as your relationship with your family, appear to play an important role in BPD

These are explained in more detail below.

Genetics

Currently, the strongest evidence that genetics may play a role in BPD is research that studied twins.

One study found if one identical twin had BPD, there was a two-in-three chance that the other identical twin would also have BPD.

However, these results have to be interpreted with caution and there is no evidence there is a gene for BPD.

Firstly, you may be more likely to develop certain personality traits. For example, you may inherit from your parents a tendency to be aggressive and emotionally unstable, rather than BPD itself.

Secondly, most identical twins grow up in the same household and in the same family environment, so they will share many environmental factors.

Neurotransmitters

It is thought many with BPD may have altered functioning of a neurotransmitter called serotonin in their brain.

Altered serotonin activity in the brain has been linked to depression, aggression and difficulty in controlling destructive urges.

There is also some limited evidence that some people with BPD also have altered functioning of two other neurotransmitters, called dopamine and noradrenaline, that may be associated with emotional instability.

Neurobiology

Researchers have used magnetic resonance imaging (MRI) scans to study the brains of people with BPD. MRI scans use strong magnetic fields and radio waves to produce a detailed image of the inside of the body.

The scans revealed that in many people with BPD, three parts of the brain were either smaller than expected or had unusual levels of activity. These parts were:

• the amygdala, which plays an important role in regulating emotions, especially the more ‘negative’ emotions such as fear, aggression and anxiety
• the hippocampus, which helps regulate behaviour and self-control
• the orbitofrontal cortex, which is involved in planning and decision making

Problems with these parts of the brain may well contribute to symptoms of BPD.

The development of these parts of the brain is affected by your early upbringing (see below). These parts of your brain are also responsible for mood regulation, which may account for some of the problems people with BPD have in close relationships.

Environmental factors

A number of environmental factors seem to be common and widespread among people with BPD. These include:

• being a victim of emotional, physical or sexual abuse
• being exposed to chronic fear or distress as a child
• being neglected by one or both parents
• growing up with another family member who had a serious mental health condition, such as bipolar disorder or a drink or drug misuse problem

A person’s relationship with their parents and family has a strong influence on how they come to see the world and what they believe about other people.

Unresolved fear, anger and distress from childhood can lead to a variety of distorted adult thinking patterns, such as idealising others, expecting others to be a parent to you, expecting other people to bully you and behaving as if other people are adults and you are not.

If you are concerned you have a borderline personality disorder (BPD), make an appointment with your GP.

You may also find the MIND and Emergence websites useful.

Your GP will probably ask about how you feel, your recent behaviour and what sort of impact your symptoms have had on your quality of life.

This is to rule out other more common mental health conditions, such as depression, and to make sure there is no immediate risk to your health and wellbeing.

Community mental health team

If your GP suspects you may have BPD, you will probably be referred to your local community mental health team (CMHT) for a more in-depth assessment. Ask if the service you are being referred to has experience of working with personality disorders.

Community mental health teams help people with complex mental health conditions such as BPD. However, some teams may focus only on people with psychotic disorders. In other areas, there are complex needs services that may be better placed to help you.

Your assessment will probably be carried out by a specialist in personality disorders, most likely a psychologist or psychiatrist.

Assessment

A checklist of internationally recognised criteria is used to diagnose BPD. A diagnosis can usually be made if you answer yes to five or more of the following questions:

• Do you have an intense fear of being left alone which causes you to act in ways that, on reflection, seem out of the ordinary or extreme, such as constantly phoning somebody (but not including self-harming or suicidal behaviour)?
• Do you have a pattern of intense and unstable relationships with other people that switch between thinking you love that person and they are wonderful to hating that person and thinking they are terrible?
• Do you ever feel you do not have a strong sense of your own self and are unclear about your self-image?
• Do you engage in impulsive activities in two areas that are potentially damaging, such as unsafe sex, drug abuse or reckless spending (but not including self-harming or suicidal behaviour)?
• Have you made repeated suicide threats or attempts in your past and engaged in self-harming?
• Do you have severe mood swings, such as feeling intensely depressed, anxious or irritable, which last from a few hours to a few days?
• Do you have long-term feelings of emptiness and loneliness?
• Do you have sudden and intense feelings of anger and aggression, and often find it difficult to control your anger?
• When you find yourself in stressful situations, do you have feelings of paranoia, or do you feel like you are disconnected from the world or from your own body, thoughts and behaviour?

Involving your family

Once a diagnosis of borderline personality disorder (BPD) has been confirmed, it is recommended you tell close family, friends and people you trust about the diagnosis.

There are several reasons for this.

Many of the symptoms of BPD affect your relationships with people close to you, so involving them in your treatment may make them aware of your condition and make your treatment more effective.

Your family and friends will be able to remain alert for any behaviour that may indicate you are having a crisis.

They may also benefit from local support groups and other services for people in a relationship with a person with BPD.

However, the decision to talk about your condition is entirely your own, and your confidentiality will be respected at all times.

Personality disorders are conditions that can cause a range of distressing symptoms and patterns of abnormal behaviour.

This could include:

• overwhelming feelings of distress, anxiety, worthlessness or anger
• difficulty managing such feelings without self-harming, for example by abusing drugs and alcohol or taking overdoses
• difficulty maintaining stable and close relationships
• sometimes, periods of loss of contact with reality
• in some cases, threats of harm to others

Read more about the symptoms of borderline personality disorder.

Personality disorders typically emerge in adolescence and persist into adulthood. They may be associated with genetic and family factors, and experiences of distress or fear during childhood, such as neglect or abuse, are common. Personality disorders range from mild to severe.

What is borderline personality disorder (BPD)?

It used to be thought people with borderline personality disorder (BPD) were at the ‘border’ between:

• neurosis, where a person is mentally distressed but can still tell the difference between their perception and reality
• psychosis, where a person is unable to tell the difference between their perception and reality, and may experience delusions and hallucinations

Now it is known this is not an accurate description. BPD is best understood as a disorder of mood and interpersonal function (how a person interacts with others).

BPD is a common personality disorder seen by healthcare professionals. Although BPD is said to be more common in women, this is probably because it is recognised less frequently in men, who may be less likely to seek treatment.

Read more about how borderline personality disorder is diagnosed.

How does BPD develop?

The causes of BPD are unclear. However, as with most conditions, BPD appears to be the result of a combination of genetic and environmental factors.

Traumatic events that occur during childhood are associated with developing BPD. An estimated eight out of 10 people with BPD experience parental neglect or physical, sexual or emotional abuse during their childhood.

Read more about the causes of borderline personality disorder.

Outlook

BPD can be a serious condition and many people with the condition self-harm and attempt suicide. It is estimated that 60-70% of people with BPD will attempt suicide at some point in their life.

However, for many with BPD, the outlook is reasonably good over time, and psychological or medical treatment may help.

Treatment may involve a range of individual and group psychological therapies (psychotherapy) carried out by trained professionals working with a community mental health team (CMHT). Effective treatment may last more than one year.

Read more about treatments for borderline personality disorder.

Recent studies have suggested the majority of those with borderline personality disorder do well over time, with most experiencing sustained relief from symptoms, and around half being completely free of symptoms and able to function well in life.

Additional treatment is recommended for people whose symptoms return.

Borderline personality disorder (BPD) can cause a wide range of symptoms which can be broadly grouped into four main areas.

The four areas are:

• emotional instability (a psychological term for this is affective dysregulation)
• disturbed patterns of thinking or perception (psychological terms for these are cognitive or perceptual distortions)
• impulsive behaviour
• intense but unstable relationships with others

Each of these areas is described in more detail below.

Emotional instability

If you have BPD, you may experience a range of often intense negative emotions, such as:

• rage
• sorrow
• shame
• panic
• terror
• long-term feelings of emptiness and loneliness

You may have severe mood swings over a short space of time. It is common for people with BPD to feel suicidal with despair and then feel reasonably positive a few hours later. Some people feel better in the morning and some in the evening. The pattern varies, but the key sign is that your moods swing in unpredictable ways.

Disturbed patterns of thinking

There are three levels of disturbed thinking that can affect people with BPD. These are ranked according to severity:

• upsetting thoughts, such as thinking you are a terrible person or feeling you do not exist. You may not be sure of these thoughts and may seek reassurance that they are not true
• brief episodes of strange experiences, such as hearing voices outside your head for minutes at a time. These may often feel like instructions to harm yourself or others. You may or may not be certain whether these are real
• prolonged episodes of abnormal experiences, where you might experience both hallucinations (voices outside your head) or distressing beliefs that no one can talk you out of (such as believing your family are secretly trying to kill you). These types of beliefs may be psychotic (delusions), and a sign you are becoming more unwell. It is important to get help if you are struggling with delusions

Impulsive behaviour

If you have BPD, there are two main types of impulses you may find extremely difficult to control:

• an impulse to self-harm, such as cutting your arms with razors or burning your skin with cigarettes. In severe cases, especially if you also feel intensely sad and depressed, this impulse can lead to feeling suicidal and you may attempt suicide
• a strong impulse to engage in reckless and irresponsible activities, such as binge drinking, drug abuse, going on a spending or gambling spree or having unprotected sex with strangers. Impulsive behaviours are especially dangerous when people are in brief psychotic states, because they may be much more likely to act impulsively if their judgement is impaired

Unstable relationships

If you have BPD, you may feel other people abandon you when you most need them or get too close and smother you.

When people fear abandonment, it can lead to feelings of intense anxiety and anger. They may make frantic efforts to prevent being left alone, such as:

• constantly texting or phoning a person
• suddenly calling that person in the middle of the night
• physically clinging on to that person and refusing to let go
• making threats they will harm or kill themselves if that person ever leaves them

Alternatively, you may feel others are smothering, controlling or crowding you, which also provokes intense fear and anger.

You may then respond by acting in ways to make people go away, such as emotionally withdrawing, rejecting them or using verbal abuse.

These two patterns will probably result in an unstable ‘love-hate’ relationship with certain people.

Many people with BPD seem to be stuck with a very rigid ‘black-white’ view of relationships. Either a relationship is perfect and that person is wonderful, or the relationship is doomed and that person is terrible. People with BPD seem unable or unwilling to accept any sort of ‘grey area’ in their personal life and relationships.

For many with BPD, emotional relationships (including relationships with professional carers) involve ‘go away!/please don’t go’ states of mind, which is confusing for them and their partners. Sadly, this can often lead to break-ups.

Most people with a borderline personality disorder (BPD) are treated by community mental health teams (CMHTs). The goal of the CMHT is to provide day-to-day support and treatment while trying to ensure you have as much independence as possible.

A CMHT can be made up of:

• social workers
• community mental health nurses (who have specialist training in mental health conditions)
• pharmacists
• counsellors and psychotherapists
• psychologists and psychiatrists (the psychiatrist is usually the senior clinician in the team)

Care programme approach (CPA)

If your symptoms are moderate to severe, you will probably be entered into a treatment process known as a care programme approach (CPA).

CPA is essentially a way of ensuring you receive the right treatment for your needs. There are four stages:

• assessment of your health and social needs
• care plan, created to meet your health and social needs
• appointment of a care co-ordinator (keyworker), usually a social worker or nurse and your first point of contact with other members of the CMHT
• reviews, where your treatment is regularly reviewed and any necessary changes to the care plan can be agreed

Psychotherapy

Treatment for BPD usually involves some type of psychological therapy, also known as psychotherapy. There are lots of different types of psychotherapy, but they all involve taking time to help you get a better understanding of how you think and feel.

As well as listening and discussing important issues with you, the psychotherapist can suggest ways to resolve problems and, if necessary, help you change your attitudes and behaviour. Therapy for BPD aims to help people get a better sense of control over their feelings and thoughts.

Psychotherapy for BPD should only be delivered by a trained professional. They will usually be a psychiatrist, psychologist or other trained mental health professional. Do not be afraid to ask about their experience.

The type of psychotherapy you choose may be based on a combination of personal preference and availability of specific treatments in your local area. Treatment for borderline personality disorder is recommended to last about a year or longer, depending on your needs and how you live your life.

Some of the recommended therapies are described below.

Dialectical behaviour therapy (DBT)

Dialectical behaviour therapy (DBT) is a type of therapy specifically designed to treat people with BPD.

DBT is based on the idea that two important factors contribute towards BPD:

• you are particularly emotionally vulnerable – for example, low levels of stress make you feel extremely anxious
• you grew up in an environment where your emotions were dismissed by those around you – for example, a parent may have told you that you had no right to feel sad or you were just ‘being silly’ if you complained of feelings of anxiety or stress

These two factors may cause you to fall into a vicious cycle – you experience intense and upsetting emotions, yet feel guilty and worthless for having these emotions. Because of your upbringing, you think having these emotions makes you a bad person. These thoughts then lead to further upsetting emotions.

The goal of DBT is to break this cycle by introducing two important concepts:

• validation: accepting your emotions are valid, real and acceptable
• dialectics: a school of philosophy that says most things in life are rarely ‘black or white’ and it is important to be open to ideas and opinions that contradict your own

The DBT therapist will use both concepts to try and bring about positive changes in your behaviour.

For example, the therapist could accept (validate) that feelings of intense sadness cause you to self-harm, and that behaving in such a way does not make you a terrible and worthless person.

But then the therapist would attempt to challenge the assumption that self-harming is the only way to cope with feelings of sadness.

The ultimate goal of DBT is to help you ‘break free’ of seeing the world, your relationships and your life in a very narrow, rigid way that leads you to engage in harmful and self-destructive behaviour.

DBT usually involves weekly individual sessions and group sessions and you will be given an out-of-hours contact number to call if your symptoms get worse.

DBT is based on teamwork. You will be expected to work with your therapist and the other people in your group sessions. In turn, the therapists work together as a team.

DBT has proved particularly effective in treating women with BPD who have a history of self-harming and suicidal behaviour. It has been recommended by the National Institute for Health and Care Excellence (NICE) as the first treatment for these women to try.

Read more about dialectical behaviour therapy on the MIND website.

Mentalisation-based therapy (MBT)

Another type of long-term psychotherapy that can be used to treat BPD is mentalisation-based therapy (MBT).

MBT is based on the concept that people with BPD have a poor capacity to mentalise.

Mentalisation is the ability to think about thinking. This means examining your own thoughts and beliefs, and assessing whether they are useful, realistic and based on reality.

For example, many people with BPD will have a sudden urge to self-harm and will then fulfil that urge without questioning it. They lack the ability to ‘step back’ from that urge and say to themselves: “That is not a healthy way of thinking and I am only thinking this way because I am upset.”

Another important part of mentalisation is to recognise other people have their own thoughts, emotions, beliefs, wishes and needs, and your interpretation of other people’s mental states may not necessarily be correct. In addition, you need to be aware of the potential impact your actions will have on other people’s mental states.

The goal of MBT is to improve your ability to recognise your own and others’ mental states, and learn to ‘step back’ from your thoughts about yourself and others and examine them to see if they are valid.

Initially, MBT is usually delivered in a hospital, where you would stay as an inpatient. The treatment usually consists of daily individual sessions with a therapist and group sessions with other people with BPD.

A course of MBT usually lasts around 18 months. Some hospitals and specialist centres encourage you to remain as an inpatient during this time. Other hospitals and centres may recommend you leave the hospital after a certain period of time but remain being treated as an outpatient, where you visit the hospital regularly.

Therapeutic communities (TCs)

Therapeutic communities (TCs) are structured environments where people with a range of complex psychological conditions and needs come together to interact and take part in therapy.

TCs are designed to help people with long-standing emotional problems and a history of self-harming by teaching them skills needed to interact socially with others.

Most TCs are residential, such as in large houses, where you stay for around one to four days a week.

As well as taking part in individual and group therapy, you would be expected to do other activities designed to improve your social skills and self-confidence, such as:

• household chores
• meal preparation
• games, sports and other recreational activities
• regular community meetings, where people discuss any issues that have arisen in the community

TCs are run on a democratic basis. This means each resident and staff member has a vote on how the TC should be run, including whether a person is suitable for admission to that community.

If your care team considers you may benefit from spending time in a TC, it does not automatically mean the TC will allow you to join.

Many TCs set guidelines on what is considered acceptable behaviour within the community, such as no drinking alcohol, no violence to other residents or staff, and no attempts at self-harming. Those who break these guidelines are usually told to leave the TC.

While some people with BPD have reported the time spent in a TC helped their symptoms, there is not yet enough evidence to tell whether TCs would help everyone with BPD.

Also, because of the often strict rules on behaviour, a TC would probably not be suitable for you if you were having significant difficulties controlling your behaviour.

Treating a crisis

You will probably be given several telephone numbers to use if you think you may be experiencing a crisis (when symptoms are particularly severe and you have an increased risk of self-harm).

One of these numbers is likely to be your community mental health nurse. Other numbers may include an out-of-hours number for social workers and your local crisis resolution team (CRT).

Crisis resolution teams support people with serious mental health conditions who are currently experiencing an acute and severe psychiatric crisis, which would require hospitalisation without the involvement of the team. An example of a severe psychiatric crisis would be a suicide attempt.

Often, people with BPD find that simply talking to somebody who understands their condition can help bring them out of a crisis.

In a small number of cases, you may be given a short course of medication, such as a tranquiliser, to calm your mood. This medication is usually prescribed for seven days.

If your symptoms are particularly severe and it is thought you pose a significant risk to your own health, you may be admitted to hospital, very occasionally via detention under the Mental Health Act if you are unable to make appropriate decisions about your safety. This will be for as short a time as possible, and you should be able to return home once your symptoms have improved. However, doctors do their best to avoid detaining anyone, unless it is absolutely essential.