The Genetic and Environmental Factors Contributing to Borderline Personality Disorder

The Genetic and Environmental Factors Contributing to Borderline Personality Disorder

Borderline Personality Disorder (BPD) is a mental health disorder that affects the way a person thinks and feels about themselves, as well as affecting their emotions and relationships with other people, causing problems functioning in everyday life. People with Borderline Personality Disorder have self-image issues, difficulty in managing their emotions and their behaviour, and a pattern of unstable relationships. 

Although Borderline Personality Disorder (BPD) is the most commonly recognised personality disorder, it is also perhaps the most complex, as both genetic and environmental factors have been found to influence the development of the condition. In the UK, around 1 in 100 people live with BPD, and it can affect people from many different backgrounds, but is three times more common in women than in men. BPD usually first occurs in the teenage years and early 20s; however, onset may occur in some adults after the age of 30, and behavioural precursors are evident in some pre-teen children. The condition appears to be worse in young adulthood and may gradually get better with age.

The term Borderline Personality Disorder is often used interchangeably with the term Emotionally Unstable Personality Disorder (EUPD), as both refer to the same underlying condition. However, EUPD emphasises the emotional instability aspect of the disorder. EUPD is a term used primarily in the United Kingdom and Europe, whereas BPD is more commonly used in the United States and other parts of the world. The Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published by the American Psychiatric Association, uses the term Borderline Personality Disorder to describe this condition. DSM-5 is used by healthcare professionals as the authoritative guide to the diagnosis of mental disorders.

What is Borderline Personality Disorder (BPD)?

According to DSM-5, Borderline Personality Disorder is “a pattern of instability in personal relationships, intense emotions, poor self-image and impulsivity. A person with borderline personality disorder may go to great lengths to avoid being abandoned, have repeated suicide attempts, display inappropriate intense anger, or have ongoing feelings of emptiness.” This definition is concurred with the UK by the National Institute for Health and Clinical Excellence (NICE), the independent public body that provides national guidance and advice to improve health and social care in England. They also make reference to the International Classification of Mental and Behavioural Disorders 10th Revision (ICD-10 F60.3) who use the term Emotionally Unstable Personality Disorder in its definition. Both definitions share the general theme of impulsiveness and lack of self-control.

NICE notes that there is some divergence between ICD-10 and DSM-5 as to whether Borderline / Emotionally Unstable Personality Disorder can be diagnosed in those younger than 18 years, and this may lead to uncertainties about the usage of the diagnosis in young people. In ICD-10 the disorder comes within the overall grouping of disorders of adult personality and behaviour, but DSM-5 specifies that BPD can be diagnosed in those younger than 18 if the features of the disorder have been present for at least one year.

A key feature of both EUPD and BPD is emotional dysregulation, which refers to the inability to manage and control emotional responses effectively. However, experiences of living with Borderline Personality Disorder (BPD) will be unique to each person. People experiencing or being diagnosed with BPD will, according to the NHS, and some notable mental health charities, have difficulties with:

• Being impulsive, meaning that the person likes to do things on the spur of the moment or acting in ways that could be damaging, for example, spending money, substance abuse, gambling, reckless driving, unsafe sex, binge eating, or sabotaging success by suddenly quitting a good job or ending a positive relationship.
• Rapid changes in self-identity and self-image that include shifting goals and values, and seeing themselves as bad or as if they don’t exist at all.
• Controlling their emotions which may include inappropriate, intense anger, such as frequently losing their temper, being sarcastic or bitter, or having physical fights.
• Suicidal thoughts, threats or behaviours, attempts to take their own life or self-harming, often in response to the fear of separation or rejection.
• Dissociation – this could be a feeling of being disconnected from their own body, or feeling disconnected from the world around them.
• Identity confusion – they might not have a sense of who they are.
• Feeling paranoid or depressed – this may include periods of stress-related paranoia and loss of contact with reality, lasting from a few minutes to a few hours.
• Hearing voices, noises, or seeing, smelling, tasting or feeling things that don’t exist outside their mind.
• Intense but unstable relationships, such as idealising someone one moment and then suddenly believing the person doesn’t care enough or is cruel and treating them badly.
• Overwhelming mood swings and intense emotions – quick swings between periods of confidence to despair, with fear of being abandoned and rejected.
• Long-lasting feelings of emptiness and feeling abandoned, even going to extreme measures to avoid real or imagined separation or rejection.
• Disturbed patterns of thinking – these can be cognitive distortions or perceptual distortions.

Not everyone will experience all of these symptoms and people can experience these symptoms differently as they can range between mild to severe. Anyone who is aware that they have any of the signs or symptoms above should talk to their doctor or to a mental health provider.

People with BPD face challenges in their everyday life. These include but are not limited to:

• Since people with BPD view themselves and others in a different way, they often have difficulty establishing and maintaining trusting relationships with others. Their wild mood swings, angry outbursts, chronic abandonment fears, and impulsive and irrational behaviours can leave loved ones feeling helpless, abused and off balance. Due to a lack of understanding, many stereotypes and stigmas surround personality disorders, so for people who are not willing and patient enough to understand the disorder, any friendship forming could be short-lived.
• Undiagnosed and untreated BPD cases can increase a person’s risk for substance abuse and death by suicide because they cannot control their thoughts and actions at that moment.
• Gaining and maintaining employment also poses a challenge for those with BPD. A review study has shown that roughly 50% of individuals with BPD manage to find employment; however, only 20% of those in employment are capable of maintaining employment and becoming financially independent of social benefits.

The genetic component of BPD

There are many theories as to what causes and influences the occurrence of Borderline Personality Disorder; however, no one factor has been recognised as the ‘true’ cause of BPD. Researchers have taken many factors into consideration when exploring its causes, and BPD appears to result from a combination of genetic, biological and/or environmental factors.

Various research studies indicate that BPD may be genetic. A person may be more vulnerable to BPD if they have a parent, sibling or a close family member who also lives with this condition. According to a 2021 study, BPD has a heritability rate of 46%. The study also suggests the condition may be more likely to affect identical twins than fraternal twins. However, there is no evidence of a particular gene being responsible for BPD. Given the complex nature of BPD, it is likely that multiple genetic factors contribute to the disorder, each having a small effect on an overall risk.

Family studies have been a useful tool for understanding the genetic factors in BPD. These studies typically examine the prevalence of BPD among the relatives of individuals with the disorder compared to the general population. If BPD is more common among the relatives of affected individuals, it suggests that genetic factors may contribute to the disorder. Family studies have provided further evidence for a genetic component in BPD, showing that first-degree relatives of individuals with BPD have a significantly increased risk of developing the disorder.

Research from the NIHR Oxford Health Biomedical Research Centre (BRC) shows our genes influence the way our brains are ‘wired up’ in childhood making us more vulnerable to a range of mental health conditions in later life. Their list of mental health conditions includes schizophrenia, autism, depression, anxiety and bipolar disorder. They went on to show that, as well as predisposing people to a number of mental health disorders, the same vulnerability network is associated with behaviours that make people more vulnerable to mental health problems, such as marijuana and alcohol misuse and impulsive behaviour; these are behaviours that are closely associated with BPD.

Another study stated that BPD often co-occurs with other psychiatric disorders, such as anxiety disorders (84.8% of individuals), mood disorders (82.7%), and substance use disorders (78.2%). They also found that psychiatric comorbidities like depressive disorders, bipolar disorder, anxiety disorders, and sleep disorders are more prevalent in female BPD cases, whereas substance use disorder and mental retardation are more prevalent in male BPD cases. 

Hormonal and chemical imbalances found in some BPD subjects may explain some of the BPD symptoms. Investigations have shown BPD patients to have imbalances of several chemicals including serotonin, dopamine, norepinephrine (noradrenaline) and acetylcholine monoamine oxidase.

It has been suggested that BPD can be attributed to brain damage caused to a baby in the womb or during or after birth. There is also some evidence of organic lesions in the brains of people with BPD. Brain imaging has reportedly seen abnormalities in the brains of BPD sufferers. Researchers have used MRI 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. Whether these problems are caused by genetics or by environmental factors either pre-birth, in early childhood or early adolescence, or whether they arise from the interplay of biological predispositions and environmental influences, is still being investigated by researchers. 

The research findings to date and any ongoing research on the genetic and biological components of BPD could enhance future diagnosis and therapies for BPD.

Environmental influences on BPD

People with BPD come from many different backgrounds, but one common factor found in people with BPD is a history of traumatic events during childhood and adolescence, events such as, for example:

• Physical abuse
• Sexual abuse
• Psychological abuse
• Emotional abuse
• Neglect
• Dysfunctional family relationships
• Domestic violence
• Community violence
• Substance use disorder (personal or familial)
• Early parental loss or separation
• Other traumatic loss or separation
• Refugee and war experiences
• Trafficking
• Discrimination, prejudice and racism
• Natural disasters

Traumatic experiences in childhood and adolescence can initiate strong emotions and physical reactions that can persist long after the event. Children may feel terror, helplessness or fear, as well as experiencing physiological reactions. More than one in three children and young people are exposed to at least one potentially traumatic event by age 18 according to the UK Trauma Council (UKTC).

Several studies have reported that being bullied during the period of primary school is a strong predictor of early BPD onset approximately up to 2–6 years after the bullying has occurred. Feelings of loneliness, anger and loss of trust that are due to victimisation by peers were frequently described by victims of bullying who had developed BPD at a young age and were also observed during experimental social trust games.

People with Borderline Personality Disorder are 13 times more likely to report childhood trauma than people without any mental health problems, according to University of Manchester research. The analysis of data from 42 international studies of over 5,000 people showed that 71.1% of people who were diagnosed with the serious health condition reported at least one traumatic childhood experience. The study was carried out by researchers at the University of Manchester in collaboration with Greater Manchester Mental Health NHS Foundation Trust and the Spectrum Centre for Mental Health Research, Lancaster University. 

It is also thought that between 25% and 60% of people with BPD also have Post-Traumatic Stress Disorder (PTSD). PTSD is a psychological response to a traumatic event, which might include traumatic events experienced in childhood. It is not uncommon for the symptoms of one to be mistaken for the other because of the overlap in symptoms and shared association with trauma, or for one condition to be missed when someone has both. Although both conditions can lead to problems maintaining personal relationships, people with BPD tend to fear abandonment, whereas people with PTSD may avoid intimacy or relationships altogether because of feeling somehow unlovable or undeserving because of the abuse they endured.

The interaction between genetics and environment

The term nature versus nature was first coined by anthropologist Francis Galton in the late 19th century. Nature versus nurture is an age-old debate about whether genetics (nature) plays a bigger role in determining a person’s characteristics than lived experience and environmental factors (nurture). However, researchers into BPD have highlighted the possibility that genetics (nature) may impact a person’s reaction to environmental factors (nurture).

It is important to note that a genetic predisposition or biological factors do not guarantee the development of BPD, although it may increase an individual’s vulnerability to the disorder. Both genetic and environmental theories are held to be credible, particularly the developmental/environmental theories, i.e. childhood experiences, and it is likely that a combination of these increases the risks of developing BPD. There is scientific literature that links the onset of BPD to the combination between genetic and environmental factors, in particular between biological vulnerabilities and the exposure to traumatic experiences during childhood.

Although genetic predispositions may play a role, environmental factors are equally critical in determining the manifestation of the disorder. It has been suggested by some mental health academics that whilst genetic predispositions can increase a person’s vulnerability to BPD, it is often the presence of environmental stressors that trigger the onset of the disorder. This dynamic interaction between genetics and environment highlights the importance of considering both factors when examining the origins of BPD. The evidence for this theory is sparse, so there is also a need to explore further the role for genetic factors mediating the response to environmental factors and life events. Understanding these gene and environmental interactions is crucial for developing targeted prevention and intervention strategies for those at risk of developing the disorder.

Risk assessment and prevention

As we have seen above, several factors related to personality development can increase the risk of developing BPD.

Childhood trauma is one of the most well-established environmental risk factors for BPD. Experiences of physical, sexual or emotional abuse and neglect have been consistently linked to an increased risk of developing the disorder.

Although BPD can run in families, it is not just due to genetic factors, but may also be because of learned behaviours and coping mechanisms that are passed down through generations. Children of parents with BPD may be more likely to develop the disorder due to genetic vulnerability and the influence of family dynamics that have not adjusted adequately or appropriately to their environment or situation, and use inappropriate coping strategies such as drug or alcohol abuse or domestic abuse to deal with them. 

Family dynamics play a crucial role in shaping an individual’s emotional and psychological development, particularly in BPD, and the family environment can contribute to developing BPD symptoms in multiple ways. An unstable, chaotic or emotionally unsupportive family environment can exacerbate the emotional dysregulation and interpersonal difficulties often experienced by individuals with BPD. Recognising and addressing these patterns can be essential to breaking the cycle of BPD in families.

Any exceptional temperamental characteristics and personality traits in childhood and adolescence should be investigated to recognise predictors of BPD at an early phase. There is a general consensus amongst mental health professionals that temperamental vulnerabilities combined with childhood adversities play a role in the development of BPD traits. Researchers have identified several temperamental traits in children or adolescents that could predispose to BPD, including:

• Affective instability
• Negative affectivity
• Negative emotionality
• Inappropriate anger
• Poor emotional control
• Impulsivity
• Aggression

Whilst avoiding childhood trauma may seem an obvious way to prevent BPD from developing later in adolescence or young adulthood, this is often not possible. However, providing support and an emotionally stable environment to a child or young person who has experienced traumas can help to prevent the onset of BPD, as can validating their feelings about a traumatic situation rather than ignoring them. Emotional validation is all about recognising, understanding and expressing acceptance of another person’s feelings. By doing this, you are creating space for that person to experience these emotions and process things without fear of judgement or rejection. Those suffering from BPD also have intense fears of being abandoned and rejected, and it is possible that providing nurturing support and positive reinforcement can help deter these feelings. 

As Borderline Personality Disorder is still being researched, there is still much to learn to further understand the disorder and whether or not it can realistically be prevented; however, BPD is successfully manageable and treatable.

Treatment and management

Anyone concerned that they or someone that they know has Borderline Personality Disorder (BPD) should in the first instance contact the GP. The GP may ask about the symptoms and how they are affecting the quality of life. The GP will want to make sure that there is no immediate risk to the person’s health and wellbeing, and will want to rule out other mental health conditions, such as depression. If the GP suspects BPD, they will probably make a referral to the local community mental health team (CMHT) for a more in-depth assessment and to confirm a diagnosis.

Once a diagnosis of BPD has been confirmed, it is recommended that a person tell their close family, friends and people that they trust about the diagnosis, as many of the symptoms of BPD affect relationships with people who are close to the person with the disorder. Involving these people in any treatment may make them more aware of the condition and make the treatment more effective.

Treatments for BPD may involve individual or group psychotherapy, and the type of psychotherapy a person may choose may be based on a combination of personal preference and the availability of specific treatments in their local area. These treatments may include:

• Dialectical behaviour therapy (DBT) – this is a type of therapy specifically designed to treat people with BPD. It is a talking therapy and a modified version of cognitive behavioural therapy (CBT). It generally involves more group therapy work than traditional CBT. The main goals of DBT include teaching people how to live in the present, develop positive ways to deal with stress, self-regulate their emotions, and improve their relationships. DBT has proved particularly effective in treating women with BPD who have a history of self-harming and suicidal behaviour and has been recommended by the National Institute for Health and Care Excellence (NICE) as the first treatment for these women to try.
• Mentalisation-based therapy (MBT) – this is another type of long-term psychotherapy that can be used to treat BPD. 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 the person examining their own thoughts and beliefs, and assessing whether they are useful, realistic and based on reality. This enables people with, for example, a sudden urge to self-harm to step back and examine the urge rather than acting upon it without question.
• Therapeutic communities (TCs) – these 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.
• Arts or creative therapies – these may be offered individually or with a group as part of a treatment programme for people with BPD. They aim to help people who are finding it hard to express their thoughts and feelings verbally. The therapy focuses on creating something as a way of expressing their feelings.

Whilst no medicine is currently licensed to treat BPD, there is evidence that it may be helpful for certain problems, or another associated mental health condition in some people, such as depression, anxiety disorder or bipolar disorder. Mood stabilisers or antipsychotics are sometimes prescribed to help mood swings, alleviate psychotic symptoms or reduce impulsive behaviour.

For anyone with BPD who is thinking about suicide or acting on suicidal thoughts, wanting to self-harm, or doing something that could put themselves or other people at risk, any of these may point to having a mental health crisis and you should immediately contact your local NHS urgent mental health helpline. They are available 24 hours a day 7 days a week. They can assess what is happening and get you to the most appropriate help and support. 

People who live with Borderline Personality Disorder may drink or use drugs in a way that is harmful. Talk to your GP or someone in your mental health team to see if they can help with alcohol or substance abuse. 

Someone experiencing BPD can try to help their symptoms by looking after themselves. Self-care is how someone takes care of things such as their diet, sleep, exercise, daily routine, relationships and how they are feeling. Breathing exercises such as mindfulness, that is breathing deeply, remaining present in the moment, and noticing small details of your surroundings – sights, sounds, smells and sensations – can benefit wellbeing. Mindfulness means being present and grounded in the current moment rather than fixating on the past or future. 

Although Borderline Personality Disorder (BPD) is the most common type of personality disorder, it is also one of the most complex with a myriad of symptoms that can lead to it being misdiagnosed, or mistaken for other mental health disorders such as:

• Depression
• Anxiety
• Post-traumatic stress disorder (PTSD)
• Substance misuse disorders
• Eating disorders
• Bipolar disorder

There are many factors that influence the accuracy (or inaccuracy) of a BPD diagnosis, one of which may include a lack of understanding of, and agreement about, the root causes of BPD, whether these are genetic factors, environmental factors or a combination of both factors. Another factor that may influence diagnosis may be medical professionals becoming focused on particular symptoms rather than the spectrum of symptoms and the diagnostic criteria for BPD specified in DSM-5 or the International Classification of Diseases (ICD-11), produced by the World Health Organization (WHO).

Other diagnosis difficulties can include the fact that medical professionals can’t use diagnostics such as blood tests or brain scans to help diagnose people with BPD. Also, many people with BPD lack insight into their disruptive behaviour and thought patterns so may not either seek help or be able to provide their GP or mental health professional with an accurate description of their symptoms, so it is not uncommon to be offered an alternative diagnosis and the incorrect care and treatment for BPD. If you are not happy with your care or treatment or feel that you may have been misdiagnosed, you can ask for a second opinion or contact the NHS Patient Advice and Liaison Service (PALS).

Final thoughts

If you are living with BPD or are supporting someone who is living with the condition, there are a number of advice and support groups that you can contact. These include:

BPD World – they provide information and support to people affected by personality disorders and have an online support forum.

Borderline Support UK – they provide a community forum supporting anyone affected by Borderline Personality Disorder.

Self-Injury Support – offers a helpline service for women of any age who self-harm, as well as text and email services for women under 24 years. Telephone 0808 800 8088 Monday – Thursday 7-10pm. 

Turning Point – they work with people who have problems with drug and alcohol use, mental health and learning disabilities. Telephone: 020 7481 7600

Rethink Mental Illness – they provide advice about a wide range of mental health conditions, treatment and support options. Advice and Information Service: 0300 5000 927 (9:30am – 1pm Monday to Friday)