Home What Is Personality Disorder? Causes of personality disorder

Causes of personality disorder

There is no widespread agreement about what causes personality disorder. There are a number of different theories and debate and research continues.  These different theories broadly reflect different ways of understanding human distress. Some people do not think it is helpful to talk about causes because this is based on the controversial notion that PD exists as a condition or disease.

Many others believe that rather than one cause leading to an individual developing PD, there are a range of factors which make it more likely and if several of these come together then a person may well develop PD. Rather than talk about causes, it might be more helpful to ask: what factors contribute to an individual becoming distressed and developing the difficulties often described as PD?

Family environment

The section on neurobiology shows how some people emphasise the impact of neglect and abuse on the development of the brain and the way in which it functions. However, others emphasise how such experiences can affect the ways in which people develop attachments and social relationships with others.

Experiences of neglect and abuse are only some of the difficult family experiences that are recognised as factors contributing to the development of PD. People given a diagnosis often experience under involvement from those in a key care giving role, and have distant and difficult relationships with both parents. This is supported by evidence showing that the way parents/caregivers respond to a child’s experience of abuse is critical in shaping the impact it has on the child, even more so than the abuse itself. Recent guidelines conclude that family environment is key in the development of difficulties often associated with PD (BPD Full Nice Guidelines p.24).

For example, a family environment where a person’s understanding and experience of their own mind and feelings are undermined causes distress and also hinders the development of social skills  key to mentalisation. Mentalisation is the ability to make sense of our own and other people’s actions by thinking through what is going on in our own and other people’s minds. It may be understood as an ability to empathise or put ourselves in others’ shoes. To give a very simple example: to understand someone else’s reaction to what we have done, we need to think about their point of view, what they are motivated by, etc.

Attachment theories

According to attachment theories, it is through relationships with caregivers (often mother or father) that individuals learn how to relate to others and develop a sense of self and others. The attachment that one has with a caregiver may shape the way in which an individual understands and interacts with people as they grow up. Consistent and sensitive caregiving is likely to lead to secure attachment. Secure attachment enables an individual to develop flexible and confident relationships with themselves and others. However, a child may develop insecure attachment if they have been threatened with harm or abandonment, or been ignored, or had their needs and feelings dismissed by caregivers, or received inconsistent care giving. Someone may also develop insecure attachment as a result of loss, separation, or trauma at later stages in life. Recent guidelines state that insecure attachment is an important factor in the development of personality disorder, since a large number of people given this diagnosis have insecure attachment. There is evidence that suggests that the effects of insecure attachment may be linked to difficulties in developing the ability to ‘mentalise’ (BPD Nice Guidelines p.25).

(From Personality Disorders 2007 P.M.G. Emmelkamp & J.H. Kamphuis)


Neurotransmitters are an essential part of how our brain cells work. They are the chemicals which act as messengers between different parts of the brain. They are thought to be involved in regulating our mood, emotions and impulses. As difficulties regulating mood and impulses are common among people given a diagnosis of personality disorder, there has been some research into the role and effect of neurotransmitters.

Some of the neurotransmitters which are thought to be linked to PD are serotonin, norepinephrine and dopamine, methoxyhydroxyphenylglycol (a metabolite of noradrenaline), acetylcholine, vasopressin , cholesterol and fatty acids, along with the hypothalamic-pituitary adrenal axis (Full BPD Nice Guidelines p.23)


A large number of people given a diagnosis of personality disorder have experienced trauma in their childhood, such as sexual, physical, and/or emotional abuse. Some argue that this can have a dramatic effect on the development and functioning of particular areas of the brain, especially those that deal with emotions, self control, attention and social functioning. There is some evidence that levels of activity in parts of the brain linked to these areas, in people given a diagnosis of borderline personality disorder, may differ from what is typically observed. It is thought that functional and structural changes in the brain caused by early experiences bring about these differences which lead to an individual being given a diagnosis of BPD.

Social factors

There has been little research into the way broader social conditions and changes within society may influence the development of personality disorder. Social psychiatry, which looks at the way that social systems and circumstances impact on mental health, has so far focussed more on other mental health diagnoses. Social class, gender, culture, society type, and social change are all social factors which may influence mental health. For example, Millon argues that in contemporary Western society social norms are breaking down and there is increasingly fast social change. He argues this is reducing social structures and the limits placed on the individual. As a result, he believes, this increases the risk of developing of personality disorder (Paris, 1996). It is argued that if certain family environments and personal experiences are factors in the development of PD, social changes which increase these factors will also have an impact.

Additional social factors include the type of society and culture in which diagnosis takes place. In some social structures, behaviours will be acceptable, even valued; in another, the same behaviour will be considered unacceptable and an indicator of mental health problems. The threshold of what is tolerated and acceptable and what is considered unacceptable will be different in different cultures. For example, in modern societies individual ambition is valued, and people who become accomplished are considered successful; in this way, narcissistic traits are rewarded. However, in ‘traditional’ societies, where group cohesion is valued above individual achievement, narcissistic traits will be much less acceptable and the threshold for what is considered unhealthy or abnormal narcissism is likely to be lower than in ‘modern’ societies.

(from Social Factors in the Personality Disorders, Joel Paris, 1996)

Those that argue that the concept of personality disorder is an unhelpful and dangerous way to understand individual distress and behaviour may also cite social factors as key to the diagnosis of PD. Bringing together information about the high numbers of people given a PD diagnosis who have experienced trauma, abuse, and extremely difficult family environments with the argument against PD as a medical condition, it could be argued that such traumatic experiences cause considerable emotional distress which is expressed in ways that come to be interpreted and labeled as personality disorder.

Biopsychosocial model

This model suggests that biological, psychological and social factors all come together to explain the development of personality disorder. It is argued that, on their own, none of these factors would lead to personality disorder, but all together they explain how an individual might be given the diagnosis.

Biology + psychology + social factors = personality disorder.

  1. Biology. It is argued that genetic factors make an individual more vulnerable to developing PD. Genes are also thought to determine personality traits and these become exaggerated or amplified in a personality disorder. In this way, genes are thought to determine which type of personality disorder an individual develops. These are the biological factors which must be present for the other factors to have an influence.
  2. Psychological factors. This model draws on the arguments outlined above about the role of traumatic experiences in childhood and difficult, dysfunctional family environments. It is argued that such experiences amplify the personality traits that biology provides.
  3. Social factors. This model is unlike other more medically based models because it argues that the broader social setting or society in which people live is crucial in the development of personality disorder. It is argued that big social issues such as fragile social networks and the loss of widely agreed values and social roles affect individuals. They argue that these issues affect some individuals more than others and will fuel the development of PD only among people who have a biological vulnerability and have experienced abuse, mistreatment and/or family dysfunction (i.e. psychological factors).

(from Social Factors in the Personality Disorders, Joel Paris, 1996)


At one stage, it was thought that people may carry genes which make them more likely to develop PD (a genetic predisposition to personality disorder). It was suggested that a combination of genes and traumatic experiences such as poor nurturing or abuse might lead to the development of PD.  However, research to date has not demonstrated a clear role for genetics and, in fact, more recent studies suggest genetics “play a less important role than previously thought” (BPD NICE full guideline, p.23). Despite research, no specific genes linked to PD have been found.


This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish.continue read more