What causes personality disorders?

Personality disorders are a group of mental health conditions that affect thoughts, behaviors, and relationships with others. People with personality disorders commonly experience emotional dysregulation, which can cause difficulties in various aspects of daily life and functioning. Personality disorders are often caused by a combination of genetic and environmental factors.

What are personality disorders?

Personality disorders impact thoughts, behaviors, emotions, and relationships. They often cause people to struggle with forming and maintaining interpersonal relationships, as well as regulating and expressing emotions. These challenges can lead to intense and overwhelming feelings, emotional outbursts, and distrust and/or instability in relationships ^[1].

Personality disorders tend to emerge and develop during childhood and adolescence, but aren’t often diagnosed until early adulthood. Symptoms can sometimes subside with age, although for some people, they may worsen ^[2].

Ten personality disorders are outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which are grouped into 3 clusters ^[3].

Cluster A

Cluster A personality disorders are characterized by odd or eccentric behaviors and thoughts. Cluster A types and their symptoms include:

• Paranoid personality disorder: Being suspicious of others, distrusting of the fidelity of romantic partners, unforgiving
• Schizoid personality disorder: Difficulties forming and managing relationships, social isolation, lack of emotional expression
• Schizotypal personality disorder: Similar symptoms to schizophrenia but less severe, such as bizarre thoughts and behaviors, magical or abnormal beliefs and experiences

Cluster B

Dramatic or volatile behaviors characterize cluster B personality disorders. Cluster B types and their symptoms include:

• Antisocial personality disorder: Being aggressive, violent, manipulative, engaging in criminal behavior, lacking in empathy
• Borderline personality disorder: Emotionally lability, intense mood swings and outbursts, unstable relationships, self-harming behaviors
• Histrionic personality disorder: Being dramatic, attention-seeking, sexually promiscuous, shallow moods, inability to form meaningful relationships
• Narcissistic personality disorder: Grandiose and egocentric, lacking in empathy, exaggerating own achievements, low tolerance to criticism

Cluster C

Anxious and fearful thoughts and behaviors characterize Cluster C personality disorders. Cluster C types and their symptoms include:

• Avoidant personality disorder: Low self-esteem and self-worth, social anxiety around others, social withdrawal
• Dependent personality disorder: Requiring emotional validation from others, being submissive and compliant, an inability to make decisions or take responsibility
• Obsessive-compulsive personality disorder: Perfectionism, inflexible and rigid thinking, anxiety about or intolerance for mistakes, controlling

Causes of personality disorders

Personality disorders are often caused by a complex combination of genetic and environmental risk factors. These factors may vary depending on the type of personality disorder.

Genetics

Currently, it is not clear exactly how genetics impact the development of personality disorders, although it is thought that some people have a genetic predisposition ^[4].

Recent research suggests that there are specific gene abnormalities associated with personality disorders that may be inherited. These genes are believed to impact the activity and production of certain neurotransmitters that influence emotion regulation ^[4][5].

Furthermore, it is also possible that people have specific personality traits that increase the likelihood of developing personality disorders. These traits may be inherited from parents, such as neuroticism, aggression, or a propensity to worry ^[6].

Childhood trauma

A great deal of research indicates a link between childhood exposure to trauma and the development of personality disorders. Much of this research focuses on borderline personality disorder, in which there is a high prevalence of childhood sexual abuse, particularly amongst those with severe symptoms ^[7][8].

Similarly, childhood sexual and physical abuse are found to be risk factors for antisocial and paranoid personality disorders. Childhood exposure to emotional abuse and neglect is a shared risk factor for all types of personality disorders. Typically, experiences of very severe childhood abuse correlate with the most severe symptoms in later life ^[8][9].

Childhood experiences greatly influence personality development and the understanding of social relationships. Exposure to trauma and abuse at a young age can lead to the development of maladaptive and unhealthy coping strategies, low self-worth, and interpersonal difficulties. As such, these experiences significantly impact the likelihood of developing a personality disorder ^[4].

However, it is important to note that not everyone who experiences childhood trauma and abuse will go on to develop a personality disorder, and not everyone with a personality disorder has experienced childhood trauma ^[1][6].

Environment

Various environmental factors can also influence the development of personality disorders. For example, the risk may be increased by growing up in a home with unstable or chaotic family dynamics or a lack of caregiver or parent support ^[1][10].

The risk may also be affected by other factors such as socioeconomic status, level of education, and cultural factors ^[5].

Gender

Although not always the case, gender differences are common in the development of personality disorders. For example, males are more likely to have antisocial personality disorder, while females are more likely to have borderline or histrionic personality disorders ^[5].

Can personality disorders be prevented?

Personality disorders often emerge in childhood, with certain behaviors or traits evident at a young age. However, diagnoses are not given until at least 18 years old. Some argue that a diagnosis at or after age 18, prevents the timely commencement of crucial preventative treatment. If signs are recognized early and interventions are implemented, there is a potential to prevent the development of severe symptoms ^[2].

As several factors commonly cause personality disorders. It is possible to alter or mitigate the risk of one or more of these factors, thereby slowing or preventing symptom development.

For example, many individuals with personality disorders experience childhood adversity. These experiences can lead to maladaptive thoughts and behaviors that underpin the symptoms of personality disorders. By implementing early intervention, these individuals can be provided with support that may enable them to learn positive coping strategies to process and manage distress ^[2][10].

Studies show that forming trusting therapeutic relationships is vital in treating personality disorders. Thus, it is likely helpful to give at-risk children and adolescents the opportunity to create these relationships prior to the development of a personality disorder. This may help to reduce the impact of their experiences and prevent the progression of severe symptoms ^[2][6][10].