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Understanding Personality Disorders


23 December 2020  |   7 min read

Personality describes the innate and enduring characteristics of an individual that shapes the way they respond to situations in life, along with their attitudes and beliefs. The adjective innate suggests that they are born with it, while enduring means that these traits could persist throughout their life, starting from childhood and continuing into adulthood.

We are all familiar with people in our lives who display certain characteristics more than others. It could be their shyness; tendency to be dramatic; quick tempered nature; sensitivity; just to name a few.

Signs and Symptoms

When these characteristics cause significant distress to oneself or conflict in their relationships, then one can be said to be suffering from a personality disorder. Personality disorders (PD) are hence defined as enduring, persistent and pervasive disorders of inner experience and behaviour that would cause distress or impairment in their social functioning.

A person with PD manifest their problems through:

  • Cognition (the way they perceive themselves or others)
  • Affect (the range, intensity and appropriateness of their emotional reactions)
  • Behaviour (social and occupational functional impairment or difficulties with impulse control)

These abnormalities should not be due to other conditions such as psychosis, affective/mood disorders, or substance misuse.

Personality disorders are more prevalent in young adults and males. The prevalence of borderline personality disorder is estimated to be 1.4%.

Diagnosis of PD is generally made after an accurate assessment of a patient’s enduring and pervasive patterns of emotional expression, interpersonal relationships, view of self and others. and is preferably done when they are not suffering from a co-morbid mental illness such as depressive illness.

Types and Characteristics

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5), a tool commonly used to diagnose mental disorders, has identified ten personality disorders that can be grouped into three broad clusters based on similarities within each cluster.

These clusters are:

Cluster A (odd/eccentric) Paranoid, Schizoid, and Schizotypal Personality Disorders

  • Paranoid
    Sensitive, suspicious, preoccupied with conspiratorial explanations, self-referential, distrust of others
  • Schizoid
    Emotionally cold, detachment, lack of interest in others, elaborate fantasy world
  • Schizotypal
    Interpersonal discomfort with peculiar ideas, appearance and behaviour (Note: ICD-10 classifies Schizotypal under schizophrenia and associated disorders)

Cluster B (emotional/dramatic) Antisocial, Borderline, Histrionic and Narcissistic Personality Disorders

  • Antisocial
    Callous lack of concern for others, irritability, aggression, inability to maintain long standing relationships, irresponsibility, disregard for the rights of others, evidence of childhood conduct issues. An extreme form of this personality disorder is described as psychopath/psychopathic. This term should be reserved for people who meet the criteria of psychopathy checklist-revised (PCL-R). They are cold, callous, self-centred, predatory, and parasitic individuals and these traits are strongly correlated with the risk of violence.
    (Note: ICD-10 uses the term “Dissocial”)
  • Emotionally unstable-impulsive
    Characterized by unpredictable moods such as an inability to control anger, and finds it hard to make clear plans for the future (Note: Identified by ICD-10, and is not listed in the DSM-5)
  • Borderline
    Unclear identity, unpredictable moods, threats or acts of self-harm, impulsivity, intense and unstable relationship (Note: ICD-10 uses the term ‘Emotionally unstable-borderline type’)
  • Histrionic
    Self-dramatization, shallow affect, egocentricity, manipulative, craving for attention
  • Narcissistic
    Need for admiration, lack of empathy, grandiosity (Note: Not listed in ICD10)

Cluster C (fearful/anxious) Obsessive-compulsive, Avoidant, and Dependent Personality Disorders

  • Avoidant
    Fear of being evaluated negatively by others, timid and insecure, self-consciousness, tension (Note: ICD10 termed it as ‘Anxious avoidant’)

  • Obsessive-compulsive
    Indecisive, pedantic, perfectionism, rigidity, preoccupation with control and orderliness (Note: ICD10 termed it as ‘Anankastic’)

  • Dependent
    Clingy and submissive, feelings of helplessness when not in relationship, need for constant care.


While there is no single convincing theory that can explain how and why some people develop PDs, contributing factors can be found in genetic, neurophysiological findings and childhood development. A genetic relationship had been identified between schizotypal personality and schizophrenia. Impulsive and violent individuals have been noted to have low levels of serotonin (5-HT), a precursor to the happy neurotransmitter-serotonin. This has led scientists to think that low levels of serotonin may be correlated with aggression. However, it is important to note that this neurobiological abnormality alone cannot explain aggressive behavior.

Harsh and inconsistent parenting is associated with conduct disorder which may later develop into antisocial PD. Severe trauma, in particular from sexual abuse, is associated with the risk of developing cluster B personality disorders, especially borderline personality disorder.


It is a commonly held opinion that PDs are resistant to psychiatric treatment and there is currently no good evidence to support or refute this argument. Patients with PD only approach a mental health professional when they are in emotional crisis or develop a mental illness.

A successful management plan is tailored to an individual’s needs and setting realistic goals that are mutually agreed between the therapist and patient. Plans should take a long-term view, recognizing that change will be observable only over a long period. Treatment goals can include: building a therapeutic relationship; limiting harm; reducing distress; and treating comorbid mental disorders (two or more diseases or conditions in the same individual at the same time). Comorbid mental disorders such as depressive illness or anxiety disorder should be identified and treated the conventional way, while specific areas such as self-harm, anger management, or improving social skills would need to be addressed separately or together.

Although personality disorders and mental illness can have similarities, they should be understood as separate from each other. In clinical practice, it is common to find an individual who would meet the criteria for a mental illness along with a personality disorder. The presentation of a mental illness is often masked, exaggerated, or distorted by the presence of comorbid personality disorder, which often makes treatment of mental illness more difficult.

There is no evidence currently to suggest that medication has any direct effect on treating personality disorders. Bearing this in mind, antipsychotic medication may be of some benefit for people with cluster A and cluster B personality disorders and antidepressants can be beneficial in impulsive, depressed and self-harming patients as well as patients with cluster C personality disorders. Mood stabilisers can reduce mood instability or impulsivity commonly seen in borderline PD.

With regards to psychotherapeutic approaches, Dialectical Behavioural Therapy (DBT), Schema-focussed Cognitive Behavioural Therapy, and Psychodynamic therapy has been found to be effective in borderline personality disorders. Psychotherapy could also be supportive in the management of cluster A personality disorders in particular.


The contributor is a Senior Consultant from the Department of Psychological Medicine at Khoo Teck Puat Hospital (KTPH).