What Is a Personality Disorder? Definition, Causes, Effects

Personality disorder definition and causes, plus learn how a personality disorder can adversely affect daily life.

Since the beginning of time, there have been people around who suffer from one type of personality disorder or another (famous people with personality disorders). Philosophers and scientists have studied the various aspects of human personality as far back as the fourth century B.C.

But it was French psychiatrist, Philippe Pinel, who first clarified and defined the concept of a personality disorder in 1801. Pinel characterized the condition as one with frequent outbursts of rage and violence, but without signs of psychotic illness (i.e. illnesses where people experience delusions and hallucinations). Over the years, a number of psychiatrists and psychologists have broadened the concept to reach the currently accepted personality disorder definition.

What Is a Personality Disorder?

What is a personality disorder and how would you know if you or someone you loved suffered from the condition? The term, personality disorder, actually refers to an entire group of mental illnesses that involve unhealthy and inflexible long-term patterns of thoughts and behaviors. The DSM-V personality disorders section (APA, 2013) lists 10 specific types:

  1. Antisocial personality disorder
  2. Avoidant personality disorder
  3. Borderline personality disorder
  4. Dependent personality disorder
  5. Histrionic personality disorder
  6. Obsessive-compulsive personality disorder
  7. Narcissistic personality disorder
  8. Paranoid personality disorder
  9. Schizoid personality disorder
  10. Schizotypal personality disorder

Here's an interesting thought: Can you imagine having one of these personality disorders and not realizing your behavior and thought patterns are "off"? Frequently, this is the case with people suffering from a personality disorder, as they often do not know that they have problematic thinking or behaviors. They think their thoughts are normal and many people suffering from personality disorders blame their problems on others.

Personality Disorder Definition – Four Core Features

When coming up with a standard personality disorder definition, the American Psychiatry Association (APA) found four core features present in all types of personality disorders. The four common features listed in the DSM-5 personality disorders section (APA, 2013) are:

  1. Distorted thought patterns
  2. Problematic emotional responses
  3. Poor impulse control
  4. Interpersonal (relational) difficulties

A person with a personality disorder will show a long-term pattern of behaviors and internal experience in two of these areas. For instance, if you know someone with an enduring pattern of inappropriate emotional responses to life events and issues who also has problems maintaining healthy relationships, that individual may have one (or more) of the DSM personality disorders.

Causes of Personality Disorders

Experts don't have a clear understanding of the exact causes of personality disorders, but theorize that two related factors, which contribute to personality development, may also contribute to the development of a disorder:

  • Genetic make-up
  • Environmental experience

Your genetics and early experience in life work together in complex ways to form your unique personality. Certain negative experiences in childhood can influence a genetic vulnerability that's already present, causing a personality disorder to develop. In other words, experts know that both genetics and nurture work together in the development of human personalities. They also know that genetics alone; nor, nurture (i.e. upbringing, childhoods experiences) alone can cause a personality disorder to develop. Scientists have only recently begun intensive study of personality disorders and the more common disorders, such as borderline personality disorder, have received the most attention.

Effects and Consequences of a Personality Disorder

Regardless of whether a person's personality disorder symptoms are mild or severe, having an untreated personality disorder can lead to severe consequences. Personality disorders can adversely affect an individual in a number of ways, putting them at a higher risk for:

  • Responding to typical life stresses in inappropriate and unproductive ways.
  • Refusing to take doctor-prescribed medications on schedule and as directed.
  • Engaging in self-destructive and risky behavior that can lead to illness or injury (i.e. substance abuse, sexual promiscuity, poor sleep and nutrition).
  • Issues raising children because they may use inconsistent, overemotional, abusive, detached, or irresponsible parenting styles. This can increase the risk of physical and mental illness in their children.
  • Poor relationships with healthcare providers and others with potential to help them. This is especially true for providers who don't detect the presence of a personality disorder. People with these disorders often have stormy relationships because they do not take responsibility for their actions and are distrustful, overly demanding and needy.

Personality disorders affect men and women with equal frequency; although, certain types are slightly more common in one gender over the other. Continue on for more information about personality disorders.

article references

APA Reference
Gluck, S. (2021, December 17). What Is a Personality Disorder? Definition, Causes, Effects, HealthyPlace. Retrieved on 2024, July 20 from

Last Updated: January 27, 2022

Medically reviewed by Harry Croft, MD

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