A personality disorder characterized by strong feelings of distrust, suspiciousness, fear and jealousy. To be considered a personality disorder these feelings must interfere with healthy functioning of the individual, but this condition is very different from paranoid schizophrenia. Someone with Paranoid Personality Disorder might think that their co-workers hate them, or that their spouse is cheating on them, while a paranoid schizophrenic might believe that Microsoft is watching them through their computer, and that Bill Gates is stalking them.

The DSM-IV defines a disorder as paranoid personality disorder when these criteria are met:

  1. A pervasive distrust and suspiciousness of others such that their motives are interpreted as malevolent, beginning by early adulthood and present in a variety of contexts, as indicated by four (or more) of the following:
    • Suspects, without sufficient basis, that others are exploiting, harming, or deceiving him or her.
    • Is preoccupied with unjustified doubts about the loyalty or trustworthiness of friends or associates.
    • Is reluctant to confide in others because of unwarranted fear that the information will be used maliciously against him or her.
    • Reads hidden demeaning or threatening meanings into benign remarks or events.
    • Persistently bears grudges, i.e., is unforgiving of insults, injuries, or slights.
    • Perceives attacks on his or her character or reputation that are not apparent to others and is quick to react angrily or to counterattack.
    • Has recurrent suspicions, without justification, regarding fidelity of spouse or sexual partner.
  2. Does not occur exclusively during the course of schizophrenia, a mood disorder with psychotic features, or another psychotic disorder and is not due to the direct physiological effects of a general medical condition.

The DSM-IV is used in America, but many other parts of the world rely on the ICD-10 (ICD-10 Classification of Mental and Behavioural Disorders), which is put out by the World Health Organization. They use slightly different criteria: a paranoid personality disorder is indicated by three or more of the following:

  • Excessive sensitiveness to setbacks and rebuffs.
  • Tendency to bear grudges persistently, i.e. refusal to forgive insults and injuries or slights.
  • Suspiciousness and a pervasive tendency to distort experience by misconstruing the neutral or friendly actions of others as hostile or contemptuous.
  • A combative and tenacious sense of personal rights out of keeping with the actual situation.
  • Recurrent suspicions, without justification, regarding sexual fidelity of spouse or sexual partner.
  • A tendency to experience excessive self-importance, manifest in a persistent self-referential attitude.
  • A preoccupation with unsubstantiated "conspiratorial" explanations of events both immediate to the patient and in the world at large.

The ICD-10 also specifies that a paranoid personality disorder is distinct from a delusional disorder or schizophrenia, and should not be diagnosed when these are present.