Delusional Disorder/Narcissistic Personality Disorder

Delusional disorder, previously called paranoid disorder, is a type of serious mental illness called a "psychosis" in which a person cannot tell what is real from what is imagined.

The main feature of this disorder is the presence of delusions, which are unshakable beliefs in something untrue.

A delusion disorder is a belief that is clearly false and that indicates an abnormality in the affected person's content of thought. The false belief is not accounted for by the person's cultural or religious background or his or her level of intelligence.

The key feature of a delusion is the degree to which the person is convinced that the belief is true. A person with a delusion will hold firmly to the belief regardless of evidence to the contrary.

Delusions can be difficult to distinguish from overvalued ideas, which are unreasonable ideas that a person holds, but the affected person has at least some level of doubt as to its truthfulness. A person with a delusion is absolutely convinced that the delusion is real.

The difference between a delusion and a false belief is that people continue to believe in a delusion no matter how much clear evidence contradicts it.

Delusions are a symptom of either a medical, neurological, or mental disorder. 

Delusions may be present in any of the following mental disorders: psychotic disorders, or disorders in which the affected person has a diminished or distorted sense of reality and cannot distinguish the real from the unreal, including:
Overvalued ideas may be present in:

A delusional disorder may develop from a preexisting paranoid personality disorder. Beginning in early adulthood, people with a paranoid personality disorder have a pervasive distrust and suspiciousness of others and their motives. 

Early symptoms of delusional disorder may include:
  • Feeling exploited 
  • Being preoccupied with the loyalty or trustworthiness of friends 
  • Reading threatening meanings into benign remarks or events 
  • Bearing grudges for a long time 
  • Responding readily to perceived slight
Persecutory delusions

These are the most common type of delusions and involve the theme of being: 
  • followed
  • harassed
  • cheated
  • poisoned
  • drugged
  • conspired against
  • spied on
  • attacked
  • obstructed in the pursuit of goals 
Sometimes the delusion is isolated and fragmented (such as the false belief that co-workers are harassing), but sometimes are well-organized belief systems involving a complex set of delusions ("systematized delusions").

A person with a set of persecutory delusions may be believe, for example, that he or she is being followed by government organizations because the "persecuted" person has been falsely identified as a spy. These systems of beliefs can be so broad and complex that they can explain everything that happens to the person.

Narcissistic Personality Disorder

This involves arrogant behavior, a lack of empathy for other people, and a need for admiration-all of which must be consistently evident at work and in relationships. People who are narcissistic are frequently described as:
  • cocky
  • self-centered
  • manipulative
  • demanding 
Narcissists may concentrate on unlikely personal outcomes (e.g., fame) and may be convinced that they deserve special treatment.

Related Personality Disorders: Antisocial, Borderline, Histrionic. Narcissism is a less extreme version of Narcissistic Personality Disorder.

Narcissism involves:
  • cockiness
  • manipulativeness
  • selfishness
  • power motives
  • vanity-a love of mirrors.
You can most quickly tell narcissism by how well a person listens. Someone who is all talk with very little interest in what others say is generally a pretty high likelihood of scoring high on the narcissism checklist.

Source: Encyclopedia of Mental Disorders