What Is Paranoia? - Definition, Symptoms & Causes

Instructor: Yolanda Williams

Yolanda has taught college Psychology and Ethics, and has a doctorate of philosophy in counselor education and supervision.

Did you know that paranoia is a symptom of several mental disorders, including schizophrenia and delusional disorder? Learn more about paranoia, its symptoms, and causes. Then, you can test your knowledge with a quiz.


Paranoia is defined as persistent irrational thoughts, feelings of persecution, or an over-inflated sense of self-importance. But what does this really mean?

We all have had suspicious or irrational thoughts at one time or another. Maybe you have watched a scary movie and felt jumpy afterward, or maybe you've had a feeling that someone was watching you even though no one was there. Later, you probably realized that your fears were unfounded and you were able to move on. Paranoid individuals, however, have suspicions and irrational thoughts that don't go away. Instead, they are exaggerated, even when there is not any evidence to suggest their suspicions are true. These fears makes it difficult for individuals with paranoia to function in society, work, or have close relationships.

Paranoid individuals have persistent irrational thoughts.

Paranoia has three main features:

  1. Intense fear or worry that something bad will take place
  2. Feeling that other individuals or causes outside the person are to blame
  3. Exaggerated beliefs or beliefs that have no support

Paranoia is a symptom of several different types of mental disorders, including:

  • Schizophrenia
  • Schizoaffective disorder
  • Anxiety disorders (i.e., phobias and generalized anxiety disorder)
  • Depression
  • Paranoid personality disorder
  • Delusional disorder

Paranoia is also a symptom of several other diseases, including:

  • Huntington's disease
  • Parkinson's disease
  • Alzheimer's disease


Symptoms of paranoia can be range from mild (i.e., feeling that the guy sitting next to you is popping his gum just to annoy you) to severe (i.e., feeling that there is an alien inside your head that is controlling your thoughts). People who experience paranoia may exhibit the following symptoms:

  • Inability to trust others
  • Being easily offended
  • Trouble forgiving others
  • Intense fear of being taken advantage of
  • Inability to handle criticism

Individuals with paranoia can easily become violent and hostile if they are feeling threatened.

  • Hostile, aggressive, or argumentative behavior
  • Unwilling to compromise
  • Being overly suspicious
  • Viewing the world as a dangerous place in which they are under constant threat
  • Belief in 'conspiracy theories,' which lack evidence or support
  • Feelings of persecution


Paranoia is thought to be caused by a breakdown of mental and emotional functions and reasoning. The exact cause of these breakdowns is still unknown. The major theories regarding the development of paranoia are:

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