Healthy Living

What Are Delusions: Types, Risks, Diagnosis, and Treatment

What Are Delusions

What are delusions?

Delusions are untrue and unrealistic beliefs of a person. A delusion separates the person from reality and imagination. It was previously known as "paranoid disorder", which is a type of serious mental disorder. People with this disorder usually experience delusions associated with real-life situations such as being deceived, poisoned, or followed. 

Delusions can be a symptom of neurological, psychiatric, or psychological disorders. Having delusions is one of the common symptoms of mental disorders such as schizophrenia, paranoia, and major depression.  Delusion is also accompanied by other psychological conditions such as delirium and psychosis. Dementia and brain cancer are other neurological conditions that cause delusions. 

The characteristics of delusions are impossibility, incorrigibility, and certainty. A person with a delusional disorder has very strong beliefs, which cannot be reasoned out or shaken. The extent and intensity of the condition may vary from person-to-person. Wishful thinking may vary depending on the pathological exaggeration of normal tendencies.

Differential Diagnosis of Delusion

  • Delirium vs. Delusion - In delirium, a person is in the state of utter confusion. Delirium may be due to physical or mental illness, metabolic disturbances in the brain, or brain dysfunction. Delirium is characterized by disturbances in the sleep cycle, disorganized speech and thought, altered perception, disorientation, and emotional liability. On the other hand, a person who experiences delusion holds on to unrealistic false beliefs. In delirium, changes in thought processes suddenly occur, whereas, in delusion, the changes gradually occur over a period of time.
  • Delusional Disorder vs. Delusion - In many psychiatric conditions, delusion is a symptom, whereas delusional disorder is an uncommon psychiatric condition. Some people with a delusional disorder may show delusion, but delusion is not accompanied by other symptoms such as thought disorders, hallucinations, and mood disorders.
  • Delusion vs. Hallucination - Hallucination involves perception in the absence of an external stimulus such as hearing voices. All sensory modalities are involved such as visual, auditory, tactual, gustatory, other movements, and sensation of balance. In delusion, the person holds on to a strong belief based on an erroneous perception of reality.
  • Dementia vs. Delusion - In terms of cognitive processes, dementia and delusion are different from each other. In dementia, the mental functioning of an individual starts to slowly decline, which includes language, problem-solving, attention, and memory.

Types of Delusion

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM–5), the four types of delusions are:

  • Bizarre Delusion - A bizarre delusion is characterized by impossible, strange, or unimaginable delusions. One example of such delusion is a belief that the person’s digestive system is taken away by an alien.
  • Non-Bizarre Delusion - In a non-bizarre delusion, a person holds to a theoretically possible but false belief. An example of a non-bizarre delusion is when a woman has a firm belief that the person living next door is deeply in love with her.
  • Mood-Congruent Delusion - In this type of delusion, the mood of the person such as mania or depression is involved. For instance, a person who is depressed may have a firm belief that people around him hate to see him. On the other hand, a person with mania may have a firm belief that he or she has an extraordinary talent that should be recognized by many.
  • Mood-Neutral Delusion - This type of delusion is not related to the mood of the person. One example is a person's firm belief that another person or group of people are inserting thoughts into his or her mind.

Delusions are categorized based on the theme of delusion that occurs due to psychiatric or psychological symptoms. The common themes of delusion are:

  • Delusional Jealousy - A person with delusional jealousy strongly believes that his or her partner has an affair. To support this false belief, the person tries to gather irrelevant pieces of evidence about the affair and confronts their significant other.
  • Control - In this type of delusion, the person feels that his thoughts, behavior, and feelings are being controlled by another person, group of people, or external forces such as voices of aliens. Their thoughts are controlled in three ways:
  1. Thought Insertion - They are being made to think in a particular way by external forces.
  2. Thought Broadcasting - They have a firm belief that their thoughts can be loudly heard.
  3. Thought Withdrawal - A firm belief that their thoughts are being removed or extracted by an outside force.
  • Nihilistic Delusion - People have a belief that they do not exist, a part of them does not exist, or the whole world does not exist. They may also have a belief that the whole world is ending soon.
  • Reference - In this type of delusion, people have a false belief that normal insignificant things or circumstances have a significant meaning. An example would be believing that people on TV shows are talking about them or directly talking to them. Another example would be believing that news headlines are specially written for them.
  • Mind Being Read - The person has a firm belief that others can read his or her mind without being heard aloud. However, this type of delusion is different from thought broadcasting delusion. An example would be a person walking into the classroom and thinking that the teacher can read his or her thoughts. 
  • Sin or Guilt - Without any possible connection, the person may feel that he or she is responsible for something. The person may feel false guilt to an extent. This type of delusion is also known as self-accusation delusion.
  • Grandiose - The person believes and is fully convinced that he or she has special talents, abilities, or power. The sense of self-importance is exaggerated by the person. The person may even feel that he or she has not yet received adequate recognition despite achieving something really great and extraordinary.
  • Persecution - The person feels that he or she is being cheated, followed, spied on, harassed, and poisoned. People may also feel that in their path of achievement, hurdles are being created and conspiracy is being planned to sabotage their success.
  • Induced Delusional Disorders - This form of delusion is quite rare. This mental disorder occurs in individuals who are in a close relationship and share the same delusional system of persecution or grandeur. For example, a dominant personality partner may influence the weaker personality partner to adopt the delusion. In this case, the dominant personality partner is affected by psychosis. Once the weaker personality partner is separated, then they recover from the delusions.
  • Somatic Delusion - This type of delusion is associated with physical appearances, the functioning of the body, and sensations. People may feel that they are unwell, have a disease, or their body is damaged. They may also be obsessed with being amputated, malformed, or feel that foul odor is being emitted from their body.

Risk Factors

It has been a challenge to find the exact cause of delusion. However, for developing delusions, the risk factors associated have been explained by several theories.

Delusional tendencies are said to run in families. Based on evidence, it has been suggested that genes make the person more vulnerable to delusions. There can be an alteration in thinking and perception due to people's distorted perception of life. Such perception can often lead to delusions. There has been a consistent pattern in the frontal lobe and right hemisphere of the brain in people with certain types of delusions. Delusions are probably caused by an overcompensation of the left hemisphere due to a deficit in the right hemisphere of the brain.

Delusions may also develop due to stressful childhood experiences. The exposure of a child to an environment such as quarreling parents, bullying, and sexual abuse are factors that can cause delusions later in life. However, not all people with delusions have a stressful childhood. When life experiences are distorted and illogical explanations are given, then it can lead to delusions. When life events threaten a person's existence, then delusions can be manifested. Delusions are caused by blaming or pointing fingers at others for difficulties or failures, stress, or firmly believing a positive opinion about themselves.

Diagnosis of Delusion

Psychiatrist and philosopher Karl Jaspers described three main criteria to consider a belief as a delusion.

  1. Certainty - People have an absolute certainty to their beliefs even though pieces of evidence say otherwise. 
  2. Incorrigibility - People's beliefs are not changed or corrected despite logical evidence.
  3. Impossibility - The belief is impossible, false, implausible, and bizarre.

In delusion, other symptoms such as fear, paranoia, and anxiety also occur. A mental state examination includes:

  • An evaluation of behavior
  • Appearance
  • Mood
  • Rate
  • Evidence of beliefs
  • Continuity of speech
  • Attention
  • Concentration
  • Orientation to time, place, and person


The underlying cause of delusion is often a psychiatric or psychological disorder. First, the disorder needs to be treated. However, its treatment can be challenging. If the root problem is first addressed, then delusions can be reduced. People having delusions may not feel the need of treatment and may not accept their delusion as false. A primary care doctor, psychiatrist, or mental health professional should be consulted by the patient’s family or relatives if they suspect a case of delusion.

  • Psychotherapy - The effectiveness of psychotherapy depends on the most important factor, which is the patient-therapist relationship. The patient should be made to believe that he is not thought of as mad or crazy by the therapist. Psychotherapy centers on the goals that the patient wants to achieve and the realistic problems that occur in the patient's life. The aim of psychotherapy is encouraging positive behavior, improving self-confidence, reinforcing achievement, and improving self-esteem.
  • Antipsychotic Drugs - The aim of antipsychotic drugs is to manage the delusions. The effects of these drugs may be temporary and can be questionable to the patient. If the patient has delusions of persecution or guilt, then he or she may get suspicious about the given medication. 

Other treatments that have been found to be ineffective or dangerous are insulin shock therapy, electroconvulsive therapy, and psychosurgery.