What Are Delusions? (2024)

A delusion is a strongly-held or fixed false belief that conflicts with reality. The Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) defines delusions as fixed beliefs that are not amenable to change in light of conflicting evidence.

Delusions are a common symptom of psychotic disorders such as schizophrenia, delusional disorder, and schizoaffective disorder. They can also be present in other psychiatric disorders, including major depressive disorder with psychotic features and mania in bipolar disorder.

This article discusses the types of delusions, examples of each type, what causes them, and how they’re diagnosed and treated.

Types and Examples of Delusions

Karl Jaspers was the first to define delusions based on the criteria of certainty, incorrigibility, and impossibility or falsity of the belief. Phillip Johnson-Laird defined delusions as failure to distinguish conceptual relevance, meaning irrelevant information is accepted as relevant. The definition of “delusions” continues to evolve.

There are four types of delusions outlined in the DSM-5:

• Bizarre delusions are implausible or impossible, such as being abducted by aliens.
• Non-bizarre delusions could actually occur in reality, such as being cheated on, poisoned, or stalked by an ex-partner.
• Mood-congruent delusions are consistent with a depressive or manic state, such as delusions of abandonment or persecution when depressed, and delusions of superiority or fame when manic.
• Mood-incongruent delusions are not affected by the particular mood state. They may include delusions of nihilism (e.g., the world is ending) and delusions of control (e.g., an external force controls your thoughts or movements).
  

Themes

There are several different delusional themes, including:

• Capgras delusion: This is the belief that a loved one like a mother or sibling has been replaced by an imposter.
• Cotard delusion: This occurs in Cotard’s syndrome, and is characterized by the belief that you are dead or your body or body parts have disintegrated or no longer exist.
• Delusion of control: This refers to the belief that an external entity is controlling your thoughts, behaviors, and impulses. This entity may be an individual like a manager, a group, or some undefined force.
• Delusion of grandiosity: This is an exaggerated or inflated self-belief regarding power, fame, knowledge, skill, talent, or strength. For example, a person may believe they are an Instagram influencer despite not having a following.
• Delusion of guilt or sin: This refers to unwarranted and extreme feelings of remorse or a severe sinking feeling that you’ve done something horribly wrong.
• Delusion of thought insertion or thought broadcasting: This refers to the belief that thoughts have been inserted into your mind or are being broadcasted to others.
• Delusion of persecution: This refers to the belief that you or someone close to you is being unfairly mistreated, harmed, or watched. The conviction is so strong that the person may seek help from the authorities. This is the most common delusion people experience.
• Delusion of poverty: This is the belief that you are or are about to become destitute, are destined to fall into poverty, or are impoverished.
• Delusion of reference: This refers to the belief that something like a poster, song, or advertisem*nt has a direct reference to or a hidden meaning for you. A person with this delusion may see a sign that has nothing to do with them, but change their whole life plan as a result.
• Delusional jealousy: This is the belief that your sexual partner is being unfaithful.
• Erotomanic delusion: Also known as erotic or love delusion, this is the belief that someone, usually someone famous or otherwise out of reach, is in love with you. A person with this delusional disorder subtype may obsessively contact or try to connect with that person and make excuses for why they’re not together.
• Nihilistic delusion: This is the belief that you or parts of you do not exist, or that some object in external reality is not actually real.
• Religious delusion: This refers to any delusion involving a god, higher power, or spiritual theme (e.g., believing that you have special powers or are the embodiment of a prophet). This may be combined with other delusions such as the delusion of control or grandeur.
• Somatic delusion: This refers to the belief that one or more of your bodily organs are functioning improperly, or are diseased, injured, or altered.

Signs of Delusions

In addition to having unshakable beliefs in things that are not true, people experiencing delusions may also exhibit:

• Confusion
• Agitation
• Irritability
• Aggressiveness
• Depression
• Self-referential thinking

What Causes Delusions?

Delusions are common to several mental disorders and can be triggered by sleep disturbance and extreme stress, but they can also occur in physical conditions, including brain injury or tumor, drug addiction and alcoholism, and somatic illness.

Biological or Genetic Theory

Research has suggested that delusions are more likely to occur in people who have a family history of psychotic disorders such as schizophrenia.

Abnormal activity of dopamine and other neurotransmitters is thought to be involved in certain delusional symptoms. Dopamine is a neurotransmitter that modulates motor control, motivation, and reward, so abnormal dopaminergic activity in the brain (hyperactivity of dopamine receptors in some brain regions and underactivity in others) can result in symptoms of psychosis.

Dysfunctional Cognitive Processing

The dysfunctional cognitive processing theory hypothesizes that delusions potentially come from the distorted ways people think about and explain life to themselves.Research suggests that individuals with delusions may be quicker to jump to conclusions, meaning they take in less information before arriving at a conclusion and do not consider or accept alternatives.

Those who have delusions have disturbed cognitive and social processing, meaning they can’t accurately read people and are more likely to incorrectly and negatively assume how others view them.

Defensive or Motivated Delusions

This theory proposes that delusions are a result of a defense mechanism or motivation to preserve positive self-view by attributing any negative things that happen to others or circ*mstances.

Other factors that could contribute to delusions include:

• Culture and religion: Spiritual, magical, and religious delusions are common in psychotic disorders, but prevalence varies with time, place, and religion.
• Low socioeconomic status: Delusion-like experiences have been associated with people in the general population with lower socioeconomic status. This may be due to higher levels of psychological distress and stress in this population.
• Being hearing or sight impaired: Research has found that people with hearing impairments are at higher risk of psychosis and have been found more likely to develop schizophrenia. One explanation is that hearing or visual impairments can influence environmental misinterpretations, leading them to perceive social environments as threatening.

Health Conditions That Cause Delusions

Delusions may be a symptom of a mental health condition or brain disorder. Some conditions that can be associated with delusions include:

• Brief psychotic disorder: Peoplecan experience brief episodes of hallucinations, delusions, or disorganized speech when triggered by a stressful event.
• Delusional disorder: People with this condition experience "non-bizarre" delusions and function relatively normally.
• Dementia: Delusions are a common neuropsychiatric symptom of dementia.
• Mood disorders: Some people with mood disorders like bipolar disorder experience delusional thinking.
• Parkinson's disease: Between 20% to 40% of people with Parkinson's disease report experiencing hallucinations or delusions.
• Post-partum psychosis: A serious mental illnessthat affects one in 500 mothers after giving birth. Symptoms can include delusions, hallucinations, rapid mood changes, and more.
• Schizoaffective disorder: This condition involves symptoms of schizophrenia, including delusional thinking, hallucinations, and mood issues like depression and mania.
• Schizophrenia: Along with delusions, this condition involves symptoms such as hallucinations, flat affect, reduced feelings of pleasure in everyday life, difficulty beginning and sustaining activities, and reduced speaking.
• Schizophreniform disorder: The symptoms of this condition are similar to schizophrenia but they are experienced for one to six months, not lifelong.
• Drug or alcohol intoxication or withdrawal: Severe drug or alcohol intoxication or withdrawal may cause psychotic symptoms including delusions.

Delusional Disorder

Delusional disorder is a mental illness in which a person has one or more firmly held false beliefs that last for a month or longer. These false beliefs are not bizarre and potentially could happen in real life, such as being followed by someone or believing their spouse is being unfaithful.

It is different than a false belief in that they continue to believe in the delusion no matter how much clear evidence contradicts it.

People with delusional disorder are functional and often employed. Their behavior is not considered bizarre.

Risk factors for developing delusional disorder include:

• A preexistingparanoid personality disorder
• A family history of schizophrenia
• Older age (middle or late adult life)

Delusional Disorder vs. Schizophrenia

Delusional disorder is different than schizophrenia in that the person has delusions without any of the other symptoms of psychosis, such as hallucinations, disorganized speech, or disorganized behavior. Also, persons with delusional disorder have delusions that could possibly occur in real life, whereas those with psychotic disorders, like schizophrenia, often have bizarre delusions.

Diagnosing Delusions

The diagnostic process for delusions or delusional disorder begins with a physical exam to rule out physical conditions. Your healthcare provider will also ask about your symptoms and take a medical history.

A mental health professional will first distinguish delusions from overvalued ideas. An overvalued idea is a rigidly held belief that is shared by others in a person’s culture or subculture, whereas a delusion is a fixed, false belief not shared by others.

If delusions are indeed present, the clinician will try to establish the presence of a particular mental health or another disorder that the delusion might be a symptom of.

For example, the DSM-5 criteria for delusional disorder are as follows:

• One or more delusions are present for a duration of one month or longer.
• The diagnostic criteria for schizophrenia has never been met. Hallucinations, if present, are not prominent and are clearly thematically related to the delusional theme.
• Apart from the impact of the delusion(s) or its ramifications, patient functioning is not markedly impaired and their behavior is not obviously bizarre or odd.
• If manic or major depressive episodes have occurred, they are brief compared to the duration of the delusional symptoms.
• The disturbance is not better explained by another mental disorder such as obsessive-compulsive disorder (OCD), and is not attributable to the physiological effects of a substance or medication or another systemic medical condition.

How Are Delusions Treated?

Treatment for delusions will depend on the cause but often includes a combination of medication and therapy.

Medications may include antipsychotics, tranquilizers, or antidepressants.

Therapy for delusions may include:

• Cognitive behavioral therapy (CBT) to help someone with delusional beliefs learn to recognize and change unhelpful thoughts and behaviors.
• Family therapy to help a spouse or family member learn how to support their loved one who is experiencing delusional thoughts or behavior patterns.
• Acceptance and commitment therapy (ACT)to help someone live with delusions, despite others not having these same beliefs.

Sometimes hospitalization may be required if the person with delusions is a danger to themselves or others.

Summary

There are numerous types and causes of delusions. Along with having unshakable beliefs in things that are not true, people experiencing delusions may have mood swings, and act confused, irritable, anxious, or aggressive.

Treatment depends on the cause of the delusions and may include medications or a combination of therapy, such as cognitive behavioral therapy, and medications.