What are Delusions in Psychology

Delusions are beliefs that persist despite evidence to the contrary. They are often associated with mental health conditions such as schizophrenia, bipolar disorder, or severe depression. Delusions can encompass a wide range of topics and are resistant to logical reasoning or contradictory evidence.

People with delusions may believe that they are being persecuted, monitored, or controlled by external forces or that they have special abilities or powers. These beliefs can be distressing and disruptive to daily life.

This article is for informational and educational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician, therapist, or other qualified health provider with any questions you may have regarding a medical or mental health condition.

Never disregard professional advice or delay in seeking it because of something you have read on this site.

What is Delusional Disorder?

Bizarre vs. Non-Bizarre Delusions

Delusions can be either bizarre or non-bizarre, and they can range from mild to severe.

Bizarre delusions are beliefs about something that can never happen, such as the belief that an individual has been abducted and cloned by aliens.

Non-bizarre delusions, however, are beliefs that could be true. Examples include the belief that an individual is being stalked, that someone is secretly in love with them, or that a spouse is cheating on them.

This distinction carries real diagnostic weight, because delusional disorder is defined by persistent non-bizarre delusions specifically.

In practice, the line is hard to draw. Whether a belief counts as “bizarre” often depends on clinicians agreeing about what is physically possible, and that agreement is far from perfect (Cermolacce, Sass, & Parnas, 2010).

Delusional disorder is a condition characterized by persistent non-bizarre delusions lasting at least one month (Joseph & Siddiqui, 2023).

These beliefs could feasibly happen in real life. Yet they remain firmly held despite evidence to the contrary.

Often, with delusional disorder, the individual will socialize and function according to social norms. They generally do not behave in an unusual manner, which makes this condition difficult to recognize from an outsider’s perspective.

Types of delusions

Many different types of delusions can be experienced, some of which include:

Delusions are classified by their theme, not by how severe they are.

Persecutory delusions dominate almost every culture studied. How often other themes occur, such as grandiose or religious delusions, varies from country to country (Stompe et al., 1999).

Erotomanic

The false belief that another person, often someone famous or of higher status, is in love with the individual.

The clinical name is de Clérambault’s syndrome. Because the person’s conviction can drive persistent unwanted contact, such as letters, calls, or visits, erotomania has a disproportionate forensic profile.

A review of erotomanic cases reaching criminal courts found that offenders showed no insight into the delusional nature of their belief (Leong, 1994).

Grandiose

The belief that the individual has an over-inflated sense of worth, knowledge, wealth, talent, power, or fame, despite a lack of evidence.

In bipolar disorder, grandiose delusions are mood-congruent.

They typically appear during manic episodes and fade as mood settles, though they can also occur independently of mood change in schizophrenia and delusional disorder.

Content is also shaped by era and culture: 19th-century grandiose delusions often involved royalty, while today’s often involve technology, celebrity, or fame (Stompe et al., 1999).

Persecutory

The belief that the individual, or someone close to them, is being spied on, followed, drugged, cheated on, or mistreated.

Persecutory delusions are by far the most common theme.

What sets them apart is safety behaviour: a person does not just hold the belief, they act on it, such as avoiding certain routes or repeatedly contacting the police.

Jealous

The belief that a romantic partner or spouse is being unfaithful, despite a lack of evidence to prove this.

This theme is sometimes called Othello syndrome, after the Shakespearean character whose jealous conviction of his wife’s infidelity persists despite her innocence.

This targets a specific, present person, which raises domestic-violence risk.

Somatic

The belief that the individual is experiencing physical sensations, bodily dysfunctions, or suffering from a medical condition.

Somatic delusions sit between psychiatry and general medicine.

Sufferers typically first see a GP or another physician rather than a mental health service, convinced the problem is physical. This is why it often goes unrecognized as psychiatric.

Nihilistic Delusions and Cotard Syndrome

Nihilistic delusions involve the belief that something fundamental about oneself, others, or the world does not exist. Examples include believing that one’s own organs have rotted away, or that the entire external world has ceased to exist.

The most striking form is Cotard syndrome, in which a person believes they are dead, do not exist, or have lost their blood or internal organs. It is strongly linked to severe depression with psychotic features.

Cotard syndrome sometimes appears alongside a conviction of immortality, trapping the person in what feels like living death. It also occurs alongside certain organic brain conditions, not only depression.

This mood link matters: nihilistic delusions are mood-congruent with severe depression, in the same way grandiose delusions are mood-congruent with mania.

Delusional Misidentification Syndromes

A further group of delusions concerns the identity of people or places rather than persecution, mood, or the body. The best known is Capgras syndrome: the belief that a close relative has been replaced by an identical impostor.

A rarer, mirror-image variant is Fregoli delusion. It is the belief that a stranger is a familiar person in disguise.

Both occur mostly in dementia, traumatic brain injury, and schizophrenia. Capgras syndrome is closely tied to a specific pattern of right-hemisphere dysfunction.

It is one of the clearest examples of a monothematic delusion: a single, tightly focused belief following a specific brain injury.

Both syndromes are central evidence for the cognitive two-factor theory: they show a delusion arising from a specific perceptual anomaly, rather than a general thought disorder.

Mixed

When a person’s delusions do not fall into a single category, or two or more types occur together, this is labeled mixed or unspecified.

This is common in practice, since conviction in one domain often recruits a persecutory explanation for why a special status has gone unrecognized.

For example, someone might believe they have a special healing power while also believing government agents are trying to suppress it, a grandiose belief reinforcing a persecutory one.

Examples of common delusions

To better understand what delusions can look like in everyday life, here are some examples linked to different types:

• Erotomanic Example: Believing a famous actor is secretly sending love messages through television broadcasts.
• Grandiose Example: Believing you have discovered a cure for all diseases or are chosen by a divine entity to lead humanity.
• Persecutory Example: Thinking that neighbors are spying on you through hidden cameras planted inside your home.
• Jealous Example: Becoming convinced that a spouse is meeting with a secret lover during lunch breaks, despite no signs of infidelity.
• Somatic Example: Being absolutely certain that insects are living under your skin, even after medical tests show no evidence.
• Mixed Example: Believing both that you have a special healing power and that government agents are trying to suppress your abilities.

Causes and Risk Factors

Although there is currently no concrete explanation for what causes delusions, researchers have some ideas as to potential causes or risk factors that may contribute to the onset of delusions.

Genetics

Genetics may play a part in developing delusions. Someone is more likely to develop delusions if a family member has a psychotic disorder involving delusions.

For instance, a parent with a delusional disorder or schizophrenia is more likely to have a child who also develops one of these conditions.

Sensory impairments

Delusional disorder tends to be more common among those with impaired vision or hearing.

Someone with vision or hearing problems may be more likely to rely on inaccurate perceptions of reality. This is because they are less able to check what they perceive against how things really are. The link is modest.

This is not to say that everyone with sensory impairments will experience delusions, and not everyone with delusional disorder also has sensory impairments.

Biological causes

Some research suggests that changes in the brain’s structure and chemistry could help explain why delusions happen.

Joyce (2018) found that people who had strokes affecting the right lateral prefrontal cortex were more likely to develop delusions. This links to the basal ganglia and limbic system.

This part of the brain also receives signals from dopamine neurons, and dopamine is a chemical that plays a big role in motivation, pleasure, and reward.

When dopamine levels are disrupted, it’s been linked to conditions like schizophrenia and psychosis, suggesting that faulty dopamine signaling might contribute to the development of delusions.

Kapur (2003) built on this idea. He proposed a fuller model called aberrant salience: faulty dopamine signaling makes ordinary, neutral events feel unusually important. A stranger’s glance or a stray remark on the radio can suddenly feel deeply significant.

The delusion makes sense of that feeling. Antipsychotics help by calming this signal, rather than erasing the belief directly.

Another study by Devinsky (2009) looked at how damage to the brain’s frontal lobes, particularly on the right side, could lead to delusions.

When the right side is damaged, the left hemisphere often overcompensates. This is especially true of areas linked to language.

In this case, the brain might “create a story” or belief that feels completely real, because the damaged side can no longer check or correct those false ideas against reality.

In both cases, damage or dysfunction in key brain areas makes it harder for a person to separate what’s real from what’s imagined. That difficulty helps explain why some delusions are so persistent.

Environmental factors

Some environmental factors may contribute to the development or exacerbation of delusions, e.g.,

1. Stressful life events: Experiencing traumatic or stressful events, such as abuse, violence, or loss, may increase the risk of developing delusions.
2. Social isolation: Lack of social support and social isolation may contribute to the development of delusions, as individuals who are socially isolated may be more prone to feelings of paranoia and mistrust.
3. Substance use: Substance use, particularly drugs like amphetamines or hallucinogens, can trigger delusions in some individuals.

These environmental factors may contribute to delusions, but none of them causes delusions on its own.

Attributional Biases

Some researchers have looked at how thinking patterns, called attributional biases, might play a role in developing and maintaining delusions (Humphreys & Barrowclough, 2010).

Attributional bias means that people tend to take credit for positive events (“I made that happen”) but blame outside forces for negative ones (“It’s someone else’s fault”).

Studies have found that this self-protective thinking style appears more often in people with persecutory delusions, possibly as a way to defend their self-esteem (Bentall, 2019).

However, not all research agrees. Some studies suggest this bias might not be unique to delusions, but instead part of broader coping strategies seen in psychosis (Humphreys & Barrowclough, 2010).

Other reviews have pointed out that inconsistencies in research methods make it hard to draw firm conclusions (Zhu et al., 2017).

Even so, understanding how attributional biases work could help shape therapies that focus on improving reasoning and making thinking patterns more flexible.

Mental Health Conditions Linked to Delusions

Delusions can occur as a feature of several different mental health conditions.

Understanding these links can help differentiate whether delusions are part of a broader psychiatric disorder or occur in isolation. Some of the key conditions associated with delusions include:

• Schizophrenia: Delusions are one of the hallmark symptoms of schizophrenia. Individuals may experience bizarre or highly implausible beliefs, often accompanied by hallucinations, disorganized thinking, and changes in behavior.
• Delusional Disorder: in delusional disorder, individuals experience persistent delusions that are often non-bizarre (e.g., believing they are being followed or deceived) without the broader deterioration of functioning typically seen in schizophrenia.
• Bipolar Disorder: During manic or depressive episodes, individuals with bipolar disorder may develop mood-congruent delusions — for example, grandiose delusions during mania (believing they have special powers) or persecutory delusions during depression (believing others are plotting against them).
• Major Depressive Disorder with Psychotic Features: Some individuals with severe depression may experience delusions that are typically negative or self-blaming in nature, such as believing they have committed terrible sins or are responsible for disasters.
• Dementia (e.g., Alzheimer’s Disease): Cognitive decline in dementia can lead to delusions, such as believing loved ones have been replaced (Capgras delusion) or that belongings have been stolen.
• Postpartum Psychosis: Occurring shortly after childbirth, postpartum psychosis can involve mood disturbances alongside delusions, posing significant risks if not treated promptly.
• Substance-Induced Psychotic Disorder: The use of substances such as amphetamines, cocaine, hallucinogens, or alcohol can sometimes trigger psychotic symptoms, including delusions, especially during intoxication or withdrawal periods.
• Posttraumatic Stress Disorder (PTSD):
  In some cases, individuals with PTSD may experience persecutory delusions related to their trauma history, although this is less common.

While delusions are a prominent symptom in many of these conditions, their nature, intensity, and accompanying symptoms can vary widely. A thorough assessment by a mental health professional is crucial to determine the underlying cause and guide appropriate treatment.

How To Manage Delusions

Managing delusions often involves a combination of medication, therapy, and supportive strategies.

Treatment can be challenging, especially if a person doesn’t recognize that their beliefs are false. A compassionate, patient-centered approach is crucial.

Medications

Antipsychotic medications are the primary treatment for delusions. They work by adjusting brain chemicals like dopamine, which are linked to psychotic symptoms.

• Typical antipsychotics (e.g., Haloperidol, Fluphenazine) have been used since the 1950s and mainly block dopamine receptors.
• Atypical antipsychotics (e.g., Risperidone, Olanzapine) also target serotonin and tend to have fewer side effects.

Sometimes, antidepressants or tranquilizers may be added to help manage anxiety or mood symptoms that accompany delusions.

Psychotherapy

Talk therapies can also help individuals cope with delusions, either alongside or instead of medication.

• Cognitive Behavioral Therapy (CBT): Helps individuals challenge unhelpful beliefs and reframe thinking patterns (Sitko et al., 2020).
• Acceptance and Commitment Therapy (ACT): Focuses on accepting thoughts without judgment and building psychological flexibility (Burhan & Karadere, 2021).
• Family Therapy and Group Therapy: Offer support, education, and strategies for dealing with social and relational challenges.

The best treatment plan is personalized to the individual’s needs, symptoms, and willingness to engage in care.

Self-Help Coping Skills for Living with Delusions

While professional treatment is important, self-help strategies can also make a big difference in daily life. Some useful coping tools include:

• Mindfulness Techniques:
  Ground yourself in the present moment through breathing exercises, meditation, or sensory awareness practices. Mindfulness can help reduce the emotional intensity of delusional thoughts (Ellett, 2023).
• Emotion Regulation Skills:
  Use techniques like deep breathing, journaling, or progressive muscle relaxation to manage strong feelings and stay calm during distressing episodes.
• Engaging in Meaningful Activities:
  Regularly participating in hobbies, exercise, creative arts, or social groups helps provide structure, enjoyment, and distraction from intrusive thoughts.
• Peer Support and Reality-Checking:
  Connecting with others who understand your experiences — through support groups or trusted friends — can help you reality-test beliefs and feel less isolated.
• Building a Safety Plan:
  Have a clear plan for what to do if delusions become overwhelming, including people to contact and coping steps to follow.
• Practicing Self-Compassion:
  Recognize that experiencing delusions is not a personal failing. Be kind to yourself, celebrate small victories, and remember that healing takes time.

These strategies won’t erase delusions entirely but can make them more manageable, helping individuals live fuller, more connected lives.

As Elyn Saks, a law professor who has written and spoken publicly about living with schizophrenia, explains, delusional beliefs during an acute episode do not rule out a full life.

She has described experiencing the conviction that her own thoughts had caused catastrophic harm, while still building a high-functioning academic career over decades of treatment. Recovery and delusion can coexist.

Do you or a loved one need mental health support?

USA

Contact the National Suicide Prevention Lifeline for support and assistance from a trained counselor. If you or a loved one are in immediate danger: https://suicidepreventionlifeline.org/

1-800-273-8255

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Contact the Samaritans for support and assistance from a trained counselor: https://www.samaritans.org/; email jo@samaritans.org .

Available 24 hours a day, 365 days a year (this number is FREE to call):

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Rethink Mental Illness: rethink.org

0300 5000 927

Critical Evaluation

No single account fully explains why delusions form, and recent research has tested some of psychology’s oldest assumptions about them.

The Reasoning-Bias Mechanism

For decades, a reasoning style called jumping to conclusions was treated as a reliable marker of delusion-proneness. The idea was that gathering unusually little evidence before deciding something is true helps explain why an implausible belief gets accepted without enough checking.

That assumption has now been tested at scale. A 2025 meta-analysis pooled 42 studies and over 7,600 participants, spanning clinical psychosis patients and the general population.

It found no meaningful link between the strength of this reasoning bias and delusion severity, across every group studied (Doherty, Weber, Hillier, Ross, & Balzan, 2025).

It may still matter for how a delusion first forms. It does mean the bias is a weaker, less specific marker of severity than earlier, smaller studies suggested.

Rival Theories, Each Partial

Two competing explanations dominate the biological and cognitive literature, and each is strong exactly where the other is weak. The cognitive two-factor theory says a delusion needs an anomalous experience plus a breakdown in normal fact-checking (Coltheart, Langdon, & McKay, 2011).

This is why the model fits Capgras and Cotard so well: a specific brain lesion supplies the first ingredient directly, ready-made.

The biological account tells a different story. The aberrant-salience account, discussed above, explains why dopamine-blocking medication reduces conviction across almost every delusional theme. Its weakness is the reverse: it says little about why one person’s experience becomes a persecutory belief and another’s becomes a grandiose one.

The two are not really rivals. One explains why an anomaly occurs; the other, why it hardens into a fixed belief.

A Continuum, Not a Category?

The bizarre/non-bizarre boundary described above assumes clinicians can agree on what counts as physically or socially possible. Research on ordinary, non-clinical populations complicates that assumption.

The evidence points the same way.

A large review of subclinical psychotic experiences found that mild, delusion-like beliefs are common in the general population, affecting roughly one in twenty people.

These milder beliefs shade gradually into clinical psychosis, rather than sitting in a wholly separate category (van Os, Linscott, Myin-Germeys, Delespaul, & Krabbendam, 2009).

This may genuinely be a spectrum, not a category.

A strict system risks drawing an artificially sharp line, especially given how inconsistently clinicians judge what counts as “bizarre” in the first place.

That has real consequences for diagnosis, not just theory.

References

Bentall, R. P. (2019). Cognitive biases and abnormal beliefs: Towards a model of persecutory delusions. The neuropsychology of schizophrenia, 337-360.

Burhan, H. Ş., & Karadere, E. (2021). Effectiveness of Acceptance and Commitment Therapy for Patients with Psychosis Being Monitored at a Community Mental Health Center: A Six-Month Follow-up Study. Alpha Psychiatry, 22(4), 206.

Cermolacce, M., Sass, L., & Parnas, J. (2010). What is bizarre in bizarre delusions? A critical review. Schizophrenia Bulletin, 36(4), 667–679. https://doi.org/10.1093/schbul/sbq001

Coltheart, M., Langdon, R., & McKay, R. (2011). Delusional belief. Annual Review of Psychology, 62, 271–298. https://doi.org/10.1146/annurev.psych.121208.131622

Devinsky, O. (2009). Delusional misidentifications and duplications: right brain lesions, left brain delusions. Neurology, 72(1), 80-87.

Doherty, R., Weber, N., Hillier, C., Ross, R., & Balzan, R. (2025). Jumping to conclusions and delusional ideation: A systematic review and meta-analysis across the psychosis continuum. Clinical Psychology Review, 120, 102618. https://doi.org/10.1016/j.cpr.2025.102618

Ellett, L. (2023). Mindfulness for psychosis: Current evidence, unanswered questions and future directions. Psychology and Psychotherapy: Therapy, Research and Practice.

Humphreys, L., & Barrowclough, C. (2010). Attributional style, defensive functioning and persecutory delusions: Symptom-specific or general coping strategy? The British Journal of Clinical Psychology, 49(2), 231–246.

Joseph, S. M., & Siddiqui, W. (2023). Delusional disorder. In StatPearls [Internet]. StatPearls Publishing.

Joyce, E. M. (2018). Organic psychosis: the pathobiology and treatment of delusions. CNS neuroscience & therapeutics, 24(7), 598-603.

Kalayasiri, R., Kraijak, K., Mutirangura, A., & Maes, M. (2019). Paranoid schizophrenia and methamphetamine-induced paranoia are both characterized by a similar LINE-1 partial methylation profile, which is more pronounced in paranoid schizophrenia. Schizophrenia research, 208, 221-227.

Nygaard, M., Sonne, C., & Carlsson, J. (2017). Secondary psychotic features in refugees diagnosed with post-traumatic stress disorder: a retrospective cohort study. BMC psychiatry, 17(1), 1-11.

Sitko, K., Bewick, B. M., Owens, D., & Masterson, C. (2020). Meta-analysis and meta-regression of cognitive behavioral therapy for psychosis (CBTp) across time: the effectiveness of CBTp has improved for delusions. Schizophrenia Bulletin Open, 1(1), sgaa023.

Stompe, T., Friedman, A., Ortwein, G., Strobl, R., Chaudhry, H. R., Najam, N., & Chaudhry, M. R. (1999). Comparison of delusions among schizophrenics in Austria and in Pakistan. Psychopathology, 32(5), 225–234. https://doi.org/10.1159/000029094

van Os, J., Linscott, R. J., Myin-Germeys, I., Delespaul, P., & Krabbendam, L. (2009). A systematic review and meta-analysis of the psychosis continuum: Evidence for a psychosis proneness–persistence–impairment model of psychotic disorder. Psychological Medicine, 39(2), 179–195. https://doi.org/10.1017/S0033291708003814

Zhu, C., Sun, X., & So, S. H. W. (2017). Associations between belief inflexibility and dimensions of delusions: A meta-analytic review of two approaches to assessing belief flexibility. British Journal of Clinical Psychology, 56(1), 59–81.

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