A delusion is a fixed false belief that persists despite clear evidence to the contrary and is not explained by a person's cultural or religious background. Delusions are a hallmark symptom of psychotic conditions including schizophrenia, schizoaffective disorder, and delusional disorder. Understanding the different types helps with accurate diagnosis and appropriate treatment — different types appear in different conditions and respond to different therapeutic approaches. If you or someone close to you is experiencing delusional thinking, contact the Cadabam's team for an assessment.
What Are the Main Types of Delusions?
The DSM-5 and ICD-11 recognise several primary types of delusions, classified by the content of the false belief. Seven main categories appear consistently across psychiatric literature. Persecutory delusions are the most common across psychotic conditions — they occur in up to 50% of schizophrenia cases.
The sections below cover each of the seven main types in turn, followed by the conditions they appear in and how they are treated.
1. Persecutory Delusions (Most Common)
Persecutory delusions are the most prevalent type. The person holds a fixed belief that they are being watched, followed, poisoned, harassed, or conspired against.
Typical examples include the belief that neighbours are spying through walls, that coworkers are plotting to get them fired, or that food is being tampered with. The fear and distress are genuine — the person is not pretending. Persecutory delusions appear most often in paranoid schizophrenia and delusional disorder, and also in severe depression with psychotic features.
2. Grandiose Delusions
Grandiose delusions involve an inflated, false belief in one's own importance, power, wealth, genius, or special connection — often to a deity or historical figure.
Examples include believing one has a secret world-saving mission, possesses superhuman abilities, is the rightful heir to a kingdom, or is a famous person in disguise. Grandiose delusions occur in schizophrenia, bipolar disorder during a manic episode, and delusional disorder (grandiose type). They are often less distressing to the person experiencing them than persecutory delusions, but they cause significant social and occupational impairment.
3. Somatic Delusions
Somatic delusions centre on the body — the false belief that the body is diseased, infested, malformed, or not functioning correctly, despite clear medical evidence to the contrary.
Common examples include believing the body is infested with parasites or insects, that internal organs are rotting, or that a body part has changed shape. Somatic delusions are seen in delusional disorder (somatic type) and in severe depression with psychotic features. They are often deeply distressing and lead to repeated medical investigations before a psychiatric cause is identified.
4. Erotomanic Delusions (De Clérambault'S Syndrome)
Erotomanic delusions involve the fixed false belief that another person — usually of higher social status — is secretly in love with the individual.
The "target" is often a celebrity, public figure, employer, or distant acquaintance. The person interprets ordinary behaviour as coded signals of love. In some cases this leads to stalking behaviour, repeated unwanted contact, or legal trouble. For a deeper look at this condition, see our guide to erotomania.
5. Jealous Delusions (Othello Syndrome)
Jealous delusions are the pathological, fixed belief that a romantic partner is being unfaithful, despite no real evidence.
This is not the same as ordinary jealousy. The conviction is unshakeable and does not respond to reassurance, evidence, or rational discussion. The person may go to great lengths to "catch" the partner — surveillance, repeated questioning, or examining belongings. Othello syndrome is associated with alcohol use disorder, Parkinson's disease, dementia, and psychotic disorders. It carries real safety risks for the accused partner.
6. Referential Delusions
Referential delusions involve the belief that external events, people, or media are sending special messages directly to the person.
Examples include believing that a news anchor is speaking to them personally, that song lyrics on the radio contain coded instructions, or that strangers' offhand comments are full of hidden meaning. Referential delusions are a common early symptom in schizophrenia — they may appear before more dramatic symptoms and are often missed.
7. Nihilistic Delusions
Nihilistic delusions involve the false belief that the self, others, or the world does not exist or is about to be destroyed.
A specific severe form is Cotard's delusion, in which the person believes they are dead, that parts of their body have ceased to exist, or that their internal organs have stopped functioning. Nihilistic delusions are seen most often in severe depression with psychotic features, and they require urgent psychiatric assessment because of the associated suicide risk.
What Conditions Cause Delusions?
Delusions are symptoms of underlying conditions, not standalone diagnoses. The most common conditions in which they appear are:
- Schizophrenia — particularly the paranoid presentation, where persecutory and referential delusions are common.
- Schizoaffective disorder — combining mood disturbance with delusions.
- Delusional disorder — non-bizarre delusions without other prominent psychotic symptoms.
- Severe depression with psychotic features — typically nihilistic, somatic, or guilt-themed delusions.
- Bipolar disorder — grandiose delusions during mania, nihilistic during severe depression.
- Dementia, especially Alzheimer's — persecutory delusions about theft or partner infidelity.
- Substance-induced psychosis — from stimulants, cannabis, alcohol withdrawal, or hallucinogens.
How Are Delusions Treated?
Delusions respond best to combined medication and therapy.
Antipsychotic medication is the primary treatment. Second-generation antipsychotics such as risperidone and olanzapine target delusions across most underlying conditions. CBT for psychosis (CBTp) helps the person gently examine the evidence for their beliefs without direct confrontation — direct argument tends to entrench delusions rather than weaken them. Family psychoeducation helps loved ones respond in ways that support rather than escalate. Inpatient care during acute episodes provides safety and rapid stabilisation. One of the central clinical challenges is engaging someone in treatment when they do not believe they are unwell — Cadabam's team has long experience with this delicate work. You can contact our team to begin.
Why Choose Cadabam'S Hospitals?
Cadabam's psychiatrists specialise in diagnosing and treating psychotic disorders, including schizophrenia and delusional disorder. Comprehensive care includes medication management, CBT for psychosis, family support, and long-term rehabilitation across Bangalore, Hyderabad, and Mysore. To begin, contact our team or explore our centres.