Delusion

A delusion is a fixed false belief. The person is completely convinced of it, and evidence or argument does not shift it. Common kinds include:

• Persecutory — being watched, followed, poisoned or plotted against
• Grandiose — having special powers, great wealth or a divine mission
• Jealous — certainty that a spouse is unfaithful without real grounds
• Reference — believing the TV, newspapers or strangers are sending personal messages

Beliefs shared by a person's community — about jinn, nazar or sehr, for example — are not delusions in themselves. Doctors look at whether a belief is out of keeping with the person's own background, held with unusual fixity, and comes with other changes in behaviour or signs of psychosisPsychosisA state in which a person loses some contact with reality — hearing or seeing things others do not, or firmly believing things that are not true. It is a symptom with many causes, and it is treatable.Read the full definition.

Arguing rarely helps and can break trust. Acknowledge the fear ("that sounds frightening") without agreeing with the content, and help the person see a doctor. Delusions occur in schizophreniaSchizophreniaA long-term mental illness that affects how a person thinks, perceives and feels, with periods of psychosis such as hearing voices or holding false beliefs. It is not a split personality.Read the full definition, bipolar disorderBipolar disorderA long-term condition with episodes of depression and episodes of abnormally high or irritable mood (mania or hypomania), usually lasting days to weeks, with more stable periods in between.Read the full definition, severe depressionDepressionA medical condition in which low mood or loss of interest lasts most of the day, nearly every day, for at least two weeks, and affects sleep, energy and daily life.Read the full definition and dementia, and usually respond to antipsychoticAntipsychoticMedicines that reduce psychotic symptoms such as hallucinations and delusions, mainly by blocking dopamine. They treat schizophrenia and mania, and are sometimes used for other conditions.Read the full definition treatment.