Updated 11 February 2013


Delusions can be defined as false beliefs that are firmly held despite evidence and argument to the contrary.

Delusions can be defined as false beliefs that are firmly held despite evidence and argument to the contrary. Persecutory delusions, a belief that you are being followed, watched, tormented or ridiculed, is the most common type.

Delusions are considered “bizarre” if they are obviously implausible and not derived from ordinary life experiences, such as believing you are a visitor from another planet or that there is a monster living inside your head. Believing you are being followed by the police would be considered non-bizarre.

It is classified as a symptom of psychosis, an abnormal mental state characterised by loss of contact with reality. Psychotic disorders are mental illnesses in which symptoms of psychosis are experienced, and include disorders such as schizophrenia, delusional disorder, schizophreniform disorder, paranoid personality disorder, schizoaffective disorder and bipolar disorder (formerly known as manic depressive illness).

What causes delusions?
The cause remains unknown. What has been found is that there can be an accumulation of associated factors, some of which appear to be risk factors. Given that psychosis is associated with a variety of medical conditions, it is likely that a number of psychological, social and biological factors are involved in its development.

Who is at risk?
People are at higher risk of developing psychotic disorders if they have:

  • A family history of psychotic disorders.

  • Substance abuse problems, especially substances like cannabis, methamphetamine (tik), cocaine and Ecstasy.

  • A schizotypal or paranoid personality disorder (personality disorders characterised by odd beliefs, peculiar behaviour and speech or longstanding suspiciousness and mistrust of people).

  • A history of a head injury or other conditions which affect the brain e.g. multiple sclerosis or a brain tumour.

How is it diagnosed?
All psychotic disorders can be diagnosed by any mental health professional or general practitioner. A full psychiatric assessment and physical examination are the main methods used to help make the diagnosis.

How is it treated?
Treatment varies depending on the cause, but usually consists of a combination of medication, education, support and counselling. It is possible to control most psychotic disorders with appropriate long-term treatment. Care in a hospital is sometimes necessary during the acute phase. Involvement and support of the family will facilitate the treatment and recovery process.

When to see a doctor
Call your doctor or mental health professional without delay if a friend or family member becomes delusional or if any other symptoms suggestive of psychosis develop.

Where to go for help
Cape Support for Mental Health gives support to families of people affected by psychosis and other prolonged mental illnesses.


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