Delusional Disorders

The development of one or more persistent delusions of persecution or jealousy

  • More common over the age of 40
  • More common in females
  • Stress may be a risk factor
  • Genetics is not a significant factor

Delusional disorders are rare, affecting only about 3 in 10,000 people worldwide. The main characteristic of these disorders is an irrational belief or set of beliefs that is not associated with other symptoms or caused by another mental illness, such as schizophrenia. These beliefs or delusions persist in spite of all rational arguments and evidence to the contrary. However, apart from behaviour related to the delusion, the person appears well, and work and relationships may not be affected.

There are several types of delusion, the most common of which is persecutory. People with this type of delusion believe they are being hounded or that somebody is trying to harm them. Extreme jealousy, in which a person has the unreasonable belief that his or her partner is unfaithful, is a common form.

Major life events, such as moving to another country, and long-term stress factors, such as poverty, may contribute to the development of delusions. A person who has a paranoid personality (see Personality disorders) is at an increased risk of delusions, as is a person who is alcohol dependent.

Delusional disorders usually develop insidiously, most often in middle age or late in life, and tend to occur more commonly in women than in men.

What might be done?

People with a delusional disorder are often suspicious or dismissive of others who are trying to help them. They may be reluctant to discuss their beliefs and unable to recognize that their delusions are irrational. Family members often seek medical advice on their behalf.

The doctor will look for additional symptoms in case delusions are being caused by another psychological illness, such as schizophrenia. The doctor will try to find out how firmly held or “fixed” the delusions are and whether the person is likely to act on them. If there is a risk of violence or self-harm, the person may need to be admitted to hospital, possibly without his or her consent.

Occasionally, an antipsychotic drug is used to reduce the intensity of severe delusions. Counselling may bring about a shift in perspective. Generally, delusional disorders tend to persist but without causing major disruption, although delusions of jealousy may pose a risk of violence to a partner.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

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