A delusion is a belief that is obviously false, indicating an abnormality in the thought process. The key feature of delusion is the extent to which a person believes the delusion is true. A person experiencing a delusion will be firmly convinced that what they think is correct, despite evidence to the contrary.
Several risk factors increase the risk of delusion developing and some of these include:
Delusions are indicative of a neurological, medical or mental disorder and some of the conditions in which they may present include the following:
Delusions are either described as bizarre or non-bizarre. A bizarre delusion is completely implausible such as believing aliens have removed a part of your brain, for example. A non-bizarre delusion is a belief that is clearly mistaken, but is at least potentially possible such as believing police or spies are watching you.
Delusions are also categorized as either mood-congruent or mood-incongruent. A delusion that is mood congruent is one that is consistent with a manic or depressed state. For example, someone with mania may decide they are famous or have special talents and someone with depression may believe the world is coming to an end. A mood-incongruent delusion is not consistent with one of these states and is instead mood neutral. For example, a person with depression may believe outsiders are inserting thoughts into their mind and they do not recognize these thoughts as their own.
Delusional disorder is a form of psychosis where a person cannot differentiate between what is imagined and what is real. The main feature of the condition is the presence of non-bizarre delusions such as being followed, deceived, cheated, poisoned or conspired against. Affected individuals can often socialize and function in a normal way, apart from the subject of their delusion and do not exhibit obviously strange behavior. However, some people can become so obsessed with their delusion that it does start to cause disruption in their life.
Although delusions may occur as a symptom of disorders such as schizophrenia, delusional disorder itself is uncommon. It is slightly more common among women than men and usually affects individuals who are middle-aged or older.
The main types of delusional disorder are described below:
The exact cause of delusional disorder is not yet clear, but researchers have been investigating the role that different biological, genetic, physiological or environmental factors might play. These are described below.