Délire monothématique

A monothematic delusion is a delusional state that concerns only one particular topic. This is contrasted by what is sometimes called multi-thematic or polythematic delusions where the person has a range of delusions (typically the case of schizophrenia). These disorders can occur within the context of schizophrenia or dementia or they can occur without any other signs of mental illness. When these disorders are found outside the context of mental illness, they are often caused by organic dysfunction as a result of traumatic brain injury, stroke, or neurological illness. People who experience these delusions as a result of organic dysfunction often do not have any obvious intellectual deficiency nor do they have any other symptoms. Additionally, a few of these people even have some awareness that their beliefs are bizarre, yet they cannot be persuaded that their beliefs are false. Some delusions that fall under this category are: Capgras delusion: the belief that (usually) a close relative or spouse has been replaced by an identical-looking impostor. Fregoli delusion: the belief that various people whom the believer meets are actually the same person in disguise. Intermetamorphosis: the belief that people in one's environment swap identities with each other while maintaining the same appearance. Subjective doubles: a person believes there is a doppelgänger or double of themselves carrying out independent actions. Cotard delusion: the belief that oneself is dead or does not exist; sometimes coupled with the belief that one is putrefying or missing internal organs. Mirrored-self misidentification: the belief that one's reflection in a mirror is some other person. Reduplicative paramnesia: the belief that a familiar person, place, object, or body part has been duplicated. For example, a person may believe that they are, in fact, not in the hospital to which they were admitted, but in an identical-looking hospital in a different part of the country. Somatoparaphrenia: the delusion where one denies ownership of a limb or an entire side of one's body (often connected with stroke).