Somatoparaphrenia is a type of delusion where one denies ownership of a limb or an entire side of one’s body. As an example, a patient would believe that her or his own arm would belong to the doctor, or that another patient left it behind. In the fifth episode of the fourth season of Grey’s anatomy, a man suffering from somatoparaphrenia, misdiagnosed as body dysmorphic disorder, wants the doctors to amputate his foot because it does not belong to him.
4. Ekbom Delusions
Delusional parasitosis ; also known as “Ekbom syndrome,” is a form of psychosis whose victims acquire a strong delusional belief that they are infested with parasites, whereas in reality no such parasites are present. Very often the imaginary parasites are reported as being “bugs” or insects crawling on or under the skin; in these cases the experience of the sensation known as formication may provide the basis for this belief.
3. Mirrored Self-misidentification
Mirrored self-misidentification is the delusional belief that one’s reflection in a mirror is some other person (often believed to be someone who is following one around). Often people who suffer from this delusion are not delusional about anything else. In the 2008 film The Eye, Jessica Alba’s character experiences visions of paranormal experiences and suffers from mirrored self-misidentification, referred to in the story as cellular memory.
2. Capgras Delusion
The Capgras delusion is a state in which a person holds a delusion that a friend, spouse, parent, or other close family member has been replaced by an identical-looking impostor. The Capgras delusion is classified as a delusional misidentification syndrome, a class of delusional beliefs that involves the misidentification of people, places, or objects.
1. Subjective Doubles
The syndrome of subjective doubles is a rare delusional misidentification syndrome in which a person experiences the delusion that he or she has a double or Doppelgänger with the same appearance, but usually with different character traits and leading a life of its own. Sometimes the patient has the idea that there is more than one double. The syndrome is usually the result of a neurological disorder, mental disorder or some form of brain damage, particularly to the right cerebral hemisphere. Sometimes the delusion takes the form of a conviction that whole or part of the patient’s personality has been transferred into another person. In this case depersonalization may be a symptom. One example from medical literature is of a man who became depersonalized after an operation and was convinced his brain had been placed into someone else’s head. He later claimed he recognized this person.