Intermetamorphosis is a delusional misidentification syndrome, related to agnosia. The main symptoms consist of patients believing that they can see others change into someone else in both external appearance and internal personality. The disorder is usually comorbid with neurological disorders or mental disorders.
An example from medical literature is a man who was diagnosed with Alzheimer's disease. After some time he mistook his wife for his deceased mother and later for his sister. As an explanation, he stated that he had never been married or that his wife had left him. Later he mistook his son for his brother and his daughter for another sister. Visual agnosia or prosopagnosia were not diagnosed, as the misidentification also took place during phone calls. On several occasions he mistook the hospital for the church he used to go to.
The disorder was first described in 1932 by P. Courbon and J. Tusques (Illusions d'intermétamorphose et de la charme), in the Journal: Annales Medico-Psychologiques issue 14, page 401-406.