Another term for zoanthropy is “clinical lycanthropy.” Whatever you call it, it is an extremely rare mental illness in which a person sincerely believes that they are about to become an animal, or that they already are. Zoonthropia is unusual but very serious and usually appears with psychosis when someone loses all contact with reality. The word comes from the Greek roots zoion, “animal”, and anthråpos, “man”. Thirty-eight cases of clinical lycanthropy and cynanthropy were discovered between 1970 and 2020. The diagnostic breakdown of clinical lycanthropy and cynanthropy case reports is presented in Figure 1. The majority of reported cases were psychotic and affective disorders: schizophrenia, psychotic depression, mania (bipolar disorder) and other psychotic disorders. Clinical lycanthropy may occur during a first psychiatric episode in adolescents and young adults (patients 1, 5, 6, Table 1). It can also occur in patients with chronic psychosis. Some reported cases have been linked to neurological disorders, including epilepsy (12, 22, 33). Clinical lycanthropy has also been reported in association with hallucinogenic drugs, alcohol and epilepsy (40).

For example, Keck et al. reported three cases of zoanthropy with electroencephalogram abnormalities (29). Lycanthropy and cynanthropy are specific forms of zoanthropy. Zoanthropy is observed on several continents, and animals are as variable as lions, tigers, hyenas, sharks or crocodiles (4). During the examination of lycanthropy, we also found other cases of zoanthropy: snake processing in Lebanon (67), pig in India (86), wild boar in Germany (87), cow in the Middle East (17), frog and bee in Germany (88), gerbil, bird, cat, rabbit, tiger in the United States (29). The ecological and cultural context is a factor influencing the content of the illusion. For example, Garlipp et al. reported a 43-year-old male with a history of bipolar disorder who was allegedly transformed into a wild boar during alcohol poisoning (87). This deception occurred after actual contact with these animals.

When a person believes they have turned into an animal, they suffer from a disorder called zoanthropy. You might worry that your sister has zoanthropy if she only talks in meows — but she`s probably pretending to be a cat. We identified 43 case reports on clinical lycanthropy and cynanthropy (Table 1). A total of 130 articles were reviewed in the first search. Finally, 30 references were recorded and 43 cases identified. In the second part of the results, we present the neurobiological hypotheses of clinical lycanthropy. The third part of the results describes the cultural aspects highlighted in the medical literature. In Supplementary Table S1, we documented other cases of zoanthropy.

“Zoanthropy.” Dictionary, Merriam-Webster, Retrieved 8 October 2022. The oldest known writings mentioning lycanthropy are found in the Greek myth of Lycaon, king of Arcadia (78). The most famous case of zoanthropy is King Nebuchadnezzar II (605-562 BC), who endured delusional illusions for the processing of beef. Nebuchadnezzar`s animal transformation is mentioned in the Bible (Daniel 4; 29-31). In ancient Egypt, Anubis, god of death and inventor of embalming, is represented with the head of a jackal, or more precisely an African golden wolf (79). Interestingly, in ancient Egypt, Anubis and the lunar circle are depicted together, showing a very ancient association of human wolves with the moon (80). In Byzantine times, physicians explained lycanthropy as a type of melancholic depression or mania (81). In the Middle Ages and Renaissance, lycanthropy was often attributed to satanic powers. Cynanthropy was described in Late Byzantine antiquity, for example in the city of Amida (eastern Turkey) (82). Aetius of Amida devotes an entire chapter to lycanthropy and cynanthropy, emphasizing its clinical importance at this time (7).

In the Middle Ages and Renaissance, lycanthropy was often attributed to satanic forces (11). Belief in werewolves and other zoanthropic phenomena is still very present in some cultures, for example in Haiti, where the werewolf refers to women who transform at night and suck the blood of young children (83). Animal transformation can occur in the cultural context of traditional possession, rituals and therapies (84, 85). The animal is then both an incarnation and a totem. “Cenesthopathy” is a concept that conceives pathological perceptions of the body (41). Some case series suggest that cenestopathies are found in schizophrenia and psychotic depression, but may also be partially different from schizophrenia (42, 43). Psychopathological studies report that cenestopathies are linked to patients` “feelings of self-existence” and strangeness of thoughts (44). Cenestopathy is thought to be more common in adolescent men or middle-aged to older women (43).

Some cases of clinical lycanthropy can be thought of as cenesthopathy, which is linked to somatosensory aberrations that affect the body diagram (16). According to a study of 30 patients diagnosed with schizophrenia (73% men, mean age 31.5 years), cenesthopopathy is associated with cognitive abnormalities: thought initiative and mental intentionality disorders, receptive speech and subjective delay or pressure of thought (45). In the case of clinical lycanthropy, the theme of illusion would be secondary to somatic hallucinations, illusions of body patterns and/or perceived changes in physical appearance. Blom reported the case of a 26-year-old man who complained of increased hair growth, “hardening” of the jaws and facial muscles, changes in the oral cavity, and sores in the corners of the mouth due to the presence of fangs (patient 7, Table 1).