Several cultures and religions round the globe carry a belief that the humans are capable of being possessed or inhabited by spirits and even the goddess. The ministry of different religions have formulated a set of procedures called exorcism for casting or expelling out the spirit. It comprises of but is not limited to reciting holy hymns or mantras, sprinkling holy water, using religious signs and amulets, burning incense, blowing conches (sankha) or causing physical discomforts like fasting or slapping the skin of the possessed person.
In the middle ages, demonic possession became a major concern of the church. Anyone found showing signs of unusual behavior or change in the personality was assumed to be possessed by the devil. In 1614, the catholic church issued the “Rituale Romanum” to standardize procedures of exorcism which have been revised for use in modern day.  Similarly exorcism have been frequently mentioned in Hinduism, Islam and Buddhism. Sikhism and Jainism, are infact, the only major religious faiths that do not allow for the possibility of spirit possession.
The cross-cultural presentation of demonic possession is variable to the extent that there is no single psychiatric disorder that fits all. There are case reports where drug resistant cases of possession syndrome have been cured by exorcism and exorcism-resistant possession have been treated with psychotherapy and anti-psychotic drugs suggesting the need for combining religious perspective with the current scientific perspective.
Possession like states are commonly seen in:
1. Multiple personality (dissociative identity) disorder: In DID, the person is dominated by two or more mutually distinct (often even opposing) personalities, each with a full range of higher mental functions and complex behavior patterns, of which only one is being manifest at one time. Usually one personality is not aware of the existence of the other(s) i.e. there are amnesic barriers between the personalities. The reported ranges of personality is from 2 to 100 (mostly 10 or less).
2. Dissociative Trance disorder: It is characterized by a sudden alteration in consciousness not accompanied by distinct alternative identity. Dissociative trance phenomena frequently involve sudden extreme changes in sensory and motor control. Typically, the individual starts to shake convulsively, hyperventilate, scream and show agitation and aggressive movements. These behaviors may be followed by collapse and loss of consciousness. Afterward, such individuals report being exhausted and may have some amnesia for the event.
3. Possession disorder: If a new identity (spirit, ghost, deity, divine power, or ancestor) takes over the control of person’s personality during the episodes, the condition is called as possession disorder. Usually the person is aware of the existence of the other (i.e. possessor) unlike, in multiple personality disorder. The person in this disorder often engages in complex activities, which may take the form of expressing otherwise forbidden thoughts or needs, negotiating for a change in family or social status, or engaging in aggressive behavior. Dissociative trance and possession disorder are the most prevalent dissociative disorders in India accounting for approximately 3.5% of psychiatric admissions.
4. Conversion disorder: The root for conversion disorder lies in trauma, post-traumatic stress disorder, adaptation to a frustrating life experience, pattern of communicating helplessness facilitating a secondary gain, etc. The major symptoms of hysteria are somnambulism, double personalities, convulsive attacks, contractures, paralyses, anesthesia and hysterical stigmata, as well as disturbances of speech, vision, alimentation and respiration.
5. Schizophrenia: Some psychiatrists have noted a high prevalence of “possession states” among schizophrenics. In the past 200 years, before hallucinations (perceptual experiences in the absence of external stimuli) were regarded as a sign of mental illness, they were rather interpreted as messages from god (divine intervention) or from the devil (demonic possession). Passivity experiences or delusions of control, subjectively are experienced as states of possession by powers outside oneself.
6. Bipolar psychosis: Bipolar disorder may be characterized by rapid and uncontrolled cycling between the two extremes of the mood – mania and depression. Bipolar psychosis or maniac-depressive psychosis presents with auditory and visual hallucinations combined with states of euphoria, catatonia and grandiose delusional beliefs.
7. Phencyclidine (Angel dust) use: Media reports presented phencyclidine (PCP) almost in terms of demonic possession. It creates dissociation of cortex from the limbic system just like the popular anesthetic – ketamine. PCP provides a feeling of euphoria, feelings of detachment from the world, strength, power, and even invulnerability. PCP overdose often presents with psychiatric manifestations that include violent behavior, psychosis, paranoia and hallucinations.
8. Malingering: Possession states have been found to be feigned for motives of different kind since past when the people around are easily influenced.
However, extraordinary phenomena like sudden ability to understand foreign languages one has never studied, display of abnormal physical strength, knowledge of hidden things or levitation (hovering in air) that are mentioned in the books of exorcists are not clearly explainable by the medical science.
The movies in horror genre have frequently adapted the themes of possession and exorcism for decades and still fascinating the audience. Hollywood movie “Exorcism of Emily Rose” based on a tragic story of a German girl Anneliese Michel (1952-1976) and Indian Malayalam movie “Manichitrathazu” remake “Bhool Bhulaiya” which is also thought to be inspired from true story of Alumoottil Tharavadu were widely appreciated for presenting interesting insight into a culture’s religious, medical and legal principles.
“And never mind that noise you heard
It’s just the beasts under your bed
In your closet in your head” – Enter Sandman (Metallica)
 The Encyclopedia of Demons and Demonology By Rosemary Guiley
 Religion, Belief and Social Work: Making a Difference By Sheila Furness, Philip Gilligan
 Gallagher RE. Among the Many Counterfeits: A Case of Demonic Possession. New Oxford Review ;2008.
 Hale AS, Pinninti NR. Exorcism-resistant ghost possession treated with Clopenthixol. The British Journal of Psychiatry. 1994; 165: 386-388.
 Psychiatry, 2 Volume Set edited by Allan Tasman, Jerald Kay, Michael B. First, Jeffrey A. Lieberman, Michelle Riba
 Forensic Science: An Introduction to Scientific and Investigative Techniques edited by Stuart H. James, Jon J. Nordby, Suzanne Bell, Jon J. Nordby, Ph.D.
is currently working as a medical officer at a Government Hospital in Nepal. He searches for and share simpler ways to make complicated medical topics simple. He also loves writing poetry, listening and playing music and travelling.