Evidence of multiple personality is not a new development of the twentieth century. In fact, evidence of multiple personality is said to exist in the images of shamans changed into animal forms or embodying spirits in Paleolithic cave paintings(1). Throughout recorded history cases of demonic possession have been reported that many experts now believe are cases of of multiple personality(2). Beginning in the eighteenth century, more detailed accounts in terms of multiple personality being a mental condition began appearing. 

Eberhardt Gmelin is sometimes credited as being the first to report a case of multiple personality(3). However, there are reports of an earlier account by Paracelsus who wrote of a woman who had amnesia about an alter personality who stole her money in 1646(4). Nevertheless, Gmelin's 1791 account of "exchanged personality" is very important as the first account of multiple personality written about in great detail(5). The case involved a 20-year-old woman living in Stuttgart who began to speak perfect French, behave like a French aristocrat and spoke German with a French accent. This took place the year the French Revolution began which is significant since, during the uprising, many French aristocrats left France and fled to Stuttgart. When she was the "French Woman" she remembered everything she did but as the "German Woman" she denied any knowledge of the "French Woman". Gmelin claimed he could cause the personalities to switch from one to the other with a movement of his hand(6). 

Around the same period of time, Benjamin Rush collected case histories of dissociation and multiple personality(7). Rush, chief surgeon of the Continental Army(8), is recognized as the "Father of American Psychiatry"(9). He wrote the first American text of psychiatry, "Medical Inquiries and Observations Upon Diseases of the Mind", published in 1812(10). Rush is also the only man who signed both the Declaration of Independence and the United States Constitution(11). He theorized that the cause for the doubling of consciousness related to a disconnection between the two hemispheres of the brain, the first of many speculations about this possibility(12). 

However, it is the case of Mary Reynolds, first published in 1816 in "Medical Repository" by Dr. Samuel Latham Mitchel that was more influential of these early cases(13). It also appears to be the first case to capture the attention of the public with accounts appearing in an article in "Harper's New Monthly Magazine" in 1860 and an autobiography by Mary Reynolds herself(14). Ms. Reynolds was born in England in 1785 and moved with her family to Meadville Pennsylvania. The atmosphere she was raised in was described as strongly religious and, as a child, she seemed melancholy, shy and given to solitary religious devotions and meditations. She was considered to be normal until her late teens. At 19, she became blind and deaf for five or six weeks. Three months later she awoke after sleeping eighteen to twenty hours seeming not to know things she had learned. Within a few weeks, however, she became familiar with her surroundings and learned reading, calculating and writing although her penmanship was crude compared to what it had been previously. Her personality at this time was described as "buoyant, witty, fond of company and a lover of nature". After about five weeks, she slept again and awoke as her prior self with no memory of what had happened(15). This new state alternated with the original one at varying length for fifteen or sixteen years until her mid thirties when the alternations stopped and she remained in the second state until her death at 61 years of age. Mitchell confirmed the account about Mary Reynolds with her relatives, the Reverend Dr. John V. Reynolds and his brother William Reynolds(16). 

Estelle's case, described in a 1840 monograph by Despine, involved an 11-year-old Swiss girl who initially presented with paralysis and exquisite sensitivity to touch and later developed a second personality who could walk, play and could not tolerate her mother's presence. Estelle exhibited marked differences in behavior, preferences and relationships between the two personality states. Despine reported being able to cure the child through treatment principles, some of which are recognized as valid today(17). 

In the late 19th century, Eugene Azam, a professor of surgery interested in hypnotism, published a number of reports of Felida X, an extensively documented case of multiple personality he followed for over 35 years(18). Felida X was born in 1843, lost her father in infancy and had a difficult childhood. She exhibited three different personalities, each considering itself to be Felida's normal state and the others to be abnormal. The second personality state first manifested when Felida was 13 years old and suffered none of the physical illnesses that the first personality suffered. Initially, switching was reported to happen almost every day after a pain in the temple and a profound sleep for two to three minutes but the frequency of switching decreased over time to the point that it would happen only every 25 to 30 days and last only a few hours at a time. The third personality, which appeared only on occasion, suffered from anxiety attacks and hallucinations. At one point, the first personality was pregnant without explanation and the second personality emerged and took responsibility for the pregnancy. 

During the late 19th century and early 20th century, Pierre Janet described a number of case of multiple personality including the cases of Leonie, Lucie, Rose, Marie and Marceline(19). Leonie appeared to have three or more personality states including a child alter named Nichette, a childhood name. In the case of Lucie, who also reportedly had three personality states, there was an alter personality named Adrienne who would seem to experience flashbacks of a traumatic childhood event. In the case of Rose, she would suffer from a variety of somnambulistic states. In some, she was paralyzed and in others she was able to walk. 

In 1906, Mortin Prince published the account of the Christine Beauchamp case in "The Dissociation of a Personality"(20). Miss Beauchamp was found to have three additional personality states including one calling herself Sally who was childlike and differed significantly from Miss Beauchamp's presenting personality, one that was very much like the presenting personality and one called the Idiot that was extremely regressed(21). 

The published case literature on multiple personality during the 19th century and the early part of the 20th century would probably occupy several volumes(22) and yet the condition was declared "extinct" by E. Stengel in 1943(23). This has been explained by one writer as follows "French-speaking psychiatry dominated the English-speaking world during the 19th century; German-speaking psychiatry has dominated much of the 20th"(24). Yet only a few months after the condition was declared extinct, a landmark paper was published in the journal founded by Morton Prince now called "The Journal of Abnormal Psychology" which "was the most quoted reference in the history of the illness"(25). Thereafter, there was a virtual blackout in the publication of accounts of multiple personality until the 1954 publication in Prince's journal of the case of Christine Costner Sizemore. In 1957, the Sizemore story was popularized by Corbett Thigpen and Hervey Cleckley(26) in "The Three Faces of Eve". The story was adapted for film with Joanne Woodward playing the title role for which she won the Best Actress Oscar. Viewed as extremely rare and bizarre at the time of this popularized account which fascinated audiences, the condition is now considered highly treatable and not nearly as rare as it was once thought. 

The re-emergence of multiple personality begins with the publication by H. Ellenberger's extensively researched "The Discovery of the Unconscious: The History and Evolution of Dynamic Psychiatry" which devoted attention to dissociation and multiple personality(27). Throughout the 1970s, a number of clinicians worked toward defining and establishing the legitimacy of the condition. Margareta Bowers along with six other contributors published "Therapy of Multiple Personality" in 1971. "Therapy of Multiple Personality" has been called "brilliant" and outlines rules for treating multiple personalities which are still used today(28). Cornelia Wilbur, M.D. (who treated Sybil) and others at the Department of Psychiatry at the University of Kentucky published a series of case reports and papers during the 1970s(29). The efforts of pioneers such as Ralph B. Allison, Dr. Wilbur, and David Caul, M.D. led to the availability of workshops on multiple personality thereby increasing the number of clinicians able to diagnose and treat the condition(30) leading to greater numbers of clinicians studying and treating the condition. 

However, it is the case of Sybil Isabel Dorsett which is considered "the most important clinical case of multiple personality in the twentieth century"(31). It is certainly one of the most famous after the publication of the book "Sybil : The true story of a woman possessed by sixteen separate personalities" by Flora Rheta Schreiber which was a best seller. The television movie "Sybil" starring Sally Field and Joanne Woodward put Lorimar Productions "on the map"(32). Sybil was the vicitm of horrific abuse inflicted on her by her psychotic mother. Her father failed to protect her from it. As a result, she developed the alter personalities which embodied feelings and emotions the 'real' Sybil could not cope with. The waking Sybil was deprived of all these emotions, and was therefore a rather drab figure. She was unaware of her other personas; while they were in 'control' of the body, Sybil suffered blackouts and did not remember the episodes(33). Cornelia Wilbur helped Sybil integrate the personalities after sixteen years of therapy. Dr. Wilbur invited Schreiber to write the popularized account after being denied publication of the story in professional journals(34). 

The case of Sybil is signficiant in several respects. Sybil's psychiatrist, Cornelia Wilbur, went to great lengths to validate the accounts of abuse including interviews with Sybil's parents, a visit with Sybil to her childhood home, and speaking with Sybil's doctor and reviewing his records(35). The case firmly linked multiple personality disorder with child abuse(36). The graphic treatment of the amnesia, fugue episodes and conflicts among alters in Schreiber's book "served as a template against with other patients could be compared and understood(37). Dr. Wilbur's therapy which included hypnosis and other therapeutic interventions and produced a successful resolution "served as an example for many multiples and their therapists"(38). 

In 1980, the decade of work by the pioneers in the field of multiple personality culminated in the publication of the DSM-III by the American Psychiatric Association in 1980. The DSM-III created a separate category for the dissociative disorders and set forth the criteria for a diagnosis of Multiple Personality Disorder(39) giving legitimacy to the condition. Since then, there has been a virtual explosion in the publication of journals, books, biographical accounts, etc. In 1980 there were a number of landmark publications including E. L. Bliss' study of fourteen patients, P. M. Coons systematic treatment of making a diagnosis, G. B. Greaves "classic" review article, B, G. Braun's treatment recommendations and S. S. Marmer(40) psychoanalytic study. In 1984, four journals devoted special issues to discussion of multiple personality disorder(41). In 1989, Frank W. Putnam of the National Institutes of Mental Health published "Diagnosis and Treatment of Multiple Personality Disorder" in 1989 and Colin A. Ross, a noted clinician and researcher, published "Multiple Personality Disorder: Diagnosis, Clinical Features, and Treatment". 1994 was another landmark year in the field of multiple personality with the publication of the DSM-IV which renamed the condition Dissociative Identity Disorder (DID) and the publication of "Guidelines for Treating Dissociative Identity Disorder In Adults" by the International Society for the Study of Dissociation. During this same time period, screening instruments, structured diagnostic instrument, and a specialized mental status examination have been developed(42). Given the increasing availability of information to the general public and clinicians, the development of screening and diagnostic instruments, and the intensity of debate surrounding the controversies surrounding Dissocitive Identity Disorder, it seems likely that the future will bring continued growth in our understanding and ability to treat it. Yet even today there are still professionals in the mental health fields who continue to believe that Dissociative Identity Disorder is not a legitimate pscyhiatric diagnosis(43). 

Source: http://www.fortea.us/english/psiquiatria/history.htm#_2