Can One Person Have Two Different Personalities?
Thanks to the movie Split, Dissociative Identity Disorder (DID) is gaining notoriety again, very few know that it is an existing mental illness
Despite being exploited endlessly by fiction since the literary classic Strange Case of Dr. Jekyll and Mr. Hyde came to light and then with the movie Split, very few people give the importance that this strange disorder truly deserves.
What Exactly is Dissociative Identity Disorder (DID)?
Personality change occurs when the individual is going through a stressful situation; it is believed that the disease is produced by failures in the integration of consciousness, perception, movements, identity, and memory, derived from psychological trauma.
In general, the true personality is passive and depressive, so it allows itself to be dominated by the rest. At the same time, many of your other personalities can be passive and manipulated by those of a hostile and dominant character.
Psychological Traumas
Multiple disorders are believed to be an extreme case of post-traumatic stress, where the person has suffered a lot and unconsciously chooses to forget everything, completely isolating their memories in different identities that will develop and become more complicated with the passage of time.

Is There a Treatment?
Dissociative Identity Disorder is the combination of many other diseases that can distract the specialist from the real disease that afflicts the patient. The individual presents post-traumatic stress, dissociative symptoms and other symptoms such as depression, poor diet, panic; drug abuse, etc, all of this makes it difficult to extract an efficient diagnosis.
Now, the treatment can also last years and is progressive, it will depend on the patient, how far he wants to go. It's about aligning all personalities and keeping them in check. Specialists usually place the person in a safe environment so that they avoid hurting themselves, then they try to find out the origin of the personalities, confronting the psychological trauma of the patient. Finally, the specialist knows all the personalities and ideas how to keep them under control, the person must accept that he has several personalities and learn to deal with them.
It is Dangerous?
It is true that there are cases, but nothing as extreme as murdering someone or forming a hellish fight club; an individual with multiple personalities may be more dangerous to himself than to outsiders; with being afraid of them no one wins, it is necessary to see it as a disease that needs to be treated as soon as possible and not to influence those who have it to hide for fear of being judged.

Cases of Dissociative Identity Disorder
A few years later, in the year 1816, another case appeared that was documented by Samuel Latham Mitchell. It was about a woman who was born in England but moved to the United States.
She was a shy and lonely young woman who after going through a state of blindness and total deafness for 6 weeks, completely changed her personality and became a totally outgoing and joking person. She could not write or read and could not recognize her family. Soon after, her primary personality reappeared and her personality changed over the course of fifteen years.
Doris Fisher was a woman who in 1917 was studied for developing up to five different personalities. Some days Doris's primary personality only manifested for five minutes a day. One of the personalities, which they named Margaret, was self-injuring to make the primary personality feel pain. In 1976 a film was released that would make known the multiple personality disease called Sybil. The film narrated the life of a woman with multiple personalities and who had more than 16 different types of personalities.
What Do The Experts Say?
On the other hand, the researcher Bernardo Kastrup, in an article published by the Journal of Consciousness Studies and the Scientific America magazine based on the so-called Dissociative Identity Disorder, cites a 2014 study in which brain scans were performed with functional magnetic resonance imaging - a technique that serves to observe the activity of the brain-, patients with DID and actors who recreated symptoms of this disorder.

It was thus shown that the brains of the people who suffered from DID were different from those of the actors, i. e., they did not emulate being others, but that they really were, for their brains.
In 2015, a group of German doctors reported a case that illustrates this well. The brain of a sighted woman suffering from multiple personality disorder, and who had blind alterations, was analyzed. It was found that, when one of these alter-egos predominated in women, the activity of her brain was that of a blind person. Instead, when the woman returned to "her being", which she saw, her brain activity reverted to that normally associated with her sight.
March 5th is observed as Dissociative Identity Disorder Awareness Day in an effort to increase awareness of and education about DID.