You can see about the phenomenon of dissociation and its types and manifestations here:

Definition. DID is an extreme case of dissociative pathology (on the dissociative continuum) that includes all the major features of other major dissociative disorders.

DID is characterized by the presence of two or more separate personalities or Ego states that alternately seize control over behavior with amnesisation of a large amount of information, which is difficult to attribute to forgetfulness.

Prevalence varies according to various sources from 0 to 2.3% of the total population (based on 33 samples in different countries of the world, 1989-2006).

Diagnostic criteria .

• Having two or more separate identities or personality states;
• Causes clinically significant distress of the body’s functioning and disturbances in professional, social and other significant areas of life;
• Personality disorder is not part of accepted religious and cultural practices, or part of the child’s normal fantasies;
• Amnesia between individuals;
• Dissociation is not caused by the action of surfactants and somatic pathology.

In ICD-10 «Multiple personality disorder» coded by code F44.81 and belongs to the group «Stress-related neurotic and somatoform disorders». «The following criteria are highlighted:

• There must be two or more personalities that do not manifest at the same time;
• Each personality has its own individuality, memory;
• Personality changes can occur suddenly and are triggered by a traumatic event;
• Personality changes are usually accompanied by amnesia;
• Organic pathology must be excluded».

In ICD-11 (beta) Dissociative identity disorder identified as an independent group disorder «Dissociative Disorders» under code 7B35.

Clinical manifestations . In the clinical picture of DID, there are symptoms of psychogenic amnesia, and episodes of fugue, and states of deep depersonalization..

The original personality is called the master personality. In the theory of structural dissociation, in this case, one speaks of «outwardly normal personality» (VNL).

The number of alternative identities in DID varies, in some cases their number reaches 45-50. The quality of existence of such identities varies greatly from solid, stable and complexly organized to fragmented, amorphous and fleeting; a separate identity may, for example, never «float up» and is only mentioned by other alternate personalities.

Alternative identities may know each other or deny the existence of each other, may have a different gender, nationality, image, style, voice, etc. Ego states have different functions.

If one personality dominates, but other personal states with their own system of values ​​and picture of the world periodically invade, then they talk about «Complex Dissociative Invasion Disorder».

Multiple personality – it is a chronic disorder that does not have definite time boundaries, and which can last a lifetime, while the specific manifestations of this disorder to one degree or another depend on the duration of the disease and the individual characteristics of the patient.

Diagnostics: difficulties and peculiarities. Diagnosis of DID is a very difficult task, since the clinical manifestations are rather masked and polymodal. Above we have considered «bouquet» disorders accompanying DID, and «isolate» out of it, DID is pretty tricky.

Additional DID indicators (markers), which the doctor can observe during the observation of the patient:

• Chaotic behavior style;
• Sudden mood swings;
• Forgetfulness of time intervals from life without the presence of organic pathology;
• Skipping appointments without any reason or explanation (including therapy);
• Amnesia of part of the childhood period;
• Conflicting information when re-taking anamnesis.

• Dissociation: thoughts and feelings are controlled as if «from the side», that others can read them and that voices comment on their actions (this is caused by the disintegration of the personal system);
• Auditory pseudo-hallucinations, but unlike schizophrenia, they last a lifetime and do not cause loss of reality;
• The presence of self-destructive tendencies in the medical history: suicidal attempts or SPP (self-harming behavior);

• Dissociation Experience Scale (DES) for assessing the severity of dissociative phenomena in both clinical and normal populations (https://www.b17.ru/tests/208/);
• The Questionnaire of Experiences of Dissociation (QED) consists of 26 questions covering a wide range of dissociative phenomena;
• The Peritraumatic Dissociation Questionnaire (OPD) consists of 9 questions, each of which is assessed on a 5-point Likert scale. Designed for subjective assessment of dissociative symptoms caused by experiencing a traumatic event (https://www.b17.ru/tests/210/);
• Dissociative Disorders Interview Schedule (DDIS). A highly structured interview designed to diagnose both dissociative disorders and depression, borderline disorder, etc.;
• Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D) according to the DSM-IV classification. It allows you to diagnose all Dissociative Spectrum Disorders.

Comorbidity. Individuals with DID, in addition to symptoms specific to this disorder, have most of the symptoms present in the clinical picture of other psychiatric disorders. Also, the specificity of dissociation and the presence of trauma at the base, «pushes» on «close» mental disorders.

• Depression (up to 88% of people with DID have symptoms of depression);
• Suicidal attempts (75%) and self-injurious behavior (35%, maybe higher, but due to amnesia is not recalled in self-reports and interviews);
• Insomnia, PTSD-like nightmares;
• Dissociative symptoms (amnesia – 98%, fugue episodes – 55%, depersonalization – 53%, somnambulism – twenty%);
• Anxiety and phobias. They can be both independent disorders and predictors of switching between ego states;
• Addiction (third persons with DID abuse surfactants);
• Hallucinations (auditory and / or visual);
• Thinking disorders caused by a crisis in the personality system, the essence of which is that none of the alter personalities is able to take control over the behavior and maintain its authenticity. Delirium is possible (20%), caused by the belief in the independence of any of the alter personalities or the idea of ​​control;
• Catatonia (14%);
• Transsexualism and transvestism, due to the fact that some alter personalities are of the opposite sex;
• Headache.

Etiology. The most likely development of DID, according to authoritative researchers of this phenomenon (Putnam, Ross, Schultz, etc.), is a history of violent trauma (sexual abuse) or the fact of neglect of parents or significant environment.

There is ample evidence that DID – a type of PTSD. It is easy to imagine a mechanism by which the identity system in the form of dissociated subsystems can perform important adaptive and coping functions of an individual who was severely and repeatedly traumatized in childhood, who experienced sexual abuse, especially in the case of incest..

Is DID possible in the absence of a history of severe childhood trauma? In theory, yes. Some theorists (Butler, Kilstrom, Klinsky) highlight personality traits that contribute to the emergence of dissociation, such as high hypnotizability, inner focus of attention (self-focus) and a tendency to fantasize..

DID therapy. The main challenge in DID therapy is integration (unification of previously isolated alternative personalities and their merger with the personality-owner) with the aim of disappearing alternative identities or significantly weakening their power.

Klaft offers a three-step DID therapy model:

• Stabilization . The client and the therapist establish contact in order to stabilize the client’s psychological status and eliminate stressful influences that can provoke the emergence of new personal states;
• Recycling trauma and resolving dissociative defense mechanisms . At this stage, it is necessary to solve three problems: a) begin to effectively eliminate amnesia and the tendency to switch from one state of identity to another; b) turn to dissociative memories and understand them, combining them with the actual state of affairs; c) restore connections between different, outwardly isolated, personal states;
• Post-integration therapy . The stage of recovery and compensation of numerous defects left by years of adaptation to different personal conditions.

Frank Putnam in his book «Diagnosis and Treatment of Multiple Personality Disorder» adheres to a similar model and distinguishes the following techniques when working with DID:

• Pronouncing. An appeal to the personality system as a whole, to all individuals at the same time. This saves time and energy, forms the co-consciousness of the entire personality system;
• Reconstruction of a complete picture by fragmentsmemories. In individuals with DID, the memory of the traumatic experience either belongs entirely to only one single alter personality, or is fragmented among some personality states. It takes time and effort to interview as many alters as possible;
• Cross-sectional survey. The idea is to ask each of the patient’s alters for details of what she believes the strengths and weaknesses of the other alters are. This method allows alters to: 1) realize the adequacy of the behavior of other alters despite their opinions about each other; 2) realize that different qualities of alter personalities complement each other, which increases the effectiveness of the response of the personality system as a whole; 3) the shortcomings of one alter personality are compensated by another. This technique integrates well all personality states into one system, which is important for DID therapy;
• Working with dreams. Dissociated and rejected experiences find their expression in dreams, which can help in the formation of a general picture of the entire personality system;
• Work with / through «Internal assistant». «Internal assistant (s)» – personality condition (s) well suited to contact and therapy provide valuable information and help the process. The earlier it is discovered «Internal assistant», the more effective is the construction of therapy;
• Using diaries and notebooks. The task is to write down every day everything that happened during the day and bring it to therapy;
• Work with «Internal pursuers». This personality state, usually hostile and opposed to the host personality, is the main source of problems for the main personality. By themselves, the pursuers will not disappear.It is important to them as quickly as possible. «isolate» and start working with them;
• Drawing up a diagram of the personality system as a whole. The personal system is asked to draw up a diagram, map, diagram that optimally reflects the ideas of personal states about their relationships, connections or about the inner world of which they are a part.

1. Fundamentals of Abnormal Psychology and Modern Life. Robert C. Carson, Duke University; James N. Butcher, Professor Emeritus, University of Minnesota; Susan M. Mineka, Northwestern University https://www.scholars.northwestern.edu/en/publications/abnormal-psychology-and-modern-life

2. Diagnosis and Treatment of Multiple Personality Disorder Frank W. Putnam

3. The Haunted Self: Structural Dissociation and the Treatment of Chronic Traumatization (Norton Series on Interpersonal Neurobiology) by Onno van der Hart Ph.D. (Author), Ellert R. S. Nijenhuis Ph.D. (Author), Kathy steel.

4. Diagnostic and statistical manual of mental disorders: DSM-5. — 5th ed.