A diagnosis is made via a medical professional’s evaluation.
Medical professionals diagnose dissociative identity disorder based on the individuals’s history and symptoms:
- Individuals have two or more identities, and their sense of being themselves and of being able to act as themselves is disrupted.
- They have gaps in their memory for everyday events, important personal information, and traumatic events – information that would not typically be forgotten.
- They are very distressed by their symptoms, or their symptoms make them unable to function in social situations or at work.
Medical professionals conduct a thorough psychiatric interview and use special questionnaires developed to help identify dissociative identity disorder and to rule out other mental health disorders.
A physical examination and laboratory tests may be needed to determine whether individuals have a physical disorder that would explain certain symptoms.
Interviews may need to be long and involve careful use of hypnosis or a sedative given intravenously to relax the person (a drug-facilitated interview).
Individuals may also be asked to keep a journal between medical appointments. These measures may allow medical professionals to encounter other identities or make the individual more likely to reveal information about a forgotten period of time.
Medical professionals may also attempt to directly contact other identities by asking to speak to the part of the mind involved in behaviours that individuals cannot remember or that seem to be done by someone else.
Medical professionals can usually distinguish dissociative identity disorder from malingering (faking physical or psychologic symptoms to obtain a benefit). Malingerers do the following:
- Tend to over-report well-known symptoms of the disorder and under-report others;
- Tend to create stereotypical alternate identities; and/or
- Usually seem to enjoy the idea of having the disorder (individuals with dissociative identity disorder often try to hide it).
If medical professionals suspect that the disorder is faked, they can also cross-check information from several sources to check for inconsistencies that rule out dissociative identity disorder.