The condition may be under-diagnosed due to skepticism and lack of awareness from mental health professionals, made difficult due to the lack of specific and reliable criteria for diagnosing DID as well as a lack of prevalence rates due to the failure to examine systematically selected and representative populations. Differential diagnoses
People with DID are diagnosed with five to seven comorbid disorders on average – much higher than other mental illnesses.Due to overlapping symptoms, the differential diagnosis includes schizophrenia, normal and rapid-cycling bipolar disorder, epilepsy, borderline personality disorder, and autism spectrum disorder. Delusions or auditory hallucinations can be mistaken for speech by other personalities. Persistence and consistency of identities and behavior, amnesia, measures of dissociation or hypnotizability and reports from family members or other associates indicating a history of such changes can help distinguish DID from other conditions. A diagnosis of DID takes precedence over any other dissociative disorders. Distinguishing DID from malingering is a concern when financial or legal gains are an issue, and factitious disorder may also be considered if the person has a history of help or attention-seeking. Individuals who state that their symptoms are due to external spirits or entities entering their bodies are generally diagnosed with dissociative disorder not otherwise specified rather than DID due to the lack of identities or personality states. Most individuals who enter an emergency department and are unaware of their names are generally in a psychotic state. Although auditory hallucinations are common in DID, complex visual hallucinations may also occur.
The majority of patients with DID report childhood sexual or physical abuse, though the accuracy of these reports is controversial. Amnesia between identities may be asymmetrical; identities may or may not be aware of what is known by another. Individuals with DID may be reluctant to discuss symptoms due to associations with abuse, shame, and fear. DID patients may also frequently and intensely experience time disturbances.Around half of people with DID have fewer than 10 identities and most have fewer than 100; although as many as 4,500 have been reported. (p 503) The average number of identities has increased over the past few decades, from two or three to now an average of approximately 16. However, it is unclear whether this is due to an actual increase in identities, or simply that the psychiatric community has become more accepting of a high number of compartmentalized memory components. Comorbid disorders
The psychiatric history frequently contains multiple previous diagnoses of various disorders and treatment failures. The most common presenting complaint of DID is depression, with headaches being a common neurological symptom. Comorbid disorders can include substance use disorder, eating disorders, anxiety disorders, bipolar disorder, and personality disorders. A significant percentage of those diagnosed with DID have histories of borderline personality disorder and post-traumatic stress disorder (PTSD). Presentations of dissociation in people with schizophrenia differ from those with DID as not being rooted in trauma, and this distinction can be effectively tested, although both conditions share a high rate of dissociative auditory hallucinations.