An important part in the diagnosis of Dissociative Identity Disorder, is something referred to as the ‘multiplicity triad’ (Ross, C.A. 1989). As part of this triad it is suggested that dissociators generally score positively in ‘symptoms’ that are typically associated with schizophrenia. This has at times led to people with DID being misdiagnosed with schizophrenia. There are however, several clear differences between dissociative identity disorder and schizophrenia, and aquiring an awareness of these differences can help in determining whether what someone is experiencing are symptoms of Schizophrenia or whether it is more likely to be DID.
There are symptoms that can be found in both DID and Schizophrenia patients. However there are also symptoms that are characteristic of dissociative identity disorder and not schizophrenia, and visa versa. This article gives an overview of the symptoms which are characteristic of one or other of these disorders; and those which are characteristic of both. The information used in this article is taken from table 3.1 in The Dissociative Identity Disorder Sourcebook by Deborah Bray Haddock.
These are potentially present in both schizophrenia and DID, but with Schizophrenia they are usually isolated symptoms (none to mild severity ratings on the SCID-D, rev.) and they occur in the context of bizarre delusions or other psychotic symptoms. In contrast, dissociative symptoms characteristic of DID are recurrent to persistent (moderate to severe severity ratings).
This is potentially present in both schizophrenia and DID, but someone suffering from Schizophrenia will generally have a lack of sense of identity and struggle to understand their role in society, whereas with DID the changes in identity are consistent and recurrent, with each of the alters having a sense of identity for themselves.
Auditory Hallucinations and Internal Dialogues
Again, these too are potentially present in both disorders. However, with Schizophrenia, a person will experience hallucinations other than voices of alter personalities. These experiences are mostly seen as occuring outside of the patient’s head.
With DID, auditory hallucinations reflect conversations between alter personalities. These voices are perceived as occuring inside the patient’s head and are often described as being similar to thoughts.
Schneiderian Symptoms and Delusions
These are potentially present in both Schizophrenia and DID. Contrasting with DID, where the only delusions are “delusions of several personalities” or of other external changes that are typical of the different personalities (such as changes in posture, voice, facial expressions etc.), delusions often seen in Schizophrenia are bizarre, paranoid delusions, and any other delusions that do not involve other personalities. For example, “The CIA is out to get me.”
Other Psychotic Symptoms
There are no other psychotic symptoms present in DID.
In Schizophrenic patients, other psychotic symptoms may include: thinking characterized by confusion or the obvious breaking up of mental links; catatonic behaviour and chronic flat affect (seeming to have little or no emotion).
Schizophrenic patients tend to have impaired reality testing, whereas DID patients have intact reality testing, and “as if” descriptions of dissociative symptoms are typical.
In Schizophrenia, “If mood episodes have occurRed during active-phase symptoms, their total duration has been brief relative to the duration of the active and residual periods” (DSM-IV, pp. 284-86). (i.e. mood episodes are brief compared to how long active and residual phases last)
In DID, the full depressive or manic syndrome may exist alongside the dissociative syndrome.
Impairment in Functioning
In Schizophrenia, “One or more areas of functioning, such as work, interpersonal, relations or self-care are markedly below the level achieved prior to the onset” (DSM-IV, p. 285).
In DID, any disruption in ability to function is usually temporary, with patients eventually returning to full premorbid level of functioning.
Course of Symptoms and Syndrome
In Schizophrenia, “Continuous signs of the disturbance for at least 6 months” (DSM-IV p. 285).
In DID, signs of the disturbance may be periodic. Rapid changes in symptoms, mood and level of impairment may occur.
Haddock, D.B. (2001) The Dissociative Identity Disorder Sourcebook , New York: McGraw-Hill.
Steinberg, M. (1994) Structured Clinical Interview for DSM-IV Dissociative Disorders Revised, Washington D.C.: American Psychiatric Press.
Ross, C. A. (1996) Dissociative Identity Disorder: Diagnosis, Clinical Features, and Treatment of Multiple Personality, New York: John Wiley.