This is a short theoretical and philosophical discussion concerning whether or not there is any difference between DID and Schizophrenia in terms of classification, diagnosis or treatment. There are not necessarily any confirmed definite answers, but I believe there are guideposts to consider.
Schizophrenia is traditionally classified under a group of functional psychoses while DID belongs to a group of neuroses. In the traditional understanding of psychosis, the patient may lose touch with reality. In neurosis, the patient retains some acknowledgment of his illness. From this traditional perspective, Schizophrenia and DID are two entirely different kinds of mental disorders.
The term schizophrenia was conceptualized by Eugene Bleuler and further refined by Kurt Schneider (1959), a German psychiatrist whose delineation of “first rank symptoms of schizophrenia” remains widely adopted. Unfortunately, Schneider’s primary criterion for schizophrenia is the experience of “hearing voices.” Hearing voices is how those with Dissociative Identity Disorder – especially pre-diagnosis – often describe their experience of alters expressing themselves internally. It is crucial to consider as an analogue the fact that having fever and abdominal pain are symptoms common in both malaria and typhoid. In other words, just as malaria and typhoid are two completely different physical illnesses with symptoms in common, Schizophrenia and DID are two distinctly different mental disorders with symptoms in common.
The first rank symptoms of schizophrenia are summarized in the following mnemonic of ABCD:
Auditory hallucinations: hearing voices conversing with one another, voices heard commenting on one’s actions;
Broadcasting of thought: a form of auditory hallucination in which the patient hears his/her thoughts spoken aloud;
Controlled thought (delusions of control);
Delusional perception.
Patients with dissociative identity disorder may report “hearing voices” even more commonly than patients with schizophrenia. If one is trained to presume that hearing voices is always an hallucination, then most therapists will jump to the conclusion that the correct diagnosis is schizophrenia. They will mistake the auditory manifestation of internal conflict between the alters to be an auditory hallucination that come from nowhere, points to nothing understandable in any context, and is completely disconnected from reality.
Spiegel and Loewenstein have commented on the considerable overlapping of the symptoms of the DID and Schizophrenia. But, if we follow Schneider’s diagnostic criteria with that presumption, we will have to come to the inclusion of DID within the group classification of schizophrenia. This is despite that fact that they are as different as apples and oranges in terms of classification (psychosis vs neurosis), diagnosis and treatment.
In my experience in treating both schizophrenic and DID patients, the hearing of voices in DID is quite distinguishable from the auditory hallucinations of a schizophrenic. This and other mistaken applications of the ABCD as applied to DID patients are discussed in Volume Two of Engaging Multiple Personalities.
A crucial difference between the two disorders is that schizophrenia usually causes the patient to be highly impaired in his/her thinking. Schizophrenic impairment is generally quite pronounced and leaves the individual severely dysfunctional. In the case of patients with DID, some can be extremely high functioning, while others can barely get along, but most have alters that are usually quite capable of relating to the outside world. Nevertheless, they may be impaired in other ways, such as having co-morbidity of drug addiction and/or alcoholism in one or more of the alters. As a side note, this may be why many DID individuals come to the realization that they may have DID in the course of addiction treatment – whether at AA, NA or at addiction treatment facilities.
Generally, specific diagnostic criteria are followed in making a diagnosis, This is necessary for consistency and uniformity so that treatment guidelines can be applied correctly. It is a key tool for clinicians but like all tools, one must know when and how to use it. When one fails to recognize that there are many psycho-pathologies that display identical symptoms to DID on first, second or even third encounters, the clinician will have failed to use the tool of the DSM properly. This highlights the importance of maintaining a proper index of suspicion for all illnesses having common symptoms – physical and/or psychological – until one or another has been definitively excluded or confirmed.
Simply put, a patient presenting with “hearing voices” may be schizophrenic but, based on the percentage of incidence in the general population, may be equally likely to have DID. This highlights the limitations inherent in relying on one or two symptoms alone in making a diagnosis for mental disorders. One must examine the entire milieu of the presenting patient. This is completely analogous to the danger of diagnosing either malaria and typhoid based on fever and abdominal pain alone.
It is an inconsistency in logic to force a psychiatrist to choose whether to follow Schneider all the way and call DID a true schizophrenia with dissociative features, while understanding that in nosology (classification in medical science,) Schizophrenia is a form of psychosis while DID is a form of neurosis. At the moment, I am merely explaining the dilemma in psychiatry. While I have no definitive answer to that dilemma, I do have my experience of treating patients with both disorders that I relied upon in my practice.
I can say, definitively, that when the logical inconsistency is ignored, psychiatrists are more and more led down an incorrect path of treatment for individuals with DID. This has dire consequences that may take years to play out, investigate and correct. Unfortunately, for many patients, the dire consequences mean more trauma is inflicted in the attempt to heal as a result of the psycho-pharmaceutical blinders the incorrect diagnoses place on the therapists, in the patient files, and on the patient directly. Having a schizophrenic patient talk to the voices he hears will exacerbate his Schizophrenia. Having a DID patient engage in communicating with the voices of alters is part of the necessary treatment of his DID disorder. So, it is crucial to be able to distinguish the two in order to properly treat, and not harm, the patient.
