“Schizophrenia” does not exist

Current classifications

The classification of mental disorders, as laid down in ICD-10 (International Classification of Diseases, 10th revision) and DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, fifth edition), is complicated, particularly psychotic illness.

Currently, psychotic illness is classified among myriad categories, including schizophrenia, schizophreniform disorder, schizoaffective disorder, delusional disorder, brief psychotic disorder, depression/bipolar disorder with psychotic features, substance induced psychotic disorder, and psychotic disorder not otherwise classified. Categories such as these do not represent diagnoses of discrete diseases, because these remain unknown; rather, they describe how symptoms can cluster, to allow grouping of patients.

This elegant solution allows clinicians to say, for example, “You have symptoms of psychosis and mania, and we classify that as schizoaffective disorder. If your psychotic symptoms disappear we may reclassify it as bipolar disorder. If, on the other hand, your mania symptoms disappear and your psychosis becomes chronic, we may re-diagnose it as schizophrenia.

“That is how our classification system works. We don’t know enough to diagnose real diseases, so we use a system of symptom based classification. The DSM-5 does this differently than ICD-10—but that does not matter, because it’s only a classification.”

If everybody agreed to use the terminology in ICD-10 and DSM-5 in this fashion, there would be no problem. However, this is not what is generally communicated, particularly regarding the most important category of psychotic illness: schizophrenia.

The American Psychiatric Association, which publishes the DSM, on its website describes schizophrenia as “a chronic brain disorder,” and academic journals describe it as a “debilitating neurological disorder,”7 a “devastating, highly heritable brain disorder,”8 or a “brain disorder with predominantly genetic risk factors.”9

Current language suggests discrete disease

This language is highly suggestive of a distinct, genetic brain disease. Strangely, no such language is used for other categories of psychotic illness (schizophreniform disorder, schizoaffective disorder, delusional disorder, brief psychotic disorder, and so on). In fact, even though they constitute 70% of psychotic illness morbidity (only 30% of people with psychotic illness have symptoms that meet the criteria for schizophrenia),10 these other categories tend be ignored in the academic literature (see box) and on websites of professional bodies. They are certainly not referred to as brain disorders or similar. It’s as if they don’t exist.

What remains is the paradox that 30% of psychotic illness morbidity is portrayed as a discrete brain disease; the other 70% of the morbidity is communicated only in classification manuals.

Psychosis susceptibility syndrome

Scientific evidence indicates that the different psychotic categories can be viewed as part of the same spectrum syndrome, with a lifetime prevalence of 3.5%,10 of which “schizophrenia” represents the minority (less than a third) with the poorest outcome, on average. However, people with this psychosis spectrum syndrome—or, as patients have recently suggested, psychosis susceptibility syndrome6—display extreme heterogeneity, both between and within people, in psychopathology, treatment response, and outcome.

The best way to inform the public and provide patients with diagnoses, therefore, is to forget about “devastating” schizophrenia as the only category that matters and start doing justice to the broad and heterogeneous psychosis spectrum syndrome that really exists.

ICD-11 should remove the term “schizophrenia.”