The term "schizophrenia," with its connotation of hopeless chronic brain disease, should be dropped and replaced with something like "psychosis spectrum syndrome," argues Professor Jim van Os at Maastricht University Medical Centre in The BMJ.

The official glossary of mental disorders used to diagnose patients is found in ICD-10 (International Classification of Diseases, 10th revision) and DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, fifth edition) but van Os argues that the classification is complicated, particularly for psychotic illness. Currently, psychotic illness is classified among many categories, including schizophrenia, schizoaffective disorder, delusional disorder, depression or bipolar disorder with psychotic features, and others, he explains.

But 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 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."

Japan and South Korea have already abandoned this term.

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

For example, 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," a "devastating, highly heritable brain disorder," or a "brain disorder with predominantly genetic risk factors."

This language is highly suggestive of a distinct, genetic brain disease, writes van Os. Yet strangely, no such language is used for other categories of psychotic illness, even though they constitute 70% of psychotic illness.

Scientific evidence indicates that the different psychotic categories can be viewed as part of the same spectrum syndrome, he adds. However, people with this psychosis spectrum syndrome display extreme diversity (heterogeneity), both between and within people, in psychopathology, treatment response, and outcome.

He believes that the best way to inform the public and provide patients with diagnoses, 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."

And he argues that ICD-11 should remove the term "schizophrenia."