Undifferentiated and Residual Schizophrenia
Both of these subtypes of the disorder are used to describe the disease in patients whose symptoms do not match the criteria outlined in previous sections. In a sense, they are classifications used to make sure everyone with schizophrenia is given a diagnosis that conveys as much information about the nature and history of his condition as possible. As with other subtypes, these diagnoses can change as symptoms change.
If a patient's symptoms cannot be placed convincingly into any of the other categories — paranoid, disorganized, or catatonic — a diagnosis of undifferentiated schizophrenia is made. The patient may not have symptoms of paranoia, disorganization, or catatonia, but he will, over the course of a month, have two or more of the following: delusions, hallucinations, disorganized speech or behavior, or negative symptoms.
This is a category that describes people whose symptoms have improved enough so they cannot be classified as paranoid, disorganized, catatonic, or undifferentiated. They still have enough remnants of the disorder, however, to register with mental health professionals as not fully recovered. Negative symptoms, for example, such as social withdrawal, reduced or limited emotional range, lack of ambition for large and small projects, and reluctance to speak may be present. Alternatively, a patient with residual schizophrenia may have “watered down” versions of psychotic symptoms: odd ideas or occasional, fleeting hallucinations. These symptoms differ from those seen in other types of schizophrenia because they are not as severe, incapacitating, organized, or persistent.
It is also possible that this subtype represents “a transition between a full-blown episode and complete remission,” according to the American Psychiatric Society's DSM-IV.
Symptoms in a Patient with Residual Schizophrenia
Has been diagnosed with another subtype of schizophrenia in the past
Shows no signs of hallucinations, delusions, disorganized speech, or grossly disorganized or catatonic behavior
Has negative symptoms
Has two or more very low-key versions of classic positive schizophrenia symptoms such as odd beliefs, strange perceptual experiences, or peculiar behavior
Adapted from the DSM-IV.