To make it easy on psych students.
A diagnosis of Schizophrenia is quite debilitating on the patient and his/her family, that’s why it is crucial to distinguish between Schizophrenic patient and other disorders on its spectrum.
Schizophrenia diagnosis is made when you have at least one of the following: delusions, hallucinations, or disorganised speech in addition to catatonic behavior or negative symptoms (e.g., diminished emotions expression). the latter symptoms must persist for at least 1 month, and continuous signs of the disturbance must persist for at least 6 months.
Brief Psychotic disorder is relatively easy to distinguish from Schizophrenia since the symptoms must be present for less than 1 month.
Delusional disorder on the other hand, can be diagnosed when the criteria mentioned above in schizophrenia are never met, and the functioning of the patient is not as impaired as in schizophrenia.
Schizoaffective disorder can be considered as schizophrenia coupled with severe mood disturbances, and the clinician can specify whether its bipolar type or depressive type.
Last but not least, the schizophreniform disorder is similar to schizophrenia but with lesser impairment in functioning. Research shows that patients with schizophreniform disorder are more receptive to treatment and report less remission rates compared to those with schizophrenia.
Always make sure that the psychotic disorder is not substance induced and is not due to another medical condition (e.g. brain tumor, multiple sclerosis)