Schizophrenia is one of the most complex of psychiatric disorders which is ranked among the top 10 illnesses contributing to the global burden of disease, per the World Health Organization (WHO).
Diagnosis is based on a standardized psychiatric interview and the use of diagnostic criteria, as specified below. Note that these criteria allow the diagnosis in the absence of prominent hallucinations or delusions (e.g., there is instead some combination of negative symptoms, disorganized speech, and/or disorganized or catatonic behavior).
Duration of active psychotic symptoms for at least 1 month, or for a shorter duration if successfully treated.
Total duration of illness for at least 6 months, including prodrome, acute phase, and residual symptoms.
Cognitive impairment and disorganization characterized by disorganized, illogical, loosely associated or bizarre speech, or by inappropriate or bizarre behaviors.
The above symptoms are idiopathic in nature—that is, they are not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medication) or another medical condition.
Dysfunction in one or more life domains as a result of the above signs or symptoms.
Other common features:
Lack of insight that symptoms and difficulties that stem from them are products of a mental illness that requires treatment.
Deterioration in personal appearance and hygiene.
Depression and anxiety symptoms, including suicidal thinking.
Abnormal motor activity, including rocking, pacing, grimacing, maintaining uncomfortable postures, stereotypies, and odd mannerisms.
Poor adherence with treatment.
Comorbid drug (including nicotine) and alcohol use-disorders, and chronic physical health problems.