No single symptom positively identifies schizophrenia. An individual may have any combination of symptoms. Furthermore, an individual's symptoms can change over time. The symptoms of schizophrenia are divided into three categories: positive, negative and cognitive symptoms.
Positive Symptoms are also known as "psychotic symptoms" because the person has lost contact with reality in certain ways. Positive symptoms can include:
Delusions, which occur when someone believes ideas that are clearly false (e.g. people are reading their thoughts or that they can control other people's minds). These beliefs are frequently unusual and/or impossible. As found by a 2010 study, people living with schizophrenia are more prone to produce confabulations, the production of false memories without a deliberate intent to lie. However, unlike neurological disorders, memory impairment is not a prerequisite for confabulation.
Hallucinations, which are imagined voices or images inside or outside an individual's head.
Negative Symptoms are deficits or normal behavior and "take away" from the person's ability and usual way of interacting with the world. As a 2000 study in Advances in Psychiatric Treatment found, these symptoms can often be confused with depression. These symptoms can include:
Cognitive Symptoms pertain to thinking processes. People living with schizophrenia often struggle with executive functioning, memory and organizing thoughts. Another common cognitive deficit associated with schizophrenia is Anosognosia, as explained previously.
According to the DSM-IV, before diagnosis can be made, two of the following must be present for at least one month: delusions, hallucinations, disorganized speech, catatonic behavior and negative symptoms.
Often differentiating between mental illnesses can be difficult. Two similar, yet different, disorders are schizophrenia and schizoaffective disorder. While schizophrenia is characterized by the above symptoms, people living with schizoaffective disorder also experience symptoms of a mood disorder, such as mania or depression. To learn more about schizoaffective disorder go to NAMI's page on Schizoaffective Disorder.