The negative symptoms of schizophrenia are characterized by a lack of behaviors that would be expected of a typical person. Negative symptoms of schizophrenia include lack of speech, low motivation, little interest in social behavior, and an inability to feel pleasure or enjoy things. The term negative symptoms reflects these missing typical behaviors, and differentiates them from "positive" symptoms like delusions, hallucinations, and disordered thinking. Negative symptoms are factors in diagnosing schizophrenia in western medicine.
Due to their broad, basic definition, there are many possible negative symptoms of schizophrenia. Similar symptoms are sometimes grouped together and groups vary according to psychiatric opinion. However, groupings are generally very similar and are meant to categorize impairments of social interaction as well as other negative symptoms.
Groups of negative symptoms can include apathy, a state called avolition in psychiatry, that is characterized by a loss of motivation to do things that were formerly enjoyable or meaningful. Alogia is marked by a considerable reduction in speech, which lowers self-expression and makes conversation difficult or lack meaningful content. Blunted emotional responses are characterized by a lowered sensitivity or indifference to events that would typically affect a person's emotions. Sometimes individuals with schizophrenia withdraw from social contact and social interaction, or perform poorly in typical social settings, all of which are examples of asocial behaviors. Other groups could include loss of the ability to feel pleasure, or other specific types of asocial behavior.
The negative symptoms of schizophrenia are persistent states. The American Psychiatric Association says that they must last for at least a month to be a factor in a schizophrenia diagnosis. Sometimes they appear to develop slowly, as when a family member notices another member becoming increasingly withdrawn, until this eventually interferes with work or another activity. European and American psychiatric guidelines recognize different but similar subcategories of schizophrenia, with various negative symptoms of schizophrenia acting as criteria in their diagnoses.
Negative symptoms can sometimes be explained and better treated if they stem from another condition that is not schizophrenic in nature. Negative symptoms can vary in intensity and psychiatrists compare them to a person's usual past behavior to make a diagnosis. Some anti-psychotic medications can have side effects that produce negative symptoms like lethargy, and this can be a factor in choosing the best medication. Schizophrenia diagnoses are not given when negative symptoms are the result of drug abuse or mood disorders like bipolar disorder or depression.