Approximately 2.5 million Americans are diagnosed with schizophrenia. An individual with schizophrenia may have difficulty distinguishing between what is real and what is imaginary. This often manifests in socially unresponsive and withdrawn behavior, including trouble with emotional expression in social settings. While the illness may develop over months or years, symptoms usually emerge between the ages of 15 and 25 and often earlier in males than females. Symptoms may come and go in cycles.
The "positive symptoms" of schizophrenia are things that are "extra," or present to those with schizophrenia but not present to everyone else. For example, someone with schizophrenia may see or smell things that other people do not see or smell, or hear voices or sounds that other people do not hear.
Positive symptoms also include fixed false beliefs (sometimes called delusions). Someone may believe that they are being followed by the FBI or have been chosen for a special role in their faith community or government. Because they are struggling with these positive symptoms of schizophrenia, individuals with schizophrenia who do not receive effective treatment often are unable to develop the skills needed to live independently or thrive in society.
Some of the most serious symptoms of schizophrenia may be hard to see. Known as "negative symptoms," these include "losses" such as the loss of motivation, emotional expression, logical communications, ability to experience pleasure and even cognitive abilities. Because the first episode of schizophrenia typically appears at a time when young people are learning how to be adults, the long-term effects of these negative symptoms can have the greatest impact.
Research suggests that schizophrenia may have several possible causes: