Schizophrenia is a complex and puzzling illness. Even the experts in the field are not exactly sure what causes it. Some doctors think that the brain may not be able to process information correctly.
Genetic factors appear to play a role, as people who have family members with schizophrenia may be more likely to get the disease themselves. Some researchers believe that events in a person's environment may trigger schizophrenia. For example, problems during intrauterine development (infection) and birth may increase the risk for developing schizophrenia later in life.
Psychological and social factors may also play some role in its development. However, the level of social and familial support appears to influence the course of illness and may be protective against relapse.
There are five recognized types of schizophrenia: catatonic, paranoid, disorganized, undifferentiated, and residual. Features of schizophrenia include its typical onset before the age of 45, continuous presence of symptoms for six months or more, and deterioration from a prior level of social and occupational functioning.
People with schizophrenia can have a variety of symptoms. Usually the illness develops slowly over months or even years. At first, the symptoms may not be noticed. For example, people may feel tense, may have trouble sleeping, or have trouble concentrating. They become isolated and withdrawn, and they do not make or keep friends. As the illness progresses, psychotic symptoms develop:
- Delusions -- false beliefs or thoughts with no basis in reality
- Hallucinations -- hearing, seeing, or feeling things that are not there
- Disordered thinking -- thoughts "jump" between completely unrelated topics (the person may talk nonsense)
- Catatonic behavior -- bizarre motor behavior marked by a decrease in reactivity to the environment, or hyperactivity that is unrelated to stimulus
- Flat affect -- an appearance or mood that shows no emotion
No single characteristic is present in all types of schizophrenia. The risk factors include a family history of schizophrenia. Schizophrenia is thought to affect about 1% of the population worldwide.
Schizophrenia appears to occur in equal rates among men and women, but women have a later onset. For this reason, males tend to account for more than half of clients in services with high proportions of young adults. Although the onset of schizophrenia is typically in young adulthood, cases of the disorder with a late onset (over 45 years) are known.
Childhood-onset schizophrenia begins after five years of age and, in most cases, after relatively normal development. Childhood schizophrenia is rare and can be difficult to differentiate from other pervasive developmental disorders of childhood, such as autism.
