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Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

What Is It?

Schizophrenia is a chronic (long-lasting) brain disorder that is easily misunderstood. Although symptoms may vary widely, people with schizophrenia frequently have a hard time recognizing reality, thinking logically and behaving naturally in social situations. Schizophrenia is surprisingly common, affecting 1 in every 100 people worldwide.

Experts believe schizophrenia results from a combination of genetic and environmental causes. The chance of having schizophrenia is 10% if an immediate family member (a parent or sibling) has the illness. The risk is as high as 65% for those who have an identical twin with schizophrenia.

Scientists have identified several genes that increase the risk of getting this illness. In fact, so many problem genes have been investigated that schizophrenia can be seen as several illnesses rather than one. These genes probably affect the way the brain develops and how nerve cells communicate with one another. In a vulnerable person, a stress (such as a toxin, an infection or a nutritional deficiency) may trigger the illness during critical periods of brain development.

Schizophrenia may start as early as childhood and last throughout life. People with this illness periodically have difficulty with their thoughts and their perceptions. They may withdraw from social contacts. Without treatment, symptoms get worse.

Schizophrenia is one of several "psychotic" disorders. Psychosis can be defined as the inability to recognize reality. It may include such symptoms as delusions (false beliefs), hallucinations (false perceptions), and disorganized speech or behavior. Psychosis is a symptom of many mental disorders. In other words, having a psychotic symptom does not necessarily mean a person has schizophrenia.

Symptoms in schizophrenia are described as either "positive" or "negative." Positive symptoms are psychotic symptoms such as delusions, hallucinations and disorganized behavior. Negative symptoms are the tendency toward restricted emotions, flat affect (diminished emotional expressiveness), and the inability to start or continue productive activity.

In addition to positive and negative symptoms, many people with schizophrenia also have cognitive symptoms (problems with their intellectual functioning). They may have trouble with "working memory." That is, they have trouble keeping information in mind in order to use it, for example, remembering a phone number that they have just heard. These problems can be very subtle, but in many cases may account for why a person with schizophrenia has such a hard time managing day-to-day life.

Schizophrenia can be marked by a steady deterioration of logical thinking, social skills and behavior. These problems can interfere with personal relationships or functioning at work. Self-care can also suffer.

As people with schizophrenia realize what it means to have the disease, they may become depressed. People with schizophrenia are therefore at greater than average risk of committing suicide. Family members and health care professionals need to stay alert to this possibility.

People with schizophrenia are also at more risk for developing substance abuse problems. People who drink and use substances have a harder time adhering to treatment. People with schizophrenia smoke more than people in the general population. The smoking leads to more health problems.

Anyone with serious and chronic mental illness is at greater risk for developing metabolic syndrome. Metabolic syndrome is a group of risk factors that increase risk for cardiovascular disease and diabetes. The risk factors include obesity, high blood pressure and abnormal lipid levels in the bloodstream.

Schizophrenia has historically been divided into several subtypes, but researchers in the last several years have determined that these divisions are probably not clinically useful.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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