Schizophrenia

Psychosis characterised by emotional, intellectual and behavioural disturbances such as withdrawal from external reality and a retreat into fantasy life, with deterioration of behaviour; also known as dementia praecox.

Persons most commonly affected: Late adolescence or early adulthood in both sexes
Organ or part of body involved: Brain
Symptoms and indications: Its first signs include social withdrawal, talking to oneself, hoarding, and other odd behavior. This behavior is at the edge of normality, however, and may not indicate development of schizophrenia. When these early signs give way to full expression of the disease, it is possible to recognize in retrospect that the disease had been developing.
Causes and risk factors: There are three main causes scientists are researching. One is genetics (heredity). Scientists recognize that the disorder tends to run in families and that a person inherits a tendency to develop the disease. Schizophrenia may be triggered by environmental events, such as viral infections or highly stressful situations or a combination of both. Similar to other genetically related illnesses, schizophrenia appears when the body undergoes hormonal and physical changes, like those that occur during puberty in the teen and young adult years. Second is chemistry. Genetics help to determine how the brain produces and uses certain chemicals. People with schizophrenia have a chemical imbalance which means they are either very sensitive to or produce too much of a brain chemical called dopamine. Dopamine, which is a neurotransmitter, allows nerve cells in the brain to send messages to each other. The imbalance of this chemical affects the way a person?s brain reacts to stimuli?which explains why a person with schizophrenia may be overwhelmed by sensory information (loud music or bright lights), which other people can easily handle. This problem in processing different sounds, sights, smells and tastes can also lead to hallucinations or delusions. Third is complications during pregnancy and birth. Some researchers suspect a viral infection, improper nutrition during pregnancy, or birth complications may increase the chances of a person developing schizophrenia.
Prevention: Currently, there is no way to prevent schizophrenia. You may be able to prevent or reduce the number of relapses. Being aware of the signs of relapse can help you or your family members seek prompt treatment, which may reduce the severity of the relapse. Things you can do to prevent relapse include: Reducing stress in your life, which may decrease the number of relapses you have. Avoid using alcohol or illegal drugs. Learning the first signs of relapse and seeking help early. 
Taking medications as prescribed.