As probably the most severe form of mental illness, schizophrenia, a 'psychotic' illness forces an individual to withdraw from the world and to live in their own fantasy world. At times, such individuals are unable to tell what is real from what is not real and believe more in their fantasy world than in reality. They can be described as being 'out of touch' with the world around them. They are often very frightened. Even their closest friends may find people who develop schizophrenia very hard to get through to.
Schizophrenia always involves a deterioration from a previous higher level of functioning.
Deterioration is generally noticeable in such areas as work and academic achievement, interpersonal relationships and personal care and hygiene. As a result, the affected person's conversation can prove very difficult to follow. In addition, the person's thinking may be coloured by delusions. Perceptual changes such that sensations become confused and the affected person hears, sees, smells and feel sensations which are not real. These unreal perceptions are also called hallucinations.