The prevalence of schizophrenia is 0.6-1% and it affects both sexes. Symptoms of schizophrenia are divided into positive and negative symptoms. The name of the categories does not describe their severity but their manifestation.
Positive symptoms include hallucinations, delusions, disrupted speech and disruptive behaviour that did not exist before the mental disorder. "Positive" means only that something is added to the person's perception. Positive symptoms today are often called psychotic symptoms, as people's experience of these symptoms is not always positive.
Negative symptoms are a lack of skills that existed before the mental disorder, such as difficulties in concentration and attention, lack of expression of emotion, incentive or initiative, lack of happiness and content-less speech. An example of content-less speech would be to answer the question "How was your day?" with the answer "Good", when it would be more natural to provide a longer answer.