For men, the peak incidence of onset of schizophrenia is between 15 and 25 years; for women, it is between 25 and 35 years. Women display a second peak of onset after 40-45 years, just before the menopause. Men appear to experience more negative symptoms and women more affective (mood-related) symptoms. After an initial episode, up to a third of individuals may make a full recovery. For most people, periods of stability may be interrupted by acute 'relapses', which may need additional interventions. It is unlikely that a diagnosis of schizophrenia would be made after a single episode. Symptoms can be divided into two groups: positive symptoms displaying an enhancement or distortion of normal function, and negative symptoms that show a depletion or loss of function. In all cases, lack of insight or awareness of their condition is very common in people with schizophrenia.

Positive symptoms include:

• Hallucinations €“ auditory hallucinations are most common, but visual, tactile, olfactory and gustatory hallucinations may also occur. Hallucinations happen without the presence of an external stimulus
• Delusions €“ paranoia or persecutory beliefs are most common, but delusions may also include ideas of grandiosity and self-importance, with or without religious context, and somatic delusions relating to beliefs of poor physical health
• Thought disorders €“ this can include disorganised speech and behaviour due to chaotic thoughts; the belief that thoughts are being 'broadcast' aloud, inserted or withdrawn from the individual; and thought 'block', where no or very few thoughts occur
• Ideas of reference €“ the belief that TV, radio, press or internet reports are about the individual or have a direct line of communication with them.
• Negative symptoms include:
• Social withdrawal and lack of engagement (e.g. minimal conversation with others)
• Poor motivation and initiative
• Lack of self-care
• Blunting/lack of emotion
• Slow movement.

Negative symptoms can easily be mistaken for depression, and indeed depression may often co-exist in people with chronic schizophrenia. This highlights the importance of an accurate history and diagnosis to ensure that effective treatment can be offered.

While it is estimated that around two-thirds of people with schizophrenia will experience recurrent relapse and some continued disability, the findings of follow-up studies over periods of 20-40 years suggest that there is a moderately good long-term global outcome in more than half of all people with schizophrenia, with a smaller proportion having extended periods of remission of symptoms without further relapses.