The symptoms of schizophrenia can be divided into positive and negative symptoms.

Positive symptoms are a feature of acute schizophrenia (acute syndromes) and negative ones are a feature of the chronic syndrome. Although the positive symptoms are often the most dramatic and, at least initially, the most distressing, the negative ones can cause the most problems, as they last longer and are more difficult to treat.

The main positive symptoms are:

• restless, noisy and irrational behavior,
• sudden mood changes,
• inappropriateness of mood,
• disordered thinking,
• feelings of being controlled by outside forces, having your thoughts and actions taken over,
• delusions,
• hallucinations,
• lack of insight - no awareness of the abnormality of your thoughts, experiences and behavior, and
• suspiciousness, which in some cases can become paranoia.

Delusions

A delusion is a fixed belief in something manifestly absurd or untrue, and that cannot be overcome by reason. Delusions cannot always be easily distinguished from rigidly held, but generally rejected, opinions, especially if a group shares these. But most are so inherently improbable, or so obviously based on defective perceptions or reasoning, as to indicate serious mental disturbance.

Psychotic delusions fall into several categories and include:

• delusions of persecution (paranoid delusions),
• delusions of grandeur,
• hypochondriacal delusions (unfounded beliefs about having an illness),
• delusions that the sufferers body shape is abnormal,
• delusions of unreality or depersonalization,
• delusions of being influenced by others or by malignant forces, and
• self-deprecatory (self-belittling) delusions of unworthiness.

Hallucinations

A hallucination is a sense perception not caused by an external stimulus. It is therefore a hallucination to see something that is not present, or to hear voices that do not come from any present source of sound. Hallucinations should be distinguished from delusions, which are mistaken ideas.

Hallucinations are a common feature of schizophrenia. They may apparently come through the senses of vision (visual hallucinations); hearing, sometimes musical (auditory); touch (tactile); taste (gustatory); or smell (olfactory), or may relate to the size of things (Lilliputian).

Hallucinations commonly occur in the general population as they are falling asleep (hypnagogic hallucinations), or while waking from sleep (hypnopompic hallucinations).

The negative symptoms include tiredness, loss of concentration and lack of energy and motivation, which may be made worse by the side effects of drugs used to treat the positive symptoms. Because of these symptoms, the individual may be unable to cope with everyday tasks.

Other behavior patterns seen in Chronic schizophrenia include:

• social withdrawal,
• underactivity,
• lack of conversation,
• lack or absence of hobbies or leisure activities,
• flatness of the expression of emotion (called flat affect),
• physical slowness,
• physical overactivity,
• self-neglect, and
• bizarre physical movements or postures (uncommon).