Signs and symptoms of schizophrenia differ greatly among patients, but may be divided into three broad categories: positive, negative and cognitive.

Positive symptoms involve an excess or distortion of normal function. They usually involve a loss of contact with reality. They can be severe at times and hardly noticeable at other times. They include:

• Hallucinations. A perception by the senses of something that is not actually there. They can involve any of the five major senses -- vision, hearing, smell, touch or taste -- although auditory (hearing) hallucinations are the most common. Many people with the disorder hear voices that may comment on their behavior, order them to do things, warn them of impending danger or talk to each other (usually about the patient).
  
  
• Delusions. Fixed false beliefs of the person despite evidence to the contrary. Common types of delusions include:
  
  
• • Persecution. These are the most common. Patients believe they are being tormented, followed, tricked, spied on or ridiculed.
    
    
  • Referential. These are also common. Patients believe that references in books, song lyrics, newspapers or other areas are directed at them.
    
    
  • Grandeur. Patients believe they are persons of high status, such as a deity or a movie star.
    
    
  • Guilt. Patients believe they have committed a grave sin or mistake.
    
    
  • Ill health. Patients believe they have a bad disease.
    
    
  • Jealousy. Patients believe their spouses or partners have been unfaithful.
    
    
  • Passivity. Patients believe they are being controlled or manipulated by outside influences, such as radio waves.
    
    
  • Poverty. Patients believe they are facing destitution, even though they have a job or money in the bank.
    
    
  • Thought control. Patients believe ideas are being put into their minds by others.
    
    
• Thought disorder. Patients often have unusual thought processes. They may have difficulty organizing thoughts or connecting them logically. Speech may be disorganized (sometimes called loose associations), or people may connect thoughts by rhymes or puns rather than logic. Thoughts also may be tangential, that is, the person may take the conversation in a totally different direction and have difficulty staying on any one topic.
  
  
• Movement disorder. Patients with schizophrenia may be clumsy and uncoordinated. They may have involuntary movements or unusual mannerisms. These may occur as side effects of some antipsychotic medications, but as symptoms they occur even before someone takes any medication.

Negative symptoms involve a loss of normal emotional and behavioral functioning. Many of these symptoms are also symptoms of other medical disorders or may occur in healthy individuals. They include:

• Flattened affect. Reduced range of emotion. This may include immobile facial expressions or monotonous voice.
  
  
• Lack of pleasure in everyday activities (anhedonia).
  
  
• Loss of ability to initiate and sustain planned activity (avolition).
  
  
• Inability to sustain conversation, even when forced to speak (alogia).

Cognitive symptoms are often subtle and may be detected only when neuropsychological tests (specifically designed tasks used to measure a psychological function known to be linked to a particular brain structure or pathway) are conducted. Cognitive symptoms can greatly create big problems in a person's ability to lead a normal life. They include:

• Poor functioning. The ability to retain and interpret information and make decisions based on that information.
  
  
• Inability to sustain attention.
  
  
• Problems with memory. The ability to retain recently learned information and access it.

Patients with schizophrenia often neglect basic hygiene and need assistance with activities of daily living. Some patients' ability to function in personal and job settings deteriorates over time. Other patients exhibit symptoms that come and go. Staying on medication and involved in treatment can help minimize symptoms.