The symptoms of schizophrenia are usually classified into one of two categories - positive or negative.

• Positive symptoms - symptoms that represent a change in behaviour or thoughts, such as hallucinations or delusions.
• Negative symptoms - symptoms that represent the reduction or total lack of thoughts or functions that you would usually expect to see in a healthy person. For example, people with schizophrenia often appear emotionless, flat and apathetic.

Negative symptoms are not usually as dramatic as positive symptoms but they can be harder to treat.

People often have episodes of acute schizophrenia, during which their positive symptoms are particularly severe, followed by periods where they experience few or no positive symptoms.

Positive symptoms of schizophrenia

Hallucinations

A hallucination is when you think that you perceive something that does not exist in reality. Hallucinations can occur in any of the five senses, but the most commonly reported hallucination in schizophrenia is hearing voices.

In some cultures and religions, hearing voices is regarded as being healthy and a sign of spiritual development. In these situations, the voices that people hear are usually friendly and supportive. However, the majority of people with schizophrenia report that the voices that they hear are unfriendly and critical.

The type of voices that are heard by people with schizophrenia usually fall into one of two groups that are listed below.

• Critical voices - the voice provides a kind of critical running commentary on the person and their actions.
• Controlling voices - a person can hear a voice that 'forces' them to commit acts that they would otherwise not do.

Delusions

A delusion is having an unshakable belief in something that is very unlikely, bizarre or obviously untrue. One of the most common delusions experienced in schizophrenia is paranoid delusions. This is where you believe that something, or someone, is deliberately trying to mislead, manipulate, hurt or, in some cases, even kill you.

Paranoid delusions can range from believing in everyday 'normal' delusions, such as being convinced that your partner is being unfaithful, to more unusual delusuions, such as believing that the CIA is plotting to assassinate you.

Another relatively common type of delusion is a delusion of grandeur. This is the belief that you have some imaginary power or authority, such as thinking you are the King of England or that you have the power to cure cancer.

Another common delusion in schizophrenia is to start attaching undue and misguided significance to everyday events. For example, you may start to think that songs being played on the radio are actually about you or that newspaper headlines are being used to send you secret messages.

Behavioural problems

During an acute schizophrenic episode, the combination of hallucinations and delusions can cause a person to act in an unusual and bizarre manner. For example, a person may cover all the windows of their flat in tin-foil because they believe that this will prevent their thoughts from being controlled by the government.

Disordered thoughts

People with schizophrenia often complain that their thinking has become confused, muddled or disorganised.

You may experience problems with concentration, your performance at work or college may suffer and even the simplest tasks, such as reading a newspaper article or sending an email, can become incredibly difficult.

Other thought disorders are described below.

• Thought insertion - this is the feeling that your thoughts are not actually your own and have been placed in your mind by another person or organisation.
• Thought withdrawal - this is the feeling that your thoughts are somehow being removed from your mind by another person or organisation.
• Thought broadcasting - this is the belief that your thoughts can be heard or read by others.
• Thought blocking - this is the feeling that your thought processes suddenly halt, leaving your mind blank with no recollection of what you were thinking about.

Negative symptoms of schizophrenia

The negative symptoms of schizophrenia can often begin to manifest themselves several years before somebody experiences their first acute schizophrenic episode. These initial negative symptoms are often referred to as the prodromal period of schizophrenia.

Symptoms during the prodromal period usually begin gradually and then slowly get worse. They include becoming more socially withdrawn and experiencing an increasing lack of care about your appearance and personal hygiene.

After some point, these negative symptoms will become more noticeable. The more noticeable symptoms are briefly outlined below.

• A lack, or 'flattening', of emotions - your voice can become dull and monotonous, and your face takes on a constant blank appearance.
• An inability to enjoy things that you used to enjoy.
• Apathy - you have no motivation to follow through on any plans and neglect household chores, such as washing the dishes or cleaning your clothes.
• Becoming increasingly uncommunicative - you may find it hard or become reluctant to speak to people.

The negative symptoms of schizophrenia can often lead to relationship problems with friends and family because they can sometimes mistake them for deliberate laziness or rudeness.