The main form of biological therapy for schizophrenia is drug therapy. Some drugs are more effective at reducing the positive symptoms such as delusions and hallucination than negative symptoms such as lack of motivation and social withdrawal. There are two main categories of drugs, neuroleptic drugs and atypical drugs. Neuroleptic drugs such as Prolixin are conventional drugs that reduce psychotic symptoms but produce some of the symptoms of neurological diseases. These drugs block the activity of the neurotransmitter dopamine within 48 hours and their effect on dopamine are believed to be very important in therapy.

However it takes several weeks of drug therapy before schizophrenic symptoms show substantial reduction. These drugs are more effective in reducing positive symptoms than negative symptoms. This is supported by Birchwood and Jackson 2001 whose conclusion was the same. These drugs appear to be a more effective treatment for schizophrenia than any of the other approaches used alone. (Comer 2001) Researches have shown that patients can get independent to drugs which means they might not be able to stop taking them otherwise they might have to face serious problems. Neuroleptic drugs also have side effects.

Windgassen 1992 found 50% of patients with schizophrenia who take neuroleptic drugs reported grogginess or sedation, 18% reported problems with concentration, and 16% had blurred vision. In addition many patients developed symptoms closely resembling those of Parkinson’s disease such as muscle rigidity, tremors and foot shuffling. Also it was found that more than 20% of patients who take neuroleptic drugs for over a year develop the symptoms of tardive dyskinesia. These symptoms include involuntary sucking and chewing and writhing movements of the mouth or face.

Atypical antipsychotic drugs (such as clozapine) also combat positive symptoms of schizophrenia but there are claims that they also have beneficial effects on negative symptoms as well. These antipsychotics also act on the dopamine system but are thought to block serotonin receptors in the brain as well. They help by only temporarily occupying the dopamine receptors and then rapidly dissociating to allow normal dopamine transmission. Atypical drugs have several advantages over neuroleptic drugs. Firstly they have fewer side effects than neuroleptic drugs.

Secondly they benefit 85% of patients with schizophrenia, compared with 65% given neuroleptic drugs. However, the atypical drugs can produce serious side effects. For example, schizophrenic patients who take clozapine have a 1-2% risk of developing agranulocytosis. This involves reduction in white blood cells, and the condition can be life threatening. Although the use of antipsychotic drugs is crucial in the treatment of schizophrenia, many people do not experience the benefits they offer, normally due to their side effects.

As a result, additional psychological treatments are used. The cognitive behavioural therapy (CBT) follows the assumption that people often have distorted beliefs which influence their behaviour in maladaptive ways. In this therapy, patients are encouraged to trace back the origins of their symptoms in order to get a better idea of how the symptoms might have developed. As well as this, they are also encouraged to evaluate the content of their delusions to consider ways in which they might test the validity of their faulty beliefs.

Next the patients would be given behavioural assignments with the aim of improving their general level of functioning. The learning of maladaptive responses to life's problems is often the result of distorted thinking by the schizophrenic. Researches over time suggest that CBT has a significant effect on improving the symptoms of patients with schizophrenia, however the majority of studies of the effectiveness of CBT have used schizophrenics who are also taking antipsychotic drugs. This leaves the question, how much of the improvement is due to CBT alone?

Also, CBT for schizophrenia works by trying to generate less distressing explanations of psychotic experiences, rather than trying to eliminate them completely. The negative symptoms shown by a schizophrenic may well serve a useful function for the person and so can be understood as safety behaviours and could cause potential damage. Lastly, it has been found that CBT doesn't actually work for all Schizophrenics, Kingdon and Kirschen found that many patients were not deemed suitable for CBT because psychiatrists believed that they would not fully engage with the therapy.