4.1 Schizophrenia

Cambridge International A Level Psychology (9990)


2026 📋 Syllabus Objectives

By the end of these notes, you should be able to:

  1. Describe the diagnostic criteria for schizophrenia using the ICD-11, and explain the types of delusions identified by Freeman et al. (2003)
  2. Explain biological (genetic and biochemical/dopamine) and psychological (cognitive) explanations of schizophrenia
  3. Describe and evaluate biological (antipsychotics and ECT) and psychological (CBT) treatments for schizophrenia, including the Sensky et al. (2000) study

OBJECTIVE 1: Diagnostic Criteria for Schizophrenia (ICD-11) & Types of Delusions


What is Schizophrenia?

Schizophrenia is a serious mental disorder — a condition that affects the way a person thinks, feels, and behaves. People with schizophrenia can have difficulty telling what is real from what is not real. It affects roughly 1 in 100 people worldwide and usually first appears in late adolescence or early adulthood.

The word "schizophrenia" comes from Greek words meaning "split mind" — but this does not mean a person has a "split personality." It means the person's thoughts and feelings become disconnected from reality.


The ICD-11: What Is It?

To diagnose any mental disorder, clinicians (doctors and psychologists) use classification systems — basically, rulebooks that list the symptoms and criteria needed to give a diagnosis. One of the most widely used systems is the ICD-11, which stands for the International Classification of Diseases, 11th Edition. It is published by the World Health Organisation (WHO) and is used in many countries around the world.

Think of the ICD-11 like a checklist: a person must show a certain number of specific symptoms for a certain amount of time before they can be diagnosed with schizophrenia.


ICD-11 Diagnostic Criteria for Schizophrenia

According to the ICD-11, a person must experience at least two of the following core symptoms, and these symptoms must be present for a significant period of time during a one-month period (and signs of the disorder must be present for at least one month overall):

The symptoms fall into two broad categories: positive symptoms and negative symptoms.

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