Positive and negative symptoms: Diagnosis & Classification of Schizophrenia Issues in the diagnosis and classification of schizophrenia

This PowerPoint is an A-Level Psychology revision presentation about **schizophrenia**, focusing on: * How schizophrenia is **diagnosed and classified** * **Positive and negative symptoms** * Issues with **reliability and validity** of diagnosis * Problems of **co-morbidity and symptom overlap** * Evaluation studies and exam tips ### Main Sections #### 1. Diagnosis and Classification The presentation explains how the two main diagnostic systems classify schizophrenia: * DSM-5 * Requires at least **two positive or negative symptoms**. * Symptoms must be present for at least **one month**, with disturbance lasting up to **six months**. * ICD-11 * Also requires at least **two positive or negative symptoms**. * Defines schizophrenia as a psychotic disorder involving difficulty distinguishing reality from fantasy. --- #### 2. Positive Symptoms These are symptoms that **add abnormal experiences** to a person's behaviour: * **Hallucinations** – hearing voices, seeing things that are not there, or perceiving distortions. * **Delusions** – false beliefs such as: * Being a religious figure. * Being watched by government agencies. * Having special powers. --- #### 3. Negative Symptoms These are symptoms involving a **loss or reduction of normal functioning**: * **Speech poverty (alogia)** – reduced speech, vague answers, difficulty maintaining conversation. * **Avolition** – lack of motivation, neglect of hygiene, work, education, and enjoyable activities. The slides emphasise that negative symptoms can be harder to diagnose because they resemble symptoms of depression. --- #### 4. Reliability and Validity The presentation explains two important issues in diagnosis: **Reliability** * Whether different clinicians reach the same diagnosis. * Includes **inter-rater reliability** (agreement between clinicians). **Validity** * Whether the diagnosis actually measures the disorder it claims to measure. * A diagnosis is invalid if symptoms are incorrectly interpreted and another disorder would fit better. Key research included: * Santelmann et al. – found lower inter-rater reliability for schizophrenia than for depression or bipolar disorder. * David Rosenhan – pseudopatients gained admission to psychiatric hospitals after reporting false symptoms, questioning diagnostic validity. --- #### 5. Co-morbidity and Symptom Overlap The presentation discusses diagnostic difficulties because: * People with schizophrenia often also experience **depression**. * Different disorders can share symptoms. * **Avolition** overlaps with depressive symptoms such as low motivation and self-neglect. * The DSM and ICD may sometimes classify the same symptoms differently.