Schizophrenia

Symptoms and classification

Schizophrenia is a mental illness where a person loses some contact with reality. It usually starts in the late teens to early thirties. It is not 'split personality', and most people with it are not violent.

Positive symptoms are extra experiences:

• Hallucinations: seeing, hearing, smelling or feeling things that are not there. Hearing voices is the most common.
• Delusions: strong false beliefs that do not change with evidence, e.g. of being followed (persecution) or of being very important (grandeur).

Negative symptoms are losses of normal abilities:

• Speech poverty: speaking less, with less content.
• Avolition: little motivation to start or finish everyday tasks, like washing or work.

Doctors use manuals: the DSM (needs positive symptoms) and the ICD (can diagnose with two negative symptoms).

Problems with diagnosis

• Reliability: do different doctors give the same diagnosis? Agreement is sometimes only moderate, and the DSM and ICD may disagree.
• Validity: does the diagnosis measure a real, single illness? People with the same label can have very different symptoms.
• Co-morbidity: many people also have depression, anxiety or substance misuse. This makes it unclear if schizophrenia is one condition.
• Symptom overlap: symptoms like hallucinations also occur in bipolar disorder.
• Gender bias: men are diagnosed more often. Women may be missed because they often keep better relationships and social skills.
• Culture bias: hearing voices of spirits or ancestors is accepted in some cultures. In the UK, people of African-Caribbean background are diagnosed far more often, which may reflect bias.

Biological and psychological explanations

Genes: family and twin studies show risk rises with closer genetic relatives: about 1% in the public, about 48% for an identical twin. Many genes each add a small risk (polygenic). As identical twins do not always both develop it, environment matters too.

Dopamine hypothesis: too much dopamine activity in pathways linked to perception and speech (hyperdopaminergia) may cause positive symptoms. Too little in the front of the brain (hypodopaminergia) may cause negative symptoms. Evidence: drugs that raise dopamine (like amphetamines) can cause similar symptoms; drugs that lower it reduce them. Other chemicals like glutamate also seem involved.

Neural correlates: brain scans show differences, e.g. lower activity in the reward system linked to avolition, and less activity in hearing areas during inner speech linked to voices. But these are correlations, not proven causes.

Family dysfunction: the old 'double bind' idea (a child gets mixed messages) has little support. Expressed emotion (criticism, hostility, over-involvement from relatives) is well supported as a cause of relapse.

Cognitive explanations: faulty thinking. Metarepresentation problems mean a person cannot recognise their own thoughts as their own, so inner speech can feel like a voice. Central control problems mean a person cannot hold back unrelated thoughts, so speech jumps between ideas.

Treatment and the interactionist approach

Drug therapy: typical antipsychotics (e.g. chlorpromazine) block dopamine receptors. Atypical antipsychotics (e.g. clozapine) act on dopamine, serotonin and glutamate. They may help negative symptoms more and cause fewer movement side effects, but some need blood tests. Medicines reduce symptoms, but do not cure, and side effects can make people stop taking them.

CBT (cognitive behavioural therapy): the person learns to notice and test their beliefs, and to cope with voices (e.g. 'Is there another explanation?'). It reduces distress, usually alongside medicine.

Family therapy: sessions with relatives to lower expressed emotion, improve communication and share knowledge about the illness. It reduces relapse.

Token economy: used in hospitals. People earn tokens for target behaviours (e.g. dressing, cleaning), swapped for rewards. It can reduce negative symptoms, but raises ethical questions and may not last outside hospital.

The diathesis-stress model says illness appears when a vulnerability (diathesis, e.g. genes, early trauma) meets stress (e.g. family conflict, cannabis use, big life changes). The more vulnerable a person is, the less stress is needed. This supports combining medicine with psychological therapy.

If you or someone you know is worried about these experiences, talk to a doctor or a trusted adult. Help works.

Try it

In step 5, try all four buttons. Notice that high genes alone, or high stress alone, may not overflow the bucket, but both together can. Then think: what could a family do to lower the 'stress' part? (Calm talk, less criticism, regular routines.)

Key formulas and definitions

• Key term: Positive symptoms = additions to normal experience (hallucinations, delusions)
• Key term: Negative symptoms = losses of normal function (speech poverty, avolition)
• Key term: Reliability = consistency of diagnosis; Validity = accuracy of diagnosis
• Key term: Co-morbidity = two or more conditions together; Symptom overlap = shared symptoms
• Key term: Dopamine hypothesis = hyper-dopamine (positive symptoms), hypo-dopamine (negative symptoms)
• Key term: Expressed emotion = criticism, hostility, over-involvement in families
• Key term: Metarepresentation = recognising one's own thoughts and actions as one's own
• Model: Diathesis (vulnerability) + Stress (trigger) → illness

Worked examples

Common mistakes

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