Defining abnormality: the four Ds

Edexcel defines abnormality using four Ds. No one of them is sufficient on its own.

• Deviance — the behaviour departs from social or statistical norms. But norms differ by culture and change over time, so this risks pathologising difference.
• Dysfunction — the person cannot cope with everyday living (work, hygiene, relationships).
• Distress — the person suffers. But some disorders (e.g. mania) involve little subjective distress.
• Danger — risk of harm to self or others. This is comparatively rare, and over-weighting it stigmatises people with mental illness.

Classification systems and their reliability

Two systems classify mental disorders: the DSM (American Psychiatric Association) and the ICD (World Health Organization).

• Reliability of diagnosis means consistency — inter-rater reliability (two clinicians reach the same diagnosis) and test-retest reliability (the same clinician reaches the same diagnosis on a different occasion).
• Validity means the diagnosis is correct and meaningful — that it predicts course and treatment response (predictive validity) and is distinct from other disorders.
• Comorbidity (having two disorders at once) and symptom overlap threaten validity: if schizophrenia and depression share symptoms, are they really separate categories?
• Cultural bias: diagnostic rates differ across ethnic groups in ways that cannot plausibly be explained by symptoms alone, suggesting clinician bias or culturally inappropriate criteria.

Exam framing: a system can be reliable but not valid — clinicians can consistently agree on a label that does not correspond to a real, distinct condition.

Reliability vs validity

Symptoms and features of schizophrenia

Schizophrenia is a psychotic disorder affecting roughly 1% of people. Edexcel names these features:

• Hallucinations — perceptions with no external stimulus, most commonly auditory (hearing voices).
• Delusions — fixed false beliefs held despite contrary evidence (e.g. of persecution or grandeur).
• Thought insertion — the experience that thoughts have been placed into one's mind by an outside force.
• Disordered thinking — thought shown in disorganised, derailed speech.

These are positive symptoms (additions to normal experience). Negative symptoms are losses — avolition (loss of motivation), alogia (poverty of speech), and flattened affect.

Sort the features

Tap a feature, then tap the category it belongs to.

Dopamine, genes and a non-biological alternative

• The dopamine hypothesis — the required neurotransmitter explanation. Excess dopamine activity (or oversensitive D2 receptors) in mesolimbic pathways is linked with positive symptoms. Evidence: drugs that raise dopamine (amphetamines) can produce psychotic symptoms; antipsychotics that block D2 receptors reduce them. The revised version adds low dopamine activity in the prefrontal cortex to explain negative symptoms.
• Genetic explanation — the second biological explanation. Family, twin and adoption studies show risk rises steeply with genetic relatedness; concordance is substantially higher in MZ than DZ twins. But concordance is well below 100%, so genes cannot be the whole story — a diathesis-stress model is needed.
• Non-biological explanation — for example the cognitive account (faulty processing and failure to monitor one's own inner speech, so it is attributed to an outside voice), or social/family factors such as high expressed emotion (critical, hostile, over-involved families predict relapse).

Carlsson et al. (2000) — the contemporary study on schizophrenia — argues that dopamine alone is too simple, and that glutamate and interactions between transmitter systems must be included, with implications for new drug targets.

Evidence for dopamine

Unipolar depression: symptoms and explanations

The second disorder must be anorexia nervosa, OCD or unipolar depression. This lesson uses depression.

• Symptoms: persistent low mood and/or anhedonia (loss of interest and pleasure) for at least two weeks, plus features such as fatigue, disturbed sleep and appetite, worthlessness or guilt, poor concentration, and thoughts of death.
• Biological explanation: the monoamine account — reduced activity of serotonin (and noradrenaline) at the synapse; plus a genetic vulnerability shown by family and twin studies.
• Non-biological explanation: Beck's cognitive theory — the negative triad (negative views of the self, the world and the future), maintained by negative schemas and cognitive biases; or Ellis's ABC model — an Activating event triggers an irrational Belief, which produces the emotional Consequence.

Which explanation?

Two treatments for each disorder

You need two treatments per disorder, one biological and one psychological.

• Antipsychotic drugs (schizophrenia): typical antipsychotics such as chlorpromazine are D2 antagonists, reducing positive symptoms but often producing movement side effects. Atypical antipsychotics such as clozapine act on dopamine and serotonin, with fewer movement effects but a risk of agranulocytosis, requiring blood monitoring.
• CBT for psychosis: helps the person test and reframe the beliefs attached to their symptoms and develop coping strategies. It does not remove symptoms, and is usually an adjunct to medication.
• SSRIs (depression): block the reuptake of serotonin, so more remains in the synapse. Effective for many, cheap, no effort required — but side effects, a delay of weeks before benefit, and relapse when stopped.
• CBT for depression: identifies and challenges irrational beliefs or the negative triad, with behavioural activation and homework. Lower relapse rates than drugs alone, but it requires motivation and commitment.

Evaluating a treatment: effectiveness (evidence, relapse rates), appropriateness (does it fit the disorder and the person?), side effects, cost, and social control — who benefits from the person being medicated?

Match the term to its meaning

Tap a term on the left, then its correct definition on the right.

Classic study: Rosenhan (1973) — On being sane in insane places

Aim: to test whether psychiatric staff can distinguish the sane from the insane.

• Study 1: eight sane pseudopatients presented at 12 psychiatric hospitals reporting one symptom — hearing a voice saying words such as 'empty', 'hollow', 'thud'. Beyond a false name and job, everything else they said was true, and once admitted they behaved normally.
• Findings: every pseudopatient was admitted; all but one were diagnosed with schizophrenia and discharged with schizophrenia in remission. Stays ranged from 7 to 52 days, with a mean of about 19 days. Normal behaviour (e.g. note-taking) was reinterpreted as a symptom, and many of the real patients — but not the staff — spotted them.
• Study 2: a hospital that doubted the findings was told to expect pseudopatients over three months. Of 193 genuine patients, 41 were judged by at least one staff member to be a pseudopatient — yet Rosenhan had sent none.

Conclusion: psychiatric diagnosis at the time lacked validity, and the label stuck: it changed how everything the person did was interpreted (a self-fulfilling, 'sticky' label). Evaluate it: huge real-world impact on DSM criteria, but it involved deception of staff, cannot easily be generalised to modern operationalised criteria, and arguably shows only that hospitals are inclined to be cautious (a type-2 error is safer than turning a genuinely ill person away).

What Rosenhan showed

Researching mental health

• Case studies (e.g. Lavarenne et al., 2013) give rich, in-depth qualitative data about rare or complex cases — but they cannot be generalised and the researcher's interpretation may be biased.
• Interviews (e.g. Vallentine et al., 2010) can be structured, semi-structured or unstructured, and are widely used with patients — but social desirability and researcher effects threaten validity.
• Longitudinal designs follow the same people over time (good for tracking course and relapse; risk of participant attrition). Cross-sectional designs compare different groups at one time (quick, but cohort effects).
• Cross-cultural research and meta-analysis (pooling many studies) increase generalisability. Primary data is collected first-hand; secondary data already exists (e.g. hospital records).
• Analysis: descriptive plus inferential statistics (chi-squared, Spearman's, Wilcoxon, Mann-Whitney U as appropriate); qualitative data by thematic analysis and grounded theory. Practitioners follow the HCPC guidelines.

Choosing a method

Issues and debates

How Topic 5 is assessed

Clinical psychology is compulsory and is assessed in Section A of Paper 2: Applications of psychology (54 marks). Section B is your chosen option — criminological, child or health.

• Be ready to describe symptoms, then give two explanations and two treatments for schizophrenia and for your second disorder — and to evaluate each.
• Expect questions on the reliability and validity of diagnosis, on cultural issues, and on research methods (case study, interview, meta-analysis, longitudinal, cross-cultural).
• Rosenhan (1973) is examinable in detail, as is your contemporary study.

Top-band moves: distinguish reliability from validity precisely; and when evaluating a treatment, cover effectiveness, appropriateness, side effects, cost and social control.

The big ideas to know

That is Topic 5 — compulsory, and assessed in Section A of Paper 2. Press Finish to see your score.