Positive Symptoms

Positive Symptoms of Schizophrenia

Schizophrenia is a severe, chronic mental disorder characterised by disruptions to thought, perception, emotion, and behaviour. Symptoms are divided into positive and negative categories. Positive symptoms are experiences or behaviours that are present in people with schizophrenia but absent (or much less pronounced) in typical functioning — they represent additions to normal experience rather than losses. The term 'positive' does not imply that these symptoms are desirable; it reflects their status as something extra, superimposed on typical functioning.

Hallucinations

Hallucinations are perceptions that occur in the absence of an external stimulus — the person perceives something that is not there. In schizophrenia, auditory hallucinations are the most common form: typically hearing one or more voices that comment on behaviour, converse with each other, or give commands. These voices are experienced as real and external, not as the person's own thoughts. Other modalities may also be affected: visual hallucinations (seeing things that are not there), tactile hallucinations (physical sensations without cause), and olfactory hallucinations (smelling things others cannot detect).

Schneider (1959) identified first-rank symptoms of schizophrenia — experiences considered highly characteristic. Auditory first-rank symptoms include: a running commentary (voices describing the person's actions); voices conversing with each other about the person; and thought echo (hearing one's own thoughts as if spoken aloud).

Delusions

Delusions are fixed, false beliefs that are held with certainty and are resistant to contradictory evidence, even when inconsistent with the person's culture and context. Common types in schizophrenia include:

• Paranoid/persecutory delusions: the belief that one is being watched, followed, harassed, or conspired against by others.
• Grandiose delusions: the belief that one has special powers, a special mission, or extraordinary importance.
• Delusions of reference: the belief that neutral events (news broadcasts, random comments) carry special personal significance or messages directed at the person.
• Passivity experiences (Schneider first-rank): thought insertion (thoughts placed in one's mind by an external agent); thought withdrawal (thoughts removed by an external agent); thought broadcasting (one's thoughts are audible to others); somatic passivity (body controlled by external forces).

Disorganised Thinking and Speech

Formal thought disorder refers to disruption of the normal coherence and organisation of thought. It is usually inferred from disorganised speech. Features include: derailment (loosely connected ideas); tangentiality (responses that drift off topic); word salad (incoherent jumble of words); clanging (selecting words by sound rather than meaning: 'I like bikes and strikes and pikes'); and neologisms (made-up words).

Disorganised or Abnormal Motor Behaviour

This includes a range of behaviours from unpredictable agitation to catatonia — a marked decrease in reactivity to the environment including rigid immobility, waxy flexibility (maintaining positions imposed by others), or stupor.

DSM-5 Diagnostic Criteria

For a diagnosis of schizophrenia, DSM-5 requires at least two of five symptom types for one month or more (at least one must be from the first three): delusions; hallucinations; disorganised speech; disorganised or catatonic behaviour; negative symptoms. These must cause significant social or occupational impairment and persist for at least six months.