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Positive symptoms

What are positive symptoms? 

Positive symptoms are a well-documented feature of schizophrenia and are arguably the most recognisable and conspicuous symptoms. Positive symptoms include hallucinations and delusions. Hallucinations are defined as a perceptual experience that occurs in the absence of any external sensory input, and are most commonly auditory, but can occur in any modality. Delusions are distortions or exaggerations of inferential thinking, which lack any logical consistency, are not explained by cultural beliefs, and persist regardless of contradictory evidence. Persecutory delusions involve the belief that people are “out to get” the individual, resulting in a lack of trust in others. Delusion of reference refers to the belief that neutral events are directed specifically towards the individual. Somatic delusions involve the belief that the individual has a physical ailment contrary to medical advice. Delusions of grandeur are characterised by an exaggerated belief that the individual has power, ability, or fame. Positive symptoms can cause extreme distress for the person. The severity of positive symptoms can significantly affect a person’s day-to-day function, quality of life, and may also be associated with impaired cognitive ability. Positive symptoms have been shown to be more responsive to antipsychotic treatment than other symptom dimensions.

What is the evidence regarding positive symptoms?

Moderate quality evidence shows a small effect of similarity of reality distortion symptoms between siblings with schizophrenia. Features of hallucinations tend to be similar across various diagnostic groups, apart from age of onset of hallucinations, which is earlier in non-clinical and dissociative disorder groups (<12 years) than in schizophrenia (late teens to early 20s), and is later in affective disorders, neurological disorders, and alcohol-related conditions (middle or older age). There is less negative content and more controllability of hallucinations in non-clinical groups. Appraisal of hallucinatory voices as malevolent or intrusive and unable to be controlled is associated with increased levels of distress, depression, or anxiety. Voices appraised as high in power or supremacy is also associated with increased distress and depression. Negative affect may be greater when the voices are personally meaningful or more emotional.

June 2017

Page last updated: 1:28  7 September 2017

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