What is early detection of psychosis?
Early detection refers to the correct identification of individuals who are at high risk of developing schizophrenia, with an emphasis on the development of frank psychosis. Generally, there are two approaches that dictate the characteristics used as markers for detection. The first is the ultra-high risk approach which focuses on a triad of at-risk mental states defined as having a family history of psychosis plus non-specific symptoms and recent decline in functioning, recent onset of attenuated psychotic symptoms with decline in functioning, and brief, intermittent and limited psychotic symptoms. The other approach is based on Huber’s Basic Symptoms, which focuses on a detailed way of describing subjective disturbances, and may be an earlier indicator of risk.
What is the evidence for early detection of psychosis?
Moderate to high quality evidence found the mean rate of transition to psychosis in those assessed as being at clinical high risk is around 16% by 2 years and 29% by 3 years. In adolescents and young adults (16-24 years) who were diagnosed with attenuated psychotic syndrome, transition rates were 11% by 6 months, 15% by 12 months, 20% by 2 years months, and 23% by 3 years. In children (<18 years) assessed as being at clinical high risk, transition rates were between 17% and 20% by 1 year follow-up and between 7% and 21% by 2 year follow-up. 36% of children and adolescents recovered from their clinical high risk status by 6-year follow-up, and 40% continued to meet clinical high risk criteria without transition to psychosis.
People assessed as being at clinical high risk of obsessive-compulsive disorder were at higher risk of psychosis transition than people assessed as being at clinical high risk of bipolar disorder, which in turn had higher risk of psychosis than people assessed as being at high risk of depression. The rate of transition to psychosis was one third the rate of transition to non-psychotic disorders in people at assessed as being at clinical high risk for any non-psychotic disorder.
Studies with older samples reported higher transition rates than studies with younger samples, and more recent publications reported lower transition rates than older publications. Studies using the basic symptoms approach reported higher transition rates than studies using the ultra-high risk approach. Studies of people receiving psychosocial treatments for high risk groups (e.g., cognitive behavioural therapy) reported lower transition rates than studies of people receiving standard care (e.g., case management). Studies of people on antipsychotics also reported lower transition rates than studies of people not on antipsychotics.
Moderate to high quality evidence suggests instruments based on ultra-high risk criteria have good sensitivity and moderate specificity. Moderate to low quality evidence found the Assessment of Basic Symptoms Scale has good sensitivity and moderate specificity. This indicates validated tools are generally good at correctly identifying individuals who do develop psychosis, but not as good at identifying individuals who do not develop psychosis.
Moderate quality evidence suggests the model with the best predictive value (86%) for transition to psychosis was a clinical model including odd beliefs, marked impairment in role functioning, blunted affect, auditory hallucinations, and anhedonia/asociality. A biological model using grey matter volume, and a neurocognitive model using IQ, verbal memory, executive functioning, attention, processing speed, and speech perception, both had positive predictive values of ~83%. An environmental model with a positive predictive value of 63% involved urbanicity, social-sexual aspects, and social-personal adjustment. The best combination model had a positive predictive value of 82% and involved disorganised communication, suspiciousness, verbal memory deficit, and decline in social functioning.
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Green - Topic summary is available.
Orange - Topic summary is being compiled.
Red - Topic summary has no current systematic review available.