Prodrome: Uncertainty in Prediction

Predicting psychosis is difficult because early changes overlap with many ordinary experiences and other mental health conditions. A sign can be associated with increased risk at the group level while remaining a poor predictor for one person. Prediction also depends on the population assessed and the period over which outcomes are measured.

A prodrome is a period of changes that precedes a more clearly defined illness episode. In psychosis, early changes may involve functioning, mood, sleep or unusual experiences. The term is often applied retrospectively because many similar changes occur in people who never develop a psychotic disorder.

No single questionnaire, genetic score or brain scan can reliably determine that an individual will develop schizophrenia. Research combines different measures, but clinical usefulness and fairness require careful evaluation. Uncertainty should be communicated openly, including the possibility that symptoms improve or lead to another diagnosis. This does not mean ignoring concerning changes. It means offering proportionate support, agreed follow-up and clear routes for reassessment without treating a possible future illness as an established fact. Present needs remain a sound basis for care even when prediction is limited.

False positives and false negatives matter. Some people identified as high risk will not develop psychosis, while some who later become ill were not previously identified. A useful service therefore supports present difficulties and provides accessible reassessment. This approach remains valuable even when prediction improves, because a probability estimate cannot replace listening to changes in the person’s actual life.

Further reading: National Institute of Mental Health; NICE clinical guideline.