The critical period

Aim: Evidence from long-term follow-up studies of schizophrenia and from the ‘new epidemiology’ of psychoses has forced us to rewrite the textbooks and challenge accepted wisdom. In this paper I aim to review the concept of my ‘Critical Period’ in the long-term trajectory of schizophrenia. Method: I will review long-term follow-up studies of first episode psychosis. Results: Studies suggest that: a. the course of the psychoses is very variable; b. much of this variability is laid down during the ‘prodromal’ and first 3 - 5 years following the first episode; c. the ‘disability’ plateaus quickly, much of it occuring before the positive symptoms develop (the ‘symptom-disability gap’) but d. the psychosocial and ecological risk factors that have now been uncovered, suggest a more protean, malleable process in the development of psychosis, as witnessed, for example by the considerable number of ‘at risk’ individuals with low-level, but disabling psychotic symptoms, who escape psychosis (the misnomer of the ‘false positive’). Conclusion: This picture presents a fresh take on my concept of the ‘critical period’ with implications for public health and prevention.