General practitioners and psychiatrists must ensure that prompt diagnostic assessment and appropriate care are available for young people who seek help (or whose families seek help) because of worrying changes in emotions, thinking, and behaviour. In a small minority of such patients it will emerge over time that the initial symptoms were, in fact, the start of a severe—and sometimes devastating—psychotic illness.

Health professionals and families will inevitably ask themselves whether more could have been done in the earliest stages. But without the benefit of hindsight, when does it become justified to prescribe antipsychotic drugs that have serious side effects? When should patients be offered at least as powerful and potentially dangerous psychotherapy addressing the causes and consequences of psychosis? Important programmes of research are under way that will inform these difficult clinical judgments.1 So …