title: [Early intervention in psychosis: concepts, current knowledge and future directions].
abstract: OBJECTIVE
  This paper seeks to provide an overview of the motives, rationale, theoretical underpinnings and foundational literature of the early intervention movement for psychoses. It also seeks to review the current status of the field, highlight its significant developments and identify its emergent trends.
  
  
  METHODS
  This paper begins by contextualizing the burden of psychosis. It then traces the origins of the early intervention movement and surveys the seminal literature that established and shapes the field. It describes the movement's characteristic elements, types, approaches, strengths, criticisms and trajectories in select Western nations. It closes with a presentation of how the early intervention movement is informing broader endeavours to transform youth mental health.
  
  
  RESULTS
  We find that the early intervention movement is predicated on the critical period hypothesis that emphasizes the significance of the early stages of the illness; and on findings that the duration of untreated psychosis influences prognoses. Early intervention redresses this situation by facilitating access to specialized, phase-specific treatment. Access is enhanced through open referral, fast response times, and public and practitioner education. Ideally, the intervention, provided for the first two years after detection, features intensive case management; low-dose antipsychotic medication; an emphasis on social functioning; family intervention; early attention to comorbid concerns; and due regard for the needs and priorities of youth and their families. Evidence suggests that specialized early intervention yields better outcomes than routine care. The cost-effectiveness of such services has not yet been definitely investigated. Criticisms of early intervention pertain to the quality of evidence for, the manner of implementation of, the allocation of resources to early intervention and its utility for persons at high risk for developing psychosis. We also identify advocacy within the field for extending early intervention to the first five years of the course of psychosis.
  
  
  CONCLUSIONS
  We conclude that the status of the early intervention movement (in terms of availability and policy) in Western public healthcare systems can be resolved into a spectrum. The United Kingdom is shown to be the leader while Canada appears at the middle of the spectrum (with the United States bringing up the rear). In the Quebec context, the picture is found to be mixed and recommendations for further research and investment are made. Finally, an examination is undertaken of how the early intervention for psychosis movement has provided the impetus for and dovetails into the larger effort to transform youth mental healthcare in general, a development that is in its nascent stages in Canada.
authors.affiliation: Département de psychiatrie, Université McGill, Institut universitaire en santé mentale Douglas, Montréal.
authors.forename: Srividya N
authors.initials: SN
authors.lastname: Iyer
authors.affiliation: Institut universitaire en santé mentale Douglas, Montréal, Canada; Département de psychiatrie, Université McGill, Montréal.
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Malla