Les troubles psychotiques représentent une des causes psychiatriques de handicap fonctionnel les plus importantes et les plus durables pour un individu. Depuis vingt ans, de nombreuses études longitudinales informent et précisent la nature du risque à la psychose, soutenant les efforts consacrés à sa détection et à son intervention précoce. Plus particulièrement, l’approche empirique visant à objectiver les états à haut risque clinique (clinical high risk [CHR]) a ouvert la voie à des pistes prometteuses. Récemment, deux systèmes de critères d’évaluation (critères de l’ultra-haut risque [UHR]) et des symptômes de base se sont imposés dans la clinique du CHR. Selon l’Association européenne de psychiatrie (AEP), ces derniers devraient être utilisés pour objectiver le syndrome de risque à la psychose. Actuellement, les données récoltées lors d’études prospectives confirment en effet leur valeur à prédire l’émergence d’un trouble psychotique chez l’adulte ; ceci reste à être confirmé pour les enfants et les adolescents. En ce qui concerne les interventions préventives l’AEP recommande, pour les patients adultes, de donner la priorité aux traitements psychologiques et, en cas d’échec, d’introduire un traitement psychopharmacologique. Les interventions menées sur le plan psychologique devraient en outre cibler la prise en charge des troubles psychiatriques associés aux états CHR (principalement anxiété et dépression) plutôt que les aspects psychotiques en eux-mêmes. Chez les enfants et les adolescents, la politique de prise en charge s’avère un peu différente. Elle stipule un suivi de l’évolution des états CHR qui tienne compte des spécificités de la période développementale où ces derniers se manifestent, et une intervention ciblée sur la détresse psychologique causée par les comorbidités psychiatriques.

In children and adolescents, psychotic disorders already represent one of the leading causes of disability-adjusted life years. During the past two decades, early detection of risk for psychosis has been intensively investigated, and in particular, predictive power for early signs of risk has been initiated and translated into clinical practice. In particular, the attenuated and transient positive symptoms of the ultra-high risk criteria, and the basic symptom criterion “cognitive disturbances”, open promising routes to an indicated prevention and have recently been considered by the European Psychiatric Association (EPA) as diagnostic criteria of a psychosis-risk syndrome. The EPA recently provided evidence-based recommendations on the early detection of clinical high risk (CHR) for psychosis in patients with mental distress. In 2015, experts in the field of early detection conducted a meta-analysis reporting on studies examining conversion rates to psychosis in non-overlapping samples meeting at least one of the main CHR criteria: ultra-high risk (UHR) and/or basic symptoms criteria, examining the effects of potential moderators (different UHR criteria definitions, single UHR criteria and age) on conversion rates. In the 42 identified samples, comprising more than 4000 CHR patients who had been mainly identified by means of UHR criteria and/or the basic symptom criterion ‘cognitive disturbances’ (COGDIS), conversion rates showed considerable heterogeneity. While UHR and COGDIS criteria were related to comparable conversion rates until a 2-year follow-up, rates for COGDIS were significantly higher for follow-up periods beyond 2 years. Differences in onset and frequency requirements of symptomatic UHR criteria, or in their different consideration of functional decline, substance use and co-morbidity, did not seem to have an impact on conversion rates. The ‘genetic risk and functional decline’ UHR criterion was rarely met and only showed an insignificant pooled sample effect. However, age significantly affected UHR conversion rates with lower rates in children and adolescents. Although more research into potential sources of heterogeneity in conversion rates is needed to facilitate improvement of CHR criteria, six evidence-based recommendations for the early detection of psychosis were developed as a basis for the EPA guidance on early intervention in CHR states. The EPA guidance on early intervention aimed to provide evidence-based recommendations on early intervention in CHR states of psychosis, assessed according to the EPA guidance on early detection. The recommendations were also made by experts in the field of early intervention in psychoses and derived from a meta-analysis of current empirical evidence on the efficacy of psychological and pharmacological interventions in CHR samples. Eligible studies had to investigate conversion rate and/or functioning as a treatment outcome in CHR patients defined by the ultra-high risk and/or basic symptom criteria. In addition to analyses of treatment effects on conversion rate and functional outcome, age and type of intervention were examined as potential moderators. Based on data from 15 studies (n=1394), early intervention generally produced significantly reduced conversion rates at 6- to 48-month follow-up compared to control conditions. However, early intervention failed to achieve significantly greater functional improvements because both early intervention and control conditions produced similar positive effects. With regard to the type of intervention, both psychological and pharmacological interventions produced significant effects on conversion rates but not on functional outcome relative to the control conditions. Early intervention in youth samples was generally less effective than in predominantly adult samples. Seven evidence-based recommendations for early intervention in CHR samples have been formulated, although more studies are needed to investigate the specificity of treatment effects and potential age effects in order to tailor interventions to the individual treatment needs and risk status. Overall, age-related specificities and developmental transitions in the early detection and intervention in psychoses should be better accounted for in future research.