Psychotic disorders are one of the most severe mental disorders in children, adolescents, and adults. Accordingly, schizophrenia spectrum and other psychotic disorders (SSD) represent the third leading cause of disability-adjusted life years in young people aged 10–24 years worldwide . Their poor outcome is generally associated with an early age of onset and a longer duration of untreated psychosis and illness .
To prevent and reduce the burden caused by psychotic disorders, during the past 2 decades, early detection of risk for psychosis has been intensively investigated, and in particular, predictive power for early signs of risk has been translated into clinical practice. This intensive research on early detection has led to the development of the clinical high-risk state for psychosis (CHR-P) construct to enable the identification of subjects at enhanced imminent risk of development of a first-episode psychotic disorder . 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 .
This editorial aims to discuss the particularities associated with the implementation of the CHR-P model in child and adolescent psychiatry, and to propose some priority axes and strategies to sustain this integration.
Do the CHR-P criteria take into account the developmental aspects that characterize children and young adolescents?
Although the incidence rates for psychosis peak around the age of 22 years , one-third of psychotic disorders have an onset before age 18 (early onset psychosis; EOP) . In these cases, the need for early detection becomes even more striking, since EOP is considered to have a poorer outcome than adult-onset psychosis (AOP) [3, 27]. Indeed, because EOP mainly occurs during adolescence, a critical developmental period for the attainment of several milestones including education and peer relationships, individuals with EOP often suffer from medium- and long-term social deficits [8, 15].
While EOP is considered to be clinically and biologically coherent with AOP, several differences have been pointed out. Individuals with EOP show higher rates of premorbid abnormalities, longer duration of untreated psychosis , and poorer outcomes [3, 8, 15]. EOP is also characterized by higher levels of auditory hallucinations , negative symptoms, bizarre behavior [5, 16, 32], and more severe cognitive deficits [1, 4, 19, 21, 22, 25, 36]. Genetic loci, which modify the age at onset, have been reported .
In comparison with adult CHR-P state, children and adolescents (CAD; aged 8–15 years old) with a CHR-P state report a high prevalence of (attenuated) psychotic symptoms (hallucinations) in both general and help-seeking populations, further underscoring age-related peculiarities of CHR-P symptoms . These seem to decrease throughout adolescence [7, 18, 29] and remit spontaneously in about three quarters of CAD with a CHR-P state [6, 11]. In addition, 1-year transition rates to full-blown psychosis appear to be lower than those observed in the adult population . A word of caution is warranted in light of the less solid evidence base for these findings in CAD.
Indeed, to date, research into the CHR-P states has predominantly been carried out in adults and older adolescents (≥ 16 years old), with little consideration of possible special requirements in CAD . In accordance with this lack of evidence, the recently published EPA guidance on early detection and intervention in CHR-P  argues that, due to the insufficient evidence for the psychosis predictive value of CHR criteria in CAD, these criteria should only be used and communicated with utmost care in CAD. Alongside, EPA guidelines state that evidence on the efficacy of psychological and pharmacological interventions in CAD with a CHR-P state is not sufficient to justify primarily preventive interventions. In line with the EPA statement and under consideration of the evidence available to date, it was recently argued that the validity of current risk criteria needs to be examined in and possibly adapted to children, adolescents, and young adults [2, 26, 31, 35].
Do child and adolescent mental health services have specific competencies and resources for early diagnosis and intervention in CHR-P?
On the basis of what has been written so far, it is not surprising that patients referred to CHR services by child and adolescent mental health services (CAMHs) have a relatively low pre-test risk for psychosis in comparison with all patients undergoing CHR assessment [10, 11]. Despite a lower transition rate to psychosis in young adolescents presenting with a CHR state, there is evidence for the predictive utility of CHR criteria in CAD and efforts should be made to support the development of CHR-P strategies by CAHMS .
Moreover, in general, it seems that CHR-P strategies which are currently in place for adults and older adolescents work well for a small fraction of help-seeking individuals, but not for the majority of patients seeking help in secondary mental health care despite the fact that pre-test risk is up to six times higher than in the general population. Indeed, it has been recently highlighted by a clinical register-based cohort study  in the UK that mostly first-episode psychosis patients (i.e., 95%) who previously sought medical advice in a secondary mental health care such as CAMHS were not tagged as CHR-P, but received a diagnosis of a full-blown mental disorder. Interestingly, diagnoses of bipolar mood disorder or acute and transient psychotic disorders were associated with a similar or even higher risk of transition to psychosis than the original CHR-P criteria themselves .
More generally, the distribution of the resources in services (CAMHS and AMHS) primarily focuses on children (0–12 years, developmental disorders) and adults (> 25 years, tertiary prevention, and chronicity management). This distribution leaves a few resources to devote the activity of prevention and early intervention that targets the adolescent and young adult populations .
In this sense, CAMH practitioners have an important role in redefining more global and trans-diagnostic criteria that take into account the specificity of CAMH services and child development.
In addition, the CHR-P topic and the consistent clinical staging approach are not currently a core subject of teaching in most child and adolescent psychiatry training schools.
ESCAP statement on how to improve the early detection of CHR-P in children and adolescents
We highlight a few selected areas related to CHR-P in children and adolescents that, in our opinion, should be addressed and implemented in the field of CAMHS.
Development and adaptation of specific and developmentally appropriate tools
As highlighted in the second paragraph, the majority of current CHR-P diagnostic tools have been developed on populations of young adults. In addition, the value and significance of under-threshold psychotic symptoms have been shown to be different in children and young adolescents.
In this sense, to our knowledge, only two tools for early detection of CHR-P have been developed specifically for children and adolescents to be employed as of age 8. The first one is the Prodromal Questionnaire—brief child version , a self-reported questionnaire that has been validated on a population of 3984 CAD (mean age 10.0 years; SE 0.01). The second one is the schizophrenia proneness instrument, child and youth version (SPI-CY) , which is the only validated structured interview for the assessment of CHR-P states in children and adolescents. The instrument was developed and validated in a sample of 64 CAD aged 8–18 years (mean age 16 years) showing good discriminative and validity values.
Overall, this evidence leads us to emphasize the need for more in-depth studies into developmental peculiarities in the early detection and treatment of psychoses with an onset of illness in childhood and early adolescence. To achieve this goal, it seems necessary to distinguish the predictive utility of risk phenomena (e.g., disorganized communication and unusual thought content/delusional ideas) and their severity category (e.g., attenuated psychotic symptoms and brief limited intermittent psychotic symptoms). In this sense, there is a strong need to develop diagnostic tools that consider all aspects of development in CAD, including biological, affective, cognitive, and social characteristics. Clinician scientists, i.e., CAP specialists who engage in both clinical and research activities , will be key players in the refinements of early intervention strategies, including CHR-P.
Develop CHR-P model competencies during training and implement the CHR-P model in CAMHS
Reasons for a lack of clearly defined CHR-P strategies in CAMHS are probably multifactorial, but the fear of generating stigma in CAD and the resistance to the influence of adult psychiatry on CAP are two important parameters. This is reinforced by a dramatic lack of information and training regarding the early intervention strategies. The younger generation of child and adolescent psychiatrists can play an important role in the diffusion of these new developments and paradigm shifts by teaching and mentoring future trainees. Accordingly, the ESCAP Research Academy supported the first residential course on “Assessment and treatment of psychiatric disorders in children and adolescents” which took place in Catania in October 2019 and during which an entire day was devoted to CHR-P. The second edition of this course will take place in Catania in October 2020 (https://www.escap.eu/index/the-urgent-need-to-interact/2nd-residential-course). In addition, the ESCAP Research Academy meeting to take place in Maastricht in 2021 will focus on early intervention strategies (https://www.escap.eu/escap-congresses/).
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Armando, M., Klauser, P., Anagnostopoulos, D. et al. Clinical high risk for psychosis model in children and adolescents: a joint position statement of ESCAP Clinical Division and Research Academy. Eur Child Adolesc Psychiatry 29, 413–416 (2020). https://doi.org/10.1007/s00787-020-01499-3