Schizophrenia spectrum disorders in children and adolescents: Clinical, phenomenological, diagnostic, and prognostic features across subtypes

Schizophrenia spectrum disorders (SSD) typically have a diagnostically recognizable onset in young adulthood, yet it is not unusual that help-seeking due to initial SSD-related clinical manifestations emerge in earlier developmental phases, such as childhood and adolescence. Varieties of SSD manifestations in children and adolescents can be distinguished according to variations in clinical expressivity, severity and timing (i.e. developmental stage). Some individuals may reach the full clinical threshold for a diagnosis of schizophrenia according to the same descriptive diagnostic criteria used for adults, and in this case, it's possible to distinguish a pre-pubertal onset in childhood (aka Very Early Onset Schizophrenia, VEOS) and a post-pubertal onset in adolescence (aka Early Onset Schizophrenia, EOS). Other individuals may not reach such clinically overt diagnostic threshold but nonetheless present Childhood Schizotypal Disorder (CSD) or a Clinical High-Risk for Psychosis (CHRP). While EOS is clinically more similar to the canonical adult-onset presentation, the other 3 subgroups (i.e. VEOS, CSD, CHRP) present more nuances and specific clinical characteristics, which require ad-hoc developmental and phenomenological considerations for appropriate differential diagnosis and prognosis. Therefore, current scoping review intends to saturate such knowledge gap with respect to early SSD-phenotypes.