A systematic literature review of childhood externalizing psychopathology and later psychotic symptoms.

Childhood onset mental health difficulties are known to be associated with later mental health disorders and worse prognoses in adulthood. Individuals who develop schizophrenia present, from childhood onwards, with cognitive deficits, psychotic-like experiences (PLEs) and internalizing and externalizing problems (EPs). People with a diagnosis of a schizophrenia spectrum disorder (SSD) are also more likely than people without this diagnosis to engage in aggressive behaviour towards others. This systematic review examines the evidence base investigating associations between childhood EPs and later psychotic symptoms. Searches were conducted on Ovid (Medline and Psychinfo), Pubmed and Scopus. PRISMA best-practice guidelines for conducting systematic literature reviews were followed. Data were extracted from predefined items and assessed using a quality rating scale. Fifteen studies were identified. Eleven of the 15 studies reported significant associations between childhood externalizing psychopathology and later psychotic symptoms, one study reported an association that did not reach significance, and three studies found no associations. Despite the substantial variations in conceptualization of EP, PLEs and SSD, this review found preliminary evidence for an association between childhood antisocial and aggressive behaviour and the later development of psychotic symptoms. Assessing children with EP for PLEs may be important to inform psychological therapies. More longitudinal studies are needed to better understand outcomes for children with presentations across the EP spectrum.