Differentiation of childhood risk profiles for schizophrenia according to the development of verbal and performance intelligence

Distinct patterns in the premorbid development of verbal and performance intelligence might differentiate the propensity for later illness among individuals putatively at risk for schizophrenia. This study applied linear mixed-effects models to four verbal and performance intelligence assessments gathered from a community sample of youth (n = 114) over ages 9–20 years, comparing developmental trajectories for at-risk youth with a triad of well-replicated antecedents of schizophrenia (ASz) and at-risk youth with a family history of schizophrenia (FHx), each relative to low-risk, typically developing peers (TD). Supplementary analyses explored heterogeneity among ASz youth according to persistence of symptoms, and FHx youth according to familial loading and presence of antecedents. Both ASz and FHx youth demonstrated early deficits (age ∼11 years) in verbal intelligence relative to TD youth, which remained stable into young adulthood. FHx youth additionally showed this stable developmental deficit relative to TD youth in performance intelligence. In exploratory supplementary analyses, verbal intelligence improved with age toward TD performance among ASz children whose psychopathological symptoms remitted during follow-up. Uniquely among FHx youth, those with a low familial loading (one second-degree affected relative only) and none/one of the three antecedents did not evidence the stable developmental deficits in verbal and performance intelligence. These distinct developmental trajectories of verbal and performance intelligence among youth presenting different profiles of schizophrenia risk may signify potential for targeted preventative interventions. Further research is needed to determine whether these trajectories distinguish later transition to schizophrenia from a cognitive vulnerability that normalises among at-risk individuals who do not transition.