Scholastic achievement at age 16 and risk of schizophrenia and other psychoses: a national cohort study

Abstract

Background. There is abundant evidence that schizophrenia is associated with cognitive deficits in childhood. However, previous studies investigating school performance have been inconclusive. Furthermore, there are several biological and social factors that could confound the association. We investigated whether school performance at age 16 is associated with risk of adult schizophrenia and other psychoses in a large national cohort, while controlling for multiple confounders.Method. Using a national sample of 907 011 individuals born in Sweden between 1973 and 1983, we used Cox regression to assess whether scholastic achievement at age 15-16 predicted hospital admission for psychosis between ages 17 and 31, adjusting for potential confounders.Results. Poor school performance was associated with increased rates of schizophrenia [hazard ratio (HR) 3.9, 95 % confidence interval (CI) 2.8-5.3], schizo-affective disorder (HR 4.2, 95 % CI 1.9-9.1) and other psychoses (HR 3.0, 95 % CI 2.3-4.0). Receiving the lowest (E) grade was significantly associated with risk for schizophrenia and other psychoses in every school subject. There was no evidence of confounding by migrant status, low birthweight, hypoxia, parental education level or socio-economic group.Conclusions. Poor school performance across all domains is strongly associated with risk for schizophrenia and other psychoses.

Differential Neurodevelopmental Trajectories in Patients With Early-Onset Bipolar and Schizophrenia Disorders

“…In the same sample, above-average grades were associated with a decreased risk for schizophrenia. 18 In the Dunedin cohort study, children who developed schizophrenia in adulthood had cognitive impairment and that was not the case for bipolar patients (n = 20). 19 In a more recent analysis of the same cohort, while lower childhood IQ was associated with increased risk of developing schizophrenia spectrum disorder, depression, and adult anxiety at age 32, a higher childhood IQ predicted increased risk of mania (n = 8) at the same age.…”

How Genes and Environmental Factors Determine the Different Neurodevelopmental Trajectories of Schizophrenia and Bipolar Disorder

“…18 Both Israeli and Swedish cohorts have shown no differences in childhood cognition between premanics and controls. Our group 19 used the National Swedish registers to examine school performance in adolescents who later developed schizophrenia and bipolar disorder. The poorer the performance at school, the greater was the risk of schizophrenia.…”

Violent behaviour among people with schizophrenia: a framework for investigations of causes, and effective treatment, and prevention

“…Not only is the level of cognitive impairment a major determinant of psychosocial functioning, it is a core feature of schizophrenia. Deficits in cognitive performance characterize children and adolescents developing the illness, are present at onset of illness, remain stable over time and are largely explained by genetic factors (Cannon & Clarke 2005;Green et al 2005;Toulopoulou et al 2007;MacCabe et al 2007). While individuals developing schizophrenia and those already affected perform more poorly than age-matched healthy persons on all measures of cognitive functioning, among persons with schizophrenia there is wide variation in levels of cognitive performance.…”