Systemic inflammation and intelligence in early adulthood and subsequent risk of schizophrenia and other non-affective psychoses: a longitudinal cohort and co-relative study

Nils Kappelmann, Golam M Khandaker, Henrik Dal, Jan Stochl, Kyriaki Kosidou, Peter B Jones, Christina Dalman, Håkan Karlsson

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

BACKGROUND: Schizophrenia is associated with impaired neurodevelopment as indexed by lower premorbid IQ. We examined associations between erythrocyte sedimentation rate (ESR), a marker of low-grade systemic inflammation, IQ, and subsequent schizophrenia and other non-affective psychoses (ONAP) to elucidate the role of neurodevelopment and inflammation in the pathogenesis of psychosis.

METHODS: Population-based data on ESR and IQ from 638 213 Swedish men assessed during military conscription between 1969 and 1983 were linked to National Hospital Discharge Register for hospitalisation with schizophrenia and ONAP. The associations of ESR with IQ (cross-sectional) and psychoses (longitudinal) were investigated using linear and Cox-regression. The co-relative analysis was used to examine effects of shared familial confounding. We examined mediation and moderation of effect between ESR and IQ on psychosis risk.

RESULTS: Baseline IQ was associated with subsequent risk of schizophrenia (adjusted HR per 1-point increase in IQ = 0.961; 95% confidence interval (CI) 0.960-0.963) and ONAP (adjusted HR = 0.973; 95% CI 0.971-0.975). Higher ESR was associated with lower IQ in a dose-response fashion. High ESR was associated with increased risk for schizophrenia (adjusted HR = 1.14; 95% CI 1.01-1.28) and decreased risk for ONAP (adjusted HR = 0.85; 95% CI 0.74-0.96), although these effects were specific to one ESR band (7-10 mm/hr). Familial confounding explained ESR-IQ but not ESR-psychoses associations. IQ partly mediated the ESR-psychosis relationships.

CONCLUSIONS: Lower IQ is associated with low-grade systemic inflammation and with an increased risk of schizophrenia and ONAP in adulthood. Low-grade inflammation may influence schizophrenia risk by affecting neurodevelopment. Future studies should explore the differential effects of inflammation on different types of psychosis.

Original languageEnglish
Pages (from-to)295-302
Number of pages8
JournalPsychological Medicine
Volume49
Issue number2
DOIs
Publication statusPublished - Jan 2019

Keywords

  • Adolescent
  • Adult
  • Aged
  • Blood Sedimentation
  • Comorbidity
  • Cross-Sectional Studies
  • Humans
  • Inflammation/blood
  • Intelligence/physiology
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Psychotic Disorders/epidemiology
  • Registries
  • Risk
  • Schizophrenia/epidemiology
  • Sweden/epidemiology
  • Young Adult

Fingerprint Dive into the research topics of 'Systemic inflammation and intelligence in early adulthood and subsequent risk of schizophrenia and other non-affective psychoses: a longitudinal cohort and co-relative study'. Together they form a unique fingerprint.

Cite this