Is lower IQ linked to increased schizophrenia risk?

  • Kappelmann N & al.
  • Psychol Med
  • 6 Apr 2018

  • from Sarfaroj Khan
  • Clinical Summaries
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Takeaway

  • Lower intelligence quotient (IQ) was found to be associated with low-grade systemic inflammation and increase in risk for schizophrenia and other non-affective psychoses (ONAP) in adulthood.
  • Low-grade inflammation may influence risk for schizophrenia by affecting neurodevelopment

Why this matters

  • Abnormal neurodevelopment plays a significant role in the worsening of schizophrenia.
  • Not many studies have assessed the association between erythrocyte sedimentation rate (ESR) and subsequent risk for schizophrenia and related psychosis.

Study design

  • Population-based cohort study of 638,213 Swedish men examined the associations of ESR with IQ (cross-sectional) and psychoses (longitudinal) between 1969 and 1983.
  • Participants’ intelligence was assessed by testing the logic/general intelligence, verbal intelligence, visuospatial perception and mechanical skills in solving mathematical or physical problems.
  • Funding: None disclosed.

Key results

  • After adjustments, with every 1-point increase in IQ, decrease in schizophrenia (HR, 0.961; 95% CI, 0.960-0.963) and ONAP (HR, 0.973; 95% CI, 0.971-0.975) was observed.
  • In patients with high ESR (7-10 mm/hour), risk for schizophrenia (aHR, 1.14; 95% CI, 1.01–1.28) was increased and risk for ONAP (aHR, 0.85; 95% CI, 0.74-0.96) was decreased.
  • After adjustment, every 1-point increase in ESR increased the risk for schizophrenia (P=.070) but decreased the risk for ONAP (P=.053).

Limitations

  • Only male participants were included.