Abstract
Background: An inverse relationship between risk of schizophrenia and premorbid IQ is a robust empirical finding. Cognitive impairment may be a core feature of schizophrenia in addition to the clinical symptoms that have historically defined the disorder.
Aims: To evaluate whether risk of schizophrenia increases linearly or nonlinearly with the lowering of premorbid IQ after adjustment for a range of confounding factors.
Methods: IQ data from the 1958 National Child Development Study, a prospective national birth cohort (n = 17 419), were linked with psychiatric admissions in England and Wales over a 20-year period. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnoses were derived from case notes.
Results: A clear nonlinear inverse relationship between general intelligence at ages 7 and 11 and risk of adult psychosis was found even after adjustment for potential social, behavioral, or demographic confounding factors. No such relationship was found for affective disorders.
Conclusions: The nonlinear relationship suggests an excess risk of schizophrenia in children with premorbid IQ in the learning disabilities range. Previous reports of a linear relationship are likely to be a result of less sensitive statistical methods for detecting nonlinearity
Aims: To evaluate whether risk of schizophrenia increases linearly or nonlinearly with the lowering of premorbid IQ after adjustment for a range of confounding factors.
Methods: IQ data from the 1958 National Child Development Study, a prospective national birth cohort (n = 17 419), were linked with psychiatric admissions in England and Wales over a 20-year period. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnoses were derived from case notes.
Results: A clear nonlinear inverse relationship between general intelligence at ages 7 and 11 and risk of adult psychosis was found even after adjustment for potential social, behavioral, or demographic confounding factors. No such relationship was found for affective disorders.
Conclusions: The nonlinear relationship suggests an excess risk of schizophrenia in children with premorbid IQ in the learning disabilities range. Previous reports of a linear relationship are likely to be a result of less sensitive statistical methods for detecting nonlinearity
| Original language | English |
|---|---|
| Pages (from-to) | 143-51 |
| Number of pages | 9 |
| Journal | Schizophrenia Bulletin |
| Volume | 40 |
| Issue number | 1 |
| Early online date | 30 Dec 2012 |
| DOIs | |
| Publication status | Published - 2014 |
Keywords
- risk of schizophrenia, premorbid IQ, epidemiology, birth cohort