Is low IQ associated with an increased risk of developing suicidal thoughts?
Studies in young male conscripts suggest that low IQ scores are associated with an increased risk of suicide. Mechanisms underlying this association are unclear.
To investigate the association of IQ, as indexed by the national adult reading test (NART), with the incidence of, and recovery from, suicidal thoughts.
An 18-month follow-up of 2,278 of the adults who took part in the Britain’s second national psychiatric morbidity survey who completed the NART at baseline.
There was no evidence that poor performance on the NART was associated with an increased incidence of suicidal thoughts over the 18 month follow-up (adjusted odds ratio per 10 unit increase in NART-IQ 1.08 (95% CI 0.86–1.36). However, amongst the 155 subjects with suicidal thoughts at baseline, those with low NART-IQ were least likely to recover from them: the adjusted odds of recovery per 10 unit increase in NART-IQ was 1.42 (95% CI 0.96–2.10).
The association between low IQ and an increased risk of suicide may be because people with low IQ experience suicidal thoughts for more prolonged periods than those with high IQ or because low IQ increase the likelihood that people experiencing suicidal thoughts act upon them.
KeywordsIQ NART suicidal thoughts cohort
We would like to thank Howard Meltzer for initial design work on the survey and other ONS staff who were involved in the fieldwork and data preparation. Contributors: The Office for National Statistics carried out the longitudinal study on which this paper is based. NS was Project Manager for the study with responsibility for the data collection, analysis and reporting of the study as a whole. DG conceived and wrote the first draft of the paper and will act as guarantor, RH conducted the analyses and all authors commented on, and contributed to, revisions of the paper. GL and RJ contributed to the design and analysis of the study and provided critical comments on the manuscript. All authors have approved the final version of the paper. Funding: The data collection was funded by the Department of Health and the Scottish Executive Health Department. The views expressed in this report are those of the authors and not the Department of Health. Ethical approval: Ethical approval for the survey work was obtained from the London MREC. Competing interests: None
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