Research reportSchool performance and risk of suicide in early adulthood: Follow-up of two national cohorts of Swedish schoolchildren
Introduction
Cohort studies carried out in Sweden (Andersson et al., 2008, Gunnell et al., 2005), Australia (O'Toole and Stankov, 1992, O'Toole and Cantor, 1995), Denmark (Osler et al., 2008), Norway (Gravseth et al., 2010) and Finland (Alaraisanen et al., 2006) suggest that low IQ and poor school performance are associated with an increased risk of suicide in males. The associations are strong, with over two-fold differences in risk between high and low scorers.
Mechanisms underlying these associations are unclear. It is possible that deterioration in cognitive function or interruption of schooling as a result of mental illness may contribute to the observed patterns of risk. Alternatively, the more limited job opportunities available to people who perform less well at school may impact on adult socioeconomic position and job security, which in turn influence suicide risk. Lastly, cognitive function may impact on problem solving skills; it is possible that people with limited problem solving ability may be more likely to see suicide as the only solution to their problems. Previous studies have not investigated changes in cognitive function in relation to subsequent suicide risk, nor have they comprehensively assessed the possible confounding (or mediating) effects of socioeconomic position.
Furthermore, recent studies of the association of cognitive function with suicide have generated unexpected findings. In a study of 21,809 Swedish schoolchildren, born in 1948 and 1953 and assessed at age 13, IQ was inversely associated with suicide in males but not females (Andersson et al., 2008). No other studies have investigated gender-specific associations of cognitive test performance with suicide. Two studies have reported that associations differ in people with and without mental illness, with a positive association between test performance and suicide in people with previous hospital admissions for psychosis (Alaraisanen et al., 2006, Andersson et al., 2008). Similar findings have been reported in relation to attempted suicide (Batty et al., 2010). Likewise, in a study of former psychiatric inpatients in Denmark, there was an inverse association between the highest level of education completed and suicide risk (Agerbo, 2007).
In our recent study of Swedish schoolchildren, assessed at age 13, we found that associations of IQ with suicide disappeared in models controlling for mean school grade, indicating it was IQ-related school performance, rather IQ per se that influenced suicide risk (Andersson et al., 2008). To further investigate the link between school performance and suicide we have studied a cohort of over 180,000 Swedish males and females with measures of school performance at ages 16 and 18/19 years. This study has considerably more statistical power than our previous analysis, more detailed information on socioeconomic position and measures of educational performance at two time points in adolescence. We have investigated whether associations between school performance and suicide a) differ in males and females; b) differ in those with and without a record of psychiatric illness and c) are influenced by deterioration in school performance between ages 16 and 18.
Section snippets
Study population
This analysis is based on all Swedish males and females who were born in 1972 (n = 113,646) and 1977 (n = 99,749) and who completed their compulsory education in Swedish schools at age 16. Complete follow-up and baseline data were available for 186,808 subjects (88%) — the main reasons for exclusion were incomplete compulsory school performance data (n = 7058) and immigration to Sweden in the two years before completing compulsory school (n = 7712) (see below).
The following databases were linked to
Results
Altogether 95,497 males and 91,311 females fulfilled the inclusion criteria for the analyses, their characteristics are given in Table 1. There were 320 suicides (230 male and 90 female) over the 12–17 year follow-up: the overall suicide rate was 7.8 per 100,000 person years in males and 3.2 per 100,000 in females.
In total 6465 (3.5%) subjects were admitted to a psychiatric hospital and 3027 (1.6%) were admitted to a hospital following episodes of self-harm over the follow-up period. The most
Main findings
We found that school performance at ages 16 and 18/19 was strongly inversely associated with suicide risk in males, but not females. Amongst males there was a fourfold higher risk among those with the lowest 20% of school grades at age 16 compared to those with the highest 20%. In the subgroup (47%) of females who studied theoretical (more academic) courses in secondary school there was weak evidence (p = 0.09) that those with better school performance had an increased risk of suicide.
The
Conclusion
Educational performance is strongly associated with suicide risk in males and this association does not appear to be confounded by socioeconomic background or severe mental illness. Further studies are needed to elucidate the mechanism(s) through which education influences risk and reasons for the gender specificity of this association. Our findings add to the literature showing that risk factors for suicide differ in men and women (Qin et al., 2000). Similarly, risk factors for suicide appear
Role of funding source
The funder was not involved in the analysis, interpretation or write up of the results presented in this paper.
Conflict of interest
No conflict declared.
Acknowledgements
This project was funded by the Swedish Council for Working Life and Social Research. The UGU (education) database is funded by the Swedish Research Council. The project was approved by the Stockholm Regional Ethical Review Board. David Gunnell is a National Institute for Health Research (NIHR) Senior Investigator.
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