The association between childhood cognitive ability and adult long-term sickness absence in three British birth cohorts: :a cohort study

Objectives: The authors aimed to test the relationship between childhood cognitive function and long-term sick leave in adult life and whether any relationship was mediated by educational attainment, adult social class or adult mental ill-health. Design: Cohort study. Setting: The authors used data from the 1946, 1958 and 1970 British birth cohorts. Initial study populations included all live births in 1 week in that year. Follow-up arrangements have differed between the cohorts. Participants: The authors included only those alive, living in the UK and not permanent refusals at the time of the outcome. The authors further restricted analyses to those in employment, full-time education or caring for a family in the sweep immediately prior to the outcome. 2894 (1946), 15 053 (1958) and 14 713 (1970) cohort members were included. Primary and secondary outcome measures: receipt of health-related benefits (eg, incapacity benefit) in 2000 and 2004 for the 1958 and 1970 cohorts, respectively, and individuals identified as 'permanently sick or disabled' in 1999 for 1946 cohort. Results: After adjusting for sex and parental social class, better cognitive function at age 10/11 was associated with reduced odds of being long-term sick (1946: 0.70 (0.56 to 0.86), p=0.001; 1958: 0.69 (0.61 to 0.77), p<0.001; 1970: 0.80 (0.66 to 0.97), p=0.003). Educational attainment appeared to partly mediate the associations in all cohorts; adult social class appeared to have a mediating role in the 1946 cohort. Conclusions: Long-term sick leave is a complex outcome with many risk factors beyond health. Cognitive abilities might impact on the way individuals are able to develop strategies to maintain their employment or rapidly find new employment when faced with a range of difficulties. Education should form part of the policy response to long-term sick leave such that young people are better equipped with skills needed in a flexible labour market.