Objectives To test the association between childhood IQ and mortality over
the normal human lifespan.
Design Longitudinal cohort study.
Subjects All 2792 children in Aberdeen born in 1921 and attending school on
1 June 1932 who sat a mental ability test as part of the Scottish mental s
Main outcome measure Survival at 1 January 1997.
Results 79.9% (2230) of the sample was traced. Childhood mental ability was
positively related to survival to age 76 years in women (0.978 (0.971 to 0
.984), P < 0.0001) and men (0.989 (0.984 to 0.994), P< 0.0001). A 15 point
disadvantage in mental ability at age 11 conferred a relative risk of 0.79
of being alive 65 years later (95% confidence interval 0.75 to 0.84); a 30
point disadvantage reduced this to 0.63 (0.56 to 0.71. However, men who die
d during active service in the second world war had a relatively high IQ. O
vercrowding in the school catchment area was weakly related to death. Contr
olling for this factor did not alter the association between mental ability
Conclusion Childhood mental ability is a significant factor among the varia
bles that predict age at death.