Intelligence in early adulthood and mortality from natural and unnatural causes in middle-aged Danish men.
BACKGROUND
High intelligence early in life has consistently been associated with decreased mortality, but the mechanisms are still not fully understood. In this cohort study, we examined the association between intelligence in early adulthood and later mortality from natural and unnatural causes taking birth weight, parental socioeconomic position, participants' own education and body mass index into account.


METHODS
13 536 Danish men born in 1953 and 1959-1961 with data from birth certificates and intelligence test scores from conscription were followed until 2009. Information on vital status was obtained from the Civil Registration System. Mortality risks were analysed by the multiple Cox proportional hazards model.


RESULTS
The risk of mortality from natural as well as unnatural causes was more than twice as high among men in the lowest scoring intelligence tertile (HRnatural deaths=2.24; 1.90-2.65 and HRunnatural deaths=2.67; 2.03-3.53). Adjusting for all covariates attenuated the estimates, but the association remained (HRnatural deaths=1.82; 1.48-2.25 and HRunnatural deaths=2.30; 1.63-3.25).


CONCLUSIONS
In men, intelligence in early adulthood was inversely associated with midlife mortality from natural and unnatural causes. The associations remained after adjustments for a range of covariates.
Section of Social Medicine, Department of Public Health, University of Copenhagen, , Copenhagen, Denmark.
Rikke Hodal
RH
Meincke
Erik Lykke
EL
Mortensen
Kirsten
K
Avlund
Susanne
S
Rosthøj
Holger Jelling
HJ
Sørensen
Merete
M
Osler
D000367:Age Factors; D001719:Birth Certificates; D001724:Birth Weight; D015992:Body Mass Index; D002423:Cause of Death; D015331:Cohort Studies; D003627:Data Interpretation, Statistical; D003718:Denmark / Q000453:epidemiology; D004522:Educational Status; D054624:Health Status Disparities; D006801:Humans; D007360:Intelligence; D007361:Intelligence Tests; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends*; D010287:Parent-Child Relations; D016016:Proportional Hazards Models; D012042:Registries; D012307:Risk Factors; D012923:Social Class; D014505:Urban Population / Q000706:statistics & numerical data
Adolescents CG; Cognition; Mortality