G. David Batty|Ian J. Deary|Linda S. Gottfredson
Premorbid (early life) IQ and Later Mortality Risk: Systematic Review
MRC/CSO Social and Public Health Sciences Unit|University of Glasgow|University of Edinburgh|University of Delaware|MRC/CSO Social and Public Health Sciences Unit|University of Glasgow|University of Edinburgh|University of Delaware|University of Edinburgh|University of Delaware|MRC/CSO Social and Public Health Sciences Unit|University of Glasgow
studies middleaged particularly olderaged adults found higher scores tests iq cognitive function lower rates later mortality interpretation findings potentially hampered problem reverse causality somatic diseases diabetes hypertension common older adults decrease cognitive function studies provide extended followup health experience individuals premorbid iq assessed childhood andor early adulthood minimize concern purpose present report systematically locate evaluate interpret findings studies systematically identified individuallevel studies linking premorbid iq later mortality using four approaches search electronic databases medline embase psychinfo scrutiny reference sections identified reports search files contact researchers field study quality assessed using predefined criteria nine cohort studies met inclusion criteria overall study quality moderate reports showed inverse iqmortality relation ie higher iq scores associated decreased mortality risk nature relation ie doseresponse threshold whether differs sex unclear iqmortality association appear explained reverse causality selection bias confounding earlylife factors also seem explain association although studies well characterized regard adult socioeconomic position appeared mediate iqmortality association studies universal finding studies higher iq first two decades life related lower rates total mortality middle late adulthood plausible mechanistic pathways exist examination required precise nature iqmortality relation particularly ethnic minorities women link iq diseasespecific outcomes also warrants research