Head circumference, apolipoprotein E genotype and cognition in the Bavarian School Sisters Study

BackgroundThe apolipoprotein E (APOE) ɛ4 allele is correlated with an earlier onset of Alzheimer's disease symptoms; larger head circumference has been associated with an individual resilience against cognitive impairment.MethodsWe explored if larger head circumference attenuates the effect of the APOE ɛ4 allele on cognition in 380 Catholic sisters covering the spectrum from normal cognitive performance to severe dementia.ResultsLinear regression analysis, adjusting for risk factors for cognitive decline, revealed that APOE ɛ4 was correlated with worse cognition and that larger head circumference attenuated the negative effect of the ɛ4 allele on cognitive performance.ConclusionLarger head circumference (i.e. larger brain size) seems to be associated with greater resilience against genetic determinants of cognitive impairment, possibly due to enhanced brain or cognitive reserve.