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

Background. - The apolipoprotein E (APOE) 64 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. Methods. - We explored if larger head circumference attenuates the effect of the APOE epsilon 4 allele on cognition in 380 Catholic sisters covering the spectrum from normal cognitive performance to severe dementia. Results. - Linear regression analysis, adjusting for risk factors for cognitive decline, revealed that APOE epsilon 4 was correlated with worse cognition and that larger head circumference attenuated the negative effect of the epsilon 4 allele on cognitive performance. Conclusion. - Larger 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. (C) 2011 Elsevier Masson SAS. All rights reserved.