Objective: The aim of the study was to examine the relationship of head circumference as a marker of maximal attained brain size to late-life cognitive impairment and dementia.
Methods: Cognitive performance was assessed and the presence of dementia was diagnosed in a cross-sectional study of 442 Catholic sisters aged 65 years and over.
Results: A head circumference below average was significantly associated with the presence of dementia even after adjustment for age, body mass index and presence of one or two apolipoprotein E epsilon4 alleles (OR = 2.0; 95% CI: 1.1-3.6). The combination of small head circumference and apolipoprotein E epsilon4 strongly increased the risk of dementia (OR = 3.59; 95% CI: 1.44-8.97).
Conclusions: The findings support the hypothesis that a larger head size reduces the risk of cognitive decline and dementia in old age.