Head size and cognitive ability in nondemented older adults are related.

In a cross-sectional analysis of 818 healthy older individuals (aged 50 to 81 years), head size was found to be related to performance on tests measuring intelligence, global cognitive functioning, and speed of information processing, but not memory. These relations were not confounded by educational level, socioeconomic background, or height. Large head/brain size may protect elderly people against cognitive deterioration, supporting a reserve hypothesis of brain aging