Does my head look big in this?

“From the Archives”, first published in the Digest 13.10.03.

Buying hats may well prove troublesome, but having a huge head also brings a key advantage – it means you’re less likely to suffer mental decline in old age.

Catherine Gale (MRC Environmental Epidemiology Unit, University of Southampton) and colleagues recruited 215 men and women aged 66-75 years, measured their head circumference (itself an indicator of brain size) and gave them two sets of intelligence tests – first at the head-measuring session and then again, three and half years later. Old records also detailed the participants’ head circumference at birth.

People with bigger heads scored more highly on the intelligence tests, and were less likely to show mental decline as indicated by a lower score at the second testing session relative to the first. In fact, the bottom quartile (25 per cent) of the sample for head size were five times more likely to exhibit mental decline than the quartile with the biggest heads.

Head circumference at birth, by contrast, had no relationship with intelligence or mental decline. This has important implications, because as the authors explained, it suggests “brain development during infancy and early childhood is more important than foetal growth in determining how well cognitive abilities are preserved in old age”.

Gale, C.R., Walton, S. & Martyn, C.N. (2003). Foetal and postnatal head growth and risk of cognitive decline in old age. Brain, 126, 2273-2278.

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest