Sex differences in the rates and association of cerebral blood flow and glucose metabolism in normative ageing

Although dysfunction in cerebral blood flow and glucose metabolism is linked to neurodegeneration, it is currently unclear if there are sex and age differences in their rates and association. Seventeen younger males (mean age 27.5 years), 20 younger females (28.4), 22 older males (76.6) and 20 older females (75.3) completed a MR/PET scan and cognitive battery. Females had higher CBF and CMR _GLC than males, regardless of age. CBF was lower in ageing. As CMR _GLC increased, the positive effect of higher CBF on working memory, cognitive flexibility, and processing speed also increased. Individuals with the highest CBF had the highest CMR _GLC . However, this association was moderated by sex and age, with significant negative associations across older females, possibly reflecting a compensatory response to a loss of blood flow and metabolism. We conclude that there are sex differences in the rates and association of cerebral blood flow and glucose metabolism in normative ageing and that high rates of blood flow and metabolism combine to support cognition.