Women's Metabolic Brain Age Consistently Lower Than Men's

As both men and women age, metabolism tends to slow down with time. A recent study, however, found that women retain a higher metabolic rate throughout their lifespan.

Prior to this study, findings in support of the theory that females may have more youthful brains in terms of metabolic rate were limited to postmortem transcriptional analyses. Researchers now were able to test this hypothesis in vivo where they analyzed sex differences in a unique brain positron emission tomography (PET) scan for over 200 human adults across their lifespan.

Included in the study were participants’ PET scans aged 20 to 82 for 205 cognitively normal adults. In humans, normal brain aging is associated with a decline in brain metabolism. Investigators were able to identify that “as the brain ages, its resting metabolism gradually shifts away from a mixture of nonoxidative and oxidative use of glucose to predominantly oxidative metabolism.” Due to researchers demonstrating that this occurs in even in a cognitively normal adult, it is unlikely that neurodegeneration alone would explain this metabolic shift.

On average, the study authors found that women’s brains appeared to be about 4 years younger. Though the reasons for sex differences in brain metabolism are not yet well understood, the implications of females having “younger” brains in terms of metabolic rate and the association with neurodegenerative diseases warrants further investigation, the authors noted.

The finding is “great news for many women,” Roberta Diaz Brinton, PhD, director of the Center for Innovation in Brain Science at the University of Arizona Health Sciences, said in a statement. However, she cautioned that though female metabolic rate may be higher overall, some women experience a significant metabolic decline after menopause, which in turn leaves them more susceptible to developing Alzheimer disease.

The authors concluded that “measures such as metabolic brain age might be useful in predicting the risk of cognitive decline and in identifying other factors that could potentially improve or worsen the trajectory of human brain aging.” However future studies are needed to validate the findings in other cohorts, and determine its predictive potential.

Reference

Goyal M, Blazey T, Su Y, et al. Persistent metabolic youth in the aging female brain [published online February 4, 2019. Proc Natl Acad Sci. doi.org/10.1073/pnas.1815917116