Greater Education Does Not Reduce the Rate of Brain Aging
Post by Lincoln Tracy
What's the science?
Educational attainment has been linked with numerous advantages across an individual’s lifespan. One proposed advantage of education relates to brain aging, where education either acts as a protector, or contributes to our cognitive reserve (how resilient our brain is). However, cross-sectional studies investigating the association between education and brain aging (where participants are only examined at one point in time) are inconclusive. In addition, data from longitudinal studies (where participants are examined at multiple time points, often months or years apart) on this association are sparse. This week in PNAS, Nyberg and colleagues used two large-scale, longitudinal datasets to test the association between education and brain aging. Brain aging was defined as brain atrophy measured by structural magnetic resonance imaging [MRI]).
How did they do it?
The authors obtained MRI and educational data from two large-scale, longitudinal studies: the European Lifebrain project and the UK Biobank. Specifically, they obtained data for 1844 MRI scans from 735 participants (29-91 years old, 368 females) from the Lifebrain project and 2578 MRI scans from 1289 participants (47-82 years old, 660 females) from the UK Biobank. Education was measured as the number of years spent in formal schooling for the Lifebrain project and whether participants had obtained a college or university degree in the UK Biobank sample. MRI data were processed to determine hippocampal, intracranial, and cortical volume. Associations between education and cortical volume in both datasets were then tested in cross-sectional and longitudinal analyses.
What did they find?
Both the Lifebrain project and the UK Biobank found age-related reductions in hippocampal volume over time. There was no association between education and cortical or hippocampal volume over time when the two datasets were analyzed separately. However, cross-sectional analysis revealed associations between education and regional cortical volume around the left central sulcus.
What's the impact?
Despite examining almost 4500 MRI scans from over 2000 individuals, the authors found no evidence to support the theory that greater amounts of education lead to decreased rates of brain aging. These findings, together with the existing literature, suggest that individuals with higher education develop more of a “passive” cognitive reserve compared to individuals with lower education, which is eroded as they age. In other words, brain aging occurs at the same rate regardless of how much education an individual has, but a greater level of education provides a greater reserve of brain (or proportion of the brain) that is required to age before adverse outcomes such as dementia occur.
Nyberg et al. Educational attainment does not influence brain aging. PNAS (2021). Access the original scientific publication here.