Despite assumptions about education's positive influence on brain structure, new findings suggest that even an additional year of schooling doesn't leave a lasting neural footprint.
Study: No effect of additional education on long-term brain structure – a preregistered natural experiment in thousands of individuals. Image Credit: Shutterstock AI / Shutterstock.com
In a recent study published in eLife, researchers report that an additional year of compulsory education does not lead to any lasting structural changes in the brain across various neuroimaging measures. These observations challenge existing theories that have linked education duration to enhanced brain resilience.
How does education affect brain structure?
Education is recognized as a fundamental right that provides broad societal, economic, and cognitive benefits. Furthermore, completing higher education has been associated with improved health, cognition, and brain structure.
Lifespan theories suggest that education may cause long-term brain structural changes. Studies show that educated individuals have thicker cortices in later life that may provide a "brain reserve" against aging effects. However, causality is unclear, as factors like genetics, income, and environment could confound prior research.
About the study
In the United Kingdom, the Raising of the School Leaving Age (ROSLA) reform required children born after September 1, 1957, to remain in school until 16 instead of 15, thus creating a distinct age cut-off for analysis. Leveraging the extensive neuroimaging data from the U.K. Biobank involving over 30,000 participants, researchers assessed whether this mandated additional year of education led to lasting changes in brain structure.
The researchers applied regression discontinuity (RD) to determine whether an additional year of education causally affects brain structure. Brain measurements were compared between individuals born before and after the ROSLA cut-off date. Whole-brain metrics such as cortical thickness, surface area, total brain volume, white matter properties, and regional data from 66 cortical and 18 subcortical areas were also obtained.
For localized neural effects, 33 cortical regions were assessed for surface area and cortical thickness in approximately 5,000 participants. Further analyses included fractional anisotropy in 27 white matter tracts and volume of 18 subcortical regions.
Study findings
Despite extensive data analysis, no statistically significant differences in brain structure were observed between those affected by ROSLA and those who were not. Placebo tests confirmed the specificity of the cut-offs, in addition to adjustments made for factors like head size, sex, and scanning date.
No discontinuity in brain metrics was observed at the cut-off, suggesting no lasting neural impact from the additional year of education. Global brain measurements remained continuous around the cut-off, including total surface area, cortical thickness, total brain volume, white matter anisotropy, white matter hyperintensities, and cerebral spinal fluid volume.
These results were robust across bandwidth ranges and remained consistent even after imputing missing data, thereby indicating no significant structural brain changes occurred due to the additional education year. Validation tests confirmed no evidence of manipulation around the ROSLA cut-off, which supports causal assumptions in the RD design.
Placebo outcomes similarly showed no association with ROSLA, thus confirming test validity. Region-specific analyses revealed no significant changes in any cortical region, nor were changes observed in fractional anisotropy across white matter tracts or subcortical volumes.
Bayesian analysis showed strong evidence supporting the null hypothesis across all global neuroimaging measures, such as total surface area, cortical thickness, and brain volume. These findings did not change across varying prior distributions, which supports the findings from the initial local-linear RD analysis.
Expanding the participant window to five months increased the sample size and confirmed the null hypothesis of no effect of the additional education year on neural measures. Placebo outcome tests further validated the robustness of this natural experiment, finding no associations.
The observational analysis found weak evidence of a positive association between education and total surface area in the one-month sample. However, expanding to the five-month window significantly strengthened the evidence for this association and for an association between education and cerebral spinal fluid volume. Other measures, such as cortical thickness, provided similar levels of support for the null hypothesis across both causal and associative analyses.
Conclusions
Overall, the study found no neural effects, globally or regionally, from an additional year of education. Causal and correlational analyses yielded different insights, with the observed associations indicating sensitivity to brain-behavior relationships without implying causation.
Although short-term neural effects of education were not assessed, the current study suggests that an additional year of education may not lead to long-term structural brain changes, thereby challenging assumptions about the impact of education neural development. These findings indicate that policies aiming to improve cognitive outcomes should go beyond simply increasing educational duration and address the broader factors that influence brain and cognitive health.
Journal reference:
- Judd, N., & Kievit, R. (2024). No effect of additional education on long-term brain structure – a preregistered natural experiment in thousands of individuals. eLife. doi:10.7554/eLife.101526.1