Education promotes cognitive reserve against dementia… but only if you’re white.

Guest author: Justina Avila-Rieger, PhD is a postdoctoral fellow of Neuropsychology in Neurology at the Gertrude H. Sergievsky Center and the Taub Institute for Research in Aging and Alzheimer’s disease at Columbia University. She completed her graduate training in clinical psychology, with an emphasis on neuropsychology and quantitative methodology, at the University of New Mexico and completed her clinical internship at the Baltimore VAMC. Her research examines racial/ethnic and sex/gender disparities in Alzheimer’s disease.

Experts have long suggested that keeping your brain active, especially through continued education, is a great way to protect our brains against dementia as we age. The idea is that education allows our brain to build up a “cognitive reserve,” which acts as a buffer to slow the onset of dementia. However, our recent paper found that this advice may only apply to White people.

Cognitive reserve is the ability to maintain thinking abilities even if the brain is damaged. Many brain functions are flexible and can compensate or change to make added resources available to cope with challenges. The term cognitive reserve is used to describe this disconnect, when cognitive function is not as impaired as would be expected given the level of brain degeneration.¹ In other words, for people with a high level of cognitive reserve, their brains can show severe signs of degeneration, yet their dementia symptoms are much milder than would be expected.

This figure illustrates the idea of cognitive reserve. People with high cognitive reserve can have severe Alzheimer’s disease (AD) neuropathology, yet not experience any cognitive symptoms. Image source

Some indicators of life experiences and contexts, including years of education, are often used as proxies for cognitive reserve because they are associated with lower dementia risk and delayed age of dementia onset.² However, the majority of cognitive reserve studies have been conducted in predominantly non-Latinx White (White) samples and do not consider racial or ethnic differences in educational experiences. (Note: Latinx is the gender-neutral form of Latino/Latina and refers to people originating from Latin America.)

In our recent study, we tracked a community of 1,553 White, Black, and Caribbean-born Latinx  older adults over time.³ We found that White individuals with more years of education had slower cognitive decline compared with White individuals with fewer years of education, despite having the same level of brain degeneration. In other words, greater years of education buffered the effects of brain degeneration for White people. However, for Black and Latinx individuals, years of education did not protect cognitive function against the effects of brain degeneration.

Why might the protective effects of education differ across racial/ethnic groups? My colleagues and I suggest that racism is likely to be the primary underlying reason that having more years of school contributed to cognitive reserve in Whites, but not among Black or Latinx participants. Most Black older adults in the United States were born and raised in the South,⁴ where Jim Crow laws enforced segregation and limited opportunities within education, health care, housing, and the labor market.⁵ Across all U.S. states, both before and after Brown v. Board of Education, racist policies and residential segregation forced Black children to attend underfunded schools that had large student/teacher ratios, shorter term length, lower teacher salaries, and inadequate budgets for supplies and school buildings.⁶ These structural inequalities contribute to lower returns from education among Blacks compared to Whites.⁷

Similarly, older Caribbean-born Latinx who grew up outside of the United States also had fewer opportunities to attend school and/or received a poor quality of education.^8,9 Years of education may not adequately represent the effect of life-course experiences that contribute to cognitive reserve across all racial/ethnic groups. As a result, the contribution of years of education to cognitive reserve is reduced for racial/ethnic minorities.

Even if educational experiences were equivalent across groups, structural racism impacts adult opportunities that might contribute to cognitive reserve across racial/ethnic groups. Racism in the labor market has served to counteract the benefits of schooling for Black Americans. For example, Black men continue to have lower employment rates than White men even if they have the same educational attainment¹⁰. It is also possible that the protective effects of education are reduced by stress associated with institutional racism and discrimination.

Do these findings mean that Black and Latinx individuals do not have cognitive reserve? Absolutely not. Rather, these findings suggest that years of education is just not a good indicator of the life-course experiences that contribute to cognitive reserve in Black and Latinx people. Several studies have demonstrated that measures of school quality may be a better indicator of educational experiences in racial/ethnic minorities than years of education.^7–9,11,12 There is also evidence that early life educational policies¹³ influence later life dementia risk and cognitive decline, above and beyond educational attainment. There are also other early life experiences¹⁴ (e.g., childhood socioeconomic status, neighborhood factors) that may better indicators of cognitive reserve among Blacks and Latinx.

Overall, our findings provide more evidence that social inequalities across the lifecourse have an impact on racial and ethnic disparities in Alzheimer’s disease. Inequalities in school opportunities, including school segregation and limited governmental investment in schools that served Black and Latinx children, as well as racial discrimination in occupation, housing, criminal justice, and healthcare can help to explain why there are diminished “brain health” returns to educational attainment for Black and Latinx older adults. Considering that Black and Latinx individuals are 2 to 3 times more likely to develop Alzheimer’s disease than White individuals,¹⁵ more research is needed to understand the life-course factors that contribute to cognitive reserve. Such work may lead to identification of factors that may narrow racial/ethnic inequalities in the onset and progression of Alzheimer’s disease.

Sources:

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2. Amieva H, Mokri H, Le Goff M, et al. Compensatory mechanisms in higher-educated subjects with Alzheimer’s disease: a study of 20 years of cognitive decline. Brain J Neurol. 2014;137(Pt 4):1167-1175. doi:10.1093/brain/awu035
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13. Dementia risk likely measurable among adolescents, young adults. Accessed August 27, 2020. https://www.healio.com/news/psychiatry/20200730/dementia-risk-likely-measurable-among-adolescents-young-adults
14. Xu H, Yang R, Qi X, et al. Association of Lifespan Cognitive Reserve Indicator With Dementia Risk in the Presence of Brain Pathologies. JAMA Neurol. Published online July 14, 2019. doi:10.1001/jamaneurol.2019.2455
15. Facts and Figures. Alzheimer’s Disease and Dementia. Accessed August 27, 2020. https://www.alz.org/alzheimers-dementia/facts-figures

Note: This post was originally titled “Education protects against dementia… but only if you’re white.” This is inaccurate, and the title has been corrected accordingly.