Ageing is universal, but it doesn’t treat everyone equally. Some people stay healthier longer, while others develop chronic conditions or disabilities much earlier. What explains this uneven pace of ageing? Genetics matter, of course, but so do lifestyle, environment, and—importantly—education.
A new study by Eileen M. Crimmins published in Demography (2025) explores how educational inequality is reshaping biological ageing in the United States. Their findings are both surprising and troubling: while Americans overall are ageing more slowly than before, the benefits are not evenly shared. People with more education are gaining more years of healthy ageing, leaving those with less education further behind.
Biological Age vs. Chronological Age
Before diving into the results, it helps to understand a key concept: biological age.
Chronological age is simple: the number of birthdays you’ve celebrated.
Biological age is more complex. It reflects how well your body’s systems—like cardiovascular, metabolic, and immune functions—are holding up.
A 60-year-old might have the body of a typical 50-year-old (younger biologically), or that of a 70-year-old (older biologically). Biological age is measured using biomarkers such as blood pressure, cholesterol, inflammation levels, and kidney function.
Why does this matter? Because biological age is strongly linked to risk of disability, disease, and death. If education influences biological ageing, then it’s not just about knowledge or jobs—it’s about who gets to live healthier, longer lives.
Tracking Biological Ageing Over 25 Years
The authors analyzed data from the National Health and Nutrition Examination Survey (NHANES). This nationally representative dataset includes biomarker measurements, lifestyle information, and demographics.
They focused on adults aged 50 to 79, comparing two periods:
1988–1994 (baseline)
2015–2018 (recent data)
The sample included nearly 10,000 people. By applying the Klemera–Doubal method of estimating biological age, the researchers tracked how biological ageing shifted across education groups over time
Education levels were grouped into:
0–11 years: less than high school
12–15 years: high school and some college
16+ years: college graduates
Key Findings
1. Biological Ageing Has Slowed Overall
The good news: Americans aged 50–79 are ageing more slowly than in the past. In 1988–1994, people’s biological age was slightly older than their chronological age. By 2015–2018, it was slightly younger.
In other words, on average, the body’s decline is happening more slowly today.
2. Inequality Has Widened
The bad news: the gap between education groups nearly doubled.
In 1988–1994, the difference in biological age between the least and most educated was about one year.
By 2015–2018, that gap had grown to almost two years.
This may sound small, but it represents a major divergence. A two-year advantage in biological ageing translates into longer health spans, reduced disability, and lower mortality risk. Over millions of people, it signals a deepening inequality.
3. Not Explained by Smoking, Obesity, or Medication
One might assume the widening gap comes from lifestyle choices or medical treatments. Yet, the study found otherwise.
Smoking declined across the population, especially among college graduates.
Obesity rose across all groups, eroding earlier health gains.
Medication use for hypertension and cholesterol increased dramatically for everyone.
Despite these shifts, none explained the growing education gap in biological ageing. The advantage seems tied more directly to broader benefits of education: stable jobs, healthier environments, higher income, and better access to healthcare.
Why Education Shapes Ageing
Education influences almost every dimension of life. Let’s break down the mechanisms connecting it to biological ageing.
1. Economic Security
Education often leads to higher-paying jobs, health insurance, and retirement security. Financial stability reduces chronic stress and allows access to healthcare and healthier lifestyles.
2. Health Literacy
Those with more schooling better understand health information, navigate medical systems, and adopt preventive practices.
3. Occupational Conditions
Less-educated workers are more likely to face physical strain, exposure to hazards, and job insecurity—all of which accelerate biological wear and tear.
4. Social Networks
Education expands social circles, providing emotional support, information exchange, and healthier behavioral norms.
5. Cumulative Stress (“Weathering”)
Lower-educated groups often face lifelong adversity—from poverty to discrimination—which compounds biological damage over decades.
Historical Context: Why Gaps Are Widening
The study doesn’t just show inequality—it shows it’s growing. Why now?
1. The Changing Value of Education
In the mid-20th century, a high school diploma could secure stable, well-paying jobs. Since the 1980s, that has changed. Manufacturing declined, wages stagnated, and many jobs offering benefits required college degrees. Those without them fell behind economically and, over time, biologically.
2. Policy Shifts
Cuts to social safety nets, rising healthcare costs, and unequal access to quality schools have deepened structural divides.
3. Lifestyle and Environment
While smoking declined broadly, obesity and sedentary living increased. Yet the capacity to buffer these risks—with gyms, healthier food, or medical care—often depends on education-linked income.
The Paradox: Biological Ageing vs. Health Outcomes
Interestingly, the study found that biological ageing slowed across all education groups—even among those with less schooling. Yet, mortality and disability rates for lower-educated adults have stagnated or worsened.
This paradox raises questions: Is biological age less predictive for disadvantaged groups? Or are external factors, like drug overdoses or suicides, offsetting the benefits of slower ageing?
Implications for Public Health
The findings carry urgent implications.
1. Health Inequality Will Likely Grow
If education-driven differences in biological ageing persist, future gaps in morbidity and mortality may widen further.
2. Policies Must Address Structural Factors
Programs focusing only on behavior (quit smoking, eat better) miss the deeper forces—like education access, job quality, and neighborhood safety—that shape biological risk.
3. Targeted Interventions
Improving biological ageing for the least educated could yield disproportionate gains for national health equity.
As the authors note, slowing ageing in disadvantaged groups might reduce multiple diseases simultaneously, making it a powerful tool for population health.
Future Risks: Obesity and Beyond
The study highlights obesity as a “countervailing trend.” Rising obesity rates slowed improvements in biological ageing for all groups. If obesity continues to climb, gains may stall—or reverse.
At the same time, new medical interventions (like GLP-1 drugs for weight loss) could widen gaps if they remain more accessible to wealthier, educated populations.
Limitations of the Study
The authors acknowledge some limits:
NHANES is cross-sectional, so it can’t track individuals over time.
Biomarker availability varied across years, limiting the scope of biological ageing measures.
Structural racism and inequality likely interact with education, shaping outcomes in ways not fully captured here
Still, the data are robust and nationally representative, making the findings highly significant.
Conclusion: Growing Apart While Growing Old
The story of American ageing is no longer just about living longer—it’s about who gets to live healthier, longer. Education, more than ever, divides the winners from the losers in this biological race.
As society debates healthcare reform, economic policy, and education investment, this study provides a stark reminder: inequality in the classroom echoes decades later in the body.
Closing the education gap isn’t just an economic or moral imperative—it’s a biological one. Ensuring that all Americans age with dignity and health will require tackling education inequality as seriously as we tackle disease.
The study is published in the journal Demography. It was led by researchers at the University of Texas at Austin.
