Background: Despite a well-established literature on the protective effect of education on health, less is known about group differences in the mechanisms underlying this association. Using a life course approach and cumulative advantage theory, this study compared Black men, Black women, White men, and White women to assess the long-term gradient (education as a continuous measure) and threshold (>12 years) effects of baseline education on change in chronic medical conditions (CMC) and depressive symptoms (DS) from baseline to 25 years later.

Methods: Data came from the Americans' Changing Lives Study, 1986-2011. The study followed Black and White respondents for up to 25 years, among whom 1271 individuals who had survived and were under follow-up were interviewed in 2011 and reported their number of chronic medical conditions and depressive symptoms (Center for Epidemiological Studies-Depression; CES-D 11). Multi-group structural equation modeling was used to compare gradient and threshold effects of education on change in chronic medical conditions and depressive symptoms from baseline (1986) to 25 years later (2011) among Black men, Black women, White men, and White women.

Results: There were group differences in the long-term association between education measured as a gradient and the change in depressive symptoms and chronic medical conditions during the follow-up, and in the association between education measured at the threshold of 12 years on change in depressive symptoms from baseline to follow-up. However, the association between education measured at this threshold and change in chronic medical conditions did not differ across race-gender groups. With the exception of Black men, who showed a gradient protective effect for baseline education against increase in the number of chronic medical associations (threshold or gradient) with change in chronic medical conditions. Among White men and White women, education had a threshold protective effect against increase in depressive symptoms from baseline to 25 years later. Black men and women showed a gradient protective effect of baseline education against an increase in depressive symptoms over the 25-year follow-up period, but unexpectedly, a threshold effect of education was also found to be associated with an increase in depressive symptoms over the follow-up period among Black men. This finding suggests that although Black men benefit from each incremental increase in education, those who graduated from high school were at an additional risk of depressive symptoms over a 25-year period.

Conclusion: Findings suggest that the intersection of race and gender influences how education is associated with long-term changes in physical and mental health of individuals from baseline to 25 years later. As the shape of the association between education and health depends on the intersection of race and gender, these groups may vary for operant mechanisms by which education operates as a main social determinant of health.