Recent empirical evidence has documented that U.S. middle-aged adults today are reporting
lower mental and physical health than same-aged peers several decades ago. Individuals who
attained fewer years of education have been most vulnerable to these historical changes. One
overarching question is whether this phenomenon is confined to the U.S. or whether it is transpiring
across other high-income and upper-middle-income nations. To examine this question,
we use nationally representative longitudinal panel data from 5 nations across different continents
and cultural backgrounds (U.S., Australia, Germany, South Korea, and Mexico). Results
revealed historical improvements in physical health for people in their 40s and early 50s across
all five nations. Conversely, the direction of historical change in mental health vastly differed
across nations. Later-born cohorts of U.S. middle-aged adults exhibit worsening mental health
and cognition. Australian middle-aged adults also experienced worsening mental health with
historical time. In contrast, historical improvements for mental health were observed in
Germany, South Korea, and Mexico. For U.S. middle-aged adults, the protective effect of education
diminished in later-born cohorts. Consistent across the other nations, individuals with
fewer years of education were most vulnerable to historical declines or benefited the least from
historical improvements. We discuss potential reasons underlying similarities and differences
between the U.S. and other nations in these historical trends and consider the role of education.