A new national analysis, drawing on 20 years of data, reveals how an unexpected factor creates a ripple effect.
For some, health changes experienced around midlife may be viewed as an unpleasant but predictable rite of passage—a bump in the road as we all gradually age. Yet a new national study shows that not everyone will have this experience. Instead, it appears that one select group with another key risk factor is at the greatest risk of encountering sudden distress around the age of 50.
Led by a group of sociologists and social epidemiologists from Stanford University and others, a 2025 study published in the peer-reviewed journal Health Affairs Scholar suggests that an overlooked group in America—the lower middle class—is experiencing a quiet but alarming decline in health. Many of these adults earn too much to qualify for need-based social programs, yet too little to comfortably absorb rising costs of healthcare, housing, and everyday life.
To understand how socioeconomic factors contribute to poor physical and mental health outcomes, the researchers analyzed two decades of data from more than five million U.S. adults ages 40 to 74, drawn from the U.S. Centers for Disease Prevention and Control (CDC)’s Behavioral Risk Factor Surveillance System. They tracked three key areas: physical health, mental health, and functional health (or the ability to perform daily functional tasks).
The results revealed a notable pattern: Across the board, Americans’ well-being has worsened over the past 20 years, but the steepest declines occurred among lower-middle-income adults—especially those aged 50 to 59. In this group, physical and functional health dropped most sharply, suggesting that the body’s basic resilience is weakening earlier in life. Mental well-being also declined, though differences between income groups were determined to be somewhat smaller in that category.
“Recent work has shown that there are particularly low levels of health and well-being prior to retirement among those households between the 15th and the 45th percentiles of household income, a group referred to as the ‘forgotten middle,’” the study states.
Importantly, the researchers found that these trends couldn’t be explained by race, smoking, or body weight. Income itself—and the stresses and constraints associated with it—appeared to be a central driver.
Underscoring the “crisis,” the researchers also note that this group faces an outsized risk of “deaths of despair”—meaning those from suicides, drug overdoses, and alcohol-related illnesses.
Knowing this, our aim should be to promote “compression of morbidity,” the researchers say—a scenario in which “as population life expectancy increases, there are also fewer years of disability and functional limitations in the population.” As we continue to grapple as a country with questions of affordability and social services, the findings underscore how a growing gap in America’s safety net leaves millions of working households vulnerable. And, as we look for solutions, it points to a need for policies that support those most at risk.
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