Edited by Lachlan Brown
For years, the U-shaped curve of happiness seemed to offer one of social science’s more reassuring stories about getting older. Average happiness appeared relatively high in youth, declined toward a low point around middle age, and then recovered. Turn the measure around and study distress instead, and researchers often saw its mirror image: a hump that peaked in midlife.
A large 2025 study argues that this familiar pattern no longer describes the world captured by recent surveys. The change is not primarily that middle-aged adults suddenly escaped life’s pressures. It is that psychological distress rose sharply among younger people. In contemporary data spanning 44 countries, the youngest adults reported the most ill-being, and average ill-being declined as age increased.
That is a profound reversal. It is also a finding that needs careful language. The study measured despair, anxiety, distress and related states, not a single universal substance called happiness. It compared population averages, not individual destinies. Understanding those boundaries makes the result more credible, not less alarming.
What the famous U-shape actually meant
The U-shape was always an average relationship between age and reported well-being. It never meant that every person would reach an emotional low in their 40s and become happier afterward. Still, the pattern appeared often enough to become influential. A widely cited international analysis of subjective well-being, for example, reported a U-shape across 132 countries, with the average low point around the late 40s.
Researchers also found a corresponding hump in ill-being measures such as worry, stress and depression. Younger and older adults tended to report less ill-being, while middle-aged adults reported more. Because both versions appeared in large datasets and in different settings, one of the new paper’s authors called the relationship among the most persistent patterns in social science.
Yet the pattern was never entirely settled. Results depend on the question asked, the ages included and the statistical choices made. A methodological reconsideration using European data found U-shapes in some countries but different patterns in others when it removed certain controls and did not force the data into a quadratic curve. The old result was replicated often, but it was never a law of human development.
How the new analysis tracked a reversal
The 2025 PLOS ONE study used several sources rather than one survey. For the United States, it examined repeated cross-sectional microdata reaching back to 1993, including recent results through 2024. For the United Kingdom, it analyzed household survey data from 2009 to 2021 and anxiety data from the Annual Population Survey from 2012 to 2021. It then tested the contemporary international pattern with Global Minds data collected from 2020 through 2025.
The time comparisons explain how the curve changed. In the United States, despair was hump-shaped by age during 2009 to 2018. In the 2019 to 2023 comparison, that hump was gone. Despair had risen fastest among people younger than 25, had also increased among adults up to 45, and was relatively unchanged among those older than 45. The resulting line declined with age.
The British picture was similar. In 2009, men and women aged 18 to 24 were less likely to be in despair than older groups. By 2021, the share in despair had risen from 2.3 to 6.4 percent among young men and from 4.4 to 12.7 percent among young women. The earlier hump in despair disappeared. Anxiety followed a comparable shift.
What happened across the 44 countries
For the global portion, the researchers pooled data from 44 countries with at least 10,000 observations each. The sample covered nations in Africa, Asia, Europe, Latin America, the Middle East and the English-speaking world. Analyses were limited to adults aged 18 to 74.
In all 44 countries, the percentage classified as distressed fell more or less linearly with age. Regression models using five measures told the same general story: distress, fear and anxiety, sadness or hopelessness, and suicidal thoughts declined with age, while the Mental Health Quotient, where a higher score is better, rose. The pattern persisted when researchers adjusted for factors including country, gender, education, employment status, year and the timing of the survey.
This does not mean every country had identical distress levels or that culture no longer matters. It means the direction of the age gradient was remarkably consistent in this dataset. Younger adults were worse off on average than older adults under the study’s measures.
Why ill-being and happiness should not be collapsed
The headline story is often told as the disappearance of the happiness U-shape, but the paper’s strongest direct evidence concerns ill-being. Happiness, life satisfaction and psychological distress overlap, yet they are not perfect opposites. Someone can find meaning in work and relationships while also experiencing anxiety. Another person may report little acute distress without describing life as deeply satisfying.
Independent evidence points in a similar direction while preserving those distinctions. The Global Flourishing Study’s first major results, based on more than 200,000 people in 22 countries, found that pooled flourishing was roughly flat from ages 18 to 49 and then rose. Many specific aspects of well-being also increased with age. But the authors noted substantial national variation: some countries retained a more U-shaped profile, while others followed different paths.
The project’s Harvard overview similarly reports that younger adults have lower well-being across countries and that the 18-to-24 group scored lowest in many nations. Taken together, the evidence supports a broad decline in young adults’ relative position. It does not establish that every measure, population and country has become identical.
The limits matter as much as the headline
The 44-country result is based largely on people of different ages surveyed during the same recent period. That cross-sectional design cannot by itself prove that a distressed 22-year-old will become steadily less distressed simply by aging. The apparent slope could combine an age effect, a cohort effect affecting today’s young adults, and historical conditions affecting everyone at a particular time.
The authors used the longer American and British series to show that the profile changed as distress rose disproportionately among younger groups. Even so, the global analysis cannot yet tell us whether this generation will carry elevated distress forward or converge with today’s older adults. The Global Flourishing Study is designed to follow the same people over time, which should eventually offer stronger evidence on that question.
Self-report also has limits. People and cultures can differ in how they interpret questions, recognize symptoms and disclose distress. Large samples and consistent results reduce some uncertainty, but they do not convert survey responses into clinical diagnoses. Nor should a population average be used to judge an individual person’s competence, credibility or needs.
No single cause has been proved
The deterioration began before COVID-19, although the pandemic appears to have worsened the British trend. The researchers discuss possible contributors including economic scarring after the financial crisis, weak wage growth, housing and employment pressures, changing expectations, and the spread of smartphones and social media. None is established as the sole explanation.
That uncertainty has practical importance. Institutions can easily turn a statistical pattern into a stereotype. Courts, employers, schools and public agencies should not assume youth is naturally carefree, but neither should they treat all young adults as psychologically fragile. Age-based averages can identify where support may be missing; they cannot decide a particular person’s capacity or reliability.
Research on well-being also repeatedly shows that the quality of social connection matters across adulthood. The Law Dictionary has previously examined how the long-running Harvard Study of Adult Development linked close relationships with later health and happiness. That does not solve the new global pattern, but it is a reminder that distress is shaped by lived conditions and institutions, not just age.
The most defensible conclusion is neither that aging automatically cures unhappiness nor that an entire generation is broken. A long-familiar social pattern has changed because younger adults now report much worse mental health relative to older groups. The urgent questions are why the shift occurred, whether it will persist, and which forms of support can reverse it.
This article provides general information about social-science research and is not legal or medical advice. Anyone facing an immediate mental-health crisis should contact local emergency or crisis services.