For years, the happiness U-curve made adulthood look almost reassuringly predictable. Wellbeing appeared to begin relatively high, decline through early and middle adulthood, reach a low point near 50, then turn upwards again.
It was a population pattern, not a timetable for anyone’s private life. Still, it became one of the most repeated findings in wellbeing research. A major analysis published in 2021 reported U-shaped associations across 145 countries, with the fitted low points clustering around the late forties.
Recent evidence has disturbed that picture. In a 2025 study using current data from 44 countries, psychological distress was highest among young adults and then declined with age. This does not show that ageing automatically makes a person happier. It shows that the relative mental health of younger adults has deteriorated enough to erase what used to be the rising half of the mirror-image curve for ill-being.
Our earlier look at the happiness U-curve examined how the familiar midlife low depended partly on the questions and statistical choices used. The narrower issue here is what researchers can reasonably mean when they say part of the curve has now vanished.
The famous low point was an average, not an appointment
The 145-country study by economist David Blanchflower assembled many datasets and several measures of subjective wellbeing. Its models included age and age squared and often adjusted for education, marriage, employment and other circumstances. Across 477 country-level estimates, the average minimum was about 48.
That number acquired more certainty in popular retellings than it possessed in the data. It did not mean everyone reaches a personal happiness floor on their 48th birthday. Nor did it mean a typical respondent was followed from young adulthood to old age. Much of the evidence compared different people at different ages, then estimated the curve that best described their answers.
There was also a mirror image. If happiness and life satisfaction formed a U, measures such as worry, stress and depression often formed a hump. Ill-being rose towards midlife, peaked, then fell. The two shapes concerned related but not perfectly interchangeable outcomes.
The 2025 study joined three different bodies of evidence
The peer-reviewed 2025 paper in PLOS One, written by Blanchflower, Alex Bryson and Xiaowei Xu, did not consist of one worldwide longitudinal survey. It assembled three complementary sources.
For the United States, the researchers used repeated Behavioral Risk Factor Surveillance System data from 1993 through 2024. Their starkest measure of “despair” identified people who said all 30 of the previous 30 days had been bad for their mental health. For Britain, they analysed General Health Questionnaire responses in the UK Household Longitudinal Study from 2009 to 2021, plus anxiety data from the Annual Population Survey from 2012 to 2021.
The international component came from the Global Minds Project. It covered 1,702,498 online respondents aged 18 to 74, surveyed from 2020 to 2025 in 44 countries with at least 10,000 responses each. Those countries spanned Africa, Asia, Latin America, the Middle East, Europe and six English-speaking nations.
This design matters. The long American and British series showed how the age profile changed over time. The 44-country sample showed that the newer age gradient was not confined to those two places. The international data alone, however, could not establish that every country had undergone the same historical transition.
What vanished was the midlife hump in ill-being
The Global Minds analysis included an overall Mental Health Quotient and measures of distress, fear and anxiety, sadness or hopelessness, and suicidal thoughts. Across the pooled sample, ill-being declined with age on all four negative measures, while the positive mental-health score rose. Adjusting for country, sex, education, labour-force status, survey year and even the time of response did not alter the general shape.
The age gap was large. Overall, 5.6 per cent of respondents met the project’s threshold for being distressed. Among those younger than 25, 13.4 per cent did. Negative Mental Health Quotient scores applied to 25 per cent of the full sample and 48 per cent of under-25s. Young women recorded worse results than young men in every one of the 44 countries for the paper’s distress and suicidality measures.
Those figures support the title’s description of the younger half disappearing, but precision is important. The global study principally measured mental ill-health, not the single life-evaluation question used in some happiness studies. A reduction in distress and an increase in life satisfaction often travel together, but they are not logical opposites in every person or survey.
A separate 2025 NBER working paper came closer to testing happiness itself. Across the United States, Britain, Australia, Canada, Ireland and New Zealand, it found that young-adult happiness and life satisfaction had declined during the previous decade while trends among older adults were less uniform. In recent data, wellbeing generally increased with age in all six countries. That evidence points in the same direction, although it is concentrated in the English-speaking world and was published as a working paper rather than a peer-reviewed journal article.
The line changed because younger adults moved down
The most consequential result is not simply that older respondents scored better. The American and British time series indicate how the ranking reversed.
In the United States, the familiar midlife hump in despair was visible from 2009 to 2018. In the 2019 to 2024 period, it had been replaced by a decline with age. Despair rose most among the youngest respondents, also increased among people up to 45, and remained roughly unchanged above 45. Among women, the youngest group had the highest despair level by the end of the period; among men, the youngest and middle-aged groups were similar, with the oldest lowest.
The British record told much the same story. In 2009, people aged 18 to 24 were less likely to be in despair than older groups. By 2021, despair among young men had risen from 2.3 to 6.4 per cent. Among young women it had risen from 4.4 to 12.7 per cent, with much of that increase occurring after 2016. The former age hump disappeared because distress below the mid-forties rose, especially among the youngest adults.
The pandemic intensified some of these changes, but the researchers found that the deterioration began earlier. They did not treat Covid-19 as a sufficient explanation.
A changed age profile does not identify its cause
The paper considers several possibilities: difficult housing and labour markets, long economic scarring after the global financial crisis, pressure on mental-health services and changes in the technological environment. None was tested as the single cause of the international result.
That restraint is necessary. A 22-year-old and a 62-year-old answering a survey in 2024 differ in age, but also in birth cohort and formative experience. They entered education and work under different conditions. They encountered different media, expectations and costs. Researchers call these age, period and cohort effects, and they are unusually difficult to untangle because a person’s age is determined by birth year and survey year.
The Global Minds survey also recruited respondents online and was not a probability sample designed to represent every resident of each country. The authors restricted the comparison to countries with large samples and found consistent regression results across regions, but sample size does not by itself remove selection bias.
There is a wider methodological argument too. A recent reanalysis of European happiness data found a much wider variety of age patterns when it avoided forcing a quadratic curve and questioned controls for circumstances that are themselves shaped by age. That does not invalidate the 145-country work. It does mean “the curve” has never been a law of human development on the level of gravity.
The Nordic countries show why averages need an age label
None of the Nordic countries appears in the 44-country Global Minds comparison, so the paper should not be presented as a direct survey of Scandinavia. Other regional evidence nevertheless fits the broader warning about national averages.
As Scandinavia Standard reported in August, a 2025 study of Norway found a marked generational reversal from the early 2010s: younger people moved from the country’s happiest age group to its least happy, while those over 60 became the happiest. The causes were not settled there either.
This is why an overall national ranking can remain strong while an important group moves in the opposite direction. The World Happiness Report’s age-specific analysis has likewise shown that rankings for younger and older residents can differ sharply. A single country score is an average across lives that may no longer share the same trajectory.
The missing half is not good news about growing older
It would be comforting to interpret the new slope as evidence that life naturally becomes easier with every birthday. The data do not justify that conclusion. In the two countries with long time series, the clearest movement was worsening mental health among younger adults, not a dramatic improvement among everyone older.
Nor should the older U-curve be replaced by an equally rigid new rule. Both shapes are summaries produced from particular questions, samples, years and statistical choices. An average line cannot predict when one person will struggle, recover or thrive.
The 2025 finding is important precisely because population patterns are not fixed. Social conditions can move one end of a famous curve within a decade. What vanished was not a biological stage that every life must pass through. It was a long-observed advantage for younger adulthood, and its disappearance is a warning about the present rather than a promise about age.