Exam stress at age 15 can increase the risk of depression and self-harm into early adulthood, research suggests.

Academic pressure is known to have a detrimental impact on mood and overall wellbeing, but until now few studies had examined the long-term effects on mental health.

Researchers at University College London examined data from nearly 5,000 young people born in 1991 and 1992 taking part in a wider ongoing study of children.

Academic pressure was assessed at the age of 15 through questionnaires on their school experiences, while mental health was tracked regularly from 16 to 22 and self-harm until they were 24.

The study, published in the Lancet Child and Adolescent Health, found that those 15-year-olds who worried most about their school work or felt the most pressure from their families to do well academically were more likely to report higher levels of depression or episodes of self-harm even into early adulthood.

They also found that for every extra point of academic pressure reported as 15-year-olds, the likelihood of depression and self-harm by the age of 16 was 25% and 8% higher respectively. This effect continued into their early 20s.

Higher rates of academic pressure at school were also associated with greater mental ill health, the authors calculated.

For every one-point increase in school stress, 24-year-olds were 16% more likely to say they had ever attempted suicide than those who experienced less academic pressure at 15.

The senior author Gemma Lewis, a professor of psychiatric epidemiology at UCL, said: “Young people report that academic pressure is one of their biggest sources of stress.

“A certain amount of pressure to succeed in school can be motivating, but too much pressure can be overwhelming and may be detrimental to mental health.”

The report says that instead of focusing on ways to help pupils cope, schools should adopt whole-school initiatives to reduce exam stress, such as “interventions that enhance social and emotional learning and relaxation skills”.

It suggests that reducing the number of high-stakes tests reduces academic stress, while families could “reduce academic pressure and encourage physical activity, socialising and sleep”.

The findings underline research by Young Minds last year that found nearly two-thirds of 15- to 18-year-olds said they struggled to cope in the run-up to GCSE and A-levels. A quarter reported panic attacks, two-fifths said their mental health worsened and one in eight self-harmed or felt suicidal.

Paul Noblet, the head of external affairs and research at Young Minds, said: “The evidence could not be clearer: academic pressures harm young people’s mental health.

“The focus needs to shift from end-of-year exams and include a mix of assessment methods. How much longer must young people say they are struggling before truly meaningful changes are made?”

Dr Sam Jones, a mental health officer at the Royal College of Paediatrics and Child Health, said the findings were symptomatic of wider pressures on children’s wellbeing.

“We are seeing a sharp rise in mental health problems among children and young people,” he said. “More younger children are struggling and there has been an increase in self-harm and eating disorders in recent years.

“What’s needed to improve young people’s wellbeing is national action to ensure equal, timely and appropriate access to both physical and mental health support, tackling child poverty, improving housing, increasing access to safe green spaces, reducing digital harms and reducing stress at school.”

The children’s commissioner, Rachel de Souza, said her research showed that despite valuing their schools and teachers, one-third of children did not enjoy school.

“I want to see an ambitious new system of supporting children’s needs in school that rebuilds trust with families, intervenes far earlier, and wraps specialist services and professionals around schools – not waiting for children to reach crisis point before help is available,” she said.

A government spokesperson said: “This government is determined to see every child achieve and thrive, which means encouraging pupils to work hard while also helping them manage stress and build resilience.

“Mental health support teams are already intervening early with children experiencing mild to moderate issues, and we’re expanding access to a mental health professional in every school, with an additional 900,000 pupils set to benefit this year.

“This builds on our support-first approach for children facing barriers to attendance, while our landmark curriculum review will reduce overall exam time and strengthen pupils’ sense of belonging.”