Most south London teenagers with mental health disorders go undiagnosed by NHS

The share of 17-year-olds receiving an NHS mental health diagnosis has risen, but researchers estimate fewer than one in 15 young people with a disorder were diagnosed through services over the study period.

New research from King’s College London suggests that only a small fraction of young people in south London who are likely living with a mental health disorder are getting a formal diagnosis from NHS mental health services, even as the share identified by those services has risen over time. The study, published in The Lancet Regional Health–Europe, found that among 17-year-olds in south London the proportion receiving any NHS mental health diagnosis increased from 2.6% in 2009 to 4.4% in 2024, but the researchers still estimated that fewer than one in 15 young people with a disorder would have been diagnosed through those services across the full study period.

The findings come against a wider backdrop of concern about unmet need among children and teenagers in London and across England. London Assembly material has previously warned that many lifetime mental illnesses begin by age 14 and that large numbers of young people in the capital go undetected or untreated, while national data from the Office for National Statistics indicates that mental health difficulties affect around one in eight children and young people in England and are becoming more common, particularly emotional disorders such as anxiety and depression. Other public health estimates have suggested that at least one in six children and young people aged seven to 16 has a probable mental health disorder, rising to one in four among those aged 17 to 19.

The study’s authors compared electronic health records from NHS mental health services with population figures and with epidemiological estimates drawn from more than 2,000 young people in the Environmental Risk Longitudinal Twin Study. They focused on depression, generalised anxiety disorder, post-traumatic stress disorder, conduct disorder and attention deficit hyperactivity disorder. Even among young people estimated to have one of those disorders and to have sought help from any health professional, fewer than one in four received a diagnosis from NHS mental health services. The gap was wider for girls than boys, and for young people from Black, Asian, mixed or other ethnic backgrounds compared with white young people.

The researchers said part of the shortfall appears to stem from many young people never reaching any professional help at all, with possible barriers including uncertainty about when support is needed, concerns about confidentiality and practical problems attending appointments. But they said that does not explain the full gap, pointing instead to barriers inside the system as well, including high access thresholds, limited capacity and the possibility that some disorders are not recognised during assessment. Lead author Stephanie Lewis said the results show that many young people who meet the criteria for a disorder are still not receiving a diagnosis, even when they have already tried to seek help, while senior author Andrea Danese argued that diagnosis matters because NHS treatment pathways are disorder-specific and that investment is needed in assessment capacity.

The study’s authors also said their figures may reflect, or even understate, the position nationally. They noted that the findings are in line with earlier evidence from the STADIA trial, which found that in eight large NHS trusts in England only around one in eight children referred to community mental health services received a recorded diagnosis within a year, despite many of those assessed showing a high probability of a common mental disorder. Together, the research adds to a long-running warning from public health bodies: that a substantial share of young people with mental illness are still not being identified early enough to get the right care.