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Polemic headlines about a mental health crisis in children, plus surging demand and long waiting lists for services, pre-date covid-19. Research indicates that children’s mental health was deteriorating in the UK before the pandemic, particularly among teenage girls and young women.6 Furthermore, pre-pandemic studies suggest that more recent generations of children with a mental health condition seemed to experience increased levels of symptoms with greater effect on their ability to function and worse outcomes than their recent predecessors.7 Systematic reviews of longitudinal studies8 9 10 provide robust evidence for increased depression rather than anxiety among young people living through the pandemic and resulting restrictions, although the prevalence of both disorders would be expected to increase in adolescence.4

Polemic headlines about a mental health crisis in children, plus surging demand and long waiting lists for services, pre-date covid-19. Research indicates that children’s mental health was deteriorating in the UK before the pandemic, particularly among teenage girls and young women.6 Furthermore, pre-pandemic studies suggest that more recent generations of children with a mental health condition seemed to experience increased levels of symptoms with greater effect on their ability to function and worse outcomes than their recent predecessors.7 Systematic reviews of longitudinal studies8 9 10 provide robust evidence for increased depression rather than anxiety among young people living through the pandemic and resulting restrictions, although the prevalence of both disorders would be expected to increase in adolescence.4 Some of the current authors conducted a systematic review of 51 studies from 15 countries that assessed children’s mental health using a validated measure before and during the pandemic.8 This review reported a slight deterioration in mental health among children during the pandemic. Only four studies were of high methodological quality, with huge variation in samples, methods, and timing in relation to the pandemic, which may explain the failure to detect any clear pattern of changes. Data on children under 10 years are lacking, and few studies consider neurodevelopmental conditions and conduct and eating disorders.8 This may be related to a decline in academic paediatrics, the more complex ethical and logistical considerations of research with younger children, which requires parental consent, and the need for teacher and parent reported data for under 8 year olds.

r neurodevelopmental conditions and conduct and eating disorders.8 This may be related to a decline in academic paediatrics, the more complex ethical and logistical considerations of research with younger children, which requires parental consent, and the need for teacher and parent reported data for under 8 year olds. A 2023 systematic review found increased symptoms of attention deficit-hyperactivity disorder (ADHD) during the pandemic in people with sub-clinical or clinical levels of difficulties before the pandemic.11 Globally, presentations to clinical services for children with eating disorders have increased.12 Evidence is mixed on suicide rates and suicidal behaviours.13 14 Given the time lag in the release of suicide statistics, future investigation of the potential impact of the pandemic is required. The prevalence of self-harm in UK children and adolescents is about 20%, and data beyond the 2023 systematic review is lacking8; this is a priority area for research, but one that often faces challenges in obtaining ethical approval.

statistics, future investigation of the potential impact of the pandemic is required. The prevalence of self-harm in UK children and adolescents is about 20%, and data beyond the 2023 systematic review is lacking8; this is a priority area for research, but one that often faces challenges in obtaining ethical approval. Studies consistently show that children facing socioeconomic adversity, and with pre-existing poor mental health or special educational needs, have worse trajectories.15 School closures are particularly difficult for families facing other adversities (box 1), which could be alleviated with group based support.2 16 Furthermore, one in five children were persistently absent from school (>10% of sessions) in England in the autumn term of 2024, which is approximately double the pre-pandemic levels.32 We urgently need to ensure outcome data collection around innovative practice to evaluate its impact and to develop evidence based interventions to support reintegration into school. Studies over time and across the age range are essential to determine whether there are developmental periods where exposure to social restrictions was more detrimental. Increasing prevalence of anxiety, depression, and self-harm in teenage girls and young women were concerns going into the pandemic.6 17

Studies consistently show that children facing socioeconomic adversity, and with pre-existing poor mental health or special educational needs, have worse trajectories.15 School closures are particularly difficult for families facing other adversities (box 1), which could be alleviated with group based support.2 16 Furthermore, one in five children were persistently absent from school (>10% of sessions) in England in the autumn term of 2024, which is approximately double the pre-pandemic levels.32 We urgently need to ensure outcome data collection around innovative practice to evaluate its impact and to develop evidence based interventions to support reintegration into school. Studies over time and across the age range are essential to determine whether there are developmental periods where exposure to social restrictions was more detrimental. Increasing prevalence of anxiety, depression, and self-harm in teenage girls and young women were concerns going into the pandemic.6 17 Children who experienced disrupted transitions, such as starting school or moving from primary or elementary, to secondary or high school, or from school to work or university, may be particularly at risk for mental health conditions; we need to research this. Children who were toddlers, babies, or born during the pandemic had greatly reduced pre-school social exposure. Anecdotal reports suggest increases in delayed language and social skills among children entering school, emphasising the need for follow-up studies.

sk for mental health conditions; we need to research this. Children who were toddlers, babies, or born during the pandemic had greatly reduced pre-school social exposure. Anecdotal reports suggest increases in delayed language and social skills among children entering school, emphasising the need for follow-up studies. We should not forget the impact of infection with covid. England’s Children with Long COVID (CLoCk) study identified more symptoms of greater severity among children who had tested positive at all data points compared with those who tested negative.18 In individuals, symptoms declined over time, and no difference in mental health outcomes was found between children who initially tested positive or negative. Vaccination did not seem to prevent development of long covid. Older teenagers, girls, and children with poorer health before covid had worse outcomes. Data linkage to health and education records would help to understand pre-pandemic health and education and in following up these cohorts. The experience of, and treatment of, children with sustained symptoms should be researched.

The pandemic stimulated increased quantity but not quality of mental health research.5 19 For example, systematic scientometric research in 2022 found 3692 articles on covid and children’s mental health, but only 23% reported new data.20 Studies excluded from the living systematic review already mentioned were mostly cross sectional, lacked pre-pandemic comparison data, and used convenient samples or bespoke measures of mental health, resulting in risks of bias or inaccuracy.5 Consistent use of metrics is crucial. Even small changes in the wording of questionnaires can substantially affect responses, making them invalid.21 Guidance on consistent measures is important to increase both the rigour and the comparability of research. However, the current guidance was developed with insufficient consultation with key stakeholders and focuses only on anxiety, depression, and impairment, ignoring common and important conditions such as eating, neurodevelopmental, and psychotic disorders.22 Such rigid insistence on particular measures risks stasis in research, and regular review of recommendations by research funders, researchers, and policy makers is essential to avoid stifling psychometric innovations, such as computer adaptive testing. Covid-19 affected researchers’ personal and professional lives, especially female academics with children, potentially limiting their work.23 Pressure for rapid response meant research was not always led by specialists in young people’s mental health or epidemiology.

Consistent use of metrics is crucial. Even small changes in the wording of questionnaires can substantially affect responses, making them invalid.21 Guidance on consistent measures is important to increase both the rigour and the comparability of research. However, the current guidance was developed with insufficient consultation with key stakeholders and focuses only on anxiety, depression, and impairment, ignoring common and important conditions such as eating, neurodevelopmental, and psychotic disorders.22 Such rigid insistence on particular measures risks stasis in research, and regular review of recommendations by research funders, researchers, and policy makers is essential to avoid stifling psychometric innovations, such as computer adaptive testing. Covid-19 affected researchers’ personal and professional lives, especially female academics with children, potentially limiting their work.23 Pressure for rapid response meant research was not always led by specialists in young people’s mental health or epidemiology. Furthermore, in the UK, the process to access administrative data and the NHS national surveys for analysis has become more complex and time consuming, hindering secondary analyses.24 Despite pressure to fill the evidence gap, robust methodology is essential to minimise misleading findings.

Covid-19 affected researchers’ personal and professional lives, especially female academics with children, potentially limiting their work.23 Pressure for rapid response meant research was not always led by specialists in young people’s mental health or epidemiology. Furthermore, in the UK, the process to access administrative data and the NHS national surveys for analysis has become more complex and time consuming, hindering secondary analyses.24 Despite pressure to fill the evidence gap, robust methodology is essential to minimise misleading findings. Nearly all research has reported mean changes across the entire studied population or sub-groups, even if stratified by different levels of risk, which might mask highly variable trajectories within individuals. An increased focus on changes within individuals over time, and their predictors, would reveal more about factors that determine resilience or poor outcomes.

Even a slight deterioration in mental health, or change in help seeking on a population level, can result in a marked increase in demand on services.12 To respond, policy makers and service commissioners and providers need to understand the drivers and vulnerable groups that lack access.25 For example, fewer children were referred to specialist services or admitted to mental health units during the first lockdown, when there were also reduced mental health presentations and prescribing for young people in primary care.26 This was rapidly followed by a sharp rise in referrals and crisis presentations, with increasing pressure on all levels of the NHS.1 Research that improves our understanding of the influences on help seeking and access are important to facilitate targeting of limited resources to those most in need.

Optimise study design–National and international funders should increase the number of developmental studies that follow children over time. Only longitudinal data can show whether a health shock is causing harm compared with other exposures. Cross sectional surveys, which ask those experiencing a health shock to recall previous health states, are biased, inaccurate, and wasteful to study. Cohort studies are expensive but are an important investment that repays in the breadth and depth of policy relevant data that can be obtained. Improve data linkage–Longer follow-up and more detailed pre-pandemic knowledge could be achieved by the mandatory linkage of epidemiological data to routinely collected health, social care, and education data, which could drive service improvement across the UK at relatively low cost. It would also provide information about health and education function before the initial study, supporting identification of vulnerable groups. However, we lack funding streams to support this work, and the bureaucracy in linking and accessing the data deters researchers and funders. Initiatives such as University College London’s ECHILD and the UK Longitudinal Linkage Collaboration are welcome.27 28 Data linkage should be a condition of funding; researchers need financial support to revisit studies after participants have passed key developmental milestones, such as leaving school or transitioning to adult health services. Researchers also need training and supervision to ensure that these sophisticated techniques are more widely deployed.

ondition of funding; researchers need financial support to revisit studies after participants have passed key developmental milestones, such as leaving school or transitioning to adult health services. Researchers also need training and supervision to ensure that these sophisticated techniques are more widely deployed. Build capacity—Paediatric research generally needs greater collaboration, engagement, and capacity building.29 Global epidemiological capacity building is needed in child mental health, including training and peer mentoring. Work by some of the current authors shows greatly reduced activity in the UK.24 Funders should provide dedicated training opportunities that focus on acquiring epidemiological expertise. Collaborate internationally— Cross border collaborations can be helpful in studying the impact of different responses to health shocks on different service systems and to study risk and protective factors; they also increase sample size where context, response, and settings are similar. We hope the UK’s re-entry to Horizon Europe, the European Union’s research funding programme, will facilitate and fund international studies. International bodies such as WHO and Unicef should encourage and fund collaborative research.

s; they also increase sample size where context, response, and settings are similar. We hope the UK’s re-entry to Horizon Europe, the European Union’s research funding programme, will facilitate and fund international studies. International bodies such as WHO and Unicef should encourage and fund collaborative research. Use validated measures—Research should use the many validated measures of child and adolescent mental health. If a bespoke measure is used, validity and reliability should be established before any publication using the measure as an outcome. This requires cooperation and good methods of training at every level, from researchers to funders and journal editors. Routine use of validated measures in clinical practice with outcome measurement would facilitate clinical research, which the UK government’s Mental Health Missionhopes to achieve.30

re as an outcome. This requires cooperation and good methods of training at every level, from researchers to funders and journal editors. Routine use of validated measures in clinical practice with outcome measurement would facilitate clinical research, which the UK government’s Mental Health Missionhopes to achieve.30 Increase research funding–With 20% of children persistently absent from school in England, and a 24% increase in the number of emerging adults unable to work owing to poor mental health,33 government cannot afford not to increase the funding allocated to research the mental health of children. Although a third of the UK population is under 25 years, the health research allocation is only 5% of the budget.3 Furthermore, mental health research, of which only a quarter is focused on children, is seriously underfunded compared with other conditions with a comparable burden of disease: annual spending is £9 (€11; $12) per affected person compared with £24 for cardiovascular disease, £127 for dementia, and £228 for cancer.31 Research into children receives a tiny proportion of this. All funders, including industry, which has tended to exclude under 18s, have a duty to contribute. Targeted funding could encourage inclusion of younger children in studies and ensure a focus across all common mental health conditions, while mandated involvement of researchers with appropriate expertise would boost research capacity and activity.

try, which has tended to exclude under 18s, have a duty to contribute. Targeted funding could encourage inclusion of younger children in studies and ensure a focus across all common mental health conditions, while mandated involvement of researchers with appropriate expertise would boost research capacity and activity. Proportionate data governance—Research has been hobbled by over-restrictive data governance.24 Strong governance around access to epidemiological and administrative data is essential, but application and data transfer processes need to be streamlined and adequately staffed. Current applications often take months or even years, deterring researchers and funders and depriving policy makers and service providers of essential evidence. Recent examples, like ECHILD, which allows researchers to apply to study linked health and education data, and transfer of the Mental Health of Children and Young People Surveys data from NHS England to the UK Data Archive, with a streamlined process for access, show what discussion and collaboration across stakeholders can achieve. Children and young people’s interests and voices must be represented and respected in prioritisation of research questions to tackle the wide evidence gap Funding calls and streams should encourage longitudinal studies across the range of mental health conditions affecting children and young people, and also ensure that funded research spans life stages from pre-school to emerging adulthood

Children and young people’s interests and voices must be represented and respected in prioritisation of research questions to tackle the wide evidence gap Funding calls and streams should encourage longitudinal studies across the range of mental health conditions affecting children and young people, and also ensure that funded research spans life stages from pre-school to emerging adulthood Linkage of study data to administrative education and health and social care to extend follow-up should be mandated as part of funding agreements, with streamlined processes to expedite both linkage and access for analysis Funders, supervisors, and journal editors should reject low quality studies, particularly those with bespoke, unvalidated measures, and cross sectional surveys of convenience samples. The considerable resources saved could support more rigorous and reliable research for policy and planning