The Effectiveness of Preventative Interventions to Reduce Mental Health Problems in at-risk Children and Young People: A Systematic Review of Reviews

Mental health problems are the leading cause of childhood disability worldwide, resulting in poor outcomes for children and young people that persist into adulthood. It is essential that those young people most at risk of developing mental health problems receive effective preventative interventions. Whilst there have been a number of systematic reviews which have examined the effectiveness of secondary prevention interventions for specific groups of children and young people, or to address identified mental health concerns, no review has engaged with the breadth of this literature. We conducted a systematic review of systematic reviews to map this complex field of secondary preventative interventions and identify effective interventions to prevent mental health problems in children and adolescents aged 3–17 years. The review protocol was registered on PROSPERO. We searched five electronic databases from inception to February 2023. The certainty of the evidence was appraised using the AMSTAR 2. We included 49 unique systematic reviews each including between 2 and 249 (mean 34) unique studies; the majority of which were reviews which included only or mostly randomised controlled trials (70%). The reviews examined selective interventions (defined as interventions which are delivered to sub-group populations of young people at increased risk of mental health problems) (n = 22), indicated interventions (defined as interventions which target young people who are found to have pre-clinical symptoms) (n = 15) or a synthesis of both (n = 12). The certainty of the evidence in the reviews was rated as high, (n = 12) moderate (n = 5), low (n = 9) and critically low (n = 23). We found evidence to support both selective and indicated interventions in a range of populations and settings, with most of this evidence available for children and young people in their mid-years (6–10 years) and early adolescence (11–13 years). There was a large body of evidence suggesting that resilience enhancing, cognitive behaviour therapy-based and psychoeducational interventions for children who experience adversity, or those with subclinical externalising problems may offer promise. Early selective interventions for a subpopulation of children and young people who have experienced adversity which combines risk reduction and resilience enhancing approaches directed at children and their families may be effective at reducing mental health problems. Supplementary Information The online version contains supplementary material available at 10.1007/s10935-024-00785-z.


Introduction
Mental health problems are the leading contributor to childhood disease burden worldwide (Baranne & Falissard, 2018;Erskine et al., 2015).Half of all adult mental health disorders emerge before the age of 14 years and three-quarters before the age of 24 years (Kessler et al., 2005).In the UK it is estimated that one in six children aged 5-16 years have a mental health problem (Digital, 2020).These children also experience poor outcomes including an increased risk of substance use (Hopfer et al., 2013), involvement in offending behaviour (Rijo et al., 2016), difficulties in their relationships with family and friends (Lim et al., 2020), diminished educational opportunities, Wickersham et al. (2021) and unplanned pregnancy/parenthood (Clayborne et al., 2019).Children who experience mental health problems are also at risk of persistent mental health problems in adulthood (Wykes et al., 2023) and later economic adversity (Evensen et al., 2017).
The rising cases of adolescent mental health problems over recent years (Wykes et al., 2023), combined with the clinically elevated rates of adolescent depression and anxiety following the COVID-19 pandemic (Racine et al., 2021), are of substantial public health concern.Whilst there are an increasing number of evidence-based interventions to treat mental health problems in children and young people (Pennant et al., 2015;Reynolds et al., 2012;Tindall et al., 2017), this treatment is not accessible to all young people (Department of Health, 2015;Radez et al., 2021), and those who do access treatment often experience long waiting times (Fargas-Malet & McSherry, 2018;Department of Health, 2015).To bring about immediate psychological and social benefits for children, young people, and families whilst also decreasing the prevalence of mental health disorders in adults in the future, effective prevention is required (Wykes et al., 2023).
There is robust evidence for primary prevention of mental health problems.Such interventions are delivered universally to children and young people and have been found to promote positive mental health and prevent the onset of mental health disorders (World Health Organization, 2020).However, it is likely that children who experience greater risk of developing mental health problems may need a more targeted approach which is proportionate to their needs (Marmot et al., 2010).There is a large and diverse evidence-base examining the effectiveness of secondary preventive interventions delivered to children and young people at greater risk than the general population.These interventions which seek to reduce the prevalence of mental health disorders in a population (Institute of Medicine Committee on Prevention of Mental, 1 3 Journal of Prevention (2024) 45:651-684 1994) may be either selective or indicated.Selective interventions target individuals who are at increased risk of developing mental health disorders on the basis of biological, psychological or social risk factors, whereas indicated interventions target individuals who are identified as having pre-clinical symptoms (Cho & Shin, 2013).These secondary preventive interventions vary depending upon the age of the child, the nature of mental health risk, and the approach taken to improving mental health outcomes.However, they broadly either seek to strengthen resilience (Dray et al., 2017) or modify risk factors within the context or the young person's response to them (World Health Organization, 2004) in order to reduce the incidence, prevalence or reoccurrence of mental health problems.
There have been multiple systematic reviews which have estimated the effectiveness of secondary preventative interventions for child and adolescent mental health.This includes reviews of interventions within school settings (Gee et al., 2020;Hugh-Jones et al., 2021;Neil & Christensen, 2009), targeted interventions for young people with sub-threshold behavioural problems (Graaf et al., 2008), depression (Bertha & Balazs, 2013) and anxiety (Hugh-Jones et al., 2021), and of selective interventions with subgroups of young people who are considered at elevated risk due to adversity (Havinga et al., 2021), physical health problems (Thabrew et al., 2018) or belonging to a minority group (Gilbey et al., 2020).However, no review has engaged with the full breadth of this literature, resulting in crucial gaps in understanding about how best to prevent mental health problems in children and young people on a population level, and what approaches are most often associated with effective secondary preventative interventions.Our review aims to map this complex field of interventions to provide an evidence overview of promising interventions to reduce child and adolescent mental health problems.In doing so, we aim to provide evidence to inform practice.Our specific review questions are:

Methods
The review followed PRISMA guidelines for conducting systematic reviews.
The review protocol was registered with PROSPERO (CRD42021290457).The following electronic databases were searched from inception until February 2023, using free text keywords and thesaurus headings: MEDLINE (Ovid); Embase (Ovid); PsycINFO (Ovid); Applied Social Science (ASSIA); Scopus and Cochrane Database of Systematic Reviews (the search strategy is included with the supplementary file).This was supplemented by searching reference lists of relevant studies as well as contacting authors who publish in the field to identify ongoing trials and unpublished work.Two reviewers independently screened all titles and abstracts using specified inclusion and exclusion criteria, retrieving full papers for all potentially eligible studies, and evaluating in full text.No language or date restrictions were applied.Relevant data were extracted independently by two reviewers, including: study design, sample characteristics, intervention details, outcome measures and intervention effects.Discrepancies at each stage were resolved by discussion or by consulting a third researcher if consensus could not be reached.

Eligibility
We included systematic reviews of randomised controlled trials, quasi-experimental designs, and outcome evaluations of secondary preventative interventions (either selective or indicated) for children and young people aged 3-17 years or their parents/ caregivers.We included reviews of studies outside of this age range providing the mean age of the sample fell within our age range.For reviews of selective intervention, we accepted the authors definition of 'at risk' populations.Indicated interventions were required to identify children and young people experiencing mental health distress below the diagnostic threshold with a valid screening tool or assessment.All intervention modalities were considered eligible.Our definition of mental health problems included both internalising (e.g.anxiety and depression) and externalising problems (e.g.aggression, delinquency, behavioural), and self-injury.We excluded reviews of interventions for children and young people with current or historic diagnosed mental health conditions, and reviews of interventions to reduce substance use in children and young people.

Data Extraction and Synthesis
Data extraction was independently completed by two reviewers using a bespoke, piloted data extraction form.Key characteristics of each of the reviews were recorded, including details of the mental health risk, intervention type (selected or indicated secondary prevention), intervention approach and content, and the main findings of each review.Our primary outcome was the reduction in mental health risk/problem score (assessed using a validated tool or diagnostic interview).Where more than one paper was published from a review, the index review was identified, and additional outcomes of interest reported as linked findings.The findings reported within included reviews were synthesised narratively by intervention type and grouped according to intervention approach and content and presented in tables according to the appraisal of confidence in the evidence (as high/moderate confidence, or low/critically low).This approach to the synthesis is in line with the aims of this systematic review of reviews, resulting in a high-level summary of the evidence (Aromataris et al., 2015).

Quality Appraisal
We used the Assessment of Multiple Systematic Reviews (AMSTAR 2) tool, a 16-item critical appraisal tool for systematic reviews of healthcare interventions (Shea et al., 2017).The tool assists in the identification of high-quality systematic reviews of randomised and non-randomised studies of interventions and provides an overall rating based on weaknesses in critical domains.The AMSTAR 2 allows for the potential impact of an inadequate rating for each domain and provides a scheme for interpreting critical weaknesses (such as a-priori registration of review protocol, risk of bias assessment of the individual studies) and non-critical weaknesses (such as performing duplication of study selection, duplication of data extraction, reporting of funding sources) within the review.Reviews were not excluded based on quality; rather the AMSTAR 2 was used to assess the confidence in the results of each review (Shea et al., 2017) and our resulting synthesis.Reviews were deemed to provide a high degree of confidence if there is no critical and one non-critical weakness assessed; moderate if there is more than one non-critical weakness; low if there is one critical weakness with or without non-critical weaknesses; critically low if there are more than one critical weakness.

Results
Our search identified 1433 potentially relevant references.Of those, 170 full papers were retrieved.Fifty-four papers reporting on 49 unique reviews met the inclusion criteria and were included in our systematic review of reviews.Figure 1 shows the flow of studies.

Selective Interventions
Reviews providing high to moderate confidence evidence for selective interventions were mostly delivered to groups of children and young people who had experienced adverse childhood experiences; most of which found evidence of effectiveness.This adversity in the majority of reviews related to having a parent who experienced mental health problems.Reviews typically examined a range of interventions and combined these within their estimates of effect.As each included intervention may vary in effectiveness, it was difficult to confidentially determine which of the interventions were effective.However, reviews reporting effective interventions typically included cognitive behavioural therapy (Havinga et al., 2021;Lannes et al., 2021;Loechner et al., 2018) or psychoeducation approaches (Bee et al., 2014;Lannes et al., 2021;Loechner et al., 2018) focused upon building resilience (Bee et al., 2014;Havinga et al., 2021;Loechner et al., 2018), with some reviews also including creative arts-based interventions (Morison et al., 2022), family therapy and skills training (Bee et al., 2014;Havinga et al., 2021).Children/young people whose parents experienced mental health problems were found to have a 47% reduction in developing the same mental health disorder as their parents at 9-24 months follow-up (Lannes et al., 2021).Significant reductions in depressive symptoms (Loechner et al., 2018) and incidence of internalising disorders (Lannes et al., 2021) were also reported by reviews examining secondary prevention in this population, with reviews reporting between 44% (Loechner et al., 2018) and 63% reduction (Havinga et al., 2021) at 12-15 month follow-up and 29% reduction at 24 month follow-up (Havinga et al., 2021).Whilst a review of creative arts-based interventions for children and adolescents exposed to traumatic events reported significant reduction of PTSD symptom scores and negative mood post-intervention compared to control group, however reductions were not found for externalising problems or anxiety (Morison et al., 2022).Only one review examining secondary prevention for children who experienced adversity did not report reductions in mental health problems.This review found there may be no evidence of a difference between psychological and social intervention groups and control groups for reducing PTSD symptoms, depressive symptoms and anxiety symptoms in children aged 7-18 years affected by humanitarian crisis at study endpoint (Papola et al., 2020).We identified one review contributing moderate certainty evidence examining interventions for suicide prevention within indigenous adolescents.This review found only two studies meeting the inclusion criteria.Both of these studies showed evidence of effectiveness as reducing risk factors and increasing protective factors associated with suicide, however the effect upon suicide ideation or attempts was not assessed (Grande et al., 2022).
Further reviews reporting evidence of low to critically low confidence reported mixed evidence.These reviews could broadly be categorised as those examining selective interventions for children and young people who had experienced adversity and those from minoritised groups.Reviews of selective interventions for groups who had experienced adversity were mostly found to be effective, including resilience enhancing interventions (Hambrick et al., 2016;Sangsawang et al., 2019;Wang et al., 2020;Watters & O'Callaghan, 2016); parenting skills training (Smedler et al., 2015), CBT (Yohannan et al., 2022).Only one review reported the potential for an increase in anxiety following a debriefing intervention for young people who had been exposed to a disaster (Pfefferbaum et al., 2017).Conversely, interventions for minoritised youth were mostly found not to be effective at reducing mental health problems in their samples; one being a sexual minoritised population (Gilbey et al., 2020), and another being an ethnic minority population (Harlow et al., 2014).One narrative synthesis examining parenting interventions for children with developmental disabilities found that interventions were effective at reducing mental health problems in children (Petrenko, 2013).A further review reported schoolbased interventions were effective at reducing violence in at-risk young people (Park-Higgerson et al., 2008).

Indicated Interventions
Reviews which provided high confidence evidence on indicated interventions mostly found interventions to be effective at reducing externalising problems in children and young people.Interventions which aim to enhance resilience through developing relational and social skills delivered directly to children and young people within the school setting, were found to be effective at reducing aggressive and violent behaviour with a small effect size at post intervention (Mytton et al., 2002;Mytton et al., 2006), with similar effects found at 12 month follow-up (Mytton et al., 2002;Mytton et al., 2006).A further review which mostly included resilience enhancing parenting interventions reported reductions in externalising symptoms and frequency of externalising behaviours with a moderate effect size in young children (Savaglio et al., 2023).
Interventions for children and young people with subclinical internalising problems mostly consisted of CBT focused upon modifying risk, and were often effective at reducing depression symptoms post intervention and/or at short term follow-up (usually 6 months) (Gee et al., 2020;Rasing et al., 2017;Ssegonja et al., 2018), and long term follow-up (12 months) (Rasing et al., 2017;Ssegonja et al., 2018).Evidence of effect upon anxiety symptoms was limited to post intervention (Gee et al., 2020), and short term follow-up (Rasing et al., 2017).A review of mostly resilience enhancing parenting interventions reported reductions in anxiety symptoms but not disorder (Savaglio et al., 2023).
A further review examining psychotherapy for self-harm in children found evidence that dialectical behaviour therapy reduces repetition of self-harm at post-intervention however the review reported there was no evidence for other psychosocial approaches (Witt et al., 2021).
Reviews contributing low and critically low confidence evidence examined a range of indicated interventions, with limited evidence of effect.There were mixed results for the effectiveness of parenting interventions to reduce child behaviour problems (Graaf  , 2008;Smedler et al., 2015).Meta-analyses found indicated interventions to be effective at reducing depression (Merry & Spence, 2007;Merry et al., 2011;Werner-Seidler et al., 2017) and anxiety symptoms (Baourda et al., 2022;Hugh-Jones et al., 2021) whilst narrative reviews reported inconsistent effects upon symptoms of depression (Thabrew et al., 2018) and anxiety (Neil & Christensen, 2009).A meta-analysis reported that psychosocial interventions reduced suicide ideation with a small effect, but not suicide attempts or self-harming behaviour (Itzhaky et al., 2022).

Combined Secondary Interventions
Four reviews contributing high or moderate confidence evidence examined a combination of selective and indicated interventions.These reviews typically found evidence of effect.A review which examined the effectiveness of secondary prevention to reduce a range of mental health problems found that interventions were effective at preventing conduct disorder, depression, anxiety and PTSD at post intervention and 12 month follow-up and that there was some evidence to suggest that younger children (under the age of 12 years) may experience greater benefit than older children (Pilling et al., 2020).A review reported evidence that CBT reduced depression symptoms compared to wait-list control with a moderate effect size in primary school children but not secondary school children and reduced anxiety only in secondary school children at 13-24 months follow-up (Caldwell et al., 2019).However, it should be noted that this evidence was based upon the findings of a single study.A review of individual, family and school-level interventions found secondary prevention within schools were effective at reducing anti-social behaviour at 6 months follow-up (Macarthur et al., 2018).Whilst a further review of the effectiveness of school-based interventions to reduce suicidality reported mixed results with around half of the included studies finding no effect (Calear et al., 2016).
Reviews contributing low and critically low confidence evidence mostly reported one or more intervention which were found to be effective at reducing mental health problems in children and young people.This included an effect upon externalising problems only (Vries et al., 2015;Wilson & Lipsey, 2007;Wilson et al., 2003), internalising problems only (Christensen et al., 2010;Cuijpers et al., 2006;Horowitz & Garber, 2006;Schwartz et al., 2019) and a range of externalising and internalising problems (Genugten et al., 2017;Waddell et al., 2007).They mostly reported small effects from the preventative interventions, with the exception of one review which estimated a reduction in anxiety with a large effect size following the Coping and Promoting Strength intervention (Schwartz et al., 2019).Due to these reviews examining very different secondary interventions, in different populations, it is difficult to draw further conclusions from the overview of the combined preventative interventions.

Discussion
Our systematic review of reviews has found a large body of evidence to support both selective and indicated interventions in a range of populations and settings.This builds upon an established evidence for preventative interventions in children and young people at risk of developing mental health problems (World Health Organization, 2020).However, the largest high and moderate confidence evidence was for selective interventions with children and young people who experienced adversity.Research consistently demonstrates that our early life experiences are of substantial importance to our health throughout the life course (Britto et al., 2017;Marmot et al., 2010).Where those early experiences are adverse, there is an immediate and long-lasting impact upon children (Bellis et al., 2015), resulting in major health and financial burden globally (Hughes et al., 2021).As such, our finding that selective preventative interventions with this group maybe effective at preventing mental health problems has important implications for practice.
The children and young people targeted by the selective interventions included those that had experienced a range of adverse childhood events, however the most common adversity related to parental mental health problems.Recent research highlighted the association between parental and child parental mental health problems, particularly in populations impacted by other family adversity such as poverty (Adjei, 2022).Whilst there is a large evidence base for interventions to address parental mental health problems, most are examining the effectiveness of interventions provided to the parent (Barrett et al., 2023).Whilst these approaches can be effective in reducing parental mental health problems, it is likely that children and young people will also require intervention to help them to overcome the impact of exposure to this adversity (McGovern et al., 2021).Whilst we found evidence that interventions were effective for children and young people who are experiencing a range of mental health problems, there was limited evidence for PTSD and self-harm.Positive effect was noted most often for those children and young people who experienced common internalising or externalising problems.Given the high prevalence of these mental health difficulties in children and young people who experience adversity (Benjet et al., 2010;Hughes et al., 2017;Parkes, 2020), our findings highlight an opportunity to affect change in this vulnerable group of children and young people, contributing to national (Wykes et al., 2023) and global (United Nations, 2015) efforts to address the disease burden caused by mental ill health and promote future health and wellbeing.
Across the body of reviews, we found that CBT, psychoeducation and family therapy and skills training were often included in reviews which reported positive outcomes.Effective interventions included those provided at an individual or family level.The components of these approaches varied but could be broadly categorised as having content focused upon reducing risk or enhancing resilience, with evidence supporting both of these approaches.Risk reduction interventions typically consist of components which may bring about a change in behaviours and thoughts which contribute to symptoms (Wampold, 2015), whilst interventions which aim to enhance resilience tend to include the development of 1 3 Journal of Prevention (2024) 45:651-684 personal resources and reinforcement of protective factors (Reavley, 2015).As many of the included reviews combined multiple studies of diverse interventions, we were unable to identify specific intervention content that is most likely to be associated with improvements in mental health beyond these broad categories.It is possible that a combination of components focused upon risk reduction and resilience enhancement across common behavioural, interpersonal, cognitive, and emotional domains maybe beneficial to improving mental health outcomes in children and young people (Singla et al., 2017;Skeen et al., 2019).Research has demonstrated the mediating effect that parent-child conflict has upon the development of mental health problems in children (Healy et al., 2022;Burt et al., 2003), with up to half of all externalising difficulties and one fifth of internalising difficulties in children who have experienced adversity being explained by parent-child conflict (Dhondt et al., 2019).Given the evidence for family level interventions highlighted within our review, a selective preventative intervention which includes components focused upon the parent-child interaction may be beneficial, although further research is needed to examine effectiveness.
Taken together, the findings of our review of reviews have important implications for practice.They provide support for early preventative intervention with children who have experienced adversity before they develop mental health concerns.This selective approach negates individual identification of risk which can be challenging and costly to implement (Dodge, 2020).It is likely that the selective intervention should contain both risk reduction and resilience enhancing components provided to both individual young people and their families.

Strengths and Limitations
Our review of reviews engages with a large international literature covering a wide range of secondary preventative interventions for the breadth of child and adolescent mental health problems.A strength of this approach is that it provides an accessible overview of up-to-date evidence covering multiple sub-populations of young people in a range of contexts.Further, our fields of enquiry can be separately considered with the potential to inform practice in this area (Pollock et al., 2020).Through rigorous methods, including duplicate screening and data extraction, we have been able to highlight promising interventions and situations to promote the mental health of children and young people.However, our review is not without its limitations.A proportion of the reviews report on the same individual studies.Within the high and moderate confidence evidence there are n = 40 studies which are included in more than one review (n = 34 included in 2 reviews; n = 5 included in three and n = 1 included in four reviews).Whilst this is not unusual in a review of reviews of this size, it does result in additional weight being given to some of the evidence.Many of the included reviews also took a broad approach when reviewing the literature, often including studies with participants from a wide age range and did not provide details of the mean age of participants.Consequently, the actual age of the children and young people who received the intervention was often unclear and therefore we were unable to identify the optimum age at which to intervene to prevent mental health problems developing.Reviews all included a range of outcome measures including self-report, validated screening tools and, to a lesser extent, diagnostic interviews.As such, the original studies which are included within the reviews may be at risk of bias.Reviews typically combined different secondary preventative interventions and reported upon pooled effects (e.g.producing of metaanalysis of CBT, psychoeducation and family therapy approaches) limiting our ability to confidentially determine which intervention types were most often found to be effective.The intensity and duration of these interventions varied greatly and as such it is unclear what intervention dose is effective.Further, comparison conditions within reviews often varied from no intervention control to an active comparison intervention, resulting in inflated and deflated results.Only a minority of the included reviews examined interventions trialled within low-middle income countries.As such, the findings of this evidence overview may not generalise to these countries.

Conclusion
Interventions to prevent mental health problems in young people are more likely to be effective if they combine both risk reduction and resilience enhancing approaches to targeting younger children and young people who have experience adversity and/ or those with subclinical externalising and internalising difficulties.Interventions may include both individual and family level interventions components.

Table 1
Reviews with high and moderate confidence findings

Table 2
Reviews with low and critically low confidence findings