Complex Interventions for Youth Mental Health: A way Forward

There is growing acknowledgement that complex mental health problems are not readily resolved by one-dimensional solutions, such as medication alone. Recent systematic reviews of interventions for youth mental health challenges indicate small-to-moderate effect sizes, especially in contexts that mimic real-world conditions. These effect sizes have not improved substantially over the last 30 years at least. In this commentary, we argue that broader multifaceted youth interventions are required, encompassing biological and psychosocial components, personalized to the needs of the individual in their sociocultural and developmental context. This interventional strategy has been referred to as ‘complex’; the Medical Research Council (MRC) in the United Kingdom (UK) has provided a useful framework for the construction, development and delivery of complex interventions. Transition to individualized, multicomponent treatments that are more consistent with the heterogeneity of mental disorders will require a shift in the way that clinical trials are designed, implemented and reported to account for real-world complexity.

To date, little attention has been given to how complex interventions intersect with youth mental health initiatives, despite growing concern regarding rates of mental health problems in young people (exacerbated during the COVID-19 pandemic), and substantial investment into models of youth mental health care.

What are Complex Interventions?

The MRC UK suggests the following to be central to the complex interventions construct ¹ : (1) there are ‘several interacting components’; (2) the interventions are ‘dependent upon the behaviours of those delivering and receiving the intervention’; (3) the intervention may result in ‘a range of possible outcomes’; and (4) there is ‘a need to tailor [the intervention] to different contexts and settings’. There are also imperatives about meaningful engagement of relevant stakeholders (e.g., patients, carers, clinicians) and ensuring a team with appropriate expertise. In planning the intervention, it is important to identify the problem; determine why change is needed and what evidence exists for what works and doesn’t work; understand context, facilitators and barriers to implementation; establish the evidence base for each element of the intervention based on established theory; and test the intervention with attention to how it changes behaviour, ensuring that, if successful, it can be scaled-up to the population level. ¹ Studies of complex interventions are in contrast to ‘efficacy’ trials which take place under strictly controlled laboratory settings, with narrow inclusion/exclusion criteria and usually testing a single intervention in isolation.

Why are Complex Interventions Necessary in Young People?

Complexity is the rule rather than the exception in mental health, notably in youth. For example, the National Comorbidity Survey Replication – Adolescent Sample ² showed that in 13–18-year olds, around 40% of youth with one mental health or substance use disorder also had another (comorbid) disorder. The Ontario Child Health Study ³ illustrates the importance of perception, communication, help-seeking and family context in relation to youth mental health. For example, there were youth versus parental report disparities: there was a higher youth-reported prevalence of any disorder in females (largely driven by depression and anxiety), whilst for parental reports, there was an excess of males, driven largely by attention-deficit hyperactivity disorder.

In youth mental health, there are added complexities related to the developmental context, including physical and emotional development, individuation and determining a sense of self. Educational and vocational factors, peer interactions, relationships and families all play important roles. In addition, youth often carries with it the desire to experiment (e.g., with substances of abuse), to challenge social constraints and to move towards autonomy, impacting mental health and substance use-related disclosures and help-seeking. All of these factors are embedded in the youths’ cultural context, including the critical importance of considering truth and reconciliation for Indigenous peoples. These components exert influence reciprocally and dynamically, with process, person, context and time interacting with greater complexity over the course of development. ⁴ Delineating ‘normal’ and even ‘necessary’ developmental processes from what might be considered ‘abnormal’ is often challenging.

The ‘clinical high risk’ (CHR) paradigm illustrates the complexity of mental health presentations in youth. The construct of CHR was initially developed to predict individuals at higher risk of developing psychosis, though it is now understood to be pleomorphic, with outcomes ranging from complete remission to evolution into mood or psychotic spectrum disorders. ⁵ This uncertainty about illness trajectory favours a personalized, multifaceted approach to address presenting symptoms and potentially avert more severe outcomes. It was the late Ian Falloon and colleagues ⁶ who conducted the first ‘modern’ CHR study, long before it became popular. The study involved a multidisciplinary team being available 24 h/day, to respond rapidly to referrals of people experiencing psychosis-like symptoms. Interventions were individualized and encompassed psychoeducation, delineation of early warning signs, home-based stress management strategies, and where required, short-term low-dose antipsychotics. Ongoing care, with stress management techniques being reinforced, and signs and symptoms being monitored, was delivered ‘according to the express needs of patients and caregivers’ to ‘train efficient problem-solving within the family unit’. ⁶ This epitomizes a complex intervention trial that moved away from the desire to test ‘simple’ interventions, and to integrate the individuals’ mental health with consideration of family members’ mental health, and social, developmental, cultural and educational context. The study also highlights how practice-based data inform the integration of different treatment components within a real clinical setting. Other apposite clinical examples include early psychosis services, family-based eating disorder programmes, multifaceted interventions for youth with autism spectrum disorder and/or attention-deficit disorder, and complex interventions for youth who have suffered childhood trauma and carry the residua thereof.

The way Forward

Youth mental health requires the development and testing of interventions that address complex intersecting needs in developmentally and culturally informed ways, including youth and family engaged intervention development and evaluation projects, reflecting the dynamic nature of youth development and the complex interrelations among multiple systems of influence. For example, the integrated youth services model uses stepped-care intervention pathways that address symptoms and functioning, but integrates various psychosocial services to address social and contextual factors. ⁷ CHR lends itself particularly to this approach. Discrete intervention trials in CHR do not reflect real-world delivery where treatments adapted for individual response are often required. Consistent with the heterogeneity of CHR and of youth mental health disorders generally, personalized and adaptive treatment strategies are required. Dynamic treatment designs such as Sequential Multiple Assignment Randomized Trial (SMART) ⁸ respond to the changing needs of participants whilst maintaining scientific integrity and rigour. Additionally, cost-effectiveness assessments need to be built into each step.

Conclusions

Complex interventions in youth mental health would benefit from a pragmatic, patient-oriented evaluative approach; this means moving away from reductionist trial-based evidence and towards mixed-methods, patient-engaged evaluative designs in which research evidence and experiential knowledge are equally valued. This approach can be additionally informed by practice-based evidence, focused on gathering data from the routine practice that is already incorporating complex interventions. In youth-oriented interventions, attending to youth and family relations and preferences in service design can enhance service appropriateness, access and patient retention, adding complexity and hastening travel across the translational Valley of Death ⁹ which characterizes the time taken for a laboratory finding (an efficacy trial) to become the standard of care in the community. We believe that the process can be hastened with the adoption of the complex interventions framework in youth mental health.