A key principle when conducting research into psychological treatments for young people is developmental context. Much of our understanding of the psychological mechanisms underpinning mental health problems comes from studies of adults; however, we can’t assume that the same principles apply to children and adolescents.

Adolescence is a developmental stage marking the transition from childhood to adulthood. It is characterised by significant psychological and physical changes:

• Biological changes – marked by onset of puberty, physically adolescents experience rapid growth spurts, hormonal changes, and sexual maturation. Brain maturation continues into the mid 20s: white matter volume steadily increases, enhancing neural connectivity, while grey matter volume peaks in childhood and then declines due to synaptic pruning
• Cognitive changes – capacities for abstract thinking, reasoning, higher order executive control, and self-reflection continue to develop throughout this time.
• Social-emotional and interpersonal change – increased sensitivity to peer evaluation and greater reliance on peer relationships. This period involves identity formation, heightened risk-taking, and a growing desire for autonomy from caregivers.

Research involving adolescents must take developmental context into account for various reasons.

• The developmental changes happening at the cognitive and social-emotional levels may affect the psychological processes which contribute to mental health problems. One example is the normative increase in self-awareness and self-consciousness during adolescence which may contribute to the heightened self-focused attention, one of the well-evidenced maintenance mechanisms in social anxiety. Similarly, disorders which centre on self-perceptions such as depression may be more likely to emerge at a time when self-concept is developing.
• Adolescence is associated with certain environmental features which are likely to affect risk of mental health problems and psychological resilience, as well as the effectiveness of any interventions accessed. These include:
  • Family factors, with teenagers typically becoming increasingly independent from yet still emotionally and financially reliant upon parents and continuing to live in the family home.
  • Peer relationships, with social groups increasing in size and complexity and the onset of romantic relationships.
  • Education, with the significant increase in academic demands and transitions from school to college and perhaps university or the workplace.
• Development is not linear and cannot always be accurately determined using age alone. There are challenges involved in sensitively measuring development in adolescents which need to be considered when conducting research that includes young people.

Stakeholders (from young people with lived experience, to health professionals and service providers) are central to the process of developing acceptable, effective and accessible treatments. Benefits might include:

• Research topics and findings will be more relevant to those affected and involved (such as families, teachers and clinicians).
• Research outcomes and culture will be improved by inclusion of people with a range of perspectives and differences.
• Youth advisors can be empowered and upskilled.

What to consider

• Extent of stakeholder involvement in research (including how flexible this can be, how it changes at different parts of research, and how power is shared between contributors).
• Role of stakeholders (as advisors, co-producers, or peer researchers).
• Fair compensation and recognition of involvement.

Throughout the research process, it is vital to consider equality, diversity, inclusion and representation to ensure that treatments will be developed to be effective, accessible and acceptable to all who may need them. Engaging with stakeholders supports researchers to consider the range of disadvantages that affect how treatments will be accessed and engaged with, including how some research practices may introduce or enhance bias in outcomes. Therefore, to effectively meet the needs of young people and families, it is important that stakeholders are involved in conceptualising, designing, conducting and interpreting research.

In mental health research, a mechanism refers to the underlying psychological, biological, social, or environmental processes through which risk factors lead to the development, persistence, or attenuation of mental health problems. Within this broad framework, our focus is on the psychological processes (cognitive, emotional, or behavioural) that play a causal role in the onset or maintenance of these difficulties. This narrower definition highlights the key internal processes that are often the direct targets for psychological intervention.

In order to target mechanisms, we need a good explanation of how the mechanism leads to the difficulty. This is the process of forming a psychological understanding of the problem.

It requires the application, and likely development, of psychological theories to make sense of the problem and causal mechanisms. This is then used to drive treatment development by testing the hypothesised model.

Research studies within the Ten Steps are informed and motivated by these theory-driven hypotheses and the findings feed back into the theory and conceptualisation – making it an iterative process or cycle.

Conceptualisation of problems may:

• Provide a novel account or theory
• Draw on existing models, theories and frameworks
• Be an adaptation of existing approaches – perhaps from across the lifespan.

Regardless of the origin of the conceptualisation, consideration of the developmental context (Keystone 1) is essential.

• To initiate this process, broad psychological theories and principles can be applied to understand a specific clinical observation within an individual.
• This can then be widened to consider how to apply this initial understanding across individuals and how it relates to other thinking/behaviour patterns.
• Visualisation may be useful in presenting and articulating the hypothesised causal processes.

First-person accounts indicate that young people often face multiple, co-occurring problems (Keystone 2). Often particular diagnoses are unclear – both in the short term and if there are longer term difficulties.

Often there is diagnostic uncertainty both in the immediate presentation and in the longer-term trajectory (e.g. Polari et al., 2018).

There are likely many interrelated contributory causal factors.  Therefore, it can be helpful to map the relationships between different causal factors and problems to understand the dynamics / interactions and treatment targets that might lead to change in a number of areas. This means the theoretical conceptualisation must be tested and refined.

The more precise the description of the problem, and the mechanisms that might lead to it, the clearer it is to test. Specific and targeted testing of the model can inform treatment development – giving a better chance of positive outcomes. Greater precision in the articulation of the problem, including the hypothesised causal mechanisms contributing to its occurrence, allows greater rigor in the development of the treatment, and likely greater chances of positive outcomes.