This project was an empirical single-case experimental design (SCED) study conducted as part of a DClinPsy doctoral thesis completed by one of the researchers. The study used a brief and highly personalised psychological intervention for adolescents experiencing headaches. The aim was to understand how participants' real-time data could guide the personalised intervention provided to adolescents, including the development of skills to cope with headaches.

The study began with an initial assessment of adolescents' (n = 6-8) headache experiences. Following this, the researchers formulated an individualised diagram for each participant to identify central problem areas or problematic responses relevant to their headaches. Based on these formulations, the team delivered a brief personalised intervention focused on developing adaptive psychological skills and coping responses.

The intervention consisted of 4-5 weekly, 30-minute, one-to-one online sessions, targeting headache-related areas of concern. These sessions drew from established Cognitive Behavioural Therapy (CBT) and Acceptance and Commitment Therapy (ACT) interventions, both of which have previously been shown to reduce headache-related disability and improve functioning.

During data collection, adolescents were prompted to complete brief online questionnaires on their smartphones. The questionnaires were personalised to each participant and measured specific psychological processes that had been identified as target areas during the assessment and formulation stages. This personalised data collection approach was then used to analyse individual-level changes and to explore how these changes facilitated progress in areas identified as important to each adolescent (e.g., school involvement or extracurricular activities). The study also examined whether overall headache-related disability decreased and whether daily functioning improved following the completion of the intervention.

Paediatric primary headaches represent a highly common health condition, affecting more than 62% of children and adolescents globally. These headaches contribute substantially to difficulties in day-to-day functioning, including disruptions in academic engagement and participation in social or leisure activities. Adolescents also report reductions in overall quality of life associated with recurrent headaches.

Despite this significant burden, current psychological treatments demonstrate only small to medium effects in reducing headache-related impairment and improving quality of life. Progress in treatment efficacy has remained relatively limited. For example, although Cognitive Behavioural Therapy (CBT) is the recommended psychological approach for managing paediatric headaches, only around half of young people receiving CBT show meaningful improvements in disability and functional outcomes. This suggests that conventional delivery formats may not adequately address individual differences in needs and symptom patterns.

Personalised psychological interventions-those tailored to the specific goals, characteristics, and difficulties of each individual-offer a promising avenue for optimising treatment effectiveness in young people. Such approaches focus on personally meaningful targets and select therapeutic components that best support progress toward those targets. A recent systematic review aggregating data across multiple studies provides evidence that personalised interventions can enhance outcomes linked to personally defined goals. However, research examining personalised treatment approaches specifically within paediatric populations remains limited.

One emerging framework for delivering personalised care is Process-Based Therapy (PBT). PBT involves the ongoing identification and monitoring of the psychological, behavioural, and environmental processes that contribute to an adolescent's headaches-such as triggers, coping behaviours, contextual stressors, and emotional responses. This approach relies on regular, repeated data collection in adolescents' natural environments, which provides therapists with up-to-date information that can be used to guide treatment decisions. The 2012 NICE guidelines for headache management in individuals over 12 years old already recommend tracking headache severity, frequency, and duration with diaries, highlighting the value of continuous monitoring.

Within our study, this ongoing assessment-feedback loop enabled therapists to observe short-term changes, refine hypotheses about maintaining processes, and adjust intervention components accordingly (e.g., introducing emotional regulation strategies if data indicated high emotional reactivity during headache episodes).

PBT appears particularly suited to paediatric headache management, where adolescents often present with diverse symptom profiles and needs. Rather than constituting a new therapeutic model, PBT represents a shift in the delivery of therapy-emphasising the selection of targeted CBT-based strategies to influence key processes of change, rather than relying on standardised, protocol-driven, diagnosis-specific treatment packages.

A defining feature of PBT is the use of continuous data collection methods such as Ecological Momentary Assessment (EMA). EMA involves gathering brief, real-time information multiple times per week in adolescents' everyday environments, enabling accurate capture of their moment-to-moment experiences. In addition to providing rich data for clinical decision-making, EMA has been shown to enhance young people's insight, self-awareness, and ability to self-manage headache-related difficulties. In this study, EMA was used to collect weekly data, supporting both progress monitoring and the ongoing tailoring of interventions to each adolescent's specific needs.

Inclusion Criteria:

• Adolescents aged 12-18.
• Recurrent headaches occurring for 3 months or more, ideally (but not necessarily) diagnosed as a primary headache by a Neurologist.
• The headache should be deemed to be resulting from a primary headache disorder as opposed to a secondary symptom of another health condition.

No current or prior engagement with psychological support for headache for up to 6 months before screening.

• Experiencing at least minimal disability or interference from headaches (e.g. PedMIDAS score of greater than 10 points
• Adolescents and their caregiver fluent in speaking and writing in English.
• Frequent access to a smartphone with consistent internet access.

Exclusion Criteria:

• Aged younger than 12 or older than 18.
• Presence, history or suspicion of secondary headache disorder.
• Receiving psychological support for headaches or having prior engagement with psychological support for headaches up to 6 months before screening.
• An indication of a need for multisystemic therapies (e.g. a PedMIDAS score of 140)
• Diagnosis of pervasive developmental disorder or serious mental health difficulty (e.g., psychosis, active suicidal thoughts) as determined by the referrer.
• Adolescents living in families experiencing significant distress or psychosocial issues.
• Adolescents and their carer not fluent in speaking and writing in English.
• Limited access to a smartphone device with a consistent internet connection.

A fully anonymised dataset may become available for further analyses.