Literature emphasises the importance of identifying and intervening in the adoption of unhealthy lifestyle behaviours (ULBs) during adolescence at an early stage, to mitigate their long-term detrimental effects. Among the possible associated factors contributing to ULBs, attention-deficit hyperactivity disorder (ADHD) has been shown to play an important role. However, little is known about ADHD subclinical manifestations.

The present study aimed to bridge the gap in the literature and shed light on the relationship between subclinical ADHD and early adoption of ULBs during adolescence. Through a clinimetric approach, prevalence of ULBs, severity of ADHD symptoms and psychosocial factors (i.e. allostatic overload, abnormal illness behaviour, quality of life, psychological well-being) were investigated among adolescents. The associations between different degrees of ADHD, ULBs and psychosocial factors were also explored.

This multicentre cross-sectional study involved 440 adolescents (54.5% females; mean age 14.21 years) from six upper secondary schools. Participants completed self-report questionnaires on sociodemographic characteristics, ULBs, ADHD symptoms and psychosocial factors.

The most common ULBs were energy drinks/alcohol consumption and problematic smartphone use. Of the sample, 22% showed subclinical ADHD and 20.2% showed clinical ADHD. The subclinical ADHD group showed several ULBs (i.e. altered mindful eating, impaired quality of sleep, problematic technology use) and psychosocial factors, akin to those of ADHD group and different from peers without ADHD symptoms.

Since subclinical ADHD manifestation is associated with ULBs, similarly to clinical ADHD, identifying subthreshold symptoms during adolescence is crucial, as it could improve health-related outcomes in adulthood across different domains.

A substantial proportion of patients receiving cognitive behavioural therapy (CBT) do not achieve remission, and drop-out is considerable. Motivational interviewing (MI) may influence non-response and drop-out. Previous research shows that MI as a pre-treatment to CBT produces moderate effects compared with CBT alone. Studies integrating MI with CBT (MI-CBT) are scarce.

To test the feasibility of MI-CBT in terms of therapist competence in MI and various participant measures, including recruitment and retention. In addition, separate preliminary evaluations were conducted, exploring the effects of CBT alone for anxiety disorders and depression, and of MI-CBT for anxiety disorders, depression and unhealthy lifestyle behaviours.

Using a randomised controlled parallel trial design, participants were recruited in routine psychiatric care and allocated to CBT alone or MI-CBT. Means in feasibility measures and within-condition Hedges’ g effect sizes in treatment outcome measures were calculated. Authors were not blind to treatment allocation, while independent raters were blind.

Seventy-three patients were assessed for eligibility, and 49 were included. Participant perceptions of treatment credibility, expectancy for improvement, and working alliance were similar for both conditions. Overall, effect sizes were large across outcome measures for both conditions, including anxiety and depressive symptoms and functional impairment. However, therapists did not acquire sufficient competence in MI and the drop-out rate was high.

MI-CBT proved feasible in some respects, but the present study did not support the progression to a randomised controlled trial designed to assess the effectiveness of MI-CBT. Additional pilot studies are needed.