This protocol describes the Parent Anxiety Transmission and Habits (PATH) randomized controlled trial, which will test whether experimentally altering parent interpretation bias reduces anxiety-promoting parenting behaviours and, in turn, improves child interpretation bias in children aged 7–12. The study will randomize 300 parents to either a smartphone app-delivered interpretation bias manipulation or a self-assessment control and follow parent–child dyads with multimodal assessments over a 3-month period.
The specific aims are: (1) to manipulate parent interpretation bias and test effects on parent behaviour; (2) to test effects of parent interpretation bias manipulation on child interpretation bias; and (3) to evaluate moderators such as parent sex, race and ethnicity, parent anxiety, child age and child sex to refine models of intergenerational transmission and inform personalised interventions.
The central hypothesis is that parents assigned to the interpretation bias manipulation will show fewer anxiety-promoting parenting behaviours than the control group, and that their children will show improved interpretation bias. The protocol specifies mediation analyses to test whether reductions in anxiety-promoting parenting behaviours mediate the relationship between changes in parent interpretation bias and child interpretation bias.
Moderator hypotheses include: stronger effects of interpretation bias manipulation on parent behaviour among parents with higher baseline anxiety, and stronger child interpretation bias effects in father–child dyads compared with mother–child dyads.
Planned statistical approaches include hierarchical linear modelling to compare trajectories between arms and mediation models (with longitudinal mixed-effects estimates) to evaluate indirect effects. Power and simulation-based methods informed sample size selection (see below).
This is a parallel-group randomized trial with two arms. A total of 300 parents will be randomized to either:
HabitWorks (HW) app interpretation bias manipulation (HW condition): an intervention version of the Word Sentence Association Paradigm (WSAP) delivered via the HW smartphone app. Each exercise presents a brief sequence (fixation, priming word reflecting benign or threatening interpretation, an ambiguous sentence) and asks participants to judge relatedness; corrective feedback encourages benign interpretations. Exercises contain 50 trials (~5 minutes) and parents are prompted to complete three exercises per week for 4 weeks (12 total exercises). Stimuli are personalized via demographic and anxiety/worry domain checklists.
Self-assessment control condition: parents complete control tasks and assessments (details of the control content were described in the source as a self-assessment control; specific control task content beyond this designation was not further reported in the source).
Parents and children will complete a series of assessments across 3 months, including baseline, intervention-period, post-intervention and follow-up measures.
Primary proximal outcome: anxiety-promoting parenting behaviours, assessed via self-report, interview, behavioural tasks and daily diary measures across the 3-month period.
Secondary distal outcome: child interpretation bias, measured with child-appropriate cognitive tasks and assessments. Both parent and child measures include self-report instruments, structured interviews, and observed behavioural tasks.
The study’s assessment strategy is comprehensive and multimodal to capture proximal changes in parenting behaviour and downstream changes in child cognitive bias. Specific named instruments in the protocol include the WSAP for parent interpretation bias and the Generalised Anxiety Disorder-7 (GAD-7) for parent anxiety screening; further instrument names and details are provided in the source protocol.
Sample size was determined by Monte Carlo simulations for mediation analyses. Using published effect sizes for the hypothesised paths and simulating longitudinal data, investigators estimated that at least 283 participants are required to achieve 80% power (alpha = 0.05). The protocol therefore targets N=300 to account for dropout.
Moderator analyses depend on subgroup distributions. To improve power for moderator tests, the study aims to recruit at least 30% fathers and 30% parents of colour. Recruitment sources include institutional recruitment platforms, medical records, social media, ResearchMatch, community partnerships, flyers and in-person events.
Recruitment began in July 2023 and will continue through December 2027 according to the protocol.
Key inclusion criteria for parents: age 18+, Massachusetts residency, fluent in English, shared or full custody of the child, ownership of an iOS or Android smartphone, at least mild anxiety symptoms (GAD-7 ≥5), at least a mild level of interpretation bias (WSAP accuracy below the healthy norm of 70%), no recent mania or psychosis history as specified, stable mental health treatment for at least 8 weeks, and no active suicidal ideation or behaviours within the past month. Parents who previously participated in the study team's parent interpretation bias trials are excluded.
Key inclusion criteria for children: age 7–12, no intellectual disability or autism that would prevent assent or task completion per parent/clinician report, and a Wechsler Abbreviated Scale of Intelligence, Second Edition two-subtest Full-Scale IQ estimate of ≥80 to ensure comprehension of procedures.
All procedures were approved by the Mass General Brigham Institutional Review Board (2022P003245). Parents provide written electronic consent and verbal consent; children provide verbal assent.
The primary analytic approach will compare parent behaviour trajectories between arms using hierarchical linear models. Child interpretation bias trajectories will be compared similarly. Mediation models will test whether change in anxiety-promoting parenting behaviours mediates the association between parent interpretation bias manipulation and child interpretation bias outcomes. Moderator analyses will probe interactions with parent sex, race/ethnicity, baseline parent anxiety, child age and child sex.
Power simulations incorporated expected effect sizes for X→M, X→Y and M→Y paths; the sample size and targeted subgroup proportions were chosen to provide reasonable power for moderator tests assuming subgroup proportions of at least ~30% for under-represented groups.
Strengths highlighted in the protocol include: a comprehensive multimethod assessment strategy (self-report, daily diary, behavioural task and interview measures), an accessible smartphone-delivered intervention to manipulate interpretation bias, and intentional recruitment to reflect the US population including fathers.
Limitations include the short-term nature of the study — it can only test impacts of interpretation bias on parenting behaviours in the short term and cannot assess durability beyond 1 month — and limited generalisability outside the child age range of 7–12 years.
Ethics approval was obtained from Mass General Brigham IRB (2022P003245). The protocol states plans to disseminate results via scientific publications, conferences, hospital lectures, press releases and public-facing blogs.
The trial is registered as NCT05665491. Results will be shared with scientific and clinical communities and the public through peer-reviewed journals, national conferences, institutional lectures, press materials and blog posts. The article is published under a Creative Commons Attribution Non-Commercial license, and recruitment and study procedures are ongoing per the protocol.