A three-arm randomised controlled trial comparing ultra-low intensity interventions for gratitude vs. things you do vs. waitlist control for depression and anxiety in health professionals

Background: Ultra-low-intensity interventions using regular SMS or emails can reduce symptoms of anxiety and depression. However, limited research has examined whether some nudged actions are more beneficial than others. Aims: The primary aim was to compare the relative benefits of SMS nudges prompting five groups of actions called the Things You Do (TYD) with nudges prompting gratitude practice. The secondary aim was to examine mechanisms of change. Methods: 305 Australian health professionals were randomly allocated to a TYD group, a gratitude group (GRAT), or a waitlist control (WL). TYD and GRAT participants first read a brief online lesson on the benefits of their respective actions, then received weekday SMS prompts for four weeks. WL participants maintained usual routines. Primary outcomes were depression (PHQ-2) and anxiety (GAD-2) symptoms. Secondary and tertiary outcomes were satisfaction with life (SWLS), gratitude (GRAT-6), frequency of TYD actions (TYDQ-15), and perceived changes in mental wellbeing, measured at mid-treatment, post-trial (week 5), and 3-month follow-up. Results: Both TYD and GRAT participants reported significantly lower PHQ-2 and GAD-2 scores and higher SWLS, GRAT-6, and TYDQ-15 scores at post-trial compared with WL, with no significant differences between active groups. Gains were sustained at follow-up. Improvements in depression symptoms were strongly associated with changes in TYD actions, although were also related to changes in gratitude. Improvements in anxiety were only associated with changes in TYD actions. Conclusion: These findings show a strong relationship between the frequency of certain actions and mental wellbeing and how symptoms of depression and anxiety can be reduced by nudging these actions. These findings also suggest that these actions may be activated by different interventions. This study demonstrates the potential of scalable, ultra-low-intensity interventions to support mental health in demanding professional roles.