A pilot study examining whether restricting and resuming specific actions systematically changes symptoms of depression and anxiety. A series of N-of-1 trials.

Anxiety and depressive disorders are highly prevalent and a leading cause of disability. Understanding how symptoms develop could lead to new preventive and clinical interventions. This pilot study examined whether systematically restricting specific behaviours (target actions) associated with good psychological health would increase psychological symptoms in healthy participants, and whether resuming those actions would reduce symptoms to baseline levels. Twelve adults participated in a series of N-of-1 trials comprising baseline (A), restriction (B) and recovery (C) phases. Outcomes were assessed weekly using measures of depression (PHQ-9), anxiety (GAD-7), and a validated 15-item measure of target actions (Big 5). Symptoms of depression and anxiety increased significantly from Phase A to Phase B and returned to baseline by the end of Phase C. Increased symptoms during Phase B were only observed in participants who restricted actions by more than 25%. Symptom increases were evident within 2 weeks of restriction, but most participants appeared to take longer to recover to baseline levels. This study demonstrates that reducing the frequency of specific actions may increase symptoms of anxiety and depression, which is reversed when those actions are resumed. This contributes to our understanding of the aetiology, maintenance, and recovery from depression, anxiety, and possibly other disorders.