Do all roads lead to Rome? A qualitative process evaluation of two types of group-based Behavioural Activation...

Approximately 1 in 3 acquired brain injury (ABI) survivors have post-ABI depression. Behavioural Activation (BA), an intervention that encourages engagement in positively reinforcing activities, shows promise. We conducted a process evaluation of two group-based BA interventions in ABI. Adults (≥18 years) recruited from ABI services, charities, and self-referral were randomized to receive either "Traditional" BA (scheduling positive activities combined with cognitive management strategies) or "Experiential" BA (completing positive activities within-session only), delivered once weekly over eight weeks. N = 49 participants completed interviews on perceived processes linked to mood and activity changes and any associated benefits (Traditional BA n = 25, Experiential BA n = 24). A positive therapeutic milieu, a sense of group cohesion, and sharing ABI-related experiences were viewed to foster psychological safety, reduce social isolation, and underlie mood/activity improvements in both groups. Traditional BA processes included developing skillsets in coping with low mood, avoidance and cognitive barriers to activities, aligning activities to values, and challenging negative thinking patterns. Experiential BA processes included in-session enjoyment, enhanced present-mindedness, and having choice and control in selecting within-session activities. Positive group processes may enhance outcomes in group-based BA in ABI. Differing group-based BA methods in ABI may have separate underlying mechanisms that should be maximized.Trial Registration: Clinicaltrials.gov, NCT03874650. Protocol version 2.3, May 26th, 2020.