Functional cognitive disorder is an increasingly recognised subtype of functional neurological disorder for which treatment options are currently limited. We have developed a brief online group acceptance and commitment therapy (ACT)-based intervention.

To assess the feasibility of conducting a randomised controlled trial of this intervention versus treatment as usual (TAU).

The study was a parallel-group, single-blind randomised controlled trial, with participants recruited from cognitive neurology, neuropsychiatry and memory clinics in London. Participants were randomised into two groups: ACT + TAU or TAU alone. Feasibility was assessed on the basis of recruitment and retention rates, the acceptability of the intervention, and signal of efficacy on the primary outcome measure (Acceptance and Action Questionnaire II (AAQ-II)) score, although the study was not powered to demonstrate this statistically. Outcome measures were collected at baseline and at 2, 4 and 6 months post-intervention, including assessments of quality of life, memory, anxiety, depression and healthcare use.

We randomised 44 participants, with a participation rate of 51.1% (95% CI 40.8–61.5%); 36% of referred participants declined involvement, but retention was high, with 81.8% of ACT participants attending at least four sessions, and 64.3% of ACT participants reported being ‘satisfied’ or ‘very satisfied’ compared with 0% in the TAU group. Psychological flexibility as measured using the AAQ-II showed a trend towards modest improvement in the ACT group at 6 months. Other measures (quality of life, mood, memory satisfaction) also demonstrated small to modest positive trends.

It has proven feasible to conduct a randomised controlled trial of ACT versus TAU.