Manualised Individual Cognitive Behavioural Therapy for mood disorders in people with mild to moderate intellectual disability: a feasibility randomised controlled trial.

Background: Evaluation of complex interventions, including standardisation of the intervention, types of outcomes selected and measures of change, is a fairly novel concept in the field of intellectual disabilities. Our aim was to explore these issues in a feasibility study of Manualised Individual Cognitive Behaviour Treatment (M-iCBT) compared to the treatment as usual alone (TAU).

Methods: Service users with mild to moderate intellectual disability experiencing a mood disorder or symptoms of depression and/or anxiety (mini PAS-ADD total score >10 or 7 respectively) were randomly assigned to either.

Results: In total, 32 participants were randomly assigned to 16 sessions of M-iCBT (n=16) in addition to TAU or TAU alone (n=16). We explored recruitment and accrual rates, willingness to participate, acceptability of the intervention and suitability of assessment tools. Mean change (95% CI) in the Beck Depression Inventory-Youth (BDI-Y) score from baseline to the 16 week endpoint (primary variable) was 0.10 (95% CI: -8.56, 8.76) and in the Beck Anxiety Inventory-Youth (BAI-Y) 2.42 (95% CI: -5.27, 10.12) in favour of TAU. However, there was a clear trend in favour of CBT in depressed participants with or without anxiety.

Limitations: The intervention targeted both depression and anxiety following a transdiagnostic model. This may have impacted the anticipated size of change in the primary outcome. The precise impact of cognitive limitations on ability to use therapy effectively is not fully understood.

Conclusions: This study demonstrates that it is feasible to carry out a pragmatic randomised controlled trial of M-iCBT for people with mild to moderate intellectual disability. However, uncertainties about its clinical and cost effectiveness can only be fully answered by further examination of its superiority against other treatments.