Evaluation of a Cognitive Therapy (Inference-based-therapy) for the Treatment of Obsessional Compulsive Disorder

Obsessional compulsive disorder (OCD) is a very debilitating psychiatric problem which affects around one million Canadians and their families. Obsessions are intense preoccupations about bad, harmful, dangerous, shocking or unlucky events which 'may' occur and which drive sufferers to perform time consuming and distressing compulsive rituals to prevent the possible event occurring. The current psychological treatment of choice is cognitive behavior (CBT) therapy which focuses on treating OCD by reducing obsessional anxiety about the likelihood and the consequences of the preoccupying event. A rival cognitive model termed the inference-based therapy (IBT), developed by the principal investigator and co-workers, considers that the OCD begins with the initial doubting inference 'maybe something is wrong' and focuses on changing the reasoning behind this doubting inference which often trumps the common sense conviction that there is no reason to doubt. This clinical trial randomly allocates participants to either IBT or CBT treatment condition or to a third generic mindfulness condition. The latter condition is a non-specific meditational-based training which has shown evidence of reducing stress and anxiety across a number of psychiatric problems including OCD. Two hundred and forty people will be recruited over a 5-year period from two principal sites (Montreal and Gatineau/Ottawa) with which the principal investigator and co-investigators have clinical links. Therapy will be administered by trained professionals following a treatment manual specific to each approach. The therapy will last a maximum of six months or until the point when the person achieves a non-clinical status. The patients will be assessed pre, post, and at six months following treatment on standard evaluation instruments as well as on subjective measures. We expect the IBT to be superior in terms of number of participants responding to treatment, rapidity of improvement and gains at follow-up.