Motivation and value influences in the relative balance of goal-directed and habitual behaviours in obsessive-compulsive disorder.

Our decisions are based on parallel and competing systems of goal-directed and habitual learning, systems which can be impaired in pathological behaviours. Here we focus on the influence of motivation and compare reward and loss outcomes in subjects with obsessive-compulsive disorder (OCD) on model-based goal-directed and model-free habitual behaviours using the two-step task. We further investigate the relationship with acquisition learning using a one-step probabilistic learning task. Forty-eight OCD subjects and 96 healthy volunteers were tested on a reward and 30 OCD subjects and 53 healthy volunteers on the loss version of the two-step task. Thirty-six OCD subjects and 72 healthy volunteers were also tested on a one-step reversal task. OCD subjects compared with healthy volunteers were less goal oriented (model-based) and more habitual (model-free) to reward outcomes with a shift towards greater model-based and lower habitual choices to loss outcomes. OCD subjects also had enhanced acquisition learning to loss outcomes on the one-step task, which correlated with goal-directed learning in the two-step task. OCD subjects had greater stay behaviours or perseveration in the one-step task irrespective of outcome. Compulsion severity was correlated with habitual learning in the reward condition. Obsession severity was correlated with greater switching after loss outcomes. In healthy volunteers, we further show that greater reward magnitudes are associated with a shift towards greater goal-directed learning further emphasizing the role of outcome salience. Our results highlight an important influence of motivation on learning processes in OCD and suggest that distinct clinical strategies based on valence may be warranted.

Disorders of compulsivity: a common bias towards learning habits.

Why do we repeat choices that we know are bad for us? Decision making is characterized by the parallel engagement of two distinct systems, goal-directed and habitual, thought to arise from two computational learning mechanisms, model-based and model-free. The habitual system is a candidate source of pathological fixedness. Using a decision task that measures the contribution to learning of either mechanism, we show a bias towards model-free (habit) acquisition in disorders involving both natural (binge eating) and artificial (methamphetamine) rewards, and obsessive-compulsive disorder. This favoring of model-free learning may underlie the repetitive behaviors that ultimately dominate in these disorders. Further, we show that the habit formation bias is associated with lower gray matter volumes in caudate and medial orbitofrontal cortex. Our findings suggest that the dysfunction in a common neurocomputational mechanism may underlie diverse disorders involving compulsion.

Long-term efficacy of Internet-based cognitive behavior therapy for obsessive-compulsive disorder with or without booster: a randomized controlled trial.

BACKGROUND: As relapse after completed cognitive behavior therapy (CBT) for obsessive-compulsive disorder (OCD) is common, many treatment protocols include booster programs to improve the long-term effects. However, the effects of booster programs are not well studied. In this study, we investigated the long-term efficacy of Internet-based CBT (ICBT) with therapist support for OCD with or without an Internet-based booster program. METHOD: A total of 101 participants were included in the long-term follow-up analysis of ICBT. Of these, 93 were randomized to a booster program or no booster program. Outcome assessments were collected at 4, 7, 12 and 24 months after receiving ICBT. RESULTS: The entire sample had sustained long-term effects from pre-treatment to all follow-up assessments, with large within-group effect sizes (Cohen's d = 1.58-2.09). The booster group had a significant mean reduction in OCD symptoms compared to the control condition from booster baseline (4 months) to 7 months, but not at 12 or 24 months. Participants in the booster group improved significantly in terms of general functioning at 7, 12 and 24 months, and had fewer relapses. Kaplan-Meier analysis also indicated a significantly slower relapse rate in the booster group. CONCLUSIONS: The results suggest that ICBT has sustained long-term effects and that adding an Internet-based booster program can further improve long-term outcome and prevent relapse for some OCD patients.

Internet-based cognitive behaviour therapy for obsessive-compulsive disorder: a randomized controlled trial.

BACKGROUND: Cognitive behaviour therapy (CBT) is an effective treatment for obsessive-compulsive disorder (OCD) but access to CBT is limited. Internet-based CBT (ICBT) with therapist support is potentially a more accessible treatment. There are no randomized controlled trials testing ICBT for OCD. The aim of this study was to investigate the efficacy of ICBT for OCD in a randomized controlled trial. METHOD: Participants (n=101) diagnosed with OCD were randomized to either 10 weeks of ICBT or to an attention control condition, consisting of online supportive therapy. The primary outcome measure was the Yale-Brown Obsessive Compulsive Scale (YBOCS) administered by blinded assessors. RESULTS: Both treatments lead to significant improvements in OCD symptoms, but ICBT resulted in larger improvements than the control condition on the YBOCS, with a significant between-group effect size (Cohen's d) of 1.12 (95% CI 0.69-1.53) at post-treatment. The proportion of participants showing clinically significant improvement was 60% (95% CI 46-72) in the ICBT group compared to 6% (95% CI 1-17) in the control condition. The results were sustained at follow-up. CONCLUSIONS: ICBT is an efficacious treatment for OCD that could substantially increase access to CBT for OCD patients. Replication studies are warranted.