Differential effects of escitalopram challenge on disgust processing in obsessive-compulsive disorder

Literature on the ability of patients with obsessive-compulsive disorder (OCD) to recognize static facial expressions of disgust is not consistent. We aimed to investigate whether OCD is associated with deficits in the recognition of disgust in a dynamic task, and if so, whether the acute administration of the selective serotonin reuptake inhibitor (SSRI) escitalopram would result in the normalization of such deficits.

OCD patients (n=20) and matched healthy controls (n=20) received a single dose of escitalopram 20mg on one day, and a single dose of placebo on another day, in randomized order, under double-blind conditions. Accuracy (i.e. the percentage of correct answers) and sensitivity to disgust stimuli (defined as the lowest level of emotional intensity expressed on the photo image after which no errors were made in the recognition of disgust for subsequent trials of increasing intensity) were compared in OCD patients and controls, with a repeated measures analysis of variance using a mixed model approach.

On placebo, the accuracy of, and sensitivity to, disgust stimuli were similar across groups. OCD patients had more accurate and more sensitive recognition of disgust after acute SSRI administration than after placebo, while controls had less accurate recognition and less sensitive recognition of disgust after acute SSRI administration than after placebo.

The use of a dynamic facial recognition task demonstrated altered responses to disgust in OCD patients compared to healthy controls after a pharmacological challenge with escitalopram. These findings suggest that the serotonergic system plays a role in disgust recognition.