Altered prefrontal suppression of striatal activity during intrusive images in obsessive-compulsive disorder.

Background

Current models of obsessive-compulsive disorder (OCD) emphasize dysfunction in frontostriatal circuits that support flexible behavioral control, leading to impulsive and compulsive actions. However, how these disruptions contribute to obsessions and intrusive thoughts remains poorly understood. Clarifying these mechanisms is essential for understanding cognitive control deficits in OCD.

Method

We examined intrusive memories elicited by emotional and neutral scenes in individuals with OCD (N = 24) and healthy controls (N = 21). Participants learned scene-cue associations and were later instructed to suppress memory retrieval when presented with reminder cues. Functional magnetic resonance imaging (fMRI) measured neural activity during suppression. Generalization of findings with alternative materials was assessed in larger samples of healthy controls (N = 73) and individuals with post-traumatic stress disorder (PTSD; N = 55).

Results

fMRI analyses showed preserved activity in frontoparietal, basal ganglia, and limbic regions in individuals with OCD, even during emotional intrusion suppression. However, unlike healthy controls, individuals with OCD failed to suppress striatal activity during intrusive memory, regardless of emotional content. Connectivity analyses indicated that this hyperactivity reflected reduced top-down inhibitory control, a disruption associated with greater obsessive symptom severity. Test of generalizability confirmed the role of frontostriatal downregulation in controlling intrusive thoughts and showed that this alteration was specific to OCD.

Conclusions

These findings emphasize the central role of frontostriatal circuits in regulating intrusive thinking. Obsessions in OCD may result from disrupted inhibitory mechanisms that normally restrict access to striatal-dependent information, contributing to persistent intrusive thoughts.