After conducting a meta-analysis of data from functional MRI studies, researchers found that patients with obsessive-compulsive disorder showed hyperactivation in certain regions of the brain during error-processing and hypoactivation in other regions during inhibitory control when compared with healthy controls.
This suggests that patients with OCD become stuck in compulsive “loops” because detected, flawed OCD behaviors are uncorrected by inhibitory control networks, according to the authors of the study published in Biological Psychiatry.
Although previous functional MRI studies report brain activation abnormalities in patients with OCD during both error-processing and inhibitory control processing, the data are limited due to small sample sizes, Luke J. Norman, PhD, postdoctoral research fellow in the department of psychiatry at University of Michigan, and colleagues wrote.
“No one knows exactly what drives people with OCD to perform unnecessary and repetitive checking, cleaning and other ritualistic behaviors, even when they’re fully aware that the behaviors don’t make sense,” Norman told Healio.com/Psychiatry. “Individual brain imaging studies are often too small to produce consistent findings, which leads to a confusing picture and stymies the translation of science to treatments. Some research groups show patients with OCD show hyperactive brain response to errors, while others show deficits of brain response to stop signals.”
Researchers conducted a large-scale meta-analysis of the existing literature using unthresholded t-maps from studies comparing patients with OCD with healthy controls during error-processing and inhibitory control. The studies included data from 239 patients with OCD and 231 healthy controls in the error-processing analysis, and 245 patients with OCD and 239 controls in the inhibitory control analysis.
“By pooling together data from many different teams around the world, we were able to examine a much larger data set to show that separate theories about abnormal error and stopping functions in the OCD brain are both relevant and actually fit together,” Norman said.
Compared with healthy controls, patients with OCD showed impaired inhibitory control as determined by reaction time measures (SMD = 0.2; 95% CI, 0.016-0.393) and more inhibitory control errors (SMD = 0.22; 95% CI, 0.039-0.399).
“The study is exciting because it suggests that OCD patients may have an ‘inefficient’ linkage between the brain system that links their ability to recognize errors and the system that governs their ability to do something about those errors,” Norman told Healio.com/Psychiatry. “That could lead their over-reaction to errors to overwhelm their under-powered ability to tell themselves to stop.”
During error processing, patients with OCD demonstrated hyperactivation in bilateral dorsal anterior cingulate cortex, supplementary motor area (SMA), pre-SMA, right anterior insula/frontal operculum and anterior lateral prefrontal cortex regions of the brain. Patients with OCD also showed hypoactivation during inhibitory control in rostral and ventral anterior cingulate cortex, bilateral thalamus/caudate and parietal lobe, right anterior insula/frontal operculum and medial orbitofrontal cortex, compared with healthy controls.
“More and more, we are beginning to understand that OCD is in fact a brain-based disorder with reliable cross-modal abnormalities in cingulo-opercular and orbito-striato-thalamic brain networks,” Norman said. “This study sets the stage for therapy targets in OCD, because it shows that error processing and inhibitory control are both important processes that are altered in people with the condition. For instance, repetitive transcranial magnetic stimulation was recently approved by the FDA to treat OCD.” – by Savannah Demko
Disclosure: Norman reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.