Reduced thickness of anterior cingulate cortex in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is characterized by a pattern of repetitive, intrusive thoughts and behaviours that patients do not want to but feel they have to perform. Functional brain imaging revealed dysfunctional pathways in OCD involving the anterior cingulate cortex (ACC), orbitofrontal cortex (OFC), and basal ganglia. Structural alterations in OCD have been discussed but analysis tools focussing on specific morphometric aspects such as cortical thickness have rarely been employed.

We acquired MRI scans from 101 OCD patients and 95 healthy control subjects. FreeSurfer analysis software was employed to model the individual grey-white and pial surfaces to compute cortical thickness as our target measure.

Relative to controls, OCD patients demonstrate cortical thinning in dorsal and subgenual ACC (false discovery rate corrected at p < .001), as well as in several other regions within the fronto-parietal network (false discovery rate corrected at p < .05). Cortical thickness could not be predicted in whole brain analyses from symptom state, but there was a modest correlation of left dorsal ACC thickness with the obsession subscore of the Yale-Brown Obsessive-Compulsive Scale as well as with the Beck Depression Inventory score.

The findings confirm and extend previous reports showing that OCD is associated with morphometric alterations. The location of the most robust cortical thinning in ACC regions matches the previously reported topography of functional alterations at resting state and during cognitive task execution.