Reduced prefrontal gyrification in obsessive-compulsive disorder

Abstract

Structural magnetic resonance imaging (MRI) studies reveal evidence for brain abnormalities in obsessive-compulsive disorder (OCD), for instance, reduction of gray matter volume in the prefrontal cortex. Disturbances of gyrification in the prefrontal cortex have been described several times in schizophrenia pointing to a neurodevelopmental etiology, while gyrification has not been studied so far in OCD patients. In 26 OCD patients and 38 healthy control subjects MR-imaging was performed. Prefrontal cortical folding (gyrification) was measured bilaterally by an automated version of the automated-gyrification index (A-GI), a ratio reflecting the extent of folding, from the slice containing the inner genu of the corpus callosum up to the frontal pole. Analysis of covariance (ANCOVA, independent factor diagnosis, covariates age, duration of education) demonstrated that compared with control subjects, patients with OCD displayed a significantly reduced A-GI in the left hemisphere (p = 0.021) and a trend for a decreased A-GI in the right hemisphere (p = 0.076). Significant correlations between prefrontal lobe volume and A-GI were only observed in controls, but not in OCD patients. In conclusion, prefrontal hypogyrification in OCD patients may be a structural correlate of the impairment in executive function of this patient group and may point to a neurodevelopmental origin of this disease.

Fig. 1

a Automated GI—inner contour legend: A-GI total inner contour trace on a coronal slice of a control subject. Colors: blue exposed inner contour right; green exposed inner contour left: yellow buried inners. A-GI automated gyrification index. b Automated GI—outer contour legend: A-GI total outer contour trace on a coronal slice of a control subject; inner contours overlaid with smoothed outer and IFH trace in red. A-GI automated gyrification index; IFH interhemisphere fissure

Fig. 2

Relationship between prefrontal GI and age legend: correlation between left and right prefrontal GI and age. GI gyrification index