The involvement of distinct neural systems in patients with obsessive-compulsive disorder with autogenous and reactive obsessions.

OBJECTIVE

To investigate the regional metabolite abnormalities and changes after treatment in patients with OCD with autogenous and reactive obsessions.

METHOD

We assessed right anterior cingulate cortex (ACC) and amygdala-hippocampal region (Am + Hpp) N-acetyl-aspartate (NAA), choline (Cho) and creatine (Cr) concentrations and NAA/Cr and Cho/Cr ratios using single-voxel proton magnetic resonance spectroscopy in 15 patients with autogenous obsessions (OCD-A), 15 patients with reactive obsessions (OCD-R) and 15 healthy controls (HC). Measurements were repeated after 16 weeks of fluoxetine treatment.

RESULTS

Baseline ACC NAA/Cr ratios of both OCD groups were significantly lower than HC. OCD-A group had significantly lower baseline NAA/Cr ratios in the Am + Hpp than other groups. These differences were more likely to be explained by higher Cr levels in ACC. We found no significant differences and changes for Cho levels and Cho/Cr ratios between groups and within groups. Significant increase in NAA/Cr ratios of OCD-A group found in the Am + Hpp was more likely to be explained by increased NAA levels. No significant changes were found in ACC NAA/Cr ratios.

CONCLUSION

While disturbed energy metabolism in ACC might reflect a common pathology in patients with OCD regardless of symptom dimension, alterations in mesiotemporal lobe are more likely for autogenous obsessions.