A clue to the neuroanatomy of obsessive-compulsive personality disorder may lay in abnormal hippocampal or amygdalar structures, according to a new observational imaging study.
MRI showed that the right and left volumes of the hippocampus and amygdala are smaller in patients with obsessive-compulsive personality disorder than in healthy controls, researchers found.
These findings lend support to the likelihood that obsessive-compulsive personality disorder “seems to be a neurocognitive function disorder rather than a personality disorder,” Mehmet Gurkan Gurok, of Firat University, Elazig, Turkey, and his associates reported in the.
The authors previously had investigated volumes of hippocampus and amygdala in patients with obsessive-compulsive disorder and found these patients had “increased white matter volumes, greater left and right thalamus volumes and significantly reduced left and right orbitofrontal cortex volumes, compared with healthy controls.”
For this study, they similarly used MRI to assess hippocampal and amygdalar volumes in 16 patients with obsessive-compulsive personality disorder (inpatients and outpatients at Firat University) and in 18 healthy controls – matched for age, sex, education, and handedness – who were studying at the hospital.
The researchers used the DSM-IV and thefor diagnoses but noted later in their limitations that “the validity of diagnosis should be questioned” for personality disorders.
Participants were excluded if they had a comorbid Axis I psychiatric diagnosis besides depression, any contraindications for MRI, history of alcohol or substance dependence within the previous 6 months, use of psychoactive medications within 4 weeks of the study, or any current severe medical conditions. In addition, neither controls nor their first-degree relatives had a history of psychiatric disorders.
The findings showed that those with obsessive-compulsive personality disorder had smaller volumes on both sides of the hippocampus, compared with healthy controls. Amygdalar volume on both the left and right sides were similarly smaller in patients with obsessive-compulsive personality disorder, compared with healthy controls (left, P = .001; right, P = .002). The authors also reported they “did not find any correlation between hippocampus and amygdala volumes and any clinical and demographic variables.”
The research was funded by Firat University. The authors reported having no conflicts of interest.