Fifteen patients recruited from the psychiatric in or outpatient’s clinic, at the Firat University School of Medicine Department of Psychiatry in Elazig, and eighteen healthy controls who were all right handed, and had a mean age of 28.1 ± 3.4 and 30.6 ± 4.2 years, respectively, were the subjects of this study. Normal volunteers were recruited from the hospital staff. Diagnoses were made by using the Structured Clinical Interview for DSM-IV (SCID) [4]. Ratings of obsessive and compulsive symptoms, and depressive signs were ascertained using the Yale-Brown Obsession Compulsion Scale (Y-BOCS) and Hamilton Depression Rating Scale (HDRS), respectively. This study was carried out under guidelines of Helsinki Declaration. Written informed consent was obtained from all subjects. The exclusion criteria consisting of the presence of any current comorbid psychiatric disorder, current severe medical problems, problems that prevent suffering from MRI investigation, presence of any neurological disease, any worry about willingness to participate in the study procedures, expressed by providing written informed consent after complete description of the study, or alcohol/substance abuse within the 6 months preceding the study. Of the patients, one had lifetime history of major depressive disorder, and one had simple phobia. On the other hand, some criteria were administered to the healthy control subjects. For inclusion in the study, healthy subjects had to meet the following inclusion criteria: Not having DSM-IV Axis I disorders in self or in a first-degree relative, as determined by the SCID non-patient version, no current or previous history of medical problems, neurologic or psychiatric disorders, no previous history of severe mental retardation, alcoholism and drug dependence or abuse in the last 6 months, and willingness to participate in the study procedures, expressed by providing written informed consent after complete description of the study. If the patients and healthy control subjects fulfilled the inclusion criteria, they were asked to participate in the study.

Briefly, MRI and ¹H-MRSI scans were acquired using a GE Signa Excite 1.5 T whole body scanner (GE Medical Systems, Milwaukee, Wisconsin), with the following values (repetition time [TR] = 2000 ms, echo time [TE] = 15.6 ms, field of view [FOV] = 240 mm, flip angle = 20⁰, bandwidth = 20.8, slice thickness = 2.4 mm, echo spacing = 15.6 ms, 8 echoes, resolution = 0.9375 × 0.9375 × 2.4 mm).

We investigated following neurochemical markers; NAA, CRE, and CHO. For all voxels, NAA, CHO, and CRE peaks were determined automatically. Position of hippocampal voxels and sample magnetic resonance spectrum are presented in Figure 1.

In addition to ¹H-MRSI scans, hippocampus of the patients and healthy controls were structurally measured. In the tracings of the hippocampus, it was benefited from standard anatomic atlases [5-7] and from Caetano et al. [8] and Brambilla et al. [9]. As described earlier [2], for the tracing of hippocampus, the process was started on the coronal slice at the point that the superior colliculus

completely connected with the thalamus and finished one slice before the mammilary bodies appeared. The lateral border was accepted as the inferior horn of the lateral ventricle. As the superior border of the hippocampus, the corona radiata and ambient cistern were accepted. The inferior border was selected as the white matter.

The statistical analyses were performed using SPSS version 13.0 (SPSS, Chicago, IL). Independent t test was used to assess differences in the volumes of hippocampus, whole brain, metabolite values, and some demographical data. Correlation analyses between volume measurements and clinical and demographic variables were carried out by means of Pearson’s correlation coefficients. For the camparisons of each metabolite ratio, NAA/CRE, NAA/ CHO, and CHO/CRE, independent t test was used. The criterion of significance level was set at p < 0.05.