Semra Ulusoy Kaymak

The aim of this study was to determine whether there was any relationship between hippocampal volume, and glucocorticoid regulation, and cognitive dysfunctions in drug-naïve major depressive disorder (MDD) patients during their first episode. Twenty drug-free female MDD patients in their first episode and 15 healthy females as control subjects were included in the study. All subjects underwent 3.0 Tesla (T) magnetic resonance imaging (MRI), comprehensive neuropsychological testing and dexamethasone suppression tests (DST). The volumes of the right and left hippocampus of the patients were found to be significantly smaller than those of the controls. Patients were found to have significantly lower scores on measures of attention, working memory, psychomotor speed, executive functions, and visual and verbal memory fields. The performance of the patients only in the recollection memory and memory of reward-associated rules were positively correlated with hippocampal volumes. The volumes of the left and right hippocampus did not correlate with basal or post-dexamethasone cortisol levels. Our findings indicate that depressed patients have smaller hippocampi even in the earlier phase of their illness. Further research efforts are needed to explain the mechanisms that are responsible for the small hippocampus in depressed patients.

Aim:  Recent neuroimaging studies support functional and structural alterations in the dorsolateral prefrontal cortex (DLPFC), particularly on the left side in patients with major depressive disorders (MDD). The aim of the present study was to examine the biochemical characteristics of left DLPFC as measured on proton (¹H) magnetic resonance spectroscopy (MRS) in patients with drug‐naïve first‐episode MDD and a healthy control group. A second aim was to assess the effect of antidepressant treatment on the metabolites of DLPFC.Methods:  Short‐echo single‐voxel ¹H‐MRS was done for the left DLPFC in 17 female drug‐free MDD patients (mean age ± SD, 30.9 ± 6.9 years) and 13 matched control subjects (mean age ± SD, 29.1 ± 6.2 years) and was repeated at 8 weeks following antidepressant treatment.Results:  Comparison of baseline values indicated that there were no significant differences in any of the metabolite ratios (N‐acetyl aspartate/creatine [NAA/Cr], myoinositol [Ino]/Cr, and choline [Cho]/Cr) between patients and controls. Significant differences were detected between pre‐ and post‐treatment Ino/Cr ratios (0.67 ± 0.13, 0.58 ± 0.22, P = 0.032, respectively), although there was no difference in NAA/Cr and Cho/Cr ratios.Conclusion:  Although no significant metabolic alterations exist in female patients with drug‐naïve first‐episode MDD as evaluated on ¹H‐MRS, an increase in Ino/Cr was observed following 8‐week antidepressant treatment. These findings give rise to the possibility that non‐neuronal cells, particularly glial cells that are probably damaged, play a role in the action of antidepressant treatment.