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Abstract: This study uses surfaced-based morphometry to investigate cortical thinning and its functional correlates in patients with major depressive disorder (MDD). Subjects with MDD (N =36) and healthy control subjects (N =36) were enrolled in the study. Each subject received T1 structural magnetic resonance imaging (MRI), clinical evaluations, and neuropsychological examinations of executive functions with the Color Trail Test (CTT) and the Wisconsin Card Sorting Test (WCST). This study used an automated surface-based method (FreeSurfer) to measure cortical thickness and to generate the thickness maps for each subject. Statistical comparisons were performed using a general linear model. Compared with healthy controls, subjects with MDD showed the largest area of cortical thinning in the prefrontal cortex. This study also noted smaller areas of cortical thinning in the bilateral inferior parietal cortex, left middle temporal gyrus, left entorhinal cortex, left lingual cortex, and right postcentral gyrus. Regression analysis demonstrated cortical thinning in several frontoparietal regions, predicting worse executive performance measured by CTT 2, though the patterns of cortical thickness/executive performance correlation differed in healthy controls and MDD subjects. In conclusion, the results provide further evidence for the significant role of a prefrontal structural deficit and an aberrant structural/functional relationship in patients with MDD. [Copyright &y& Elsevier]

Abstract: In this study, short echo time 1H-magnetic resonance spectroscopy (MRS) was applied for quantification of neurometabolites using the LC Model algorithm in Taiwanese adolescents with attention-deficit hyperactivity disorder (ADHD). Proton magnetic resonance spectra were acquired bilaterally on the prefrontal area (part of the anterior cingulate gyrus and part of the medial frontal gyrus) in 15 adolescents with ADHD (average age of 13.88years) and 22 controls (average age of 14.85years). Absolute metabolite levels and ratios relative to creatine plus phosphocreatine (Cr+PCr) were obtained to be compared between groups. Results showed that adolescents with ADHD had significantly lower mean right prefrontal levels of Cr+PCr as compared with the controls. No significant differences between groups were noted in the remainder of the prefrontal metabolites. As for the group comparison of relative ratios, the N-acetylaspartate/Cr+PCr ratio was significantly higher in the right prefrontal regions of ADHD adolescents. This finding provides evidence of a right prefrontal neurochemical alteration in ADHD adolescents, which is consistent with current ADHD theory of prefrontal neuropathology with developmental mechanism. In addition, it highlights the importance of the method in interpretation of MRS findings in the context of ADHD. [Copyright &y& Elsevier]

Abstract: Numerous neuroimaging studies have suggested that obsessive–compulsive disorder (OCD) patients had a neurobiological abnormality in the frontal-subcortical circuits. On the other hand, there are distinct differences in the responses to pharmacological treatment among OCD patients. In the present study, we measured the concentration of N-acetyl aspartate (NAA), a putative marker of neuronal viability, with proton magnetic resonance spectroscopy (MRS) in OCD patients with different pharmacological responses. Participants comprised 20 patients and 26 healthy control subjects. OCD patients were divided into three groups according to the pharmacological response; responders to a selective serotonin reuptake inhibitor (SSRI) (group A: n =7), responders to SSRI with an atypical antipsychotic (group B: n =8) and non-responders to either SSRI or SSRI with an atypical antipsychotic (group C: n =5). Short echo proton MRS was used to measure NAA concentrations in the anterior cingulate, the left basal ganglia and the left prefrontal lobe of subjects. A significantly lower NAA concentration was observed only in group B compared with control subjects in the anterior cingulate. Our results suggest that a subgroup of OCD patients who respond to an SSRI with an atypical antipsychotic have distinct biological abnormalities in the anterior cingulate. [Copyright &y& Elsevier]