Kyungun Jhung

Abnormalities of emotional awareness and perception in patients with obsessive–compulsive disorder

BACKGROUND Emotional awareness deficit may play a critical role in the production and maintenance of obsessive-compulsive symptoms and social dysfunction in patients with obsessive-compulsive disorder (OCD). The aim of this study was to investigate characteristics of emotional awareness such as empathy and alexithymia in OCD patients. In addition, we examined whether impaired emotional awareness measured by self-assessment questionnaires was associated with emotional facial recognition ability in OCD patients. METHODS Study participants included 107 patients with OCD and 130 healthy age- and sex-matched volunteers. The Interpersonal Reactivity Index (IRI) and Toronto Alexithymia Scale-20 were applied as measures of empathy and alexithymia. A subset of 56 patients with OCD additionally performed the emotional perception task of face expression. RESULTS Patients with OCD scored significantly lower for perspective taking, and significantly higher for personal distress of IRI, and significantly higher for alexithymia compared to normal controls. Impaired emotional awareness such as lower perspective taking and fantasy seeking had a perception bias towards disgust in response to ambiguous facial expressions in OCD patients. LIMITATIONS The OCD group consisted of patients in different stages of the illness and with different degrees of severity. CONCLUSIONS OCD involves the impairment of emotional awareness and perception and it may relate to social dysfunction and to impairments in the ability to shift naturally from obsessive thoughts to other thoughts in response to social situations in patients with OCD.

Theta-gamma coupling during a working memory task as compared to a simple vigilance task

Theta-gamma coupling (TGC) is known to reflect working memory processes, but it is unclear whether TGC as measured by scalp electroencephalography (EEG) reflects working memory processes or nonspecific attentional processes. In this study, we examined the degree of TGC during a visuo-spatial working memory task (2-back task) vs. a simple vigilance task in 13 young participants. During the working memory task, TGC increased in the frontal area at approximately 40 Hz. In addition, TGC was also significantly different at high-gamma frequency despite no differences in gamma power between the two tasks, and a correlation between TGC only during the working memory task and hit rate was observed. These results suggest that TGC reflects working memory processes and may be a useful bio-physiological marker of working memory.

Influence of BDNF and COMT polymorphisms on emotional decision making

Decision making is an important brain function. Although little is known about the genetic basis of decision making, it has been suggested that it is mediated by the modulation of neurotransmitter systems. We investigated how the BDNF Val66Met and COMT Val158Met polymorphisms affect emotional decision making using the Iowa Gambling Task (IGT). One hundred sixty-eight healthy Korean college students (93 males, 75 females) with a complete dataset were included in the data analysis. The IGT and genotyping for the polymorphisms of BDNF Val66Met and COMT Val158Met were performed. Both Met/Met and Val/Met of the BDNF Val66Met polymorphism were significantly associated with a lower mean score of blocks 3-5 of the IGT and with less improvement from block 1 to block 3-5 than the Val/Val. However, the BDNF was not significantly associated with the score of block 1, and the COMT Val158Met polymorphism produced no significant effect on IGT performance. No interaction effect was observed between the BDNF and the COMT for the IGT. These findings suggest the BDNF Val66Met may affect the emotional decision making performance.

Further evidence of a dissociation between decision-making under ambiguity and decision-making under risk in obsessive–compulsive disorder

BACKGROUND Deficits in decision-making have been suggested as a key concept in understanding the symptoms of obsessive-compulsive disorder (OCD). However, evidence in the extant literature remains inconclusive on whether patients with OCD show inferior performance on laboratory decision-making tasks. The aims of the present study were therefore to (1) assess decision-making under ambiguity and under risk in patients with OCD and (2) study the influence of neuropsychological and clinical variables on decision-making in OCD. METHODS The sample consisted of 65 patients with OCD and 58 controls. The Iowa gambling task (IGT) and the game of dice task (GDT) were used to examine decision-making under ambiguity and decision-making under risk, respectively. In addition, reversal learning and executive function were assessed in terms of their relationship with decision-making tasks. RESULTS Patients with OCD showed impairment in the IGT, but not in the GDT. Reversal learning was neither impaired nor correlated with IGT performance. Among the clinical variables, illness severity and depression were associated with IGT scores. Executive function was impaired, but no significant relationship was found between executive function and GDT performance in OCD patients. LIMITATIONS Almost all OCD patients were on medication when they performed decision-making tasks. CONCLUSIONS Patients with OCD are impaired in decision-making under ambiguity, but not under risk. These findings demonstrate that decision-making processes are dissociated in OCD.

The 1287 G/A polymorphism of the Norepinephrine Transporter gene (NET) is involved in Commission Errors in Korean children with Attention Deficit Hyperactivity Disorder

BackgroundPrevious evidence supports the role of noradrenergic systems in ADHD, and norepinephrine transporter (NET) is critical in regulating the noradrenergic system. The present study aimed to investigate the association between NET gene polymorphism and the performance measures of the Continuous Performance Test (CPT) in Korean ADHD children.MethodsEighty-seven children (mean age = 9.23 ± 1.99 years) with ADHD were recruited from a university hospital. Genotypes of G1287A of the NET gene (SLC6A2) were analyzed. All participants completed the CPT, with performance measures of omission errors, commission errors, reaction time and reaction standardization computed. The relationship between G1287A polymorphisms and CPT performance measures was examined.ResultsThere were 46 subjects with the G/G genotype, 35 subjects with the G/A genotype and 6 subjects with the A/A genotype. Among the three groups, there were no significant differences in the performance of CPTs. When dichotomized according to whether the subjects have the rare allele or not, subjects with the homozygous G/G genotype showed significantly lower commission errors compared to those without G/G genotypes (by independent T-test, t = -2.18, p = 0.026).DiscussionOur study found a significant association between commission errors of the CPT and the G1287A genotype of the NET gene in Korean ADHD children. These findings suggest a protective role of the G/G genotype of the NET polymorphisms in the deficits of response inhibition in ADHD children.

Perception bias of disgust in ambiguous facial expressions in obsessive–compulsive disorder

Impaired recognition of facial expressions of disgust has been suggested for patients with obsessive-compulsive disorder (OCD). This study aimed to compare the perception of negative emotions by OCD patients and controls using both non-ambiguous and ambiguous facial expressions. Forty-one OCD patients and thirty-seven controls performed the computerised emotion perception task. There were no differences between OCD patients and controls in the frequency of correct identification of non-ambiguous facial expressions. However, OCD patients were more likely to perceive disgust and less likely to perceive anger in response to ambiguous facial expressions when controlling for covariates. In OCD patients, a higher cleaning dimension was associated with a lower perception of anger and a higher perception of disgust when presented with ambiguous facial expressions. The domains of core disgust and contamination-based disgust domains of disgust sensitivity were positively correlated with the perception of ambiguous facial expressions as disgust, as well as cleaning symptom dimension scores. Our findings suggest that OCD patients, particularly those with higher washing/contamination symptoms, are more likely to perceive disgust in ambiguous facial expressions.

Norepinephrine transporter gene (SLC6A2) is involved with methylphenidate response in Korean children with attention deficit hyperactivity disorder.

The purpose of this study was to investigate the association between the methylphenidate (MPH) response and the norepinephrine transporter (NET) gene polymorphisms in Korean children with attention deficit hyperactivity disorder (ADHD). One hundred and fourteen children with ADHD (mean age 9.08±1.94 years) were recruited from a child psychiatric clinic in South Korea. The genomic DNA was extracted from the blood lymphocyte. Patients were administered MPH for 8 weeks. Good response was defined as a decrease of more than 50% from the baseline ADHD rating scale-IV scores or Clinical Global Impression-Severity score was 1 or 2 after treatment. We compared the MPH response according to the genotype of G1287A of the NET gene (SLC6A2). In patients with G/G genotype, 41 patients (71.9%) showed good response and 16 patients (28.1%) showed poor response when it was measured by the ADHD rating scale-IV. In comparison, 23 patients (46.0%) with G/A genotype and four patients (57.1%) with A/A genotype showed good response (P=0.018, by the Fishers exact test). When we compared the response of MPH between patients with G/G genotype and those without G/G genotype, 41 patients (71.9%) with G/G genotype showed good response, whereas only 27 patients (46.4%) without G/G genotype showed good response. [Pearson &khgr;2=7.143, degrees of freedom (df)=1, P=0.008]. Our study found a significant association between the G1287A genotype of the NET gene and the MPH response in Korean children with ADHD. These findings support the significant role of the NET gene in ADHD treatment with MPH.

Small-world networks in individuals at ultra-high risk for psychosis and first-episode schizophrenia during a working memory task

Disturbances of functional interaction between different brain regions have been hypothesized to be the major pathophysiological mechanism underlying the cognitive deficits of schizophrenia. We investigated the small-world functional networks in individuals at ultra-high risk (UHR) for psychosis, first-episode schizophrenia (FESPR) patients, and healthy controls. All participants underwent the electroencephalogram during a control task and a working memory (WM) task. Small-world properties of the theta band were reduced in FESPR relative to controls during the WM task. Small-worldness of the UHR during the WM task exhibited intermediate value between that of controls and FESPR. These results imply that the suboptimal organization of the brain network may play a pivotal role in the schizophrenia pathophysiology.

Frontostriatal Connectivity Changes in Major Depressive Disorder After Repetitive Transcranial Magnetic Stimulation: A Randomized Sham-Controlled Study.

OBJECTIVE The aim of this randomized, sham-controlled study was to investigate the therapeutic effects of underlying neurobiological changes after 2-week repetitive transcranial magnetic stimulation (rTMS) treatment using functional connectivity magnetic resonance imaging in patients with major depression. METHODS Twenty-four patients with major depressive disorder diagnosed with DSM-IV-TR criteria were randomly assigned to the active rTMS (n = 13) or sham (n = 11) groups from January 2009 to June 2011. rTMS was given for 2 weeks at 110% of the motor threshold for 10 minutes at 10 Hz over the left dorsolateral prefrontal cortex (DLPFC). Resting state functional connectivity was evaluated before and after rTMS. The 17-item Hamilton Depression Rating Scale (HDRS) was administered, and neurocognitive tasks were performed. We examined between-group differences in functional connectivity changes from the bilateral DLPFC. RESULTS Participants in the active rTMS group showed significant clinical improvement in HDRS scores compared to those in the sham group (P < .001). After 2-week rTMS, there were significant differences in changes in DLPFC-left caudate connectivity (corrected P < .05): the active group showed a greater reduction of connectivity strength between the DLPFC and left caudate compared to the sham group. Reduced levels of DLPFC-left caudate connectivity predicted improvement in depressive symptoms (r = 0.58, P = .001). Additionally, a positive correlation between residual depressive symptoms and connectivity strength after 2-week rTMS was found (r = 0.46, P = .023). CONCLUSIONS High-frequency rTMS over the left DLPFC showed therapeutic effects in patients with major depression. The therapeutic effect of rTMS is related to the modulation of functional connectivity in the frontostriatal network. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT01325831​.

Abnormal Brain Activity in Social Reward Learning in Children with Autism Spectrum Disorder: An fMRI Study

Purpose We aimed to determine whether Autism Spectrum Disorder (ASD) would show neural abnormality of the social reward system using functional MRI (fMRI). Materials and Methods 27 ASDs and 12 typically developing controls (TDCs) participated in this study. The social reward task was developed, and all participants performed the task during fMRI scanning. Results ASDs and TDCs with a social reward learning effect were selected on the basis of behavior data. We found significant differences in brain activation between the ASDs and TDCs showing a social reward learning effect. Compared with the TDCs, the ASDs showed reduced activity in the right dorsolateral prefrontal cortex, right orbitofrontal cortex, right parietal lobe, and occipital lobe; however, they showed increased activity in the right parahippocampal gyrus and superior temporal gyrus. Conclusion These findings suggest that there might be neural abnormality of the social reward learning system of ASDs. Although this study has several potential limitations, it presents novel findings in the different neural mechanisms of social reward learning in children with ASD and a possible useful biomarker of high-functioning ASDs.