Hye Youn Park

The Effects of Pharmacological Treatment on Functional Brain Connectome in Obsessive-Compulsive Disorder

BACKGROUND Previous neuroimaging studies of obsessive-compulsive disorder (OCD) have reported both baseline functional alterations and pharmacological changes in localized brain regions and connections; however, the effects of selective serotonin reuptake inhibitor (SSRI) treatment on the whole-brain functional network have not yet been elucidated. METHODS Twenty-five drug-free OCD patients underwent resting-state functional magnetic resonance imaging. After 16-weeks, seventeen patients who received SSRI treatment were rescanned. Twenty-three matched healthy control subjects were examined at baseline for comparison, and 21 of them were rescanned after 16 weeks. Topological properties of brain networks (including small-world, efficiency, modularity, and connectivity degree) were analyzed cross-sectionally and longitudinally with graph-theory approach. RESULTS At baseline, OCD patients relative to healthy control subjects showed decreased small-world efficiency (including local clustering coefficient, local efficiency, and small-worldness) and functional association between default-mode and frontoparietal modules as well as widespread altered connectivity degrees in many brain areas. We observed clinical improvement in OCD patients after 16 weeks of SSRI treatment, which was accompanied by significantly elevated small-world efficiency, modular organization, and connectivity degree. Improvement of obsessive-compulsive symptoms was significantly correlated with changes in connectivity degree in right ventral frontal cortex in OCD patients after treatment. CONCLUSIONS This is first study to use graph-theory approach for investigating valuable biomarkers for the effects of SSRI on neuronal circuitries of OCD patients. Our findings suggest that OCD phenomenology might be the outcome of disrupted optimal balance in the brain networks and that reinstating this balance after SSRI treatment accompanies significant symptom improvement.

Impaired mismatch negativity is associated with current functional status rather than genetic vulnerability to schizophrenia

The aim of this study is to investigate whether mismatch negativity (MMN) is associated with functional status or is a state-independent trait for schizophrenia. We assessed MMN in 26 patients with schizophrenia, 20 healthy subjects with high genetic loading, and 48 healthy controls. Repeated measures analysis of variance and Pearson׳s correlations were used to test the hypothesis that MMN is not state-independent. We found a significant main effect of group, indicating differences in the peak amplitudes of the MMN among the three groups. Post-hoc analyses revealed that schizophrenia patients showed a significant reduction in the peak amplitude of MMN, but subjects at high genetic risk and healthy controls did not. Additionally, significant correlations between Global Assessment of Functioning scores and MMN peak amplitude at Fz and Cz were found in patients with schizophrenia. These findings suggest that MMN may reflect current functional status rather than a genetic risk for schizophrenia.

Altered asymmetry of the anterior cingulate cortex in subjects at genetic high risk for psychosis

OBJECTIVE Many studies have reported that patients with schizophrenia often have structural abnormalities of the anterior cingulate cortex (ACC) and that some of these seem to be of genetic origin, therefore predating the onset of illness. The present study aimed to investigate whether these alterations in the ACC are genetic in origin by comparing the morphological patterns of three groups: normal controls, subjects at genetic high risk (GHR) for psychosis, and patients with schizophrenia. The relationships between morphological variations and executive function were also investigated. METHODS This study examined the magnetic resonance images of cingulate sulcus/paracingulate sulcus (CS/PCS) folding patterns in 222 subjects (103 normal subjects, 30 individuals at GHR, and 89 patients with schizophrenia) and evaluated differences in the morphological and asymmetrical patterns of the ACC among groups. Neurocognitive tests were then performed and differences in cognitive performance were analyzed according to morphological variation. RESULTS Differences in PCS folding were detected; the control group was significantly more likely than were other groups to show a well-developed left PCS (p=0.009) and leftward asymmetry of the PCS (p<0.001). However, neither GHR subjects (p=0.346) nor patients (p=0.784) showed this leftward asymmetry. No statistically significant differences in CS continuity were observed. A more prominent left PCS (p=0.031) and leftward PCS asymmetry (p=0.030) were both associated with higher scores on the working memory task. CONCLUSION The results suggest that GHR subjects have distinct neurodevelopmental anomalies that resemble those of patients with schizophrenia even though they do not display any psychotic symptoms. Certain developmental alterations in the ACC, such as the loss of leftward sulcal asymmetry in patients with schizophrenia, might be related to genetic factors. Additionally, this morphological alteration might partly account for the impaired executive function in schizophrenia.

Factors contributing to the duration of untreated prodromal positive symptoms in individuals at ultra-high risk for psychosis

Individuals at ultra-high risk (UHR) for psychosis experience a considerable delay before appropriate clinical attention is provided. Therefore, we investigated the correlates of this delay by examining clinical, socio-demographic and neuropsychological contributors to the duration of untreated prodromal positive symptoms (DUPP) in them (n=73). The slowly progressive mode of functional decline, defined as a small percentage drop in the Global Assessment of Functioning (GAF) score within the past year, and male gender, explained a considerable portion of the DUPP in the multivariate regression model (F=9.269, p<0.001). Slower functional decline may be correlated with delayed care during the UHR period.

Delirium and its consequences in the specialized palliative care unit: Validation of the Korean version of Memorial Delirium Assessment Scale

Delirium is highly prevalent in patients with advanced cancer. This study aimed to investigate delirium rates and potential associated factors such as mortality in patients admitted to an acute palliative care unit (APCU). Our second aim was to validate the Korean version of the Memorial Delirium Assessment Scale (K‐MDAS).