A Study on the Characteristics and Consultation Request Type of Inpatients Referred for Depressive Symptoms / 정신신체의학

Objectives@#：The purpose of this study is to investigate the characteristics of depressive patients who admitted to general hospital. We examined the clinical characteristics of patients who were referred to the Department of Psychiatry as depressive symptoms, according to the type of consultation request, and comparing ‘with re-consultation’ and ‘without re-consultation’ groups. @*Methods@#：We performed a retrospective chart review of 4,966 inpatients who were referred to the Department of Psychiatry from August 2005 to December 2011. @*Results@#：For about 6 years, among the inpatients referred for psychiatric consultation, a total of 647 patients were referred for depressive symptoms, accounting for 13.82% of the total consultations. The average age of depressive patients was 58.6 years, which was higher than the average of 56.4 years of overall patients. Among the depressive patients, 275 patients were included in ‘with re-consultation’ group and there was no statistically significant difference when comparing ‘with re-consultation’ group and ‘without re-consultation’ group. How-ever, there was a difference in the tendency of the two groups in the type of consultation request. ‘With re-consultation’ group was in the order of frequency of consultation type 3-2-1, whereas the ‘without re-consultation’ group was in the order of frequency of consultation type 2-3-1. @*Conclusions@#：The group of inpatients who were referred for depressive symptoms in general hospital showed the largest proportion of the group of patients referred to the Department of Psychiatry. ‘With re-consultation’ group had a higher rate of re-consultation due to the occurrence of new symptoms after hospitalization compared to ‘without re-consultation’ group. Therefore, doctors in each department and psychiatrists should pay attention to the depressive symptoms of inpatients and actively discuss treatment plans to improve the quality of medical services, identify risk factors, and make efforts to intervene early if necessary.

The Mediating Effect of Insomnia on the Relationship between Panic Symptoms and Depression in Patients with Panic Disorder

Background@#This study aimed to determine if sleep disturbances may mediate the relationship between panic symptoms and depression in patients with panic disorder (PD). @*Methods@#Electronic medical records were retrospectively reviewed for 110 consecutive patients with diagnosed PD in an outpatient clinic between October 2018 and December 2019. Measurements include the PD Severity Scale, Beck Depression Inventory-II (BDI-II) and Insomnia Severity Index (ISI). Statistical analyses were performed to assess any potential relationship between PD, insomnia and depression. @*Results@#Of the PD patients, 88 (80%) and 89 (80.9%) had comorbid depression (BDI-II ≥ 14) and insomnia (Korean version of the ISI ≥ 8), respectively. In a mediation model using insomnia as the mediating variable, the total effect of panic symptom severity on depression was significant (t = 7.23, P < 0.001). There were significant effects of panic symptoms on insomnia (t = 4.62,P < 0.001) and of insomnia on depression (t = 6.69, P < 0.001). The main effect of panic symptom severity on depression was also significant, after controlling for the effect of insomnia (t = 5.10, P < 0.001), suggesting partial mediation. @*Conclusion@#Both depressive symptoms and insomnia are common in patients with PD and depression was partially mediated by insomnia in these patients. These results suggest that an intervention for insomnia in patients with PD might help prevent the development of depression.

The Mediating Effect of Insomnia on the Relationship between Panic Symptoms and Depression in Patients with Panic Disorder

Background@#This study aimed to determine if sleep disturbances may mediate the relationship between panic symptoms and depression in patients with panic disorder (PD). @*Methods@#Electronic medical records were retrospectively reviewed for 110 consecutive patients with diagnosed PD in an outpatient clinic between October 2018 and December 2019. Measurements include the PD Severity Scale, Beck Depression Inventory-II (BDI-II) and Insomnia Severity Index (ISI). Statistical analyses were performed to assess any potential relationship between PD, insomnia and depression. @*Results@#Of the PD patients, 88 (80%) and 89 (80.9%) had comorbid depression (BDI-II ≥ 14) and insomnia (Korean version of the ISI ≥ 8), respectively. In a mediation model using insomnia as the mediating variable, the total effect of panic symptom severity on depression was significant (t = 7.23, P < 0.001). There were significant effects of panic symptoms on insomnia (t = 4.62,P < 0.001) and of insomnia on depression (t = 6.69, P < 0.001). The main effect of panic symptom severity on depression was also significant, after controlling for the effect of insomnia (t = 5.10, P < 0.001), suggesting partial mediation. @*Conclusion@#Both depressive symptoms and insomnia are common in patients with PD and depression was partially mediated by insomnia in these patients. These results suggest that an intervention for insomnia in patients with PD might help prevent the development of depression.

Predictors of Psychiatric Outpatient Adherence after an Emergency Room Visit for a Suicide Attempt

Objective@#This study aimed to investigate the potential correlation between baseline characteristics of individuals visiting an emergency room for a suicide attempt and subsequent psychiatric outpatient treatment adherence. @*Methods@#Medical records of 525 subjects, who visited an emergency room at a university-affiliated hospital for a suicide attempt between January 2017 and December 2018 were retrospectively reviewed. Potential associations between baseline characteristics and psychiatric outpatient visitation were statistically analyzed. @*Results@#107 out of 525 individuals (20.4%) who attempted suicide visited an outpatient clinic after the initial emergency room visit. Several factors (e.g., sober during suicide attempt, college degree, practicing religion, psychiatric treatment history) were significantly related to better psychiatric outpatient follow-up. @*Conclusion@#Several demographic and clinical factors predicted outpatient adherence following a suicide attempt. Therefore, additional attention should be given to suicide attempters who are at the risk of non-adherence by practitioners in the emergency room.

Mature Defense Mechanisms Affect Successful Adjustment in Young Adulthood-Adjustment to Military Service in South Korea

OBJECTIVE: A defense mechanism is an automatic psychological process necessary for successful adaptation. It reflects adaptive capacity. The purpose of this study is to explore the relationship between the adaptation ability of individuals who face mandatory military service and the pattern of defense mechanisms. METHODS: The subjects were 69 men (21.4±2.2 years) who expressed psychological difficulties in three military service situations. Control group was 36 men (24.0±1.4 years) who had successfully completed military service. We examined psychiatric history, the pattern of defense mechanisms, and depression and anxiety levels. Defense mechanisms were compared between two groups. RESULTS: The maladjusted group used immature defenses more frequently than the control group did. There were no differences in the defense patterns according to diagnosis. The control group used more identification and rationalization, classified as immature defenses. The temporarily maladjusted group used more somatization, regression, and avoidance. CONCLUSION: Using mature defense mechanisms helped young adults to adapt to a particular situation. The maturity of the defense is more valuable than the psychiatric diagnosis. Some immature defenses are also helpful to adapt. We cautiously assume that some defenses can be protective or risk factors in adapting to stressful situations by young adults.

Analysis of State-Trait Anxiety Inventory for Patients Diagnosed with Insomnia in an Outpatient Department / 수면정신생리

OBJECTIVES@#Insomnia patients who visited the psychiatric outpatient of a university department, were divided into those patients with insomnia alone and those with depression or anxiety disorder, along with insomnia. The study analyzed their demographic characteristics and the differences in State-Trait Anxiety Inventory (STAI) results among the patient groups.@*METHODS@#Patients who visited the psychiatric department in Konkuk University hospital from 1 January 2006 to 31 December 2018. If they were diagnosed with insomnia disorder based on DSM IV-TR and had undergone STAI, their electronic records were retrospectively analyzed. Based on the records, the patients were classified into those with insomnia disorder only, those with insomnia and anxiety disorder, and those with insomnia and depressive disorder. This study analyzed the demographic characteristics and STAI results of each group, and compared the differences among those groups.@*RESULTS@#During the period, 99 of 329 insomnia disorder patients who had performed STAI were diagnosed with depressive concurrent disorder and 61 with concurrent anxiety disorder. There was no difference in demographic characteristics of age and sex ratio among the three patient groups, and all had greater than 70% proportions of patients aged from 50s to 70s (71.8%, 77.1%, and 73.8% respectively). The average scores of STAI-I were 51.85 ± 10.15 for the patients with anxiety disorders and 54.18 ± 10.32 for those with depressive disorders, both of which were higher than the score of the patients with insomnia alone (44.55 ± 8.89). However, the score difference was not statically significant between the anxiety and depression groups. Similarly, in the STAI-II comparison, the averages of patients with anxiety or depressive disorders along with insomnia were 49.98 ± 8.31 and 53.19 ± 10.13 respectively, which were higher than that of the insomnia only group (42.71 ± 8.84), but there was no significant difference between the anxiety and depressive disorder groups.@*CONCLUSION@#Although there were no differences in demographic data between the patients with insomnia only and those with accompanying depressive or anxiety disorder, the STAI-I and II scores were lower in the insomnia only group. In the future, it is necessary to consider other demographic characteristics including comorbidities and to conduct similar analyses with a larger sample.

Reversed Hand Movement during Sleep in Patients with Obstructive Sleep Apnea

OBJECTIVE: Previous findings suggest that hand movement laterality is reversed during sleep. The present study aimed to verify this phenomenon and evaluate whether the extent of reversal is correlated with the severity of sleep apnea. METHODS: A total of 184 participants (mean age: 44.5±13.0 years; 81.5% males) wore actigraphs on both hands during sleep, and nocturnal polysomnography was simultaneously performed. RESULTS: Actigraphic indices of hand movement were significantly higher for the left hand than those for the right hand (p < 0.001), including total activity score, mean activity score, mean score in active periods and fragmentation index. Additionally, calculated differences between the fragmentation index for the left versus right hands were significantly correlated with the apnea-hypopnea index (AHI, r=0.149, p=0.032). The AHI was not significantly correlated with differences in hand movement between both hands movement assessed by total activity score (r=0.004, p=0.957), mean activity score (r=0.011, p=0.876), mean score in active periods (r=-0.080, p=0.255). CONCLUSION: More severe symptoms of obstructive sleep apnea was associated with larger degree of hand movement reversal at night. This result support the theory that homeostatic deactivation occurs in the dominant hemisphere during sleep.

The Characteristics and Types of Psychiatric Consultation for Insomnia Symptom in Hospitalized Patients / 수면정신생리

OBJECTIVES: The purpose of this study was to explore insomniac demographic characteristics and the type of consultation provided to hospitalized patients asked to the Department of Psychiatry for insomnia and to compare patient insomnia characteristics by consultation type. METHODS: We performed a retrospective chart review of 4,966 patients who were hospitalized from August 1, 2005 to December 31, 2011 that received consultation in the Department of Psychiatry. Among them, 236 patients were referred for insomnia. We compared the differences in demographic characteristics and types of consultation between the insomnia patient group and other patient group. We also compared the difference between demographic characteristics and type of consultation by dividing total subjects into ‘with reconsultation’ and ‘without reconsultation’ groups. RESULTS: Our results came from the analysis of 9,689 consecutive consultation requests. There were 4,966 patients that participated in the study over 6 years and 6 months. The overall consultation rate was 3.3% of all admissions and insomnia patients comprised 4.8% of those. The ratio of re-consultation for insomnia was 27.5%. There was no significant difference in mean age between the insomnia ‘with reconsultation group’ and the insomnia ‘without reconsultation group’, but the ‘with reconsultation’ group had significantly more male patients and medical patients than the ‘without re-consultation’ group. For insomnia patients, consultation types were in the order of Mending request (51.3%), Paralle request (36.6%), Complementary request (9.0%) and this composition differed from that of total admission patients. CONCLUSION: Hospitalized patients referred for insomnia showed a higher proportion of male patients, lower rates of re-consultation compared with other patients, and most of these were for secondary insomnia. Each doctor should be aware of the possibility of inpatient insomnia, conduct positive assessments and referrals as necessary, and psychiatrists who might be asked for consultation need to prepare an active intervention with initial diagnosis and treatment, as well as recommendations for the timing of reconsultation.

Change of Heart Rate Variability in Depressive Disorder after Physical or Psychological Stress / 수면정신생리

OBJECTIVES: This study was designed to assess the change of heart rate variability (HRV) at resting, upright, and psychological stress states in depressive disorder patients. METHODS: HRV was measured at resting, upright, and psychological stress states in 62 depressive disorder patients. We used visual analogue scale (VAS) score to assess tension and stress severity. Beck depression inventory (BDI) and state trait anxiety inventories I and II (STAI-I and II) were used to assess depression and anxiety severity, respectively. Differences between HRV indices and VAS score were evaluated using paired t-tests. Gender difference analysis was conducted with ANCOVA. RESULTS: SDNN (standard deviation of normal to normal intervals), LF/HF (low frequency/high frequency), and VLF (very low frequency) were significantly increased, while NN50 and pNN50 were significantly decreased in the upright position compared to resting state. SDNN, RMSSD (root mean square of the differences of successive normal to normal intervals), and VLF were significantly increased, while pNN50 was significantly decreased in the psychological stress state compared to resting state. SDNN, NN50, and pNN50 were significantly lower in an upright position compared to a state of psychological stress, and LF, HF, and LF/HF showed no significant differences CONCLUSION: The LF/HF ratio was significantly increased after physical stress in depressive disorder. However, the LF/HF ratio was not significantly increased after psychological stress, and the change in LF/HF ratio after physical stress and psychological stress did not significantly differ from each other. Significant increase in SDNN, NN50, and pNN50 in an upright posture compared to psychological stress suggests that depressive patients react more sensitively to physical stress than psychological stress.

Neuropsychiatric Symptoms and Increased Risks of Progression from Amnestic Mild Cognitive Impairment to Alzheimer's Dementia

OBJECTIVES: Neuropsychiatric symptoms (NPS) are common in dementia and in mild cognitive impairment (MCI). They might be a predictor of progression to dementia. This study aimed to investigate the effects of NPS on the natural course in MCI. METHODS: 306 community-dwelling Korean elderly with MCI from local dementia center were assessed for NPS using Neuropsychiatric Inventory (NPI). Subjects were assessed again after more than a year from baseline. 52 subjects (17.0%) were progressed to dementia. We compared baseline NPI scores between stable and deteriorated groups. RESULTS: Subjects progressing to dementia had a significantly higher prevalence of NPS (45.3% vs. 65.4%) than subjects who remained stable. Delusion (2.8% vs. 9.6%), agitation/aggression (14.6% vs. 26.9%), depression (21.7% vs. 40.4%) and disinhibition (4.3% vs. 19.2%) were more common in deteriorated group. After adjustment for other variables, on logistic regression analysis, only disinhibition at baseline was shown to be a risk factor for progression to dementia (OR=4.88, 95% CI=1.37-17.36, p=0.01, R²=302). CONCLUSION: These findings suggest that NPS in MCI may be a predictor of progression to dementia. NPS may be a useful item including delusion, agitation/aggression, depression, and disinhibition. To study course and nature of NPS may lead to better understanding of Alzheimer's disease.

Correlational Analysis of Supine Position Time and Sleep-related Variables in Obstructive Sleep Apnea Syndrome / 수면정신생리

OBJECTIVES: A supine sleep position increases sleep apneas compared to non-supine positions in obstructive sleep apnea syndrome (OSAS). However, supine position time (SPT) is not highly associated with apnea-hypopnea index (AHI) in OSAS. We evaluated the correlation among sleep-related variables and SPT in OSAS. METHODS: A total of 365 men with OSAS were enrolled in this study. We analyzed how SPT was correlated with demographic data, sleep structure-related variables, OSAS-related variables and heart rate variability (HRV). Multiple linear regression analysis was conducted to investigate the factors that affected SPT. RESULTS: SPT had the most significant correlation with total sleep time (TST ; r = 0.443, p < 0.001), followed by sleep efficiency (SE ; r = 0.300, p < 0.001). Snoring time (r = 0.238, p < 0.001), time at < 90% SpO2 (r = 0.188, p < 0.001), apnea-hypopnea index (AHI ; r = 0.180, p = 0.001) and oxygen desaturation index (ODI ; r = 0.149, p = 0.004) were significantly correlated with SPT. Multiple regression analysis revealed that TST (t = 7.781, p < 0.001), snoring time (t = 3.794, p < 0.001), AHI (t = 3.768, p < 0.001) and NN50 count (t = 1.993, p = 0.047) were associated with SPT. CONCLUSION: SPT was more highly associated with sleep structure-related parameters than OSAS-related variables. SPT was correlated with TST, SE, AHI, snoring time and NN50 count. This suggests that SPT is likely to be determined by sleep structure, HRV and the severity of OSAS.

Asymmetrical Electroencephalographic Change of Human Brain During Sleep Onset Period

OBJECTIVE: Human cerebral hemisphere is known to function asymmetrically with daytime left hemisphere superiority in most right-handed persons. It may have relevance to the localization of specific function of the brain. This study attempted to reveal whether the functional cerebral asymmetry in the wakeful state is still maintained throughout the sleep onset period. METHODS: Thirty-channel EEG was recorded in 61 healthy subjects. The EEG power spectra of each of the seven frequencies were compared between the two kinds of 30-second states; the wakeful stage and the late-sleep stage 1. RESULTS: The asymmetrical indices of sleep stage 1 at several fronto-central leads were decreased in the delta, theta, alpha-2, and all beta bands. Conversely, at parts of parieto-occipital leads showed an increase in the indices of the theta, alphas, beta-1, and beta-2 bands. Any fronto-central leads did not show an increase in the index, and no parieto-occipital leads showed a decrease. CONCLUSION: During the sleep onset period, power spectral asymmetry of the brain showed a different pattern from the wakeful stage. This asymmetrical pattern of EEG powers may suggest a reversal of the left hemispheric dominance during sleep.

Gender Differences in Somatic Symptoms and Current Suicidal Risk in Outpatients with Major Depressive Disorder

OBJECTIVE: Although somatic symptoms are common complaints of patients with major depressive disorder (MDD), their associations with suicide are still unclear. METHODS: A total of 811 MDD outpatients of aged between 18 to 64 years were enrolled nationwide in Korea with the suicidality module of the Mini-International Neuropsychiatric Interview (MINI) and the Depression and Somatic Symptom Scale (DSSS). RESULTS: On stepwise regression analysis, current suicidality scores were most strongly associated with chest pain in men, and neck or shoulder pain in women. Severe chest pain was associated with higher current suicidality scores in men than in women, whereas severe neck or shoulder pain showed no significant differences between the genders. In conclusion, MDD patients of both sexes with suicidal ideation showed significantly more frequent and severe somatic symptoms than those without. Current suicidal risk was associated with chest pain in men, and neck or shoulder pain in women. CONCLUSION: We suggest that clinicians pay attention to patients' somatic symptoms in real world practice.

The Severity of Sleep Disordered Breathing Induces Different Decrease in the Oxygen Saturation During Rapid Eye Movement and Non-Rapid Eye Movement Sleep

OBJECTIVE: To investigate how differences in oxygen saturation between non-REM (NREM) and REM sleep in patients according to the severity of sleep apnea. METHODS: We studied 396 male patients diagnosed with simple snoring or obstructive sleep apnea syndrome (OSAS) on nocturnal polysomnography. Patients were divided into groups by the OSAS severity. We compared the average oxygen saturation between REM and NREM sleep in each group. RESULTS: In the simple snoring group, average oxygen saturation was significantly greater during REM than during NREM sleep. In the severe OSA group alone, average oxygen saturation was greater in NREM than in REM sleep. The difference of NREM-REM average oxygen saturation correlated significantly with AHI in the severe OSA group. CONCLUSION: More severe hypoxemia was seen in REM than NREM sleep in the severe OSAS group. The differential oxygen decrease between REM and NREM sleep is likely due to the differentially occurring sleep breathing events in each sleep stage according to the SDB severity. The more AHI increases in the severe OSAS patients, the more prominent the hypoxemia of REM sleep compared with NREM sleep is likely to appear. This suggests that the pressure of continuous positive airway pressure should be increased to control the hypoxemia of REM sleep in extremely severe OSAS.

Nocturia Improvement With Surgical Correction of Sleep Apnea / 대한배뇨장애요실금학회지

PURPOSE: To evaluate changes in nocturia after surgical correction of obstructive sleep apnea (OSA). METHODS: A total of 66 patients were included in the present study. All had been diagnosed with OSA syndrome by polysomnography and underwent uvulopalatopharyngoplasty (UPPP). Preoperative and postoperative lower urinary tract symptoms (LUTS), quality of life (QoL), and nocturia episodes were evaluated using the International Prostate Symptom Score (IPSS) and overactive bladder symptom score (OABSS) questionnaires. Three months postoperatively, telephone interviews were performed to determine the success of surgery, current LUTS, and nocturia episodes. Patients were divided into surgical success and failure groups. Surgical success was defined as snoring decrease more than 50% based on the patient’s subjective judgment. RESULTS: The response rate was 56% and success rate was 73%. In all patients, nocturia episodes significantly decreased from 1.7±1.1 to 0.8±1.2 (P=0.002). Mean IPSS score, OABSS score, and QoL scores were also significantly improved. The success group showed a significant decrease in nocturia episodes, and total IPSS, OABSS, and QoL scores. However, the failure group did not show significant changes in all parameters. CONCLUSIONS: OSA correction improved nocturia as well as other LUTS. These improvements were not observed in the failure group. This study shows that OSA is a cause of nocturia and that other LUTS and nocturia can be improved by surgical correction of OSA.

Characteristics of Patients with Dementia and the Demands of Caregivers: Inpatients of Public Long-term Care Hospital versus Outpatients of General Hospitals

OBJECTIVE: The aim of this study is to clarify the characteristics of patients with dementia using long-term care hospitals and the demands of their caregivers. It will provide a perspective for establishing the specialized dementia hospital and appropriate dementia services in the future. METHODS: The survey was performed to the caregivers of the dementia inpatients of 71 public long-term care hospitals and outpatients from local hospitals. We distributed the questionnaires to 3,600 caregivers. Of these, 1,572 returned and then included in the analysis. RESULTS: High number of both inpatients (85.7%) and outpatients (61.5%) were diagnosed with dementia in psychiatric or neurologic department. Time laps from onset of symptoms thought as dementia to actual diagnosis was about a year. Caregivers of dementia inpatients wanted mostly dementia related welfare and care products (85.5%), physical and exercise program (84.0%), specialized dementia ward (83.1%), behavioral management (82.1%), and cognitive rehabilitation (80.5%). CONCLUSION: It is important to provide adequate management to both the patients with dementia and the caregivers. Thus, specialized institutional arrangements and medical service improvement supported by government is needed to reduce the psychological and financial burden of caregivers. We hope these results will be used to establish the principals and standards of specialized dementia hospital.

The Relationship between Type D Personality and Suicidality in Low-Income, Middle-Aged Adults

OBJECTIVE: Low-income adults are considered to be a group at high risk for suicide. We sought to examine the effect of type D personality and other socio-demographic factors on suicidality in low-income, middle-aged Koreans. METHODS: In total, 306 low-income, middle-aged Koreans [age: 49.16+/-5.24 (40-59) years, 156 males, 150 females] were enrolled from the Korean National Basic Livelihood Security System. Socio-demographic data, including employment status, income, health, marital status, and educational attainment, were gathered. Beck's 19-item Scale for Suicidal Ideation (SSI) was applied to evaluate suicidality, and the DS14 was used to assess type D personality. RESULTS: Unemployment (p<0.01) and absence of spouse (p=0.03) predicted higher SSI scores independent of other socioeconomic factors. All type D personality scores [i.e., negative affectivity (NA), social inhibition (SI), and total score] predicted higher SSI scores independent of all socioeconomic factors (all, p<0.001). Subjects with type D personality had higher SSI scores (p<0.001), and the association between suicidality and socio-demographic factors (employment or physical health) could be found only in subjects without type D personality. CONCLUSION: Type D personality was a risk factor for suicide in low-income Koreans, independently from socio-economic factors. In addition, the socio-demographic factors were less prominently associated with suicidality in those with type D personality.

The Change of Heart Rate Variability in Anxiety Disorder after Given Physical or Psychological Stress / 수면정신생리

OBJECTIVES: This study was designed to assess the change of heart rate variability (HRV) at resting, upright, and psychological stress in anxiety disorder patients. METHODS: HRV was measured at resting, upright, and psychological stress states in 60 anxiety disorder patients. We used visual analogue scale (VAS) score to assess tension and stress severity. Beck depression inventory (BDI) and state trait anxiety inventories I and II (STAI-I and II) were used to assess depression and anxiety severity. Differences between HRV indices were evaluated using paired t-tests. Gender difference analysis was accomplished with ANCOVA. RESULTS: SDNN (Standard deviation of normal RR intervals) and low frequency/high frequency (LF/HF) were significantly increased, while NN50, pNN50, and normalized HF (nHF) were significantly decreased in the upright position compared to resting state (p < 0.01). SDNN, root mean square of the differences of successive normal to normal intervals, and LF/HF were significantly increased, while nHF was significantly decreased in the psychological stress state compared to resting state (p < 0.01). SDNN, NN50, pNN50 were significantly lower in upright position compared to psychological stress and nVLF, nLF, nHF, and LF/HF showed no significant differences between them. CONCLUSION: The LF/HF ratio was significantly increased after both physical and psychological stress in anxiety disorder, but did not show a significant difference between these two stresses. Significant differences of SDNN, NN50, and pNN50 without any differences of nVLF, nLF, nHF, and LF/HF between two stresses might suggest that frequency domain analysis is more specific than time domain analysis.

The Change of Cortical Activity Induced by Visual Disgust Stimulus / 수면정신생리

OBJECTIVES: There are a lot of studies that analyze the interaction between the emotion of disgust and the functional brain images using fMRI and PET. But studies using sLORETA (standardized low resolution brain electromagnetic tomography) almost do not exist. The aim of this research is to explore the relationship of the emotion of disgust and the cortical activation using sLORETA analysis. METHODS: Forty five healthy young adults (27.1+/-2.6 years) participated in the study. While they were watching 4 neutral images and 4 disgusting images associated with mutilation selected from the international affective picture system (IAPS), participants' EEGs were taken for 30 seconds per one picture. Through these obtained EEG data, sLORETA analysis was performed to compare EEGs associated with neutral and negative images. RESULTS: During looking for visual disgusting stimulus, all participants reported unpleasantness, arousal and stress. In sLORETA analysis, the decrease of current density in theta wave was shown at left frontal superior gyrus (BA10) and middle gyrus (BA10, 11). This voxel cluster consists of a total of 11 voxels and the threshold of t value indicating statistically significant decreases in the current density (p<0.05) was -1.984. There were no differences between male and female in the degree of being disgusted by the stimuli. CONCLUSION: This finding may suggest that the activation of dorsolateral prefrontal cortex might be associated with regulating disgust emotion.

Application of Detrended Fluctuation Analysis of Electroencephalography during Sleep Onset Period

OBJECTIVES: Much is still unknown about the neurophysiological mechanisms or dynamics of the sleep onset process. Detrended fluctuation analysis (DFA) is a new tool for the analysis of electroencephalography (EEG) that may give us additional information about electrophysiological changes. The purpose of this study is to analyze long-range correlations of electroencephalographic signals by DFA and their changes in the sleep onset process. METHODS: Thirty channel EEG was recorded in 61 healthy subjects (male : female = 34 : 27, age = 27.2 +/- 3.0 years). The scaling exponents, alpha, were calculated by DFA and compared between four kinds of 30s sleep-wakefulness states such as wakefulness, transition period, early sleep, and late sleep (stage 1). These four states were selected by the distribution of alpha and theta waves in O1 and O2 electrodes. RESULTS: The scaling exponents, alpha, were significantly different in the four states during sleep onset periods, and also varied with the thirty leads. The interaction between the sleep states and the leads was significant. The means (+/- standard deviation) of alphas for the states were 0.94 (+/- 0.12), 0.98 (+/- 0.12), 1.10 (+/- 0.10), 1.07 (+/- 0.07) in the wakefulness, transitional period, early sleep and late sleep state respectively. The mean alpha of anterior fifteen leads was greater than that of posterior fifteen leads, and the two regions showed the different pattern of changes of the alpha during the sleep onset periods. CONCLUSIONS: The characteristic findings in the sleep onset period were the increasing pattern of scaling exponent of DFA, and the pattern was slightly but significantly different between fronto-temporal and parieto-occipital regions. It suggests that the long-range correlations of EEG have a tendency of increasing from wakefulness to early sleep, but anterior and posterior brain regions have different dynamical process. DFA, one of the nonlinear analytical methods for time series, may be a useful tool for the investigation of the sleep onset period.