Psychometric Properties of the Insomnia Severity Index and Its Comparison With the Shortened Versions Among the General Population.

OBJECTIVE: The aim of this study was to explore the psychometric properties of the Insomnia Severity Index (ISI) based on modern test theory, such as item response theory (IRT) and Rasch analysis, with shortened versions of the ISI among the general population. METHODS: We conducted two studies to evaluate the reliability and validity of the shortened versions of the ISI in a Korean population. In Study I, conducted via online survey, we performed an exploratory factor analysis (n=400). In Study II, confirmatory factor analysis (CFA) was conducted (n=400). IRT and Rasch analysis were performed on all samples. Participants symptoms were rated using the ISI, Dysfunctional Beliefs and Attitudes about Sleep-16 items, Dysfunctional Beliefs about Sleep-2 items, Patient Health Questionnaire-9 items, and discrepancy between desired time in bed and desired total sleep time. RESULTS: CFA showed a good fit for the 2-factor model of the ISI (comparative fit index=0.994, Tucker-Lewis index=0.990, root-meansquare-error of approximation=0.039, and standardized root-mean-square residual=0.046). The 3-item versions also showed a good fit for the model. All scales showed good internal consistency reliability. The scale information curve of the 2-item scale was similar to that of the full-scale ISI. The Rasch analysis outputs suggested a good model fit. CONCLUSION: The shortened 2-factor ISI is a reliable and valid model for assessing the severity of insomnia in the Korean population. The results are needed to be explored further among the clinical sample of insomnia.

Validation of the Grief Support in Healthcare Scale among frontline nursing professionals working in COVID-19 inpatient wards in Korea.

Introduction: During the COVID-19 pandemic, healthcare workers (HCWs) have been exposed to higher levels of anxiety and psychological stress than the general population. Nurses who cared for COVID patients could not avoid repeated mourning as they witnessed the deaths of their patients. Therefore, tools are needed to evaluate whether there is adequate support for the grieving process of HCWs in both qualitative and quantitative manners. Methods: Data from 229 nurses who witnessed the deaths of COVID-19 inpatients were analyzed using an online survey of nurses working in three tertiary hospitals. Factor analysis was conducted to validate the 10-item Korean version of Grief Support in Healthcare Scale (GSHCS). Stress and Anxiety to Viral Epidemics-9 was used to measure stress and anxiety caused by coronavirus, Generalized Anxiety Disorder-7 was used to measure overall anxiety, and Patient Health Questionnaire-9 was used for depression. Convergent validity correlation analysis was also performed with GSHCS. Results: The two-factor model showed a good fit for the 10-item GSHCS (χ 2 = 35.233, df = 34, p = 0.410, CFI = 0.999, TLI = 0.990, RMSEA = 0.013, SRMR = 0.064). Cronbach's alpha is 0.918 and McDonald's omega is 0.913, suggesting that the 10-item version of the GSHCS is reliable for determining psychometric properties. Conclusion: According to this study, the 10-item Korean version of the GSHCS is a reliable and valid measure of psychological support for grief among frontline nursing professionals who have witnessed the deaths of patients they cared for while working in COVID-19 inpatient wards. A two-factor model of the GSHCS has a good model fit and good convergent validity with other rating scales that measure viral anxiety, depression, and general anxiety.

Grief Response of Nursing Professionals Is Associated With Their Depression, Loneliness, Insomnia, and Work-Related Stress While Working in COVID-19 Inpatients Wards.

OBJECTIVE: We aimed to explore whether nursing professionals' psychological states affect their grief response for a patient's death in the coronavirus disease-2019 (COVID-19) inpatients' ward. METHODS: Survey was conducted among frontline nursing professionals working in COVID-19 inpatients wards at three tertiary-level affiliated hospitals of the University of Ulsan during April 7-26, 2022. Participants' information such as age, years of employment, or marital status were collected, and their responses to rating scales including Pandemic Grief Scale (PGS) for healthcare workers, Stress and Anxiety to Viral Epidemics-9 items (SAVE-9), Patient Health Questionnaire-9 (PHQ-9), Loneliness and Social Isolation Scale, and Insomnia Severity Scale (ISI) were collected. RESULTS: All 251 responses were analyzed. We observed that 34% reportedly suffered from depression. The linear regression analysis showed that a high PGS score was expected by high SAVE-9 (ß=0.12, p=0.040), high PHQ-9 (ß=0.25, p<0.001), high loneliness (ß=0.17, p=0.006), and high ISI score (ß=0.16, p=0.006, F=20.05, p<0.001). The mediation analysis showed that the depression of nursing professionals directly influenced their pandemic grief reaction, and their work-related stress and viral anxiety, insomnia severity, and loneliness partially mediated the association. CONCLUSION: We confirm that frontline nursing professionals' depression directly influenced their grief reaction, and their work-related stress and viral anxiety, insomnia severity, and loneliness partially mediated the association. We hope to establish a psychological and social support system for the mental health of nurses working in the COVID-19 wards.

Network structure of insomnia symptoms in shift workers compared to non-shift workers.

Insomnia is a commonly occurring sleep problem in shift workers. So far, no studies have investigated how insomnia symptoms present differently in shift workers and non-shift workers. The purpose of this study was to compare the network structures and centrality indices of shift and non-shift workers using network analysis and network comparison test. Participants included 1339 hospital employees, where 542 were shift workers and 797 were non-shift workers. Overall, a significant difference between network structures were observed. In particular, daytime dysfunction emerged as a strongly connected symptom in shift workers, as evidenced by strength centrality. Increased use of sleeping medication and decreased habitual sleep efficiency were more strongly associated with increased daytime dysfunction in shift workers. Sleep latency and sleep quality were also more strongly linked in shift workers. These results are in part attributable to differing causes of insomnia in shift and non-shift workers. Furthermore, the results indicate that shift workers are more vulnerable and susceptible to changes in sleep-related indices, such as sleep efficiency and latency. The findings suggest that certain insomnia symptoms are more consequential in shift workers, emphasizing the need for a differentiated approach in treating insomnia according to shift work.

Validation of the Korean Version of the Positive and Negative Sleep Appraisal Measure (PANSAM) as a Tool for Evaluating Dysfunctional Beliefs about Sleep among the General Population.

We explored the reliability and validity of the Korean version of the Positive and Negative Sleep Appraisal Measure (PANSAM) scale using pre-existing sleep-related questionnaires among the general population. Through an online survey, data from 400 South Korean participants were collected from 10 to 18 January 2022. Symptoms were measured with the PANSAM, Insomnia Severity Index (ISI), the 16-item Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS-16), the Glasgow Sleep Effort Scale (GSES), and the discrepancy between desired time in bed and the desired total sleep time (DBST) index. The four PANSAM subscales were reliable and valid tools for measuring individuals' dysfunctional beliefs about sleep. A confirmatory factor analysis revealed that the full-scale and four-factor model showed a good fit. The full scale and each subscale were significantly correlated with ISI, DBAS-16, and GSES scores. The DBST index was significantly correlated with Subscales 2 and 3. In conclusion, the Korean version of the PANSAM scale and its four subscales can be applied when clinicians measure dysfunctional beliefs regarding sleep among the general population in South Korea. The PANSAM should be explored among other clinical groups to elucidate its applicability as a trans-diagnostic tool while conducting cognitive behavioral therapy for insomnia.

Effect of Long-Term Benzodiazepines for Chronic Insomnia on Cognitive Function and Waking Electroencephalography: A Case-Control Study.

OBJECTIVE: The relationship between benzodiazepine use and cognitive decline in insomnia patients has been reported, but still conflicting. Thus, we tried to determine whether long-term exposure of benzodiazepine might be associated with changes of cognition and electroencephalography (EEG) findings in patients with chronic insomnia. METHODS: Insomniacs using benzodiazepines (n=29), drug-free insomniacs (n=27), and age- and sex-matched controls (n=28) were recruited. Neurocognitive function tested with Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet Neuropsychological Assessment Battery, quantitative EEG in awake state, and information of benzodiazepine usage were obtained. RESULTS: Drug-free insomniacs reported more severe symptoms than insomniacs using benzodiazepine (p<0.001). Insomniacs using benzodiazepine showed a decrease of executive function in Trail Making Test A than drug-free insomniacs and controls (0.73±0.66 vs. 1.27±0.38 vs. 1.09±0.47, p<0.001) and in categorical fluency than drug-free insomniacs (-0.01±0.99 vs. 1.26±0.97, p=0.002). However, such decrease of executive function was not proportional to daily dose or cumulative dose of benzodiazepine. The EEG was not significantly different between insomniacs using benzodiazepine and drug-free insomniacs, while EEG of insomniacs showed low relative theta power in frontal and parietal regions but high relative beta power in frontal region than that of controls. CONCLUSION: Benzodiazepine users with chronic insomnia showed an impairment of executive function compared to drug-free insomniacs and controls although they showed relatively decreased severity of insomnia symptoms. Chronic insomniacs showed a hyper-arousal manifestation in front-parietal region of brain regardless of benzodiazepine exposure.

Effects of subjective-objective sleep discrepancy on the response to cognitive behavior therapy for insomnia.

OBJECTIVE: This study aimed to evaluate the clinical correlates of sleep discrepancy and how subjective-objective sleep discrepancy (SD) affects the results of cognitive behavioral therapy for insomnia (CBT-I) in patients with insomnia disorder. METHODS: A total of 33 patients aged >55 years with insomnia disorders participated in this prospective cohort study. Sleep discrepancy (SD) was defined as the difference between the sleep duration derived from the PSG and self-report questionnaires. SD > 2 h was classified as high SD. Self-report questionnaires, and polysomnography (PSG) were performed before 4 weeks of group CBT-I. Statistical analyses were performed to investigate the association of SD with baseline characteristics and CBT-I results, and compare intergroup difference of pre and post-treatment of high SD and low SD. RESULTS: Patients in the high SD group reported poor subjective sleep, such as lower sleep quality, shorter sleep duration, longer sleep latency, and lower sleep efficiency. However, they had longer sleep duration, higher sleep efficiency in the PSG. There were 35% males in low SD group, but no males in high SD group. After 4 weeks of group CBT-I, SD was positively associated with the effect of CBT-I on subjective total sleep time (r = 0.499, p < 0.006) and sleep efficiency (r = 0.463, p = 0.01) after adjusting age, sex and apnea-hypopnea index. CONCLUSION: The results of this study suggest that patients in the high SD group may respond better to CBT-I than those in lower SD group. Evaluation of SD may help clinicians to decide tailored treatment strategies for treating insomnia disorders.

Lifestyle Changes that Impact Personal Quality of Life in the COVID-19 Pandemic in South Korea.

OBJECTIVE: We investigated which factors in psychological changes positively or negatively affect the quality of life to suggest desirable directions in the period of the COVID-19 pandemic. METHODS: Online survey was conducted with 1,011 adults more than 19 years old in Busan, South Korea. Quality of life was measured using the World Health Organization Quality of Life-BREF. Questions regarding the psychological changes were about COVID-19-related concerns, distress in complying with quarantine guidelines, and interest in seeking something to do alone. RESULTS: Quality of life was perceived to be below average (mean±SD, 2.86±0.53). The more economic worries there were, the lower the quality of life in psychological, social relationships and environmental domains. The more distress one experienced when maintaining their personal hygiene, the higher the quality of life related to their physical health. Likewise, the more difficult it was to maintain social distances, the higher the quality of life associated with psychological and social relationships. The more interested someone was in how to spend time alone, the higher the quality of life in all domains significantly. CONCLUSION: We can minimize the negative impacts of COVID-19 by maintaining economic stability, maintaining prosocial behaviors related to personal hygiene and making good use of personal time.

The Prevalence of Depression, Anxiety and Associated Factors among the General Public during COVID-19 Pandemic: a Cross-sectional Study in Korea.

BACKGROUND: Since its first case confirmed on January 20, 2020, Korea has been through three waves of the COVID-19 pandemic. Fears of the fourth wave persist as new cases continue to emerge. In such unpredictable times, the mental well-being of people is of crucial importance. This study examined the levels of depression and anxiety and their predictors among the Korean general public in Busan, Korea, during the COVID-19 pandemic. METHODS: We conducted a cross-sectional study via a self-reported questionnaire administered to 2,288 adult residents (aged 19-60 years) of Busan, Korea. Participants' depression and anxiety were assessed using the Korean version of the Patient Health Questionnaire-4 (PHQ-4), which consists of PHQ-2 and Generalized Anxiety Disorder-2 (GAD-2), with the cutoff score of 3. RESULTS: The mean age of the participants was 39.71 years. COVID-19 had several psychosocial impacts on people. It was revealed that 80.3% had restrictions in outside activities, 47.3% reported financial difficulties, and 53.6% had a fear of death or fatal outcome when infected with COVID-19. We performed logistic regression analysis to identify the factors associated with depression and anxiety. A total of 30.7% participants were classified as at risk of depression based on cutoff score of 3 on PHQ-2. Logistic regression analysis revealed that changes in sleep pattern due to COVID-19 were most strongly associated with depression, followed by restrictions in outside activities due to social distancing and increased family conflicts due to COVID-19. Also, 22.6% participants were classified as at risk of anxiety based on a cutoff score of 3 on GAD-2. Analysis revealed that changes in sleep pattern due to COVID-19 were most strongly associated with anxiety, followed by spending a lot of time searching for COVID-19-related information and having a fear of death or fatal outcome when infected with COVID-19. CONCLUSION: The results are alarming; 30.7% had a PHQ-2 score of 3 or higher, indicating depression, and 22.6% had a GAD-2 score of 3 or higher, indicating anxiety. Changes in sleep pattern had the strongest association with both depression and anxiety. Our results can be used to formulate mental health policies tailored to the context of the city. Our findings suggest the high prevalence of depression and anxiety in the society during the COVID-19 pandemic, which places growing importance on early intervention for mental health problems during these times.

Preliminary Investigation of Association between Methylphenidate and Serum Growth Markers in Children with Attention-Deficit/Hyperactivity Disorder: A Cross-Sectional Case-Control Study.

OBJECTIVES: It remains unclear whether methylphenidate (MPH) has yadverse effects on growth in children. This study aimed to investigate the association of MPH with serum biological markers of growth in children with attention-deficit/hyperactivity disorder (ADHD). METHODS: The present study included 103 children with ADHD (64 drug-naive children, 39 MPH-treated children) and 112 control subjects. Children with ADHD were diagnosed on the basis of a semi-structured interview. Levels of biochemical markers of growth, including insulin-like growth factor-I, thyroid stimulating hormone (TSH), free T4, calcium, phosphorus, alkaline phosphatase, vitamin D, hemoglobin, total protein, albumin, total cholesterol, and hematocrit were measured in these individuals. RESULTS: Except in case of TSH, no intergroup differences were found in the levels of the growth markers. The levels of TSH were found to be lower in the MPH-treated boys with ADHD than in the drug-naive and control groups (p < 0.05), although the levels of TSH in all the groups were within normal limits. CONCLUSION: In this cross-sectional study, no significant association was found between MPH and growth markers. This calls for the need to carry out prospective longitudinal research studies in the future that investigate the effect of MPH on the growth trajectory in children.

Minimal Effects of Binaural Auditory Beats for Subclinical Insomnia: A Randomized Double-Blind Controlled Study.

BACKGROUND: Auditory binaural beat (BB) stimulation is known to modulate electroencephalographic activity by brain entrainment, but few studies have established whether BB can affect the sleep state. We examined the effect of θ BB in improving sleep disturbances and daytime alertness. METHODS: We conducted double-blind and sham-controlled randomized trial. Subjects with subclinical insomnia were randomly assigned and listened to music for 2 weeks with or without θ BB for 30 minutes before going to sleep. RESULTS: There were 43 participants (32 female; mean age, 34.3 ± 10.4 years) who finished the trial. The insomnia severity decreased at 2 weeks in both groups without significant differences in Insomnia Severity Index score (4.41 ± 4.32 vs 2.71 ± 4.66, P = 0.656), although the effect was much stronger for the music with the BB group than for the music-only group (Cohen d = 1.02 vs 0.58). In awake electroencephalographic analysis, the relative ß power after 2 weeks was higher in the music with the BB group than in the music-only group (0.2 ± 7.02 vs -3.91 ± 6.97, P = 0.041). CONCLUSIONS: Auditory θ BB with music does not induce evident improvement of sleep disturbances more than does pure music, but could alter brain activity toward increasing daytime alertness in subclinical insomnia, which needs to be corroborated in a clinical population.

Multidimensional Comparison of Cancer-Related Fatigue and Chronic Fatigue Syndrome: The Role of Psychophysiological Markers.

OBJECTIVE: The present study compared cancer-related fatigue (CRF) and chronic fatigue syndrome (CFS) using multidimensional measurements with the aim of better understanding characteristics and exploring markers of two similar fatigue syndromes. METHODS: Twenty-five patients with CRF and twenty patients with CFS completed questionnaires, including the Fatigue Severity Scale (FSS), Hospital Anxiety Depression Scale (HADS), Perceived Stress Scale (PSS), and Pittsburgh Sleep Quality Index (PSQI). Additionally, levels of high sensitivity C-reactive protein (hs-CRP), heart rate variability (HRV), and electroencephalography (EEG) were obtained. Neurocognitive functioning was also evaluated. RESULTS: Both groups showed comparable levels of psychological variables, including fatigue. Compared to CFS subjects, CRF patients had significantly higher hs-CRP levels and a reduced HRV-index. The within-group analyses revealed that the FSS score of the CRF group was significantly related to scores on the HADS-anxiety, HADS-depression, and PSQI scales. In the CFS group, FSS scores were significantly associated with scores on the PSS and the absolute delta, theta, and alpha powers in frontal EEG. CONCLUSION: Findings indicate that different pathophysiological mechanisms underlie CFS and CRF. Inflammatory marker and HRV may be potential biomarkers for distinguishing two fatigue syndromes and frontal EEG parameters may be quantitative biomarkers for CFS.

A validation study on three screening questionnaires for obstructive sleep apnea in a Korean community sample.

PURPOSE: Obstructive sleep apnea (OSA) is highly prevalent and causes serious cardiovascular complications. Several screening questionnaires for OSA have been introduced, but only few validation studies have been conducted in general population. The aim of the present study was to assess the diagnostic value of three OSA screening questionnaires (Berlin Questionnaire, BQ; STOP-Bang Questionnaire, STOP-B; Four-Variable Screening Tool, Four-V) in a Korean community sample. METHODS: A total of 1148 community-dwelling participants completed the BQ, STOP-B, and Four-V. An overnight in-laboratory polysomnography (PSG) was conducted in randomly selected 116 participants. Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, and area under the curve (AUC) were calculated. RESULTS: The Four-V with cutoff ≥ 8 showed high sensitivity for overall OSA (69.4%), and the Four-V with cutoff ≥ 9 showed high specificity for both overall OSA (81.5%) and moderate to severe OSA (69.0%). On the other hand, the STOP-B showed acceptable sensitivity and specificity for both overall OSA (61.3 and 79.6%, respectively) and moderate to severe OSA (72.4 and 67.8%, respectively). The STOP-Bang also showed the largest area under the receiver-operator characteristic curve for both overall OSA (0.752) and moderate to severe OSA (0.750). The BQ showed the lowest performance in predicting OSA. CONCLUSIONS: Among the three questionnaires, the STOP-B was revealed as the most useful screening tool for OSA in terms of sensitivity, specificity, and area under the receiver-operator characteristic curve in the population of South Korea.

Symptom Persistence after Iron Normalization in Women with Restless Legs Syndrome.

OBJECTIVE: The aim of this study was to determine the clinical course of restless legs syndrome (RLS) and potential risk factors for the persistence of RLS symptoms after iron normalization in women with RLS and low serum ferritin (<50 µg/L). METHODS: We reviewed 39 women with RLS and iron deficiency, who achieved iron normalization after oral iron replacement for three months. Risk factors contributing to symptom persistence were estimated by logistic regression analyses. Remission was defined as no RLS symptoms for at least 6 months after the iron normalization. RESULTS: Over the observation period of 2.5±1.4 years, 15 patients reported no RLS symptom whereas 24 patients still complained of RLS symptoms. The remission rate of RLS with iron replacement was 38.5%. The relative risk of symptom persistence was increased by the duration of RLS symptoms (OR: 1.88, 95% CI: 1.01-3.49) or by the age at RLS diagnosis (OR: 1.25, 95% CI: 1.01-1.56). CONCLUSION: Almost two-third of RLS patients with iron deficiency showed persistence of the symptom even after iron normalization. Considering that longer duration of RLS symptoms and older age at RLS diagnosis were risk factors for symptom persistence, early intervention of iron deficiency in RLS is warranted.

Modest Improvement of Untreated Severe Sleep-Disordered Breathing in the Middle-Aged and Elderly.

OBJECTIVE: It has been reported that untreated sleep-disordered breathing (SDB) deteriorates over time, however this remains contentious. The aim of the present study is to evaluate the clinical course of SDB in middle-aged and older SDB patients, and to identify how relevant factors contribute to the change in SDB severity. METHODS: Baseline and follow-up polysomnographic data of 56 untreated SDB patients (mean age, 61.2±5.71) were obtained retrospectively and the mean interval was 62.4±22.0 months. Subgroup analysis was performed based on the baseline severity, and the factors associated with the course of SDB were analyzed. RESULTS: At the baseline, 13 subjects were simple snorers, 15 had mild to moderate SDB, and 28 were severe SDB patients. While there was no significant change in apnea-hypopnea index (AHI) as a whole, subgroup analysis showed decrease of AHI in severe SDB patients (43.9±10.6 to 35.6±20.0, p=0.009). The change in supine time percent and baseline AHI were associated with the change in AHI (ß=0.387, p=0.003; ß=-0.272, p=0.037). CONCLUSION: Untreated SDB did not deteriorate over time with modest improvement in severe SDB. A proportion of severe SDB patients might expect decrease in SDB severity irrespective of changes in sleep position or body weight.

Psychiatric disorders and suicide attempts among adolescents victimized by school bullying.

OBJECTIVE: We conducted a cross-sectional school-based study to investigate psychiatric disorders and suicide risk among adolescents victimized by bullying. METHOD: The study was designed in two stages. In the screening stage, 33,038 middle school students were screened for psychopathology. Next, in the face-to-face interview stage, 1196 participants were assessed for psychiatric disorders using a structured diagnostic instrument. We also collected information about the participants' experiences of bullying and history of suicidal ideation/attempts. RESULTS: The results indicate that adolescents with a history of bullying victimization were more likely to be diagnosed with depression and psychosis than those without such a history. Multivariate logistic regression models revealed that bullying victimization was significantly associated with suicide attempts even after adjusting for demographic characteristics, depression and psychosis. CONCLUSIONS: Bullying victimization is a risk factor for depression, psychosis, and suicide ideation and attempts. The findings warrant an early intervention and suicide prevention program for victimized students and anti-bullying policies in schools.

Differential effects of circadian typology on sleep-related symptoms, physical fatigue and psychological well-being in relation to resilience.

Various physiological and psychological functions are influenced by circadian typology (CT), which was reported to be related to resilience. However, few studies have assessed the effects of CT in relation to resilience. The aim of the present study was to assess the influence of CT on sleep-related symptoms, physical fatigue and psychological well-being in relation to resilience. The present study included a total of 1794 healthy hospital employees, and they completed the Morningness-Eveningness Questionnaire, Connor-Davidson Resilience Scale, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Fatigue Severity Scale, Hospital Anxiety and Depression Scale and World Health Organization Quality of Life Scale Abbreviated Version. Subjects with evening type showed lower sleep quality, more daytime sleepiness and physical fatigue than neither types and morning types. Additionally, evening types were more depressed and anxious and reported a poorer quality of life. CT was found to be a significant predictor of sleep quality, but CT was minimally associated with physical fatigue and psychological well-being in the regression analysis. Instead, resilience was substantially related to all of the variables measured. In conclusion, CT independently predicts sleep quality, but the effects of CT on physical fatigue and psychological well-being are negligible compared to those of resilience.

Alterations of awake EEG in idiopathic REM sleep behavior disorder without cognitive impairment.

The aim of this study was to find electroencephalographic (EEG) changes in subjects with drug-naïve idiopathic rapid eye movement sleep behavior disorder (iRBD) who had no cognitive impairment. A total of 57 iRBD patients confirmed by polysomnography (PSG) and 33 sex and age-matched healthy controls were included and their waking EEG was recorded from five cortical regions for 15min. Power spectral analyses by fast Fourier transforms were performed on EEG data. In PSG data, the iRBD patients showed sleep disturbances of short total sleep time, decreased sleep efficiency, increased sleep latency and frequent awakening compared to controls. After adjusting for sleep parameters, the absolute alpha power in frontal region in iRBD patients was higher than that in controls (1.2±0.3 vs. 0.9±0.3, p=0.037). Dominant occipital frequency (DOF) was lower in iRBD patients than in controls after adjusting for the sleep covariates (9.2±0.3Hz vs. 9.5±0.4Hz, F=8, p=0.006). iRBD patients without cognitive impairment also showed EEG alteration in frontal and occipital cortex at wakefulness, which could be an early marker of cerebral dysfunction in iRBD patients.

Blood lead concentrations and attention deficit hyperactivity disorder in Korean children: a hospital-based case control study.

BACKGROUND: Because the developing brain of a child is vulnerable to environmental toxins, even very low concentration of neurotoxin can affect children's neurodevelopment. Lead is a neurotoxic heavy metal which has the harmful effect on the striatal-frontal circuit of brain. This area of the brain is known to be closely related to attention deficit hyperactivity disorder (ADHD) pathophysiology. The primary objective of the present study was to investigate whether elevated blood lead concentration is a risk factor for ADHD. The secondary objective was to examine the association between blood lead concentration and symptom severity. METHODS: We conducted a frequency-matched, hospital-based case-control study with 114 medically diagnosed ADHD cases and 114 controls. The participants were matched for age and sex. The diagnoses of ADHD were assessed with semi-structured diagnostic interviews. The participants completed the continuous performance test (CPT), and their parents completed the ADHD-rating scale (ADHD-RS). Blood lead concentrations were measured by using graphite furnace atomic absorption spectrometry featuring Zeeman background correction. RESULTS: Children with ADHD exhibited blood lead concentrations that were significantly higher than those of the controls ( 1.90 ± 086 µg/dℓ vs. 1.59 ± 0.68 µg/dℓ, p = 0.003). The log transformed total blood lead concentration was associated with a higher risk of ADHD (OR: 1.60, 95 % CI: 1.04-2.45, p < 0.05). The analysis also revealed that the children with blood lead concentrations above 2.30 µg/dℓ were at a 2.5-fold (95 % CI: 1.09-5.87, p < 0.05) greater risk of having ADHD. After adjusting for covariates, our multivariate regression models indicated that blood lead concentrations were not significantly associated with ADHD-RS or CPT profiles among the ADHD cases. CONCLUSION: Even low blood lead concentrations are a risk factor for ADHD in children. This study warrants primary prevention policies to reduce the environmental lead burden. Future studies may be required to ascertain the effects of lead on symptom severity in ADHD.

Symptom Severity of Restless Legs Syndrome Predicts Its Clinical Course.

OBJECTIVE: This study examines the clinical course of restless legs syndrome according to its severity and factors associated with the remission of restless legs syndrome symptoms. METHODS: The remission or persistence of restless legs syndrome symptoms was investigated by considering patients with restless legs syndrome at the sleep clinic of Seoul National University Bundang Hospital. All subjects were observed for at least 18 months, and an incidence of remission was defined as having no restless legs syndrome symptoms for at least 1 year. Restless legs syndrome severity was evaluated by the International Restless Legs Syndrome Study Group Rating Scale. RESULTS: A total of 306 patients participated in this study. Over the observation periods of 4.1 ± 1.6 years, the cumulative incidence of remission is 32.5% (95% confidence interval [CI], 27.0-38.0) and decreased with baseline restless legs syndrome severity (P < .001): 60% (95% CI, 44.9-75.1), 44% (95% CI, 34.4-53.6), and 16.7% (95% CI, 10.6-22.8) in mild, moderate, and severe to very severe restless legs syndrome cases, respectively. Most cases of remission (82/96) were observed within 1 year, and the remission occurred sooner for mild restless legs syndrome. The hazard ratios of remission by Cox proportional hazards model were lower for moderate (0.556; 95% CI, 0.340-0.909) and severe to very severe (0.193; 95% CI, 0.108-0.343) restless legs syndrome than for mild restless legs syndrome. The remission incidence was lower for those patients who had a family history of restless legs syndrome and were older at restless legs syndrome diagnosis. CONCLUSIONS: Mild restless legs syndrome severity, no family history, and young age at restless legs syndrome diagnosis were significant predictors of restless legs syndrome remission. More than 80% of patients with severe restless legs syndrome showed a chronic clinical course.