Modest Effects of NeurofeedbackAssisted Meditation Using a Wearable Device on Stress Reduction: A Randomized, Double-Blind, and Controlled Study

Background@#To evaluate the therapeutic effectiveness and safety of a neurofeedback wearable device for stress reduction. @*Methods@#A randomized, double-blind, controlled study was designed. Participants had psychological stress with depression or sleep disturbances. They practiced either neurofeedback-assisted meditation (n = 20; female, 15 [75.0%]; age, 49.40 ± 11.76 years) or neurofeedback non-assisted meditation (n = 18; female, 11 [61.1%]; age, 48.67 ± 12.90 years) for 12 minutes twice a day for two weeks. Outcome variables were self-reported questionnaires, including the Korean version of the Perceived Stress Scale, Beck Depression Inventory-II, Insomnia Severity Index, Pittsburgh Sleep Quality Index, and State Trait Anxiety Index, quantitative electroencephalography (qEEG), and blood tests. Satisfaction with device use was measured at the final visit. @*Results@#The experimental group had a significant change in PSS score after two weeks of intervention compared with the control group (6.45 ± 0.95 vs. 3.00 ± 5.54, P = 0.037). State anxiety tended to have a greater effect in the experimental group than in the control group (P = 0.078). Depressive mood and sleep also improved in each group, with no significant difference between the two groups. There were no significant differences in stress-related physiological parameters, such as stress hormones or qEEG, between the two groups.Subjective device satisfaction was significantly higher in the experimental group than in the control group (P = 0.008). @*Conclusion@#Neurofeedback-assisted meditation using a wearable device can help improve subjective stress reduction compared with non-assisted meditation. These results support neurofeedback as an effective adjunct to meditation for relieving stress.

OxyMask is not superior to a non-rebreathing oxygen mask for oxygen supply in a post-anesthesia care unit in Korea: a comparative study / 이화의대지

Objectives@#OxyMask, a novel product, has recently been used to administer oxygen postoperatively to patients who have undergone general anesthesia. This study aimed to evaluate the incidence of hypoxia in patients under general anesthesia upon arrival to the post-anesthesia care unit (PACU) using arterial blood gas analysis, and to compare the effectiveness of OxyMask with a non-rebreathing oxygen mask for oxygen administration. @*Methods@#We retrospectively investigated anesthesia-related data from the electronic medical records of 460 patients treated from April to November 2021. We analyzed patients aged 20 years or older who had undergone general anesthesia and whose perioperative arterial blood gas analysis results were available upon arrival to the PACU. These patients were grouped into the non-rebreathing oxygen mask (n=223) and OxyMask (n=237) groups, and statistical analysis was performed utilizing their anesthesia records. @*Results@#No patients exhibited hypoxia upon arrival to the recovery room. The oxygen concentration increased after oxygen administration; its concentration during the recovery room period (Δ2 PaO2 ) was 10.7±42.3 and 13.9±38.5 mmHg in the non-rebreathing oxygen mask and OxyMask groups, respectively.This difference was not statistically significant. Moreover, the arterial oxygen saturation between the end of surgery and upon arrival to the PACU (Δ1 SaO2 ) and the arterial oxygen saturation 20 minutes after oxygen administration at the PACU (Δ2 SaO2 ) did not significantly differ between the groups. @*Conclusion@#OxyMask was not superior to a non-rebreathing oxygen mask in terms of the effectiveness of oxygen supply.

Physiological Predictors of Treatment Response to Biofeedback in Patients With Panic Disorder / 정신신체의학

Objectives@#：Biofeedback is a useful non-pharmacological treatment for panic disorder (PD), but no studies have identified physiological markers related to the treatment response. This study investigated predictors of the treatment response for biofeedback in patients with PD. @*Methods@#：A retrospective study based on the electronic medical records of 372 adult patients with PD was performed. Patients received biofeedback treatment at least once, and physiological markers including heart rate, heart rate variability, respiratory rate, skin conductance, skin temperature, and electromyography were collected before the treatment began. The patients were classified as responders or non-responders based on the change inClinical Global Impression-Severity (CGI-S) score. @*Results@#：The response rate to biofeedback treatment was 30.4%. Multivariable logistic regression analysis revealed that a higher CGI-S score at baseline and fewer benzodiazepine prescriptions were associated with a better response to biofeedback treatment. According to subgroup analyses, the baseline CGI-S score, dose of benzodiazepines, and skin conductance are candidate predictors of the response to biofeedback treatment in men, while only baseline disease severity was associated with the treatment response in women. @*Conclusions@#：The present results suggest that skin conductance may be target marker and predictor for biofeedback in male patients with PD.

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.

Age-Limited Effects of Low-Frequency Transcutaneous Electric Nerve Stimulation on Insomnia: A 4-Week Multi-Center, Randomized Controlled Study

Objective@#Insomnia disorder is a common condition with considerable harmful effects on health. We investigated the therapeutic efficacy and safety of low-frequency transcutaneous electric nerve stimulation (LF-TENS) as an alternative treatment option for insomnia disorder. @*Methods@#A 4-week, multi-center, randomized controlled study was conducted. A total of 160 individuals aged 40 to 80 years with insomnia disorder were included and randomized to the experimental group receiving active device (n=81) or control group receiving sham device (n=79). Both groups used the device for four weeks, more than five days a week. The participants also completed pre- and post-intervention assessment with questionnaires, sleep diaries, wrist actigraphy, and blood tests. @*Results@#There was no significant between-group difference in the changes of mood and sleep parameters and blood test results among the two study groups. Meanwhile, in the exploratory sub-group analysis of patients aged over 60 years, the experimental group showed better improvement after intervention in the change of Pittsburgh Sleep Quality Index (PSQI) score (-2.63±3.25 vs. -1.20±2.28, p=0.039; Cohen’s d=0.99 vs. 0.45) and blood cortisol level (-1.65±3.37 μg/dL vs. -0.16±3.49 μg/dL, p=0.007; Cohen’s d=0.56 vs. 0.05). In addition, no serious adverse reaction occurred during the study period in both groups. @*Conclusion@#The effect of LF-TENS was limited to older patients aged over 60 years, which might be related to the modulation of hypothalamic-pituitary-adrenal axis activity.

REM Sleep Behavior Disorder among Veterans with and without Post-Traumatic Stress Disorder

Objective@#Among veterans, the prevalence of rapid eye movement sleep behavior disorder (RBD) is higher than among the general population, and some evidence suggests that this is related to post-traumatic stress disorder (PTSD). The purpose of this study was to determine whether the frequency of RBD differs depending on the presence of PTSD or trauma. @*Methods@#Patients who underwent nocturnal polysomnography (PSG) and sleep-related questionnaire surveys at the Veteran Health Service Medical Center were reviewed retrospectively. Based on patients with PTSD (n=20; 100% male; 67.9±8.5 years of age), we matched patients exposed to trauma without PTSD (n23; 100% male; age 64.0±13.4) and patients without trauma (n=21; 100% male; age 59.86±10.9). @*Results@#PTSD patients reported dream enactment behavior more than the trauma-exposed group without PTSD or the control group (p=0.006). After adjusting for age, there were more RBD patients in the PTSD group than in the trauma exposed group (p=0.049). @*Conclusion@#The results showed that RBD occurred significantly more in veterans with PTSD than those exposed to trauma, which suggests that there may be a pathophysiological association between PTSD and RBD.

Clinical Perspectives of Parkinson's Disease for Ophthalmologists, Otorhinolaryngologists, Cardiologists, Dentists, Gastroenterologists, Urologists, Physiatrists, and Psychiatrists

Parkinson's disease (PD) is a multisystemic disorder characterized by various non-motor symptoms (NMS) in addition to motor dysfunction. NMS include sleep, ocular, olfactory, throat, cardiovascular, gastrointestinal, genitourinary, or musculoskeletal disorders. A range of NMS, particularly hyposmia, sleep disturbances, constipation, and depression, can even appear prior to the motor symptoms of PD. Because NMS can affect multiple organs and result in major disabilities, the recognition and multidisciplinary and collaborative management of NMS by physicians is essential for patients with PD. Therefore, the aim of this review article is to provide an overview of the organs that are affected by NMS in PD together with a brief review of pathophysiology and treatment options.

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.

Prevalence of unrecognized depression in patients with chronic pain without a history of psychiatric diseases

BACKGROUND: We aimed to investigate the prevalence of unrecognized depression in patients with chronic pain, but with no history of psychiatric diseases. METHODS: Patients with chronic pain who did not have a history of psychiatric disease were selected for this study. The Beck Depression Index (BDI) was used to evaluate depression. Participants' socio-demographic characteristics and pain-related characteristics were also recorded. RESULTS: The study included 94 consecutive patients with chronic pain (28 men and 66 women). Based on the BDI scores, 33/94 (35.1%) patients with chronic pain had comorbid depression. The prevalence of depression was significantly higher in our cohort than it was in the general population (P < 0.001). The standardized incidence ratio, adjusted for age and sex, was 2.77 in men and 2.60 in women. Patients who were unmarried (odds ratio [OR] = 3.714, P = 0.044), and who had subjective sleep disturbance (OR = 8.885, P < 0.001), were more likely to have moderate to severe depression. Patients with high education levels (OR = 0.244, P = 0.016), and who were economically active (OR = 0.284, P = 0.023), were less likely to have moderate to severe depression. CONCLUSIONS: Our results indicate that unrecognized depression in patients with chronic pain is common. Therefore, pain physicians should actively seek to identify these problems rather than relying on the patient to volunteer such information.

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 (β=0.387, p=0.003; β=-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.

Changes in Psychotropic Prescription Patterns in Patients Admitted to an Open Psychiatric Ward : Eleven-Year Comparison in a University Hospital in Gyeonggi-Do

OBJECTIVES: This study investigated the patterns of psychotropic medications prescribed to patients admitted to an open psychiatric ward. METHODS: We reviewed 4282 medical records of patients who were discharged from an open psychiatric ward from May 2003 through April 2014. Data were collected on each patient's age, sex, length of hospital stay, number of past admissions, discharge diagnosis, and kinds and dosages of psychotropic medications at discharge. RESULTS: Among the 1384 male and 2898 female patients, 3.56 psychotropic medications were prescribed on average, with the number increasing across years, from 3.30 in 2003-2008 to 3.76 in 2009-2014. Prescription rates of antipsychotics, anxiolytics, and hypnotics significantly increased in patients with depressive disorders, bipolar disorders, anxiety disorders, delirium, dementia, and amnestic and other cognitive disorders. Only lithium prescription rates decreased significantly. Prescriptions for two or more anxiolytics and antipsychotics increased during the survey years, while antidepressant polypharmacy rates decreased. CONCLUSIONS: Recently, there has been a significant increase in the number of psychotropic medications prescribed, including antipsychotics, anxiolytics, and hypnotics. Caution should be exercised when prescribing medications to avoid cost increases and the risk of side effects, with uncertain gains in the quality of care.

Relationship between Sleep Disturbances and Cognitive Impairments in Older Adults with Depression / 수면정신생리

OBJECTIVES: Depression, sleep complaints and cognitive impairments are commonly observed in the elderly. Elderly subjects with depressive symptoms have been found to show both poor cognitive performances and sleep disturbances. However, the relationship between sleep complaints and cognitive dysfunction in elderly depression is not clear. The aim of this study is to identify the association between sleep disturbances and cognitive decline in late-life depression. METHODS: A total of 282 elderly people who underwent nocturnal polysomnography in a sleep laboratory were enrolled in the study. The Korean version of the Neuropsychological Assessment Battery developed by the Consortium to Establish a Registry for Alzheimer's Disease (CERAD-K) was applied to evaluate cognitive function. Depressive symptoms were assessed with the geriatric depression scale (GDS) and subjective sleep quality was measured using the Pittsburg sleep quality index (PSQI). RESULTS: The control group (GDS< or =9) when compared with mild (10< or =GDS< or =16) and severe (17< or =GDS) depression groups, had significantly different scores in the Trail making test part B (TMT-B), Benton visual retention test part A (BVRT-A), and Stroop color and word test (SCWT)(all tests p<0.05). The PSQI score, REM sleep duration, apnea-hypopnea index and oxygen desaturation index were significantly different across the three groups (all indices, p<0.05). A stepwise multiple regression model showed that educational level, age and GDS score were predictive for both TMT-B time (adjusted R2=35.6%, p<0.001) and BVRT-A score (adjusted R2=28.3%, p<0.001). SCWT score was predicted by educational level, age, apnea-hypopnea index (AHI) and GDS score (adjusted R2=20.6%, p<0.001). Poor sleep quality and sleep structure alterations observed in depression did not have any significant effects on cognitive deterioration. CONCLUSION: Older adults with depressive symptoms showed mild sleep alterations and poor cognitive performances. However, we found no association between sleep disturbances (except sleep apnea) and cognitive difficulties in elderly subjects with depressive symptoms. It is possible that the impact of sleep disruptions on cognitive abilities was hindered by the confounding effect of age, education and depressive symptoms.

Introduction to Sleep Disorders / 한양의대학술지

A total of 85 sleep disorders are described in the International Classification of Sleep Disorders, 2nd ed. Knowledge about those sleep disorders will be essential not only for good and healthy sleep but also for maintaining adequate physical and mental function during daytime. Sleep medicine has a relatively short history compared to other medical fields, thus, many sleep disorders are not familiar to the general public and even to physicians. In this small review about various sleep disorders, I will briefly introduce basic concepts about insomnia, sleep-related breathing disorder, hypersomnia, circadian rhythm sleep disorders, parasomnia and sleep-related movement disorders. These sleep disorders are frequently encountered in clinical settings, and understanding them will give us insight about the basic mechanism of sleep-wake states.

Mild Impairments in Cognitive Function in the Elderly with Restless Legs Syndrome / 수면정신생리

OBJECTIVES: Cognitive impairment in restless legs syndrome (RLS) patients can be affected by sleep deprivation, anxiety and depression, which are common in RLS. The objective of this study is to investigate relationship between cognitive impairment and RLS in the non-medicated Korean elderly with controlling for psychiatric conditions. METHOD: The study sample for this study comprised 25 non-medicated Korean elderly RLS patients and 50 age-, sex-, and education-matched controls. All subjects were evaluated with comprehensive cognitive function assessment tools-including the Korean version of Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet (CERAD-K), severe cognitive impairment rating scale (SCIRS), frontal assessment battery (FAB), and clock drawing test (CLOX). Sleep quality and depression were also assessed with Pittsburgh sleep quality index (PSQI) and geriatric depression scale (GDS). RESULTS: PSQI and GDS score showed no difference between RLS and control group. There was no significant difference between two groups in nearly all the cognitive function except in constructional recognition test, in which subjects with RLS showed lower performance than control group (t=-2.384, p=0.02). Subjects with depression (GDS> or =10) showed significant cognitive impairment compared to control in verbal fluency, Korean version of Mini Mental Status Examination in the CERAD-K (MMSE-KC), word list memory, trail making test, and frontal assessment battery (FAB). In contrast, no difference was observed between subjects who have low sleep quality (PSQI>5) and control group. CONCLUSIONS: At the exclusion of the impact of insomnia and depression, cognitive function was found to be relatively preserved in RLS patients compared to control. Impairment of visual recognition in RLS patients can be explained in terms of dopaminergic dysfunction in RLS.

Designing Clinical Studies and Keeping Research Ethics

Data from clinical studies are needed for psychiatrists to make quick and scientific decisions based on the best available evidence in clinical settings. Various methods of clinical studies are useful for clinicians to have reliable answers to unmet clinical needs. Although randomized controlled trials may provide high-quality information about major issues, well-designed, naturalistic and observational studies often give us unbiased explanation for real-world phenomena. Adequate selection of clinical variables and appropriate number of participants are key factors of well-designed clinical studies. Statistical methods can add an extra dimension to initial design of clinical studies. Given ethical issues in clinical studies on psychiatric disorders, special regards should be paid to participants' ability to provide informed consents. New strategies of clinical studies need to be developed to meet clinical needs and protect the rights and welfare of study participants.

The Association of Obesity with Insulin Resistance in Male Patients with Obstructive Sleep Apnea Syndrome in Korea

OBJECTIVE: Obstructive sleep apnea syndrome (OSAS) has been associated with cardiovascular complications and insulin resistance has been implicated in the pathogenesis and progression of atherosclerosis. We investigated whether insulin resistance is associated with OSAS independent of obesity. METHODS: A total of 183 male patients with OSAS and 52 healthy controls were assessed by nocturnal polysomnography (NPSG). After NPSG, serum concentrations of total cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, glucose and insulin were measured. Insulin resistance was determined by calculating the homeostasis model assessment for insulin resistance (HOMA-IR). RESULTS: Subjects were divided into normal control, mild-to-moderate OSA group (n=96) and severe OSA group (n=87). There were no significant differences among groups in age, body mass index (BMI), neck circumference or waist circumference. Serum concentrations of total cholesterol, LDL cholesterol, triglycerides, glucose, insulin and HOMA-IR scores of normal controls did not differ from those of the mild-to-moderate or severe OSAS groups. HOMA-IR significantly correlated with anthropometric variables, oxygen desaturation index, triglyceride and LDL cholesterol. Stepwise multiple linear regression analysis showed that waist circumference (beta=0.35) and triglycerides (beta=0.27) were significant determinants of HOMA-IR (adjusted R2=20%, p<0.01). CONCLUSION: Insulin resistance was related to obesity itself rather than OSAS severity or nocturnal hypoxemia-related variables. In preventing cardiovascular complications in OSAS patients, weight reduction should be considered.

The Influence of the Amount of Mandibular Advancement in the Application of Mandibular Advancement Device for Obstructive Sleep Apnea Patients / 수면정신생리

OBJECTIVES: The purposes of this study were to estimate the effect of mandibular advancement device (MAD) and to evaluate the influence of the advancement amount of mandible in the application of MAD for obstructive sleep apnea (OSA) patients. METHODS: From the patients who were diagnosed as OSA by polysomnographic study at Seoul National University Bundang Hospital from January 2007 to February 2009, the patients who chose MAD as treatment option were included in this study. All the patients' data including clinical records and polysomnographic studies (both pre- and post-treatment) were reviewed and analyzed. RESULTS: Successful results were obtained in 65 patients of 86 patients (75.6%). In the follow-up period, mild discomfort of anterior teeth or temporomandibular joint (TMJ) were described in 28 patients, especially in the cases the amount of mandibular advancement were more than 7.0 mm. There was no direct relationship between the amount of mandibular advancement and clinical outcome. CONCLUSION: MAD was effective treatment option for the OSA patients regardless of severity. For the prevention of potential dental complications, the amount of mandibular advancement should be considered at the time of MAD treatment.

Prevalence and Clinical Features of Probable REM Sleep Behavior Disorder- An Epidemiological Study in Osan City / 수면정신생리

OBJECTIVES: REM sleep behavior disorder (RBD) has received little attention in epidemiologic studies. This study aimed to determine the prevalence of probable REM sleep behavior disorder (pRBD) in the elderly population and its clinical features. METHODS: A random sample of 1,588 was selected from a roster of 14,050 elderly population living in Osan city. The subjects were asked to fill out the REM sleep behavior disorder screening questionnaire (RBDSQ). Subjects whose score were 5 or higher on RBDSQ underwent a diagnostic phase of person-to-person assessment by experts in RBD. RESULTS: Among 1,588 subjects, 886 elderly subjects participated in the screening phase and 123 subjects were assessed in the diagnostic phase. Eleven subjects were diagnosed as having pRBD, so prevalence was 1.5% (95% CI=0.70-2.30%). The frequency of depression and cognitive decline was significantly increased in patients with pRBD compared to subjects without pRBD, and there was no difference in sleep disturbances between two groups. CONCLUSIONS: Probable REM sleep behavior disorder is not rare in the elderly but frequently under-recognized. More attention should be paid to evaluation and treatment of RBD.

The Influence of Sleep Apnea Syndrome on Cognitive Functions in Patients with REM Sleep Behavior Disorder

OBJECTIVES: We investigated the effects of sleep apnea syndrome (SAS) on cognitive functions in patients with REM sleep behavior disorder (RBD). We also studied correlations between sleep variables related with SAS and parameters of cognitive function tests. METHODS: Twenty two RBD patients with SAS and 20 RBD patients without SAS participated in the study. The diagnoses of RBD and SAS were confirmed on polysomnography. All the participants performed neuropsychological tests by the Korean version of the Consortium to Establish a Registry for Alzheimer's disease (CERAD-K) Assessment Packet. RESULTS: There were no differences between two groups in age and sex, education, body mass index, and results of the Beck depression inventory (BDI) and the Epworth sleepiness scale (ESS). No difference was found in any of parameters of the CERAD-K between two groups. The cognitive functions were not correlated with BDI, ESS, or variables related with SAS. CONCLUSION: SAS had no influence on cognitive functions of RBD patients. The result could be explained by negligible effects of SAS on cognitive functions among aged population and no difference in daytime sleepiness between the RBD patients with and without SAS.