Hyun Jae Kim

Who is at risk for having persistent insomnia symptoms? A longitudinal study in the general population in Korea☆

OBJECTIVES Our study had three goals: (1) to investigate the longitudinal course of insomnia symptoms over 4 years (3 time points) by analyzing the trajectory of insomnia symptoms for all participants, (2) to compare persistent insomnia symptom to nonpersistent insomnia symptom groups on mental health and quality of life (QoL), and (3) to conduct exploratory analyses on the relative contribution of multiple factors to persistence of insomnia symptoms. METHODS Our population-based longitudinal study utilized a community-based sample from the Korean Genome and Epidemiology study (KoGES). Participants were 1247 individuals (40.1% men; mean age, 54.3±7.1 years). Insomnia, QoL (measured by 12-item Short-Form health survey [SF-12]), sleep-interfering behaviors, and depression (measured by the Beck Depression Inventory [BDI]) were followed with biennial examinations at 3 data points spaced 2 years apart (baseline, time 1, and time 2). RESULTS Among individuals experiencing insomnia symptoms at baseline, the most common trajectory was to experience persistent nocturnal insomnia symptoms across all 3 time points. Those with persistent insomnia symptoms had significantly lower physical and mental QoL (measured by SF-12) and higher depression (measured by BDI) at time points compared to those without persistent nocturnal insomnia symptoms. A follow-up exploratory receiver operating characteristic curve (ROC) analysis identified poor sleep quality, frequent sleep-interfering behaviors, and low mental health QoL as the strongest predictors of persistent insomnia symptoms above other well-known risk factors. CONCLUSIONS In particular, an interaction between poor sleep quality, sleep-interfering behaviors, and mental health QoL appeared to be the strongest risk factor for persistent insomnia symptoms.

Genome-Wide Profiling of Antigen-Induced Time Course Expression Using Murine Models for Acute and Chronic Asthma

Background: Asthma is a complex-trait disease caused by complicated interactions among multiple genetic and environmental risk factors. The clinical symptoms of asthma, such as periodic airway obstruction, hyperresponsiveness and mucus hypersecretion, are mediated by acute and chronic bronchial inflammation. Methods: To better understand the mechanisms by which allergen-induced acute inflammation leads to chronic asthma accompanied by irreversible airway remodeling, we analyzed time course transcriptional responses in the lungs of model mice that were exposed to aerosolized ovalbumin for up to 9 weeks after an initial sensitization. Results: We observed increased levels of total plasma IgE and histological changes in lung tissues from the ovalbumin-treated mice, which is consistent with the typical inflammatory phenotypes of asthma pathogenesis. Our oligonucleotide microarray analyses revealed a total of 776 differentially expressed genes induced by antigenic challenge (≧1.5-fold change, p < 0.05). Of these genes, most of the immune-responsive genes were transiently up-regulated in the early phase of the allergen treatment (within a week) with a concomitant up-regulation of genes involved in mucus production. These genes were not differentially regulated in the mice challenged for a longer period of time (up to 6 weeks). We also identified some of the genes implicated in extracellular matrix remodeling, for which the time course expression did not necessarily coincide with the expression patterns of immune-responsive genes. Conclusion: Our data suggest that there is a complex interregulatory genetic network associated with the structural changes that accompany the progression of the allergic inflammatory reaction in chronic asthma.

Amyloid Burden in Obstructive Sleep Apnea

To test the hypothesis that excessive amyloid deposition is a biological link between obstructive sleep apnea (OSA) and Alzheimers disease, we determined whether OSA increases cerebral amyloid burden, relative to controls, using Pittsburgh Compound B (PiB) PET imaging. The subjects were adult participants (age 50-65 years) from the Korean Genome and Epidemiology Study. Polysomnography, brain MRI including 3D images, and a detailed neuro-cognitive function test battery were done in 2011-2012. Nineteen OSA subjects (Apnea-Hypopnea Index [AHI] ≥15/h, 21.2±5.1/h; age 58.5±4.1 years; 9 male) and 19 controls (AHI 1.8±1.3/h; age 58.5±4.2 years; 9 male) underwent 60-min dynamic 11C-PiB PET. All subjects were right-handed with normal cognitive function and brain MRI. Controls were matched by age, gender, education, and APOE genotype. A voxel-wise comparison of PiB-PET images between the two groups was performed after spatial and count normalization with cerebellar gray matter as a reference. Covariates included the status of sleep duration, hypertension, diabetes, body mass index, exercise, depressive mood, smoking, and alcohol drinking. Cortical thickness on 3D MRI was also measured and compared between the two groups. The OSA group showed a higher PiB deposition in the right posterior cingulate gyrus and right temporal cortex (corrected p < 0.05). There was no area of higher uptake in the control compared with OSA. Regional differences in cortical thickness were not significant. The study suggests that OSA accelerates amyloid deposition and may contribute to the development or progression of Alzheimers disease.

Daytime sleepiness associated with poor sustained attention in middle and late adulthood

OBJECTIVE We aimed to determine the association between psychomotor vigilance task (PVT) performance and sleep-related factors including sleep duration, daytime sleepiness, poor sleep quality, insomnia, and habitual snoring in a population-based sample. METHODS This was a cross-sectional analysis from the ongoing prospective cohort study, the Korean Genome and Epidemiology Study. We measured PVT performance and documented demographics, sleep-related factors, life style, and medical conditions in community dwelling adults (N = 2499; mean age 57.1 ± 7.3; male 1259). Associations between PVT parameters and sleep-related factors were tested, adjusting for age, gender, smoking, alcohol use, education, body mass index, hypertension, diabetes, depression, and the interval between mid-sleep time and PVT test. RESULTS High Epworth Sleepiness Scale (ESS, ≥8) was associated with slower mean reciprocal response speed (mean RRT) (3.69 ± 0.02 vs. 3.77 ± 0.01, p < 0.001), higher probability for increased lapses (≥4) (OR 1.48, CI 1.12-1.88, p = 0.001), and more negative RRT slope (-0.036 ± 0.002 vs. -0.030 ± 0.001, p = 0.02). Older age, female gender, low education level, depressive mood, and the interval between mid-sleep and PVT test were also associated with poor performance. Sleep duration, habitual snoring, insomnia, or poor sleep quality (the Pittsburgh Sleep Quality Index score > 5) was not related to PVT parameters. CONCLUSIONS At the population level, our results revealed important modifiers of PVT performance, which included subjective reports of daytime sleepiness.

Association of Mild Obstructive Sleep Apnea With Cognitive Performance, Excessive Daytime Sleepiness, and Quality of Life in the General Population: The Korean Genome and Epidemiology Study (KoGES)

Study Objectives Research points to impaired cognitive performance in sleep clinic patients with obstructive sleep apnea (OSA). However, inconsistent findings from various epidemiologic studies make this relationship less generalizable. The current study investigated the association between OSA and functional outcome measures, such as cognition, daytime sleepiness, and quality of life, in a Korean general population sample. Methods A total of 1492 participants from the Korean Genome and Epidemiology Study (KoGES) were included in the analyses. The presence of OSA measured by overnight polysomnography (PSG) was defined by apnea-hypopnea index (AHI) >5. Cognitive performance was determined with scores from a comprehensive neuropsychological battery. Excessive daytime sleepiness and quality of life were additionally measured through subjective reports. Results After adjusting for various demographic and medical characteristics, OSA was independently associated with lower performance in the Digit Symbol Test (52.73 ± 17.08 vs. 58.72 ± 18.03, OSA vs. not, p = .02). Hypoxia measures were not related to cognitive performance. OSA was associated with higher odds of displaying excessive daytime sleepiness (odds ratio = 1.72, 95% CI: 1.05-2.80), but there was no significant relationship between OSA and quality of life. Conclusions Cognition was unexpectedly unaffected overall. However, OSA was associated with impairment in a multidomain test that taps skills generally associated with frontal lobe function. The results suggest that research on protective and adaptive brain mechanisms to OSA stress can provide unique insights into the brain-sleep interface. As the study runs longitudinally, it will enable future studies on the impact of OSA on cognitive decline.

Assessing Sleep Disorders in the Asian Client

Sleep disorders are commonly seen in various health-care settings, such as primary care, sleep clinics, and mental health facilities. The three most commonly seen sleep disorders are insomnia, obstructive sleep apnea (OSA), and narcolepsy. A large proportion of Asian-Americans complain of sleep disorders, but cultural considerations when treating an Asian-American patient for a sleep disorder have been largely underemphasized. The main objective of this chapter is to provide psychologists with a comprehensive overview of various sleep disorders, provide prevalence rates in Asian-Americans when available, introduce subjective and objective assessment tools in diagnosing sleep disorders, and discuss cultural considerations associated with Asian-Americans for various sleep disorders.