Waking qEEG in older adults with insomnia and its associations with sleep reactivity and dysfunctional beliefs about sleep.

Sleep quality often deteriorates with age, and insomnia among the elderly increases the risks of both physical and psychiatric disorders. To elucidate the mechanisms and identify useful diagnostic biomarkers for insomnia in the elderly, the current study investigated the associations of waking brain activity patterns with susceptibility to stress-induced insomnia (sleep reactivity) and dysfunctional beliefs about sleep, major factors precipitating and maintaining insomnia, respectively. Forty-five participants aged 60 years or older with insomnia completed self-reported measures assessing depression, anxiety, sleep quality, dysfunctional beliefs about sleep, and sleep reactivity. Participants were then examined by quantitative electroencephalography (qEEG) during wakefulness, and spectral analysis was conducted to examine associations of regional frequency band power with these insomnia-precipitating and -maintaining factors. Dysfunctional beliefs about sleep were significantly correlated with higher beta/high-beta frequency band powers, while sleep reactivity was correlated with higher theta and delta frequency band powers. These findings suggest that sleep reactivity of older adults is associated with widespread cortical deactivation leading to poor stress coping, while their dysfunctional beliefs about sleep are associated with hyperactivation which is related to cognitive processes. These associations suggest that cognitive inflexibility and maladaptive stress-coping contribute to insomnia among the elderly.

Moderating effect of shift work on sleep and depression in individuals at high risk of bipolar disorder.

BACKGROUND: Social Zeitgeber Theory posits that disruptions in social rhythms can increase susceptibility to bipolar disorder (BD). Shift work (SW) is one of the external factors that cause instability in social rhythms and the sleep-wake cycle. This study evaluated the moderating influences of SW on the risks of BD and sleep-related parameters and depressive symptoms. Furthermore, we evaluated the specific work schedules including daytime, nighttime, and regular and irregular rotating SW. METHODS: An online survey was administered to 6665 participants, with 3379 (50.7 %) classified as individuals with high scores of Mood Disorder Questionnaire (MDQ). The survey included the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Scale (ISI), Epworth Sleepiness Scale (ESS), and Center for Epidemiologic Studies Depression Scale (CES-D). RESULTS: A multivariate regression model revealed significant interactive effects of MDQ positivity and SW on PSQI, ISI, and CES-D scores, but not ESS scores. In a secondary analysis of the high MDQ screen group, daytime workers had lower scores in sleep disturbances and depressive symptoms compared to those engaged in other forms of SW. LIMITATIONS: Online surveys were accessible voluntarily, leading to potential selection bias. Cross-sectional data identified associations, not causal relationships. Only a self-reported questionnaire was used. CONCLUSIONS: Our findings emphasize the advantages of a daytime work schedule for individuals at high risk of BD. In accordance with the principles of social rhythm interpersonal therapy, sleep interventions for individuals at high risk of BD should include the maintenance of a consistent daytime schedule.

Shift schedules and circadian preferences: the association with sleep and mood.

Object: We explored the circadian preferences of non-shift workers (non-SWs) and various types of shift workers (SWs), and the associations of these preferences with sleep and mood. Methods: In total, 4,561 SWs (2,419 women and 2,142 men aged 37.00 ± 9.80 years) and 2,093 non-SWs (1,094 women and 999 men aged 37.80 ± 9.73 years) completed an online survey. Of all SWs, 2,415 (1,079 women and 1,336 men aged 37.77 ± 9.96 years) reported regularly rotating or fixed schedules ("regular SWs"), and 2,146 (1,340 women and 806 men aged 36.12 ± 9.64 years) had irregular schedules ("irregular SWs"). Of the regular SWs, 2,040 had regularly rotating schedules, 212 had fixed evening schedules, and 163 had fixed night schedules. All participants completed the Morningness-Eveningness Questionnaire (MEQ) exploring circadian preferences, the short form of the Center for Epidemiological Studies-Depression Scale (CES-D) evaluating depression, the Insomnia Severity Index (ISI), and the Epworth Sleepiness Scale (ESS). Results: Compared to non-SWs, SWs had lower MEQ scores, i.e., more eveningness, after controlling for age, gender, income, occupation, and weekly work hours (F = 87.97, p < 0.001). Irregular SWs had lower MEQ scores than regular SWs (F = 50.89, p < 0.001). Among regular SWs, the MEQ scores of fixed evening and fixed night SWs were lower than those of regularly rotating SWs (F = 22.42, p < 0.001). An association between the MEQ and ESS scores was apparent in non-SWs (r = -0.85, p < 0.001) but not in SWs (r = 0.001, p = 0.92). Conclusion: SWs exhibited more eveningness than non-SWs; eveningness was particularly prominent in SWs with irregular or fixed evening/night shifts. Eveningness was associated with sleepiness only in non-SWs, but not in SWs.

Brain structural correlates of subjective sleepiness and insomnia symptoms in shift workers.

Background: Studies on the brain structures of shift workers are limited; thus, this cross-sectional study aimed to compare the brain structures and the brain structural correlates of subjective sleepiness and insomnia symptoms between shift workers and non-shift workers. Methods: Shift workers (n = 63) and non-shift workers (n = 58) completed questionnaires assessing subjective sleepiness and insomnia symptoms. Cortical thickness, cortical surface area, and subcortical volumes were measured by magnetic resonance imaging. The brain morphometric measures were compared between the groups, and interaction analyses using the brain morphometric measures as the dependent variable were performed to test the interactions between the study group and measures of sleep disturbance (i.e., subjective sleepiness and insomnia symptoms). Results: No differences in cortical thickness, cortical surface area, or subcortical volumes were detected between shift workers and non-shift workers. A single cluster in the left motor cortex showed a significant interaction between the study group and subjective sleepiness in the cortical surface area. The correlation between the left motor cortex surface area and the subjective sleepiness level was negative in shift workers and positive in non-shift workers. Significant interaction between the study group and insomnia symptoms was present for the left/right putamen volumes. The correlation between the left/right putamen volumes and insomnia symptom levels was positive in shift workers and negative in non-shift workers. Conclusion: Left motor cortex surface area and bilateral putamen volumes were unique structural correlates of subjective sleepiness and insomnia symptoms in shift workers, respectively.

Identifying unique subgroups in suicide risks among psychiatric outpatients.

BACKGROUND: The presence of psychiatric disorders is widely recognized as one of the primary risk factors for suicide. A significant proportion of individuals receiving outpatient psychiatric treatment exhibit varying degrees of suicidal behaviors, which may range from mild suicidal ideations to overt suicide attempts. This study aims to elucidate the transdiagnostic symptom dimensions and associated suicidal features among psychiatric outpatients. METHODS: The study enrolled patients who attended the psychiatry outpatient clinic at a tertiary hospital in South Korea (n = 1, 849, age range = 18-81; 61% women). A data-driven classification methodology was employed, incorporating a broad spectrum of clinical symptoms, to delineate distinctive subgroups among psychiatric outpatients exhibiting suicidality (n = 1189). A reference group of patients without suicidality (n = 660) was included for comparative purposes to ascertain cluster-specific sociodemographic, suicide-related, and psychiatric characteristics. RESULTS: Psychiatric outpatients with suicidality (n = 1189) were subdivided into three distinctive clusters: the low-suicide risk cluster (Cluster 1), the high-suicide risk externalizing cluster (Cluster 2), and the high-suicide risk internalizing cluster (Cluster 3). Relative to the reference group (n = 660), each cluster exhibited distinct attributes pertaining to suicide-related characteristics and clinical symptoms, covering domains such as anxiety, externalizing and internalizing behaviors, and feelings of hopelessness. Cluster 1, identified as the low-suicide risk group, exhibited less frequent suicidal ideation, planning, and multiple attempts. In the high-suicide risk groups, Cluster 2 displayed pronounced externalizing symptoms, whereas Cluster 3 was primarily defined by internalizing and hopelessness symptoms. Bipolar disorders were most common in Cluster 2, while depressive disorders were predominant in Cluster 3. DISCUSSION: Our findings suggest the possibility of differentiating psychiatric outpatients into distinct, clinically relevant subgroups predicated on their suicide risk. This research potentially paves the way for personalizing interventions and preventive strategies that address cluster-specific characteristics, thereby mitigating suicide-related mortality among psychiatric outpatients.

Sleep Reactivity and Sleep Efforts in Shift Workers.

OBJECTIVE: The current study aimed to investigate the differences in sleep reactivity and sleep effort differs among late night shift workers (LSWs) and non-late night shift workers (non-LSWs), and non-shift workers (non-SWs). METHODS: In total, 6,023 participants (1,613 non-SWs, 3,339 LSWs, and 1,071 non-LSWs) were recruited. Non-SWs was defined as those who works at fixed schedules during standard daylight. LSWs was defined as who work late night hours (10 PM-6 AM), while non-LSWs was SWs who did not work during late night. All completed the Ford Insomnia Response to Stress Test (FIRST), the Glasgow Sleep Effort Scale (GSES), the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), the Insomnia Severity Index (ISI), and the short-term Center for Epidemiologic Studies-Depression scale (CES-D) through online survey. RESULTS: LSWs and non-LSWs reported higher FIRST, GSES scores than non-SWs. In addition, LSWs reported higher FIRST, GSES scores than non-LSWs. FIRST scores were correlated with CES-D, PSQI, ISI, and ESS for LSWs, non-LSWs, and non-SWs alike. GSES scores were also correlated with CES-D, PSQI, ISI, and ESS for LSWs, non-LSWs, and non-SWs alike. CONCLUSION: SWs showed higher sleep reactivity and sleep effort than non-SWs. LSWs had higher sleep reactivity and sleep effort than non-LSWs, and these variables are associated with insomnia, daytime sleepiness, and depressive symptoms. Our findings suggests that late night schedule, may increase sleep reactivity and sleep effort, which are associated with sleep and mood disturbances.

Effects of co-sleeping with a shift worker on sleep, mood and cognition.

Objective: Although the negative effects of shift work on workers' sleep and mood are well-known, the effects of shift work on their sleep partners' sleep and mood have rarely been investigated. The current study explored the effects of co-sleeping with a shift worker (SW) on the partner's subjective sleep quality, daytime sleepiness, depressive symptoms, and cognitive disturbances. Methods: Online sleep and work-environment self-report questionnaires (e.g., including the presence of co-sleepers, work schedules of the co-sleepers, and their work schedules) were administered. The questionnaires also included the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), the Cognitive Failures Questionnaire (CFQ), and the short-term Center for Epidemiologic Studies-Depression scale (CES-D). Participants consisted of co-sleepers of SWs (n = 657), co-sleepers of non-SWs (n = 2186), and solo sleepers (n = 2432). Results: Significant between-group differences in the PSQI, ESS, CFQ, and CES-D were observed after controlling for age, gender, work shift, and parenting (p < 0.001). Co-sleepers of SWs showed higher PSQI, ESS, CFQ, and CES-D scores than co-sleepers of non-SWs and solo sleepers. Solo sleepers reported significantly higher PSQI and CES-D scores than co-sleepers of non-SWs. The PSQI, ESS, CFQ, and CES-D scores were significantly correlated in all groups. The association between the ESS and PSQI was stronger in co-sleepers of SWs than in solo sleepers. The association between the ESS and CES-D was stronger in co-sleepers of SWs than in solo sleepers. Conclusions: Co-sleeping with SWs is associated with poor sleep quality, daytime sleepiness, depressive symptoms, and cognitive disturbances in the partner.

Circadian misalignment alters resting-state functional connectivity of the salience network in rotating shift workers.

STUDY OBJECTIVES: This study compared resting-state functional connectivity (rsFC) of the salience network (SN) between rotating shift workers (RSWs) and controls. Furthermore, we examined whether rsFC of the SN was correlated with sleep, emotion, cognition, and attention. METHODS: The 60 RSWs and 57 controls enrolled in this study completed self-report questionnaires and sleep diaries to assess subjective sleep quality, and polysomnography and actigraphy to evaluate objective sleep and 24-hour rest-activity rhythm parameters. The participants also underwent resting-state functional magnetic resonance imaging and structural T1 scans. We performed a seed-based rsFC analysis of the SN using the anterior cingulate cortex (ACC) and anterior insula (AI) as seed regions. Furthermore, AI and ACC rsFC were compared in RSWs and controls, and we analyzed correlations between rsFC and variables of interest showing significant group differences. RESULTS: Compared with controls, RSWs showed reduced rsFC between the ACC and right insula, and increased rsFC of the ACC with the left occipital lobe and right superior frontal gyrus extending to the supplementary motor area (SFG/SMA). Moreover, RSWs showed reduced rsFC between the right AI and right superior parietal lobule (SPL). Finally, rsFC between the ACC and right AI was correlated with 24-hour rest-activity rhythmicity. CONCLUSIONS: Although RSWs did not show sleep disturbance, emotional distress, cognitive impairment, or attention deficits, alterations of right insula, left occipital lobe, right SFG/SMA, and right SPL rsFC in the SN indicate that impairments in salience detection and top-down attentional control may emerge in shift workers over time.

Job burnout among workers with different shift regularity: interactive factors between sleep, depression, and work environment.

Object: We investigated burnout and associated factors in non-shift workers (NSWs), shift workers with regular rotating shifts (RRSWs), and shift workers with irregular or unpredictable rotating shifts (IRSWs). Methods: In total, 5,125 adult workers (1,966 NSWs, 1,936 RRSWs, and 1,223 IRSWs) participated in an online self-reported survey. Job burnout and three dimensions thereof (exhaustion, cynicism, and professional efficacy) were assessed using the Maslach Burnout Inventory-General Survey (MBI-GS). The Center for Epidemiological Studies Depression Scale (CES-D) (depressive symptoms), Pittsburgh Sleep Quality Index (PSQI) (subjective sleep quality), and Korean Occupational Stress Scale (KOSS) (stressful job environment) were also used. Results: Both types of shift workers scored higher in terms of exhaustion, cynicism, and poor professional efficacy on the MBI-GS compared with NSWs after controlling for age and gender. IRSWs exhibited higher scores on the exhaustion and professional efficacy dimensions of the MBI-GS compared with RRSWs. After controlling for the CES-D and PSQI scores, we found no significant difference in cynicism among the groups. After controlling for the KOSS score, we found no significant difference in professional efficacy. All MBI-GS dimensional scores were correlated significantly with the CES-D, PSQI, and KOSS scores in all three groups. Conclusion: The job burnout level of rotating shift workers, especially those with irregular shifts, was higher than that of other workers. Cynicism in shift workers may be largely attributable to poor sleep or depression; the poor efficacy of shift workers may be explained by their stressful work environment.

Fatigue and somatization in shift-workers: Effects of depression and sleep.

OBJECTIVE: We investigated the differences in fatigue and somatization between shift and non-shift workers and explored the effects of sleep and depression on fatigue and somatization in shift workers. METHODS: In total, 4543 shift workers and 2089 non-shift workers completed self-reported questionnaires. The Center for Epidemiologic Studies Depression Scale (CESD), Pittsburgh Sleep Quality Index (PSQI), Fatigue Severity Scale (FSS), and Somatization subscale of the Symptom Checklist 90-item version (SCL-SOM) were used to measure depression, sleep quality, fatigue, and somatization, respectively. Fatigue and somatization were compared between shift and non-shift workers after controlling for different sets of covariates. RESULTS: Compared to non-shift workers, shift workers reported higher FSS (mean difference: 2.19 ± 0.30, p < 0.01) and SCL-SOM (mean difference: 1.77 ± 0.21, p < 0.01) scores after controlling for age, gender, presence of medical illness, occupational category, monthly income, length of service, and weekly working hours. The between-group difference in FSS score was no longer significant after additionally controlling for CES-D (p = 0.15) or PSQI (p = 0.18). The between-group difference in SCL-SOM score showed only non-significant trends after additionally controlling for CES-D (p = 0.09) or PSQI (p = 0.07). The group difference in SCL-SOM scores disappeared after controlling for both CES-D and PSQI scores (p = 0.99). CONCLUSIONS: Shift workers had higher fatigue and somatization levels than non-shift workers and the group difference was associated with disturbed sleep and depressed mood in shift workers.

Effects of sleep and impulsivity on suicidality in shift and non-shift workers.

INTRODUCTION: Shift workers are known to have a higher suicide risk than non-shift workers. Sleep disturbance and impulsivity are also risk factors for suicidality. This study investigated the effects of poor sleep and impulsivity on suicidality in shift and non-shift workers. METHODS: In total, 4572 shift workers (37.0 ± 9.84 years, 2150 males) and 2093 non-shift workers (37.8 ± 9.73 years, 999 males) participated in an online self-report survey. Suicidality was assessed using the Suicidal Behaviors Questionnaire. The Pittsburgh Sleep Quality Index was employed to explore subjective sleep quality, the Insomnia Severity Index to detect insomnia, the Epworth Sleepiness Scale (ESS) to evaluate excessive daytime sleepiness (EDS), the Center for Epidemiological Studies-Depression (CES-D) Scale to assess depressive symptoms, and the Impulsive Behavior Scale (UPPS-P) to explore impulsivity. RESULTS: Shift workers showed poorer sleep quality, and greater impulsivity and suicidality, than non-shift workers. Impulsivity, sleep duration, sleep quality, and insomnia were significantly associated with suicidality, independent of depression. For both shift and non-shift workers, sleep quality moderated the association between impulsivity and suicidality. However, the moderating effects of sleep duration and EDS on the association between impulsivity and suicidality were apparent only in non-shift workers, while a moderating effect of insomnia was observed only in shift workers. CONCLUSION: Shift work, sleep disturbances and impulsivity may exacerbate suicide risk. In addition, the interrelationships among insomnia, EDS, impulsivity, and suicidality may differ between shift and non-shift workers.

The Influence of Life Stress and Sleep Disturbance on White Matter Integrity.

OBJECTIVE: This study investigated whether sleep and stress mutually interact to induce changes in white matter integrity. METHODS: Diffusion tensor imaging (DTI) was conducted on 36 participants (male=22, female=14; mean age=38.33±12.78 years). Participants were divided into three groups depending on their sleep quality and stress levels: poor sleepers with stress, poor sleepers without stress, and good sleepers. Sleep quality and stress level were evaluated using the Pittsburgh Sleep Quality Index and the Life Experiences Survey, respectively. Fractional anisotropy (FA) values were calculated employing DTI tractography. RESULTS: After controlling for age and sex, poor sleepers with stress exhibited a lower FA of the left inferior cerebellar peduncle (ICP) than did poor sleepers without stress (t=2.81, p=0.02). Poor sleepers without stress showed a higher FA of the right middle longitudinal fasciculus (MdLF) than did good sleepers (t=3.35, p=0.006). CONCLUSION: The current study reports the effects of sleep, stress, and their interaction on the white matter integrities of the ICP and MdLF. ICP change seems to be associated with sleep disturbances related to stress, while MdLF change would be associated with sleep disturbances unrelated to stress.

Sleep disturbances and depressive symptoms of shift workers: Effects of shift schedules.

This study explored sleep disturbances and depression among various types of shift workers (SWs) and non-SWs, focusing on work schedule diversity. We enrolled 6,654 adults (4,561 SWs, 2,093 non-SWs). Based on self-report questionnaires on work schedules, the participants were classified according to shift work type: non-shift work; and fixed evening, fixed night, regularly rotating, irregularly rotating, casual, and flexible shift work. All completed the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), and short-term Center for Epidemiologic Studies-Depression scale (CES-D). SWs reported higher PSQI, ESS, ISI, and CES-D than non-SWs. Fixed SWs (fixed evenings and fixed nights) and true SWs (regularly and irregularly rotating SWs) scored higher on the PSQI, ISI, and CES-D than non-SWs. True SWs scored higher on the ESS than fixed SWs and non-SWs. Among fixed SWs, fixed night SWs scored higher on the PSQI and ISI than fixed evening SWs. Among true SWs, irregular SWs (irregularly rotating and casual SWs) scored higher on the PSQI, ISI, and CES-D compared to regularly rotating SWs. The PSQI, ESS, and ISI independently were associated with the CES-D of all SWs. We found an interaction between the ESS and the work schedule on the one hand, and the CES-D on the other, which was stronger in SWs than non-SWs. Fixed night and irregular shifts were linked with sleep disturbances. The depressive symptoms of SWs are associated with sleep problems. The effects of sleepiness on depression were more prominent in SWs than non-SWs.

Neural activation underlying emotional interference of cognitive control in rotating shift workers: moderating effects of the prefrontal cortex response on the association between sleep disturbance and depressive symptoms.

STUDY OBJECTIVES: This study investigated the altered neural function involved in emotional interference and its role in linking sleep disturbance and depressive/anxiety symptoms in rotating shift workers. METHODS: Sixty rotating shift workers and 61 controls performed the emotional Stroop task in three blocks (emotional-related, sleep-related, and neutral words) during functional magnetic resonance imaging (fMRI) assessments. Sleep disturbance and depressive/anxiety symptoms were assessed using self-report measures and sleep diaries. Actigraphy was used to assess the sleep and circadian variables. fMRI scans were performed to compare brain activation during the emotional Stroop task. The proposed moderating models were tested using the PROCESS macro in SPSS software. RESULTS: A significant condition effect on reaction time was detected. Regardless of the group, reaction times were longer in the negative emotional word and sleep-related conditions than in the neutral word condition. Whole-brain analysis revealed that rotating shift workers show greater neural activation in the left dorsolateral prefrontal cortex (DLPFC) compared with controls while performing the emotional Stroop task with negative emotional words. Sleep disturbance was more strongly associated with depressive symptoms when activation of the left DLPFC was higher during the emotional Stroop task with negative words. CONCLUSIONS: The left DLPFC may play important roles in increased sensitivity to emotional information, possibly due to circadian misalignment, and has moderating effects on the association between sleep disturbance and depressive symptoms in rotating shift workers. These findings will help to identify possible brain regions where interventions can be performed to correct sleep and mood problems in rotating shift workers.

Cognitive Appraisal of Sleep and Brain Activation in Response to Sleep-Related Sounds in Healthy Adults.

Purpose: Sounds play important roles in promoting and disrupting sleep. How our brain processes sleep-related sounds and individual differences in processing sleep-related sounds must be determined to understand the role of sound in sleep. We investigated neural responses to sleep-related sounds and their associations with cognitive appraisals of sleep. Participants and Methods: Forty-four healthy adults heard sleep-related and neutral sounds during functional magnetic resonance imaging using a 3T scanner. They also completed the Dysfunctional Beliefs and Attitudes about Sleep (DBAS) questionnaire, which was used to assess cognitive appraisals of sleep. We conducted a voxel-wise whole-brain analysis to compare brain activation in response to sleep-related and neutral sounds. We also examined the association between the DBAS score and brain activity in response to sleep-related sounds (vs neutral sounds) using region of interest (ROI) and whole-brain correlation analyses. The ROIs included the anterior cingulate cortex (ACC), anterior insula (AI), and amygdala. Results: The whole-brain analysis revealed increased activation in the temporal regions and decreased activation in the ACC in response to sleep-related sounds compared to neutral sounds. The ROI and whole-brain correlation analyses showed that higher DBAS scores, indicating a negative appraisal of sleep, were significantly correlated with increased activation of the ACC, right medial prefrontal cortex, and brainstem in response to sleep-related sounds. Conclusion: These results indicate that the temporal cortex and ACC, which are implicated in affective sound processing, may play important roles in the processing of sleep-related sounds. The positive association between the neural responses to sleep-related sounds and DBAS scores suggest that negative and dysfunctional appraisals of sleep may be an important factor in individual differences in the processing of sleep-related sounds.

Evidence of White Matter Integrity Changes in the Anterior Cingulum Among Shift Workers: A Cross-Sectional Study.

Introduction: We investigated the white matter integrity in shift and non-shift workers and its associations with sleep and activity. Methods: Diffusion tensor imaging (DTI) was performed on 61 shift workers and 31 non-shift workers. Their sleep and activity profiles were assessed using the Pittsburgh Sleep Quality Index (PSQI), sleep diaries, and actigraphy. Fractional anisotropy (FA) (a measure of white matter integrity) was calculated using DTI tractography. Results: Shift workers exhibited higher FA values in the bilateral anterior cingulum than did non-shift workers. An increased FA in the right anterior cingulum was correlated with poor sleep quality (ie, a high PSQI score) in shift workers. An increased FA in the right anterior cingulum was also correlated with higher actigraphic activity indices (the mesor and M10 indices) in shift workers. Discussion: The white matter integrity of the anterior cingulum was altered in shift workers, perhaps in association with sleep and activity disturbances.

Gray Matter Volume of Thalamic Nuclei in Traumatized North Korean Refugees.

The current study investigated differences in the regional gray matter (GM) volume of specific thalamic nuclei between North Korean (NK) refugees and South Korean (SK) residents. It also investigated associations between thalamic GM volume changes and psychological symptoms. Psychological evaluations and magnetic resonance imaging were conducted on 50 traumatized NK refugees and 55 non-traumatized SK residents. The regional GM volume ratios in the bilateral thalami were calculated for all participants using voxel-based morphometry. NK refugees showed greater GM volume ratios in the right medial-posterior nuclei and left medial nuclei compared with SK residents. NK refugees also exhibited more depressive symptoms than SK residents. However, increased GM volume ratios in both right medial-posterior nuclei and left medial nuclei were correlated with fewer depressive symptoms in NK refugees, but not in SK residents. The findings indicate that traumatized NK refugees had increased GM volumes in the right medial-posterior nuclei and left medial nuclei, which were associated with fewer depressive symptoms. The enlarged specific thalamic nuclei presented among refugees in the current study might be associated with a neurobiological compensatory mechanism that prevents the development or progression of depression in refugees after repetitive traumatic experiences.

Life stress, sleep disturbance and depressive symptoms: The moderating role of prefrontal activation during emotion regulation.

OBJECTIVES: Evidence suggests that emotion regulation difficulty may play an important role in the association between life stress, sleep disturbance and depressive symptoms. We proposed two models depicting the possible moderating roles of prefrontal cortex activation during emotion regulation in the associations among these variables and tested them. We hypothesized that (1) the association between stress and sleep disturbance would differ across prefrontal cortex activation during emotion regulation (moderation model) and (2) the indirect effects of stress on depressive symptoms through sleep disturbance would depend on prefrontal cortex activation during emotion regulation (moderated mediation model). METHODS: Forty-eight healthy adults without sleep disorders based on nocturnal polysomnography participated in this study. They received functional magnetic resonance imaging scans while performing an emotion regulation task. They also completed questionnaires assessing life stress, sleep disturbance and depressive symptoms. The proposed models were tested using the PROCESS macro for SPSS. RESULTS: As hypothesized, there was a significant moderating effect of prefrontal cortex activation during emotion regulation on the association between life stress and sleep disturbance. Furthermore, right lateral prefrontal cortex activation had a moderating role in the indirect effect of life stress on depressive symptoms through sleep disturbance. CONCLUSION: These findings highlight the important role of prefrontal cortex function during emotion regulation in the associations between stress, sleep disturbance and depressive symptoms. Increasing lateral prefrontal cortex recruitment when regulating the emotional response to negative life events may be critical for the prevention and intervention of depression as well as sleep problems.

Negative life stress, sleep disturbance, and depressive symptoms: The moderating role of anterior insula activity in response to sleep-related stimuli.

BACKGROUND: This study investigated the effects of anterior insula (AI) activation on the association between stress and sleep disturbance as a neurobiological basis of the trait-like degree of sleep reactivity to stress. Additionally, it examined the effects of AI activity on the association between sleep disturbance and depression. METHODS: The participants were 48 adults. To assess AI activation in response to sleep-related stimuli (SS) compared to neutral stimuli (NS), we extracted mean AI parameter estimates for the SS-NS contrast. We examined whether the interaction between life stress and AI activation would predict sleep disturbance and whether the interaction between sleep disturbance and AI activation would predict depression. RESULTS: At higher levels of bilateral AI activation in response to SS, higher levels of stress were associated with greater sleep disturbance (left AI x stress: b = 1.07, SE = 0.44, p < 0.05; right AI x stress: b = 1.05, SE = 0.48, p < 0.05). In addition, at higher levels of right AI activation, higher levels of sleep disturbance were associated with more severe depressive symptoms (right AI x sleep disturbance: b = 2.55, SE = 1.10, p < 0.05). LIMITATION: This study assessed sleep quality and depressive symptoms based on self-reported questionnaires. CONCLUSION: This study revealed moderating effects of AI activation on the association between negative life stress and sleep disturbance. Additionally, AI activation strengthened the association between sleep disturbance and depression. AI activation may reflect a crucial etiological diathesis for insomnia and stress-related disorders.