Multi-proteomic analyses of 5xFAD mice reveal new molecular signatures of early-stage Alzheimer's disease.

An early diagnosis of Alzheimer's disease is crucial as treatment efficacy is limited to the early stages. However, the current diagnostic methods are limited to mid or later stages of disease development owing to the limitations of clinical examinations and amyloid plaque imaging. Therefore, this study aimed to identify molecular signatures including blood plasma extracellular vesicle biomarker proteins associated with Alzheimer's disease to aid early-stage diagnosis. The hippocampus, cortex, and blood plasma extracellular vesicles of 3- and 6-month-old 5xFAD mice were analyzed using quantitative proteomics. Subsequent bioinformatics and biochemical analyses were performed to compare the molecular signatures between wild type and 5xFAD mice across different brain regions and age groups to elucidate disease pathology. There was a unique signature of significantly altered proteins in the hippocampal and cortical proteomes of 3- and 6-month-old mice. The plasma extracellular vesicle proteomes exhibited distinct informatic features compared with the other proteomes. Furthermore, the regulation of several canonical pathways (including phosphatidylinositol 3-kinase/protein kinase B signaling) differed between the hippocampus and cortex. Twelve potential biomarkers for the detection of early-stage Alzheimer's disease were identified and validated using plasma extracellular vesicles from stage-divided patients. Finally, integrin α-IIb, creatine kinase M-type, filamin C, glutamine γ-glutamyltransferase 2, and lysosomal α-mannosidase were selected as distinguishing biomarkers for healthy individuals and early-stage Alzheimer's disease patients using machine learning modeling with approximately 79% accuracy. Our study identified novel early-stage molecular signatures associated with the progression of Alzheimer's disease, thereby providing novel insights into its pathogenesis.

Differentiation between suicide attempt and suicidal ideation in patients with major depressive disorder using cortical functional network.

Studies exploring the neurophysiology of suicide are scarce and the neuropathology of related disorders is poorly understood. This study investigated source-level cortical functional networks using resting-state electroencephalography (EEG) in drug-naïve depressed patients with suicide attempt (SA) and suicidal ideation (SI). EEG was recorded in 55 patients with SA and in 54 patients with SI. Particularly, all patients with SA were evaluated using EEG immediately after their SA (within 7 days). Graph-theory-based source-level weighted functional networks were assessed using strength, clustering coefficient (CC), and path length (PL) in seven frequency bands. Finally, we applied machine learning to differentiate between the two groups using source-level network features. At the global level, patients with SA showed lower strength and CC and higher PL in the high alpha band than those with SI. At the nodal level, compared with patients with SI, patients with SA showed lower high alpha band nodal CCs in most brain regions. The best classification performances for SA and SI showed an accuracy of 73.39%, a sensitivity of 76.36%, and a specificity of 70.37% based on high alpha band network features. Our findings suggest that abnormal high alpha band functional network may reflect the pathophysiological characteristics of suicide and serve as a clinical biomarker for suicide.

Machine learning-based classification using electroencephalographic multi-paradigms between drug-naïve patients with depression and healthy controls.

BACKGROUND: Electroencephalography (EEG) is a supplementary diagnostic tool in psychiatry but lacks practical usage. EEG has demonstrated inconsistent diagnostic ability because major depressive disorder (MDD) is a heterogeneous psychiatric disorder with complex pathologies. In clinical psychiatry, it is essential to detect these complexities using multiple EEG paradigms. Though the application of machine learning to EEG signals in psychiatry has increased, an improvement in its classification performance is still required clinically. We tested the classification performance of multiple EEG paradigms in drug-naïve patients with MDD and healthy controls (HCs). METHODS: Thirty-one drug-naïve patients with MDD and 31 HCs were recruited in this study. Resting-state EEG (REEG), the loudness dependence of auditory evoked potentials (LDAEP), and P300 were recorded for all participants. Linear discriminant analysis (LDA) and support vector machine (SVM) classifiers with t-test-based feature selection were used to classify patients and HCs. RESULTS: The highest accuracy was 94.52 % when 14 selected features, including 12 P300 amplitudes (P300A) and two LDAEP features, were layered. The accuracy was 90.32 % when a SVM classifier for 30 selected features (14 P300A, 14 LDAEP, and 2 REEG) was layered in comparison to each REEG, P300A, and LDAEP, the best accuracies of which were 71.57 % (2-layered with LDA), 87.12 % (1-layered with LDA), and 83.87 % (6-layered with SVM), respectively. LIMITATIONS: The present study was limited by small sample size and difference in formal education year. CONCLUSIONS: Multiple EEG paradigms are more beneficial than a single EEG paradigm for classifying drug-naïve patients with MDD and HCs.

Association between the loudness dependence of auditory evoked potentials and age in patients with schizophrenia and depression.

OBJECTIVE: Although serotonergic dysfunction is significantly associated with major depressive disorder (MDD) and schizophrenia (SCZ), comparison of serotonergic dysfunction in both diseases has received little attention. Serotonin hypotheses have suggested diminished and elevated serotonin activity in MDD and SCZ, respectively. However, the foundations underlying these hypotheses are unclear regarding changes in serotonin neurotransmission in the aging brain. The loudness dependence of auditory evoked potentials (LDAEP) reflects serotonin neurotransmission. The present study compared the LDAEP between patients with SCZ or MDD and healthy controls (HCs). We further examined whether age was correlated with the LDAEP and clinical symptoms. METHODS: This prospective clinical study included 105 patients with SCZ (n = 54) or MDD (n = 51). Additionally, 35 HCs were recruited for this study. The LDAEP was measured on the midline channels via 62 electroencephalography channels. RESULTS: Patients with SCZ or MDD showed a significantly smaller mean LDAEP than those in HCs. The LDAEP was positively correlated with age in patients with SCZ or MDD. CONCLUSIONS: Changes in central serotonergic activity could be indicated by evaluating the LDAEP in patients with SCZ or MDD. Age-related reductions in serotonergic activity may be screened using the LDAEP in patients with SCZ or MDD.

Effect of Self-administered Transcranial Direct Stimulation in Patients with Major Depressive Disorder: A Randomized, Single-blinded Clinical Trial.

OBJECTIVE: In numerous studies that have addressed transcranial direct current stimulation (tDCS) devices, participants visit the hospital regularly and undergo stimulation directed by health professionals. This method has the advantage of being able to deliver accurate stimuli in a controlled environment, but it does not adopt the merits of tDCS portability and applicability. Thus, it may be necessary to investigate how self-administered tDCS treatment at home affects depression- related symptoms. METHODS: In this randomized, single-blinded clinical trial, 58 patients with major depressive disorder were assigned to active and sham tDCS stimulation groups, and treatment responses were evaluated biweekly over six weeks. Both active and sham tDCS treatment group were treated with escitalopram. All participants were instructed the protocol and usage of at-home tDCS device, and self-administered tDCS treatment at their home. RESULTS: The beck-depression inventory score decreased significantly as treatment progressed, and the degree of symptom improvement was significantly higher in the active group than in the sham tDCS group. There were no significant differences between the two groups in other indices, including the Hamilton Depression Scale. CONCLUSION: These results suggest that patient-administered tDCS treatment might be effective in improving subjective symptoms of depression.

Machine Learning-Based Electroencephalographic Phenotypes of Schizophrenia and Major Depressive Disorder.

Background: Psychiatric diagnosis is formulated by symptomatic classification; disease-specific neurophysiological phenotyping could help with its fundamental treatment. Here, we investigated brain phenotyping in patients with schizophrenia (SZ) and major depressive disorder (MDD) by using electroencephalography (EEG) and conducted machine-learning-based classification of the two diseases by using EEG components. Materials and Methods: We enrolled healthy controls (HCs) (n = 30) and patients with SZ (n = 34) and MDD (n = 33). An auditory P300 (AP300) task was performed, and the N1 and P3 components were extracted. Two-group classification was conducted using linear discriminant analysis (LDA) and support vector machine (SVM) classifiers. Positive and negative symptoms and depression and/or anxiety symptoms were evaluated. Results: Considering both the results of statistical comparisons and machine learning-based classifications, patients and HCs showed significant differences in AP300, with SZ and MDD showing lower N1 and P3 than HCs. In the sum of amplitudes and cortical sources, the findings for LDA with classification accuracy (SZ vs. HCs: 71.31%, MDD vs. HCs: 74.55%), sensitivity (SZ vs. HCs: 77.67%, MDD vs. HCs: 79.00%), and specificity (SZ vs. HCs: 64.00%, MDD vs. HCs: 69.67%) supported these results. The SVM classifier showed reasonable scores between SZ and HCs and/or MDD and HCs. The comparison between SZ and MDD showed low classification accuracy (59.71%), sensitivity (65.08%), and specificity (54.83%). Conclusions: Patients with SZ and MDD showed deficiencies in N1 and P3 components in the sum of amplitudes and cortical sources, indicating attentional dysfunction in both early and late sensory/cognitive gating input. The LDA and SVM classifiers in the AP300 are useful to distinguish patients with SZ and HCs and/or MDD and HCs.

Comparison of frontal alpha asymmetry among schizophrenia patients, major depressive disorder patients, and healthy controls.

BACKGROUND: Electroencephalography (EEG) frontal alpha asymmetry (FAA) has been observed in several psychiatric disorders. Dominance in left or right frontal alpha activity remains inconsistent in patients with major depressive disorder (MDD), patients with schizophrenia, and healthy controls. This study compared FAA among patients with MDD and schizophrenia, and healthy controls. METHODS: We recruited 20 patients with MDD, 18 patients with schizophrenia, and 16 healthy individuals. The EEG alpha frequency ranged from 8 Hz to 12 Hz. FAA was expressed as the difference between absolute power values of right and left hemisphere electrodes in the alpha frequency range (common-log-transformed frontal right- and left-hemisphere electrodes: F4-F3, F8-F7, FP2-FP1, AF4-AF3, F6-F5, and F2-F1). Hamilton depression and anxiety rating scales were evaluated in patients with MDD. Positive and negative syndrome scales were evaluated in patients with schizophrenia. RESULTS: Patients with schizophrenia showed significantly lower left FAA than healthy controls (F4-F3, schizophrenia vs. healthy controls: - 0.10 ± 0.04 vs. -0.05 ± 0.05). There were no significant differences in FAA between patients with schizophrenia and MDD as well as between patients with MDD and healthy controls. CONCLUSIONS: The present study suggests that FAA indicates a relatively lower activation of left frontal electrodes in schizophrenia. The left-lateralized FAA could be a neuropathological attribute in patients with schizophrenia, but a lack of sample size and information such as medication and duration of illness might obscure the interpretation and generalization of our findings. Thus, further studies to verify the findings would be warranted.

A direct comparison of the electrophysiological effects of transcranial direct and alternating current stimulation in healthy subjects.

OBJECTIVE: Despite the clinical effectiveness of transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), the comparability of these interventions in neurophysiological aspects have not been thoroughly investigated. Thus, we aimed to directly compare the electrophysiological effects of single-session tDCS and gamma-tACS in healthy subjects, matching the intervention protocol as closely as possible. METHODS: This was a randomized, double-blinded, and active-controlled study. Sixty healthy college students were enrolled in the study. Both tACS with, at 40 Hz frequency, and tDCS have the same current intensity (2 mA, 30 min) within the same target area (right and left dorsolateral prefrontal cortex). Resting-state electroencephalography (EEG) was recorded before and after single-session stimulation. RESULTS: Significant differences in theta, alpha, low-beta, and gamma frequencies were found between tDCS, tACS, and the sham groups. Low-beta source activity of the middle temporal gyrus was decreased only after an intervention with tACS. CONCLUSION: The present study indicates that tDCS and tACS resulted in an increased range of frequency activity, including slow- and fast-wave bands. Specifically, tDCS modulates the frontal region, while tACS modulates neural oscillations at the fronto-central, parietal, and temporal areas. The tACS also decreased low-beta source activity in the middle temporal gyrus. Identifying the common and unique EEG patterns of tDCS and tACS may help shed light on their potential clinical benefits and distinctive neuropathology in various clinical symptoms.

Heart and Brain Interaction of Psychiatric Illness: A Review Focused on Heart Rate Variability, Cognitive Function, and Quantitative Electroencephalography.

Heart rate variability (HRV) reflects beat-to-beat variability in the heart rate due to the dynamic interplay of the sympathetic and parasympathetic nervous systems. HRV is considered an index of the functional status of the autonomic nervous system. A decrease in HRV is thus observed in individuals with autonomic dysfunction. Abnormal HRV has been reported in a range of mental disorders. In this review, we give an overview of HRV in patients with major depressive disorder (MDD), schizophrenia, and posttraumatic stress disorder (PTSD), one of whose core symptoms is cognitive dysfunction. The association between HRV and cognitive function is highlighted in this review. This review consists of three main sections. In the first section, we examine how HRV in patients with MDD, schizophrenia, and PTSD is characterized, and how it is different when compared to that in healthy controls. In the second section, beyond the heart itself, we discuss the intimate connection between the heart and the brain, focusing on how HRV interacts with quantitative electroencephalography (qEEG) in the context of physiological changes in the sleep cycle. Lastly, we finish the review with the examination of the association between HRV and cognitive function. The overall findings indicate that the reduction in HRV is one of main manifestations in MDD, schizophrenia, and PTSD, and also more generally HRV is closely linked to the change in qEEG and also to individual differences in cognitive performance.

Changes in Global and Nodal Networks in Patients With Unipolar Depression After 3-Week Repeated Transcranial Magnetic Stimulation Treatment.

Objectives: Repeated transcranial magnetic stimulation (rTMS) therapy has been applied in depressive disorders, but its neurobiological effect has not been well understood. Changes in cortical source network after treatment need to be confirmed. The present study investigated the effect of 3-week rTMS therapy on the symptom severity and cortical source network in patients with unipolar depression. Methods: Thirty-five patients with unipolar major depressive disorder participated in the study. High-frequency (10 Hz) rTMS was applied at the left dorsolateral prefrontal cortex during 3 weeks (five consecutive weekdays every week). Clinical symptoms were examined using the Hamilton Rating Scale for Depression and Anxiety. The resting state electroencephalography was recorded with 62 scalp channels before and after rTMS treatment. Results: Clinical symptoms significantly improved after rTMS treatment in both the active (p = 0.001) and sham groups (p = 0.002). However, an increased cortical source network in global and nodal levels was observed only in the active group after a 3-week treatment. Conclusions: The present study indicates that rTMS treatment leads to improved symptoms in patients with unipolar depression. Furthermore, treatment outcome of real effect was assured in changes of cortical source network.

The Efficacy of Miniaturized Repetitive Transcranial Magnetic Stimulation in Patients with Depression.

OBJECTIVE: The present study aimed to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) at a high frequency using a miniaturized device compared to standard rTMS and sham rTMS for the treatment of depression. METHODS: Fifty-four patients with depression were randomly assigned to either 15 days of miniaturized, standard, or sham rTMS. The stimulation consisted of 60 trains of 5 seconds at 10 Hz for 30 minutes. Clinical measures were assessed at baseline and on the final day of the stimulation. RESULTS: A repeated-measures analysis of variance revealed a significant main effect of time and a time by group interaction on Hamilton Rating Scale for Depression scores. There were no significant correlations between individual motor thresholds and changes of clinical outcomes. Our results revealed a significant reduction in the Hamilton Rating Scale for Depression in the miniaturized and standard groups compared to the sham group. CONCLUSION: The antidepressant utility of miniaturized rTMS using subthreshold stimulation was comparable to that of standard stimulation.

Three Weeks of rTMS Treatment Maintains Clinical Improvement But Not Electrophysiological Changes in Patients With Depression: A 6-Week Follow-Up Pilot Study.

Our previous study demonstrated that 3 weeks of repetitive transcranial magnetic stimulation (rTMS) increases P200 amplitudes and improves the symptoms of depression and anxiety in depression patients. In the present study, we investigated whether 3 weeks of rTMS treatment maintained the P200 amplitude in patients with depression at 6 weeks of follow-up. We measured the 6-week maintenance effects of rTMS using clinical questionnaires and an auditory oddball paradigm. Twenty-one patients with medication-resistant major depression participated in this pilot study. All patients underwent rTMS treatment for 3 weeks; they completed clinical ratings and performed the auditory oddball task at the pre-treatment, post-treatment, and 6-week follow-up visit (3 weeks after finishing rTMS treatment). The results revealed an increase in P200 amplitudes as well as improvements in the symptoms of depression and anxiety by 3 weeks of rTMS treatment. Furthermore, the results demonstrated maintenance effects on clinical ratings at 6-week follow-up. Depression and anxiety scales showed improvements in post-treatment and maintenance effects at the 6-week follow-up. Although P200 amplitude showed a significant main effect for 3 time points (baseline, post-treatment, and 6-week follow-up visit), at 2 time point comparisons, P200 amplitudes significantly increased in post-treatment compared to those of the baseline condition but did not show the maintenance effects of long-term rTMS at the 6-week follow-up compared to those of the baseline condition (  p = .173, Bonferroni correction). Standardized low-resolution brain electromagnetic tomography (sLORETA) for P200 showed significant activation in the left middle frontal gyrus in post-treatment but no significant activation at the 6-week follow-up. Moreover, the amplitudes of overall topographic distribution were reduced at 6 weeks of follow-up. The 3 weeks of rTMS treatment induced the maintenance of the improvements in the symptoms of depression and anxiety. However, considering the results of the event-related potential (ERP) and sLORETA, 3 weeks of rTMS treatment may not be sufficient to maintain this improvement, implying that a treatment period of more than 3 weeks may be required to reveal the electrophysiological maintenance effect of rTMS.

Unsuccessful reduction of high-frequency alpha activity during cognitive activation in schizophrenia.

AIMS: Electroencephalogram (EEG) alpha activity during resting state reflects the 'readiness' of an individual to respond to the environment; this includes the performance of cognitive processes. Alpha activity is reported to be attenuated in schizophrenia (SCZ). Understanding the interaction between alpha activity during rest and when cognitively engaged may provide insights into the neural circuitry, which is dysfunctional in SCZ. This study investigated the changes of alpha activity between resting state and cognitive engagement in SCZ patients. METHODS: Thirty-four SCZ patients and 29 healthy controls (HC) were recruited. EEG was performed in the resting state and during an auditory P300 task. All experimental procedures followed the relevant institutional guidelines and regulations. RESULTS: In SCZ, high-frequency alpha activity was reduced in the resting state. High-frequency alpha source density was decreased in both the resting-state and a P300 task condition in patients, compared to HC. HC, but not SCZ patients, showed a reduction in high-frequency alpha source density during the P300 task compared to the resting state. The negative correlation between high-frequency alpha source density in the resting state and positive symptoms was significant. CONCLUSIONS: High-frequency alpha activity in SCZ patients and its unsuccessful reduction during cognitive processing may be biological markers of SCZ.

Mismatch Negativity and Cortical Thickness in Patients With Schizophrenia and Bipolar Disorder.

INTRODUCTION: Mismatch negativity (MMN) is a measure of automatic neurophysiological brain processes for detecting unexpected sensory stimuli. This study investigated MMN reduction in patients with schizophrenia and bipolar disorder and examined whether cortical thickness is associated with MMN, for exploratory purposes. METHODS: Electroencephalograms were recorded in 38 patients with schizophrenia, 37 patients with bipolar disorder, and 32 healthy controls (HCs) performing a passive auditory oddball paradigm. All participants underwent T1 structural magnetic resonance imaging scanning to investigate the cortical thickness of MMN-generating regions. Average MMN amplitudes from the frontocentral electrodes were analyzed. RESULTS: Patients with schizophrenia and bipolar disorder exhibited significantly reduced MMN amplitude compared with HCs. In bipolar disorder, we found intermediate MMN amplitude among the groups. Average MMN and cortical thickness of the right superior temporal gyrus (STG) were significantly negatively correlated in patients with schizophrenia. In patients with bipolar disorder, average MMN was significantly correlated with cortical thickness of the left anterior cingulate cortex and the right STG. MMN showed negative correlations with social and occupational functioning in schizophrenia, and with the Korean auditory verbal learning test for delayed recall in bipolar disorder. CONCLUSIONS: MMN reduction was associated with cortical thinning in frontal and temporal areas in patients, particularly with an auditory verbal hallucination-related region in schizophrenia and emotion-related regions in bipolar disorder. MMN was associated with functional outcomes in schizophrenia, whereas it was associated with neurocognition in bipolar disorder.

Frontal Alpha Asymmetry, Heart Rate Variability, and Positive Resources in Bereaved Family Members with Suicidal Ideation after the Sewol Ferry Disaster.

OBJECTIVE: After the Sewol ferry disaster, bereavement with suicidal ideation was a critical mental health problem that was accompanied by various neuropsychological symptoms. This study examined the frontal alpha asymmetry (FAA), heart rate variability (HRV), and several psychological symptoms in bereaved family members (BFM) after the Sewol ferry disaster. METHODS: Eighty-three BFM after the Sewol ferry disaster were recruited. We assessed FAA, HRV, and psychological symptoms, including depression, post-traumatic stress, post-traumatic growth factor, anxiety, grief, and positive resources, between BFM with the presence and absence of current suicidal ideation. RESULTS: Compared to BFM without suicidal ideation, BFM with suicidal ideation showed a higher FAA with right dominance. Significant differences in psychological symptoms were observed between the groups. In BFM with suicidal ideation, the low: high frequency (LF:HF) ratio correlated with social resources and support. CONCLUSION: The FAA and LF:HF ratio may be biomarkers that represent the pathological conditions of BFM with suicidal ideation. If researched further, they may shed light on the interaction between bereavement with suicidal ideation and social resources for therapeutic intervention.

Association of the loudness dependence of auditory evoked potentials with clinical changes to repetitive transcranial magnetic stimulation in patients with depression.

BACKGROUND: Although the application of repetitive transcranial magnetic stimulation (rTMS) for treatment of depression has been well investigated, there are few biological predictors of clinical outcomes to rTMS treatment. Previous studies have suggested that the loudness dependence of auditory evoked potentials (LDAEP) can be used as a predictor of response to antidepressant treatment. However, little is known about the association between rTMS and LDAEP. The present study aimed to investigate whether baseline LDAEP is associated with clinical changes to rTMS treatment in patients with major depressive disorder (MDD), and to explore the effect of high-frequency rTMS on LDAEP. METHODS: Thirty patients were randomized to receive 15 sessions of active (n = 15) or sham rTMS (n = 15). LDAEP and clinical measures of depression were assessed before and after 10 Hz rTMS treatment for 15 days. RESULTS: Baseline LDAEP was associated with changes in scores on the Hamilton Rating Scale for Depression. There were no significant effects of rTMS on LDAEP. Patients with high LDAEP exhibited more favorable clinical changes than those with low LDAEP following treatment with rTMS. LIMITATIONS: The sample was relatively small, and the participants were not divided into responders and non-responders group due to small sample. An influence of medication has not been controlled. CONCLUSIONS: Our findings suggest that high baseline LDAEP may be associated with favorable clinical changes to rTMS treatment in patients with MDD. Further studies are required to replicate and validate the potential use of LDAEP as a predictor of clinical changes to rTMS treatment.

Heart rate variability associated with posttraumatic stress disorder in victims' families of sewol ferry disaster.

Posttraumatic stress disorder (PTSD), which is caused by a major traumatic event, has been associated with autonomic nervous function. However, there have been few explorations of measuring biological stress in the victims' family members who have been indirectly exposed to the disaster. Therefore, this longitudinal study examined the heart rate variability (HRV) of the family members of victims of the Sewol ferry disaster. We recruited 112 family members of victims 18 months after the disaster. Sixty-seven participants were revisited at the 30 months postdisaster time point. HRV and psychiatric symptoms including PTSD, depression and anxiety were evaluated at each time point. Participants with PTSD had a higher low frequency to high frequency ratio (LF:HF ratio) than those without PTSD. Logistic regression analysis showed that the LF:HF ratio at 18 months postdisaster was associated with a PTSD diagnosis at 30 months postdisaster. These results suggest that disrupted autonomic nervous system functioning for longer than a year after trauma exposure contributes to predicting PTSD vulnerability. Our finding may contribute to understand neurophysiologic mechanisms underlying secondary traumatic stress. Future studies will be needed to clarify the interaction between autonomic regulation and trauma exposure.

Heightened aversion to risk and loss in depressed patients with a suicide attempt history.

Suicide attempters have been found to be impaired in decision-making; however, their specific biases in evaluating uncertain outcomes remain unclear. Here we tested the hypothesis that suicidal behavior is associated with heightened aversion to risk and loss, which might produce negative predictions about uncertain future events. Forty-five depressed patients with a suicide attempt history, 47 nonsuicidal depressed patients, and 75 healthy controls participated in monetary decision-making tasks assessing risk and loss aversion. Suicide attempters compared with the other groups exhibited greater aversion to both risk and loss during gambles involving potential loss. Risk and loss aversion correlated with each other in the depressed patients, suggesting that a common pathophysiological mechanism underlies these biases. In addition, emotion regulation via suppression, a detrimental emotional control strategy, was positively correlated with loss aversion in the depressed patients, also implicating impairment in regulatory processes. A preliminary fMRI study also found disrupted neural responses to potential gains and losses in the subgenual anterior cingulate cortex, insula cortex, and left amygdala, brain regions involved in valuation, emotion reactivity, and emotion regulation. The findings thus implicate heightened negative valuation in decision-making under risk, and impaired emotion regulation in depressed patients with a history of suicide attempts.

Increased beta power in the bereaved families of the Sewol ferry disaster: A paradoxical compensatory phenomenon? A two-channel electroencephalography study.

AIM: The Sewol ferry capsizing accident on South Korea's southern coast resulted in the death of 304 people, and serious bereavement problems for their families. Electroencephalography (EEG) beta frequency is associated with psychiatric symptoms, such as insomnia. The aim of this study was to investigate the relation between frontal beta power, psychological symptoms, and insomnia in the bereaved families. METHODS: Eighty-four family members of the Sewol ferry victims (32 men and 52 women) were recruited and their EEG was compared with that of 25 (13 men and 12 women) healthy controls. A two-channel EEG device was used to measure cortical activity in the frontal lobe. Symptom severity of insomnia, post-traumatic stress disorder, complicated grief, and anxiety were evaluated. RESULTS: The bereaved families showed a higher frontal beta power than healthy controls. Subgroup analysis showed that frontal beta power was lower in the individuals with severe insomnia than in those with normal sleep. There was a significant inverse correlation between frontal beta power and insomnia symptom in the bereaved families. CONCLUSION: This study suggests that increased beta power, reflecting the psychopathology in the bereaved families of the Sewol ferry disaster, may be a compensatory mechanism that follows complex trauma. Frontal beta power could be a potential marker indicating the severity of sleep disturbances. Our results suggest that sleep disturbance is an important symptom in family members of the Sewol ferry disaster's victims, which may be screened by EEG beta power.

Electroencephalographic Correlates of Suicidal Ideation in the Theta Band.

Previous studies have indicated that the abnormalities of brain activity are associated with suicidal behavior. However, few studies have explored neurophysiologic biomarkers of suicidal ideation (SI) in healthy subjects. Here, we studied alterations of theta quantitative EEG (QEEG) in frontal regions associated with SI in young healthy subjects. Resting QEEG data were recorded from 90 young healthy subjects. The subjects were divided into two group based on Scale for Suicidal Ideation (SSI) scores: a high SSI group (n = 33) and a low SSI group (n = 57). Individual frontal electrodes (Fp1, Fp2, F7, F3, Fz, F4, F8) and central midline electrodes (FCz, Cz) were examined for absolute and relative power in the theta band. Clinical state and social support was assessed using the Hospital Anxiety and Depression Scale and Functional Social Support Questionnaire. We found that theta absolute and relative power in all channels was positively correlated with SSI, except Fp1, F7 and F8. The high SSI group showed higher theta relative power at F3, Fz, FCz, and Cz than the low SSI group. Theta relative power in the fronto-central region was significantly increased in the high SSI group compared to that in the low SSI group. Hierarchical regression analysis showed that SSI score was the most powerful predictor of fronto-central theta power. The findings suggest that brain electrical activity at the fronto-central region may be associated with differences in SI in young healthy subjects. EEG activity in theta band has clinical potential as a biomarker for preventing suicide.