Reduced left precentral regional responses in patients with major depressive disorder and history of suicide attempts

Discriminative analysis of schizophrenia and major depressive disorder using fNIRS

BACKGROUND

Research into the shared and distinct brain dysfunctions in patients with schizophrenia (SCZ) and major depressive disorder (MDD) has been increasing. However, few studies have explored the application of functional near-infrared spectroscopy (fNIRS) in investigating brain dysfunction and enhancing diagnostic methodologies in these two conditions.

METHODS

A general linear model was used for analysis of brain activation following task-state fNIRS from 131 patients with SCZ, 132 patients with MDD and 130 healthy controls (HCs). Subsequently, seventy-seven time-frequency analysis methods were used to construct new features of fNIRS, followed by the implementation of five machine learning algorithms to develop a differential diagnosis model for the three groups. This model was evaluated by comparing it to both a diagnostic model relying on traditional fNIRS features and assessments made by two psychiatrists.

RESULTS

Brain activation analysis revealed significantly lower activation in Broca's area, the dorsolateral prefrontal cortex, and the middle temporal gyrus for both the SCZ and MDD groups compared to HCs. Additionally, the SCZ group exhibited notably lower activation in the superior temporal gyrus and the subcentral gyrus compared to the MDD group. When distinguishing among the three groups using independent validation datasets, the models utilizing new fNIRS features achieved an accuracy of 85.90 % (AUC = 0.95). In contrast, models based on traditional fNIRS features reached an accuracy of 52.56 % (AUC = 0.66). The accuracies of the two psychiatrists were 42.00 % (AUC = 0.60) and 38.00 % (AUC = 0.50), respectively.

CONCLUSION

This investigation brings to light the shared and distinct neurobiological abnormalities present in SCZ and MDD, offering potential enhancements for extant diagnostic systems.

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.

Prefrontal brain activity and self-injurious behavior in adolescents with major depressive disorder: A functional near-infrared spectroscopy (fNIRS) study

In clinical practice, accurately identifying self-injurious behavior among adolescents with major depressive disorder (MDD) is crucial for individualized treatment. This study aimed to examine the differences in prefrontal cortex activation using the functional near-infrared spectroscopy (fNIRS) during the verbal fluency task (VFT) assessment of adolescents with MDD and self-harm (SH) compared with those without SH. A total of 60 eligible patients were included for final analysis, with the SH group containing 36 participants, and the Non-SH group containing 24 participants. We found that right middle frontal gyrus (rMFG) was more activated in the SH group than that in the Non-SH group during the VFT assessments (z = -3.591, p = 0.004, FDR correction). The z-scores of beta values of rMFG exhibited a good discriminatory power with the area under the curve (AUC) in distinguishing the two groups (AUC = 0.775, p < 0.001). These findings reveal that the fNIRS-VFT paradigm may be a useful tool for discovering neurobiological differences among adolescents with MDD.

Negative family and interpersonal relationship are associated with centromedial amygdala functional connectivity alterations in adolescent depression

The amygdala, known for its functional heterogeneity, plays a critical role in the neural mechanism of adolescent major depressive disorder (aMDD). However, changes in its subregional functional networks in relation to stressful factors remain unclear. We recruited 78 comorbidity-free, medication-naive aMDD patients and 40 matched healthy controls (HC) to explore changes in resting-state functional connectivity (FC) across four amygdala subregions: the centromedial nucleus (CM), the basolateral nucleus (LB), the superficial nucleus (SF), and the amygdalostriatal transition area (Astr). Then, we performed partial correlation analysis to investigate the relationship between amygdala subregional FC and stressful factors as measured by the Chinese Version of Family Environment Scale (FES-CV) and the Adolescent Self-Rated Life Events Scale (ASLEC). Compared to HC, aMDD patients demonstrated significantly decreased functional connectivity between the left CM and left precentral gyrus, as well as between left SF and left precentral gyrus, and between left LB and posterior cingulate gyrus (PCC)/precuneus. In aMDD group, left CM-precentral gyrus FC exhibited negative correlation with interpersonal relationship and punishment, and positive correlation with family cohesion and expressiveness. This study reveals distinct patterns of abnormal functional connectivity among amygdala subregions in aMDD. Our findings suggest that the CM network, in particular, may be involved in stress-related factors in aMDD, which provide a potential target for the prevention and treatment of adolescent depression.

Divergent suicidal symptomatic activations converge on somato-cognitive action network in depression

Individuals with depression have the highest lifetime prevalence of suicide attempts (SA) among mental illnesses. Numerous neuroimaging studies have developed biomarkers from task-related neural activation in depressive patients with SA, but the findings are inconsistent. Empowered by the contemporary interconnected view of depression as a neural system disorder, we sought to identify a specific brain circuit utilizing published heterogeneous neural activations. We systematically reviewed all published cognitive and emotional task-related functional MRI studies that investigated differences in the location of neural activations between depressive patients with and without SA. We subsequently mapped an underlying brain circuit functionally connecting to each experimental activation using a large normative connectome database (n = 1000). The identified SA-related functional network was compared to the network derived from the disease control group. Finally, we decoded this convergent functional connectivity network using microscale transcriptomic and chemo-architectures, and macroscale psychological processes. We enrolled 11 experimental tasks from eight studies, including depressive patients with SA (n = 147) and without SA (n = 196). The heterogeneous SA-related neural activations localized to the somato-cognitive action network (SCAN), exhibiting robustness to little perturbations and specificity for depression. Furthermore, the SA-related functional network was colocalized with brain-wide gene expression involved in inflammatory and immunity-related biological processes and aligned with the distribution of the GABA and noradrenaline neurotransmitter systems. The findings demonstrate that the SA-related functional network of depression is predominantly located at the SCAN, which is an essential implication for understanding depressive patients with SA.

Classification of fNIRS signals from adolescents with MDD in suicide high- and low-risk groups using machine learning

Prefrontal cortex activation is attenuated during cognitive tasks in patients with suicidal ideation or major depressive disorder (MDD). However, the apparent relationship between patients with MDD, especially suicide high-risk (SHR) adolescents, and the characteristics of their hemodynamic responses has not yet been elucidated. To investigate this relationship, we recruited 30 patients with MDD aged 13-19. Functional near-infrared spectroscopy (fNIRS) data were collected for all patients during a Stroop test. Through a ten-time iterative leave-one-out cross-validation via 1000 iterative random search-based feature selections, we achieved a generalized classification accuracy of 70.3±5.0 % (from min. 63.3 % to max. 76.7 %). From the results of random search-based feature selection, Ch08oxy and Ch09deoxy were identified as the two most relevant fNIRS channels. This finding implies that these fNIRS channels can be used as neurological biomarkers to distinguish SHR adolescents with MDD from suicide low-risk (SLR) adolescents. In addition, we determined the oxy-Hb channels of the SHR group, except for Ch01oxy, Ch02oxy, Ch11oxy, and Ch14oxy, were hyperactivated compared to the SLR group.

A study on the functional near-infrared spectroscopy on impaired prefrontal activation and impulsivity during cognitive task in patients with major depressive disorder

BACKGROUND

This study aimed to examine the association between prefrontal activation during a verbal fluency task (VFT) and impulsivity among patients with major depressive disorder (MDD), using functional near-infrared spectroscopy (fNIRS).

METHODS

We enrolled a total of 119 participants, 60 with MDD patients and 59 with healthy controls (HCs), aged 18 to 34 years. The Barratt Impulsiveness Scale-11 (BIS-11) was used to assess impulsivity after completing baseline demographic, clinical, and physical assessments. A VFT was used to examine prefrontal activation during cognitive executions while fNIRS was monitored. The changing values of oxygenated hemoglobin (oxy-Hb) and their associations with the BIS-11 score were analyzed.

RESULTS

The data analysis comprised 109 participants in total (54 MDD; 55 HCs). Spearman's correlation analysis of the MDD group showed a negative correlation between changes in oxy-Hb and BIS-11 values in the right prefrontal cortex, notably the right frontopolar cortex (FPC) and ventromedial prefrontal cortex (VMPFC). After adjusting for sex, age, years of education, and Hamilton Depression Rating Scale (HAMD), significance was maintained in the right FPC [ρ = -0.317, p = 0.027], and the right VMPFC [ρ = -0.327, p = 0.022]. Furthermore, multivariate linear regression suggested a significant association in the right prefrontal cortex with BIS-11 score [β = -1.904, SE = 0.799, p = 0.0214].

CONCLUSIONS

Impaired prefrontal activation during a verbal fluency task, led to higher impulsivity in patients with MDD.

Neural association between cognitive function and anhedonia in adolescents with melancholic major depressive disorder: A fNIRS study

BACKGROUND

Cognitive dysfunction is common among adolescent patients with major depressive disorder (MDD). However, the pattern and magnitude of cognition impairment in patients during melancholic episodes remains unclear. The purpose of this study was to compare the neurocognitive performance and the underlying cerebral blood flow activation of adolescent patients with melancholic and non-melancholic features.

METHODS

Fifty-seven and 44 adolescent patients with MDD with or without melancholic feature (MDD-MEL/nMEL) and 58 healthy controls (HCs) were recruited. We used the repeatable battery for the assessment of neuropsychological status (RBANS) measuring neurocognitive function, and used functional near infrared spectroscopy (fNIRS) monitoring cerebral hemodynamic changes, described by β value. The non-parametric test and post-hoc analysis were conducted in RBANS scores and β values among three groups. Spearman correlation and mediating analysis was performed for RBANS scores, β values, and clinical symptoms in the MDD-MEL group.

RESULTS

There were no significant difference in RBANS scores between MDD-MEL and MDD-nMEL group. Compared with patients in MDD-nMEL, patients in MDD-MEL have lower β values in eight channels (ch10, ch16, ch20, ch25, ch27, ch37, ch41, ch45). The cognitive function is significantly correlated with anhedonia, and the β values play a partial mediating role between anhedonia and cognitive function.

LIMITATION

It's a cross-sectional study and monitoring longitudinal effects are needed to further elucidate the mechanism.

CONCLUSION

The cognitive function in adolescents with MDD-MEL may not significantly differ from those with MDD-nMEL. However, the anhedonia may influenced the cognitive function by altering the function of medial frontal cortex.

Dorsolateral prefrontal activation in depressed young adults with and without suicidal ideation during an emotional autobiographical memory task: A fNIRS study

OBJECTIVE

Previous studies have proved that there is a strong association between dorsolateral prefrontal cortex and mood symptoms. This study aimed at using functional near-infrared spectroscopy technology to invest brain activity in dlPFC of depressed individuals with and without suicidal ideation during emotional autobiographical memory test, and to understand their differences in brain cognitive mechanisms. It is helpful to improve our ability to predict and subsequently to prevent suicide.

METHODS

85 young adults participated in the study by a simple random sampling method, with health control (34participants), depression with suicidal ideation (17participants), and depression without suicidal ideation (34participants). The average oxyhemoglobin in dlPFC of subjects during EAMT was collected by a 53-channel fNIRS imaging device.

RESULTS

A marginal significant difference was found between three groups in left dlPFC and right dlPFC. Post hoc analysis revealed that: (1) under negative emotion, depression without suicidal ideation group had higher activation than healthy control group in left dlPFC. (2) under positive emotion, depression with suicidal ideation group had lower activation than healthy control in right dlPFC.

CONCLUSIONS

Results indicated that the depressed individuals with suicidal ideation had some deficits in executive function in right dlPFC, while the depressed adults without suicidal ideation may have mechanism of resource compensatory recruitment in left dlPFC and the dlPFC abnormality involved in the pathophysiology, may localize within left hemisphere. The depressed individuals with and without suicidal ideation had the different mechanisms in dlPFC and fNIRS can be a neuroimaging biomarker characterizing or predicting suicidality in depressed individuals.

Machine learning based identification of structural brain alterations underlying suicide risk in adolescents

Suicide is the third leading cause of death for individuals between 15 and 19 years of age. The high suicide mortality rate and limited prior success in identifying neuroimaging biomarkers indicate that it is crucial to improve the accuracy of clinical neural signatures underlying suicide risk. The current study implements machine-learning (ML) algorithms to examine structural brain alterations in adolescents that can discriminate individuals with suicide risk from typically developing (TD) adolescents at the individual level. Structural MRI data were collected from 79 adolescents who demonstrated clinical levels of suicide risk and 79 demographically matched TD adolescents. Region-specific cortical/subcortical volume (CV/SCV) was evaluated following whole-brain parcellation into 1000 cortical and 12 subcortical regions. CV/SCV parameters were used as inputs for feature selection and three ML algorithms (i.e., support vector machine [SVM], K-nearest neighbors, and ensemble) to classify adolescents at suicide risk from TD adolescents. The highest classification accuracy of 74.79% (with sensitivity = 75.90%, specificity = 74.07%, and area under the receiver operating characteristic curve = 87.18%) was obtained for CV/SCV data using the SVM classifier. Identified bilateral regions that contributed to the classification mainly included reduced CV within the frontal and temporal cortices but increased volume within the cuneus/precuneus for adolescents at suicide risk relative to TD adolescents. The current data demonstrate an unbiased region-specific ML framework to effectively assess the structural biomarkers of suicide risk. Future studies with larger sample sizes and the inclusion of clinical controls and independent validation data sets are needed to confirm our findings.

Multiple examinations indicated associations between abnormal regional homogeneity and cognitive dysfunction in major depressive disorder

Background

This study aimed to investigate the relationships between regional neural activity and multiple related indicators in patients with major depressive disorder (MDD).

Methods

Forty-two patients and 42 healthy controls (HCs) were enrolled. Pearson/Spearman correlation analyses were applied to examine the associations between abnormal regional homogeneity (ReHo) and different indicators in the patients.

Results

Compared with HCs, patients with MDD had increased ReHo in the left inferior temporal gyrus (ITG) and decreased ReHo values in the left putamen, anterior cingulate cortex (ACC), and precentral gyrus. The ReHo of the left putamen was positively correlated with the PR interval, Repeatable Battery for the Assessment of Neuropsychological Status 4A, and Discriminant analysis (D), and negatively correlated with Ae (block) and Ae (total) in the patients. The ReHo value of the left ACC was positively correlated with the severity of depression, Stroop Color Word Test of C - 2B + 100 in reaction time, and negatively correlated with Ce (Missay) and Perseverative Responses in the patients. The ReHo of the left ITG was positively correlated with the Neuroticism scores and negatively correlated with the Lie scores in the patients.

Conclusion

These results suggested that the decreased ReHo of the salience network might be the underpinning of cognitive impairments in patients with MDD.

Resting state functional connectivity as a marker of internalizing disorder onset in high-risk youth

While research has linked alterations in functional connectivity of the default mode (DMN), cognitive control (CCN), and salience networks (SN) to depression and anxiety, little research has examined whether these alterations may be premorbid vulnerabilities. This study examined resting state functional connectivity (RSFC) of the CCN, DMN, and SN as markers of risk for developing an onset of a depressive or anxiety disorder in adolescents at high familial risk for these disorders. At baseline, 135 participants aged 11-17 completed resting-state functional magnetic resonance imaging, measures of internalizing symptoms, and diagnostic interviews to assess history of depressive and anxiety disorders. Diagnostic assessments were completed again at 9- or 18-month follow-up for 112 participants. At baseline, increased CCN connectivity to areas of the visual network, and decreased connectivity between the left SN and the precentral gyrus, predicted an increased likelihood of a new onset at follow-up. Increased connectivity between the right SN and postcentral gyrus at baseline predicted first episode onsets at follow-up. Altered connectivity between these regions may represent a risk factor for developing a clinically significant onset of an internalizing disorder. Results may have implications for understanding the neural bases of internalizing disorders for early identification and prevention efforts.

The associations between suicide-related behaviors, prefrontal dysfunction in emotional cognition, and personality traits in mood disorders

Suicide is a serious public health problem, and it is urgent to identify biomarkers associated with suicide to prevent it. We aimed to clarify the association across suicidal behavior, personality traits, and brain activation by emotional stimulation tasks using near-infrared spectroscopy (NIRS) in patients with mood disorders. 11 mood disorder patients with a history of suicide attempt (MDSA), 18 mood disorder patients with no history of suicide attempt (MDNSA), and 17 healthy individuals were studied. The MDSA patients showed significantly high impulsivity and hopeless compared to healthy subjects, great response to the thread word task in the orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC) compared to MDNSA patients, and the significant correlation between the personality traits and brain activation. The MDNSA did not show the trend. The results suggest that the personality traits and the activation of OFC and DLPFC during the negative emotional cognitive stimuli is associated with suicidal behavior, indicating the findings are involved in the pathophysiology of suicidality in mood disorders.

Altered resting-state cerebral blood flow and functional connectivity mediate suicidal ideation in major depressive disorder

The relationships among cerebral blood flow (CBF), functional connectivity (FC) and suicidal ideation (SI) in major depressive disorder (MDD) patients have remained elusive. In this study, we characterized the changes in CBF and FC among 175 individuals including 47 MDD without SI (MDDNSI), 59 MDD with SI (MDDSI), and 69 healthy control (HC) who underwent arterial spin labeling and resting-state functional MRI scans. Then the voxel-wise CBF, seed-based FC and partial correlation analyses were measured. Mediation analysis was carried out to reveal the effects of FC on the association between CBF and behavioral performances in both subgroups. Results showed that CBF was higher in MDDSI patients in the bilateral precuneus compared to HC and MDDNSI participants. MDDSI patients exhibited enhanced FC in the prefrontal-limbic system and decreased FC in the sensorimotor cortex (SMC) relative to MDDNSI patients. CBF and FC were significantly correlated with clinical variables. More importantly, exploratory mediation analyses identified that abnormal FC can mediate the association between regional CBF and behavioral performances. These results highlight the potential role of precuneus gyrus, prefrontal-limbic system as well as SMC in the process of suicide and provide new insights into the neural mechanism underlying suicide in MDD patients.

How aerobic exercise improves executive function in ADHD children: a resting-state fMRI study

The aim of the study is to explore the functional magnetic resonance imaging (fMRI) characteristics of the improvement in executive function by aerobic exercise in children with attention deficit hyperactivity disorder (ADHD). Seventeen children with ADHD were selected for 8 weeks of rope skipping aerobic training, and fMRI findings and executive function were examined before and after training. Regional homogeneity (ReHo) and degree centrality (DC) indexes were used in fMRI analysis, while the flanker task was used to test executive function. A paired t-test was used to compare the fMRI indexes and response time of executive function before and after training. After aerobic exercise, the brain regions in which the ReHo value of ADHD children significantly increased included the left middle frontal gyrus and the right superior frontal gyrus; the brain region in which the DC value increased was the right posterior cingulate cortex. The flanker task response time decreased significantly (P<0.05, after correction) after aerobic exercise. The study findings support the hypothesis that aerobic exercise can improve the executive function of ADHD children, and the brain mechanism involved is mainly related to the enhancement of spontaneous pre-frontal lobe activity.

Cortical activation and functional connectivity during the verbal fluency task for adolescent-onset depression: A multi-channel NIRS study

OBJECTIVE

Depression disorder is accompanied by cognitive impairments. However, there is limited research focused on cognitive impairments and their neurological mechanism in adolescents with depression. The purpose of the current study is to illustrate the differences in brain activity patterns between depressed adolescents and healthy controls (HCs).

METHOD

A total of 72 adolescents with depression, as well as 74 HCs, were recruited. We utilized functional near-infrared spectroscopy (fNIRS) to monitor the concentrations of oxyhemoglobin (Oxy-Hb) in the brains of participants while they performed the verbal fluency task (VFT) to examine cognitive impairment in adolescents with depression.

RESULTS

Our study demonstrated that adolescents with depression had significantly less cortical activation in the hemodynamic responses of Oxy-Hb at channels mainly located in the prefrontal cortex (PFC) than HCs during the 60-s task period (false discovery rate (FDR)-corrected p < 0.05). The mean channel-to-channel connectivity was 0.400 for HCs (SD = 0.149) and 0.303 (SD = 0.138) for adolescents with depression, and the HC group had a higher mean channel-to-channel connectivity strength than the depression group (t = -15.586, p < 0.001). For the patient group, we found significant negative correlations between HAMD scores and mean Oxy-Hb changes in Channel 38 (r = -0.33, p < 0.01), Channel 39 (r = -0.34, p < 0.01), Channel 41 (r = -0.25, p < 0.05), Channel 42 (r = -0.28, p < 0.05), and Channel 44 (r = -0.27, p < 0.05), and these channels were mainly located in areas with little difference between groups.

CONCLUSIONS

Our study provides neurological evidence about the executive function (EF) in depressed adolescents. Adolescents with depression exhibited an abnormal activation pattern and decreased task-related functional connectivity compared to HCs. The changed Oxy-Hb concentration of PFC during VFT was not sensitive to depression symptoms.

Impaired Oxygenation of the Prefrontal Cortex During Verbal Fluency Task in Young Adults With Major Depressive Disorder and Suicidality: A Functional Near-Infrared Spectroscopy Study

BACKGROUND

Few previous studies have focused on prefrontal activation in young adults diagnosed with major depressive disorder (MDD) and suicidality via functional near-infrared spectroscopy (fNIRS).

MATERIALS AND METHODS

A total of 59 healthy controls (HCs), 35 patients with MDD but without suicidality, and 25 patients with MDD and suicidality, between the ages of 18-34 years, were enrolled. Changes in oxygenated hemoglobin (oxy-Hb) levels of the prefrontal cortex at baseline, 4 weeks, and 8 weeks, were evaluated using a protocol consisting of three consecutively repeated trials of rest, speech, and verbal fluency test (VFT) via fNIRS. MDD was diagnosed and suicidality was evaluated based on Mini International Neuropsychiatric Interview (MINI).

RESULTS

Oxy-Hb levels were impaired in patients with MDD compared with HCs (p = 0.018 for left prefrontal cortex; p = 0.021 for right ventromedial prefrontal cortex; p = 0.002 for left frontopolar cortex). Among the three groups including HCs, MDD without suicidality, and MDD with suicidality, prefrontal oxygenation was most decreased in MDD patients with suicidality. A significantly impaired prefrontal oxygenation in the right ventrolateral prefrontal cortex (VLPFC) was detected after adjusting for covariates in MDD patients with suicidality, compared to those without suicidality.

CONCLUSION

Impaired prefrontal oxygenation during cognitive execution may serve as a diagnostic biomarker for suicidality in young adult patients with MDD.

Probing depression, schizophrenia, and other psychiatric disorders using fNIRS and the verbal fluency test: A systematic review and meta-analysis

Accessible neuroimaging tools that can identify specific frontal lobe dysfunction associated with psychiatric disorders could be useful for improving disease diagnosis and prognosis and treatment development. Functional near-infrared spectroscopy (fNIRS), in conjunction with the verbal fluency test (VFT), has emerged as an inexpensive and convenient method for understanding psychiatric disorders. However, questions remain regarding the specificity and uniqueness of fNIRS measurements for different disorders and the soundness of the methods applied previously. To address these knowledge gaps, we conducted a systematic review and meta-analysis of fNIRS studies using the VFT to probe psychiatric disorders. A literature search was conducted using PubMed and PsycINFO on October 27, 2020. Overall, 82% and 49% of the 121 included studies reported significantly reduced changes in oxyhemoglobin concentrations (HbO) and significantly fewer produced words during the VFT in psychiatric patients compared with healthy controls, respectively. For most psychiatric disorders, changes in HbO are more sensitive than changes in deoxyhemoglobin concentrations and VFT performance to detect psychopathologies. In addition, meta-analyses based on the proportion of channels that exhibited significant differences in HbO changes between patients and controls and on the effect sizes of group differences consistently showed that for major depression and schizophrenia, hypoactivation could be found across the frontotemporal regions, but its topographical distribution is disorder-specific. Thus, the fNIRS-VFT paradigm holds promise for understanding, detecting, and differentiating psychiatric disorders, and has the potential for developing accessible neuroimaging biomarkers for different psychiatric disorders. The findings are discussed with regard to the strengths and weaknesses of the applied methods, following by recommendations.

Machine Learning-Based Identification of Suicidal Risk in Patients With Schizophrenia Using Multi-Level Resting-State fMRI Features

BACKGROUND

Some studies suggest that as much as 40% of all causes of death in a group of patients with schizophrenia can be attributed to suicides and compared with the general population, patients with schizophrenia have an 8.5-fold greater suicide risk (SR). There is a vital need for accurate and reliable methods to predict the SR among patients with schizophrenia based on biological measures. However, it is unknown whether the suicidal risk in schizophrenia can be related to alterations in spontaneous brain activity, or if the resting-state functional magnetic resonance imaging (rsfMRI) measures can be used alongside machine learning (ML) algorithms in order to identify patients with SR.

METHODS

Fifty-nine participants including patients with schizophrenia with and without SR as well as age and gender-matched healthy underwent 13 min resting-state functional magnetic resonance imaging. Both static and dynamic indexes of the amplitude of low-frequency fluctuation (ALFF), the fractional amplitude of low-frequency fluctuations (fALFF), regional homogeneity as well as functional connectivity (FC) were calculated and used as an input for five machine learning algorithms: Gradient boosting (GB), LASSO, Logistic Regression (LR), Random Forest and Support Vector Machine.

RESULTS

All groups revealed different intra-network functional connectivity in ventral DMN and anterior SN. The best performance was reached for the LASSO applied to FC with an accuracy of 70% and AUROC of 0.76 (p < 0.05). Significant classification ability was also reached for GB and LR using fALFF and ALFF measures.

CONCLUSION

Our findings suggest that SR in schizophrenia can be seen on the level of DMN and SN functional connectivity alterations. ML algorithms were able to significantly differentiate SR patients. Our results could be useful in developing neuromarkers of SR in schizophrenia based on non-invasive rsfMRI.

Clinical Utility of Functional Near-Infrared Spectroscopy for Assessment and Prediction of Suicidality: A Systematic Review

Introduction: Suicide is a pressing psychiatric concern worldwide with no established biomarker. While there is some evidence of the clinical utility of functional near-infrared spectroscopy (fNIRS) in assessing and predicting suicidality, no systematic review of such evidence has been conducted to date. Therefore, this review aimed to systematically review and gather evidence from existing studies that used fNIRS signals to assess suicidality and its associated changes in the brain, and those that examined how such signals correlated with suicide symptomatology. Methods: PubMed, EMBASE, and Cochrane Library databases were used in a systematic literature search for English-language articles published between 2000 and December 19, 2020 that focused on the utility of fNIRS for (i) assessing suicidality and its associated changes in the brain, and (ii) correlating with suicide symptomatology. Studies were included if they utilised fNIRS to evaluate variations in fNIRS-measured cerebral hemodynamic responses in patients with different mental disorders (e.g., major depressive disorder, schizophrenia), as well as in healthy controls, of any age group. Quality of evidence was assessed using the Newcastle-Ottawa quality assessment scale. Results: A total of 7 cross-sectional studies were included in this review, all of which had acceptable quality. Across all studies, fNIRS demonstrated reduced cerebral hemodynamic changes in suicidal individuals when compared to non-suicidal individuals. One study also demonstrated the potential of fNIRS signals in correlating with the severity of suicidality. Conclusions: This review provides a comprehensive, updated review of evidence supporting the clinical utility of fNIRS in the assessment and prediction of suicidality. Further studies involving larger sample sizes, standardised methodology, and longitudinal follow-ups are needed.

Gray matter volume alterations associated with suicidal ideation and suicide attempts in patients with mood disorders

BACKGROUND

Mood disorders are severe mental disorders related to increased suicidal behavior. Finding neural features for suicidal behavior, including suicide attempts (SAs) and suicidal ideation (SI), in mood disorders may be helpful in preventing suicidal behavior.

METHODS

Subjects consisted of 70 patients with mood disorders and suicidal behavior, 128 patients with mood disorders without suicidal behavior (mood disorders control, MC), and 145 health control (HC) individuals. All participants underwent structural magnetic resonance imaging (MRI). We used voxel-based morphometry (VBM) techniques to examine gray matter volumes (GMVs).

RESULTS

Significant differences were found in GMVs of the left and right middle frontal gyrus among the patients with mood disorders and suicidal behavior, MC, and HC. Post hoc comparisons showed significant differences in the GMVs of the above regions across all three groups (P < 0.01): HC > MC > mood disorders with suicidal behavior. However, there were no significant differences in the GMVs of the left and right middle frontal gyrus between the mood disorders with SI and mood disorders with SAs groups.

CONCLUSIONS

These findings provide evidence that abnormal regional GMV in the middle frontal gyrus is associated with suicidal behavior in mood disorders. Further investigation is warranted to determine whether the GMV alterations in mood disorders with SI are different from these in mood disorders with SAs.

Prefrontal dysfunction associated with a history of suicide attempts among patients with recent onset schizophrenia

Suicide is a major cause of death in patients with schizophrenia, particularly among those with recent disease onset. Although brain imaging studies have identified the neuroanatomical correlates of suicidal behavior, functional brain activity correlates particularly in patients with recent-onset schizophrenia (ROSZ) remain unknown. Using near-infrared spectroscopy (NIRS) recording with a high-density coverage of the prefrontal area, we investigated whether prefrontal activity is altered in patients with ROSZ having a history of suicide attempts. A 52-channel NIRS system was used to examine hemodynamic changes in patients with ROSZ that had a history of suicide attempts (n = 24) or that lacked such a history (n = 62), and age- and sex-matched healthy controls (n = 119), during a block-design letter fluency task (LFT). Patients with a history of suicide attempts exhibited decreased activation in the right dorsolateral prefrontal cortex compared with those without such a history. Our findings indicate that specific regions of the prefrontal cortex may be associated with suicidal attempts, which may have implications for early intervention for psychosis.

Reduced Temporal Activation During a Verbal Fluency Task is Associated with Poor Motor Speed in Patients with Major Depressive Disorder

OBJECTIVE

Substantial research has revealed cognitive function impairments in patients with major depressive disorder (MDD). However, the relationship between MDD cognitive function impairment and brain activity is yet to be elucidated. This study aimed to reveal this relationship using near-infrared spectroscopy (NIRS) to extensively measure frontotemporal cortex function.

METHODS

We recruited 18 inpatients with MDD and 22 healthy controls. Regional oxygenated hemoglobin changes (oxy-Hb) were measured during a verbal fluency task and its relationship to cognitive function was assessed. Cognitive function was assessed using the Japanese version of the Brief Assessment of Cognition in Schizophrenia.

RESULTS

Compared to healthy controls, patients with MDD displayed poorer motor speed, attention and speed of information processing, and executive function. In the bilateral prefrontal and temporal surface regions, regional oxy-Hb changes were significantly lower in patients with MDD than in healthy individuals. Moreover, we observed a correlation between reduced activation in the left temporal region and poor motor speed in patients with MDD.

CONCLUSION

We suggest that reduced activation in the left temporal region in patients with MDD could be a biomarker of poor motor speed. Additionally, NIRS may be useful as a noninvasive, clinical measurement tool for assessing motor speed in these patients.

Delayed prefrontal hemodynamic response associated with suicide risk in autism spectrum disorder

Adults diagnosed with Autism spectrum disorder (ASD) are at high risk of experiencing suicidality compared with other clinical groups. Recently, near-infrared spectroscopy (NIRS) studies have investigated the association between frontotemporal functional abnormalities and suicidality in patients with mood disorders. However, whether these prefrontal hemodynamic responses are associated with suicide vulnerability in individuals with ASD remains unclear. Here, we used 24-channel NIRS to examine the characteristics of prefrontal hemodynamic responses during a verbal fluency task in 20 adults with ASD and in age-, sex-, and intelligence quotient-matched healthy controls. In addition, we used Spearman's correlation analysis to identify the relationship between the time-course of prefrontal hemodynamic activation and the current suicide risk in patients with ASD. We found no significant differences between the verbal fluency task-induced prefrontal hemodynamic responses in the ASD vs. control group. However, we found a significant positive correlation between the current suicide risk score and the time-course of prefrontal hemodynamic activation in the ASD group. Thus, the 24-channel NIRS system appears to be useful in assessing suicide risk in individuals with ASD.

Validating a functional near-infrared spectroscopy diagnostic paradigm for Major Depressive Disorder

Reduced haemodynamic response in the frontotemporal cortices of patients with major depressive disorder (MDD) has been demonstrated using functional near-infrared spectroscopy (fNIRS). Most notably, changes in cortical oxy-haemoglobin during a Japanese phonetic fluency task can differentiate psychiatric patients from healthy controls (HC). However, this paradigm has not been validated in the English language. Therefore, the present work aimed to distinguish patients with MDD from HCs, using haemodynamic response measured during an English letter fluency task. One hundred and five HCs and 105 patients with MDD took part in this study. NIRS signals during the verbal fluency task (VFT) was acquired using a 52-channel system, and changes in oxy-haemoglobin in the frontal and temporal regions were quantified. Depression severity, psychosocial functioning, pharmacotherapy and psychiatric history were noted. Patients with MDD had smaller changes in oxy-haemoglobin in the frontal and temporal cortices than HCs. In both regions of interest, oxy-haemoglobin was not associated with any of the clinical variables studied. 75.2% and 76.5% of patients with MDD were correctly classified using frontal and temporal region oxy-haemoglobin, respectively. Haemodynamic response measured by fNIRS during an English letter fluency task is a promising biomarker for MDD.

Prediction of attempted suicide in men and women with crack-cocaine use disorder in Brazil

Background

Suicide is a severe health problem, with high rates in individuals with addiction. Considering the lack of studies exploring suicide predictors in this population, we aimed to investigate factors associated with attempted suicide in inpatients diagnosed with cocaine use disorder using two analytical approaches.

Methods

This is a cross-sectional study using a secondary database with 247 men and 442 women hospitalized for cocaine use disorder. Clinical assessment included the Addiction Severity Index, the Childhood Trauma Questionnaire, and the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, totalling 58 variables. Descriptive Poisson regression and predictive Random Forest algorithm were used complementarily to estimate prevalence ratios and to build prediction models, respectively. All analyses were stratified by gender.

Results

The prevalence of attempted suicide was 34% for men and 50% for women. In both genders, depression (PR_M = 1.56, PR_W = 1.27) and hallucinations (PR_M = 1.80, PR_W = 1.39) were factors associated with attempted suicide. Other specific factors were found for men and women, such as childhood trauma, aggression, and drug use severity. The men's predictive model had prediction statistics of AUC = 0.68, Acc. = 0.66, Sens. = 0.82, Spec. = 0.50, PPV = 0.47 and NPV = 0.84. This model identified several variables as important predictors, mainly related to drug use severity. The women's model had higher predictive power (AUC = 0.73 and all other statistics were equal to 0.71) and was parsimonious.

Conclusions

Our findings indicate that attempted suicide is associated with depression, hallucinations and childhood trauma in both genders. Also, it suggests that severity of drug use may be a moderator between predictors and suicide among men, while psychiatric issues shown to be more important for women.

Resting-state functional connectivity of the anterior cingulate cortex in young adults depressed patients with and without suicidal behavior

Functional alterations in the subregions of the anterior cingulate cortex (ACC) have been observed in patients with major depressive disorder (MDD). Studies have shown that higher depressive symptoms are associated with altered functional connectivity (FC) in different ACC sub-regions. Suicide is highly prevalent in patients with MDD; however, it is unclear whether suicidal behavior is associated with the FC alterations in the subregions of the ACC in these indibiduals. Seventy-six patients with MDD (41 with and 35 without a history of suicidal behavior) underwent functional magnetic resonance imaging (fMRI) and were assessed using the Hamilton Rating Scale for Depression (HAMD), the Scale for Suicide Ideation (SSI), and the Columbia Scale for Rating of Suicide Severity. We investigated the FC between the ACC subregions and other brain regions in young MDD patients with and without a history of suicidal behavior. The FC in the subregions of the ACC-superior frontal gyrus differed significantly between the two groups. Additionally, the anterior sgACC-right caudate FC and the pgACC-left insula FC were found to be abnormal in the suicidal MDD group. Interestingly, the suicidal ideation score positively correlated with decreased FC in the pgACC-superior frontal gyrus in both groups, but it negatively correlated with increased FC in the anterior sgACC-superior frontal gyrus in the non-suicidal MDD group. Our findings indicate that altered connections of subregions in the ACC may be involved in the neurological mechanisms underlying suicide in young adults with MDD.

Diagnostic and Predictive Applications of Functional Near-Infrared Spectroscopy for Major Depressive Disorder: A Systematic Review

INTRODUCTION

Major depressive disorder (MDD) is a global psychiatric disorder with no established biomarker. There is growing evidence that functional near-infrared spectroscopy (fNIRS) has the ability to aid in the diagnosis and prediction of the treatment response of MDD. The aim of this review was to systematically review, and gather the evidence from existing studies that used fNIRS signals in the diagnosis of MDD, correlations with depression symptomatology, and the monitoring of treatment response.

METHODS

PubMed, EMBASE, ScienceDirect, and Cochrane Library databases were searched for published English articles from 1980 to June 2019 that focused on the application of fNIRS for (i) differentiating depressed versus nondepressed individuals, (ii) correlating with depression symptomatology, and in turn (iii) monitoring treatment responses in depression. Studies were included if they utilized fNIRS to evaluate cerebral hemodynamic variations in patients with MDD of any age group. The quality of the evidence was assessed using the Newcastle-Ottawa quality assessment scale.

RESULTS

A total of 64 studies were included in this review, with 12 studies being longitudinal, while the rest were cross-sectional. More than two-thirds of the studies (n = 49) had acceptable quality. fNIRS consistently demonstrated attenuated cerebral hemodynamic changes in depressed compared to healthy individuals. fNIRS signals have also shown promise in correlating with individual symptoms of depression and monitoring various treatment responses.

CONCLUSIONS

This review provides comprehensive updated evidence of the diagnostic and predictive applications of fNIRS in patients with MDD. Future studies involving larger sample sizes, standardized methodology, examination of more brain regions in an integrative approach, and longitudinal follow-ups are needed.

Prefrontal Asymmetry during Cognitive Tasks and its Relationship with Suicide Ideation in Major Depressive Disorder: An fNIRS Study

Reduced oxygenation changes in the prefrontal cortex during cognitive tasks have been reported in major depressive disorder (MDD). However, prefrontal asymmetry during cognitive tasks and its relation to suicide ideations have been less frequently examined in patients with MDD. This study investigated prefrontal asymmetry and its moderating effect on the relationship between depression severity and suicidal ideation in MDD patients during cognitive tasks. Forty-two patients with MDD and 64 healthy controls (HCs) were assessed for changes in oxygenated and deoxygenated hemoglobin (Hb) in the prefrontal cortex using functional near-infrared spectroscopy (fNIRS) during the verbal fluency task (VFT), Stroop task, and two-back task. Depression, anxiety, and suicide ideation were measured through self-report questionnaires. Relatively smaller left oxy-Hb changes during VFT, but not during the Stroop or two-back tasks, were found in MDD patients compared with HCs. Furthermore, prefrontal asymmetry during VFT moderated the effect of depression severity on suicide ideation, and was significantly and positively correlated with suicide ideation in patients with MDD. Specifically, relatively greater left oxy-Hb changes were associated with greater suicide ideation. These findings suggest fNIRS-measured prefrontal asymmetry as a potential biomarker for MDD and for the assessment of suicidal risk in patients with MDD.

Common and different neural markers in major depression and anxiety disorders: A pilot structural magnetic resonance imaging study

Although anxiety and depression often co-occur and share some clinical features, it is still unclear if they are neurobiologically distinct or similar processes. In this study, we explored common and specific cortical morphology alterations in depression and anxiety disorders. Magnetic Resonance Imaging data were acquired from 13 Major Depressive Disorder (MDD), 11 Generalized Anxiety Disorder (GAD), 11 Panic Disorder (PD) patients and 21 healthy controls (HC). Regional cortical thickness, surface area (SA), volume and gyrification were measured and compared among groups. We found left orbitofrontal thinning in all patient groups, as well as disease-specific alterations. MDD showed volume deficits in left precentral gyrus compared to all groups, volume and area deficits in right fusiform gyrus compared to GAD and HC. GAD showed lower SA than MDD and PD in right superior parietal cortex, higher gyrification than HC in right frontal gyrus. PD showed higher gyrification in left superior parietal cortex when compared to MDD and higher SA in left postcentral gyrus compared to all groups. Our results suggest that clinical phenotypic similarities between major depression and anxiety disorders might rely on common prefrontal alterations. Frontotemporal and parietal abnormalities may represent unique biological signatures of depression and anxiety.

Frontal haemodynamic responses in depression and the effect of electroconvulsive therapy

BACKGROUND

Reduced frontal cortex metabolism and blood flow in depression may be associated with low mood and cognitive impairment. Further reduction has been reported during a course of electroconvulsive therapy but it is not known if this relates to mood and cognitive changes caused by electroconvulsive therapy.

AIMS

The purpose of this study was to investigate frontal function while undertaking cognitive tasks in depressed patients compared with healthy controls, and following electroconvulsive therapy in patients.

METHODS

We measured frontal haemodynamic responses to a category verbal fluency task and a working memory N-back task using portable functional near infra-red spectroscopy (fNIRS) in 51 healthy controls and 18 severely depressed patients, 12 of whom were retested after the fourth treatment of a course of electroconvulsive therapy. Mood was assessed using the Montgomery Åsberg Depression Rating Scale and cognitive function using category Verbal Fluency from the Controlled Oral Word Association Test and Digit Span backwards.

RESULTS

Compared to healthy controls, depressed patients had bilaterally lower frontal oxyhaemoglobin responses to the cognitive tasks, although this was only significant for the N-Back task where performance correlated inversely with depression severity in patients. After four electroconvulsive therapy treatments oxyhaemoglobin responses were further reduced during the Verbal Fluency task but the changes did not correlate with mood or cognitive changes.

DISCUSSION

Our results confirmed a now extensive literature showing impaired frontal fNIRS oxyhaemoglobin responses to cognitive tasks in depression, and showed for the first time that these are further reduced during a course of electroconvulsive therapy. Further research is needed to investigate the biology and clinical utility of frontal fNIRS in psychiatric patients.

Deficits in Regional Cerebral Blood Flow on Brain SPECT Predict Treatment Resistant Depression

BACKGROUND

Depression remains an important risk factor for Alzheimer's disease, yet few neuroimaging biomarkers are available to identify treatment response in depression.

OBJECTIVE

To analyze and compare functional perfusion neuroimaging in persons with treatment resistant depression (TRD) compared to those experiencing full remission.

METHODS

A total of 951 subjects from a community psychiatry cohort were scanned with perfusion single photon emission computed tomography (SPECT) of the brain in both resting and task related settings. Of these, 78% experienced either full remission (n = 506) or partial remission (n = 237) and 11% were minimally responsive (n = 103) or non-responsive (11%. n = 106). Severity of depression symptoms were used to define these groups with changes in the Beck Depression Inventory prior to and following treatment. Voxel-based analyses of brain SPECT images from full remission compared to the worsening group was conducted with the statistical parametric mapping software, version 8 (SPM 8). Multiple comparisons were accounted for with a false discovery rate (p < 0.001).

RESULTS

Persons with depression that worsened following treatment had reduced cerebral perfusion compared to full remission in the multiple regions including the bilateral frontal lobes, right hippocampus, left precuneus, and cerebellar vermis. Such differences were observed on both resting and concentration SPECT scans.

CONCLUSION

Our findings identify imaging-based biomarkers in persons with depression related to treatment response. These findings have implications in understanding both depression to prognosis and its role as a risk factor for dementia.

Frequency-Dependent Spatial Distribution of Functional Hubs in the Human Brain and Alterations in Major Depressive Disorder

Alterations in large-scale brain intrinsic functional connectivity (FC), i.e., coherence between fluctuations of ongoing activity, have been implicated in major depressive disorder (MDD). Yet, little is known about the frequency-dependent alterations of FC in MDD. We calculated frequency specific degree centrality (DC) – a measure of overall FC of a brain region – within 10 distinct frequency sub-bands accessible from the full range of resting-state fMRI BOLD fluctuations (i.e., 0.01–0.25 Hz) in 24 healthy controls and 24 MDD patients. In healthy controls, results reveal a frequency-specific spatial distribution of highly connected brain regions – i.e., hubs – which play a fundamental role in information integration in the brain. MDD patients exhibited significant deviations from the healthy DC patterns, with decreased overall connectedness of widespread regions, in a frequency-specific manner. Decreased DC in MDD patients was observed predominantly in the occipital cortex at low frequencies (0.01–0.1 Hz), in the middle cingulate cortex, sensorimotor cortex, lateral parietal cortex, and the precuneus at middle frequencies (0.1–0.175 Hz), and in the anterior cingulate cortex at high frequencies (0.175–0.25 Hz). Additionally, decreased DC of distinct parts of the insula was observed across low, middle, and high frequency bands. Frequency-specific alterations in the DC of the temporal, insular, and lateral parietal cortices correlated with symptom severity. Importantly, our results indicate that frequency-resolved analysis within the full range of frequencies accessible from the BOLD signal – also including higher frequencies (>0.1 Hz) – reveals unique information about brain organization and its changes, which can otherwise be overlooked.

Mitochondrial DNA Copy Number Raises the Potential of Left Frontopolar Hemodynamic Response as a Diagnostic Marker for Distinguishing Bipolar Disorder From Major Depressive Disorder

Background: Given a lack of markers, diagnoses of bipolar disorder (BD) and major depressive disorder (MDD) rely on clinical assessment of symptoms. However, the depressive mood states of BD and depressive symptoms of MDD are often difficult to distinguish, which leads to misdiagnoses, which in turn leads to inadequate treatment. Previous studies have shown that the hemodynamic responses of the left frontopolar cortex measured by near-infrared spectroscopy (NIRS) differ between BD and MDD; these hemodynamic responses are associated with altered mitochondrial metabolism; and mitochondrial DNA copy number (mtDNAcn), an index of mitochondrial dysfunction, tends to decrease in BD and increase in MDD patients. In this study, we confirmed that mtDNAcn trends in opposite directions in BD and MDD. We then determined whether mtDNAcn could enhance the utility of NIRS as a diagnostic marker to distinguish between BD and MDD. Methods: We determined mtDNAcn in peripheral blood samples from 58 healthy controls, 79 patients with BD, and 44 patients with MDD. Regional hemodynamic responses during a verbal fluency task (VFT) in 24 BD patients and 44 MDD patients, matched by age and depression severity, were monitored using NIRS. Results: Measurements of mtDNAcn were lower in BD patients and higher in MDD patients than in controls. The left frontopolar region exhibited the most significant differences in mean VFT-related oxy-Hb changes between the BD and MDD groups. Multivariate logistic regression analysis with variables including age, sex, hemodynamic response of the left frontopolar region, and mtDNAcn showed high accuracy for distinguishing BD from MDD (area under the curve = 0.917; 95% confidence interval = 0.849-0.985). For the BD group, we observed a positive correlation between hemodynamic responses in the left frontopolar region and mtDNAcn, while for the MDD group, we observed a negative correlation. Conclusions: Our findings suggest that the association between hemodynamic response and mitochondrial dysfunction in BD or MDD plays an important role in differentiating the pathophysiological mechanisms of BD from those of MDD.

Gray Matter Volume Reductions Were Associated with TPH1 Polymorphisms in Depressive Disorder Patients with Suicidal Attempts

OBJECTIVE

Structural changes of brain areas have been reported in depressive disorder and suicidal behavior (SB), in which TPH1 also has been known as a promising candidate gene. We investigated gray matter volume (GMV) differences, TPH1 rs1800532 and rs1799913 polymorphisms previously found to be associated with depressive disorder and SB, and the relationship between the two markers.

METHODS

Thirteen depressive disorder patients with suicidal attempts (SA) and twenty healthy controls were included. We examined GMV differences using a voxel-based morphometry and regions of interest analysis. Direct sequencing was used for genotyping.

RESULTS

The patients showed significant GMV reduction in left cerebral region including middle frontal gyrus, inferior frontal gyrus, and anterior cingulate cortex; in right middle temporal gyrus; in left cerebellar tonsil; and in right cerebral region including precentral gyrus and postcentral gyrus (corrected p<0.005). The right precentral and postcentral gyri GMV values of AA and CA genotypes patients were significantly decreased compared to those of CC genotype subjects (corrected p=0.040).

CONCLUSION

These findings show the possibility that both GMV reductions and TPH1 rs1800532/rs1799913 A allele may be involved in the pathogenesis of depressive disorder patients with SA.

Delayed hemodynamic responses associated with a history of suicide attempts in bipolar disorder: a multichannel near-infrared spectroscopy study

Bipolar disorder (BD) is associated with a high risk of suicide compared with other psychiatric disorders. Recent studies using near-infrared spectroscopy (NIRS) reported frontotemporal functional abnormalities in BD. However, it remains unclear whether NIRS signal changes are associated with vulnerability toward suicide in BD. We recruited 20 patients with depressed BD with a history of suicide attempts (suicide attempters; SAs) and 28 control patients with BD who did not have a history of suicide attempts (non-attempters; NAs). Regional hemodynamic responses during a verbal fluency task were monitored using NIRS. Compared with the NA group, the SA group exhibited significantly reduced activation during VFT in the bilateral precentral and superior temporal gyri and left supramarginal, inferior frontal, postcentral, and middle temporal gyri. Furthermore, compared with the NA group, the SA group exhibited delayed activation timing of the NIRS signal in the prefrontal region. In BD patients, current suicide risk was noted to be significantly and positively associated with delayed activation timing of the NIRS signal in the prefrontal region. The findings of this study suggest that the observed specific NIRS signal pattern in BD patients is associated with vulnerability toward suicide.

Event-Related Potential Measures of Attention Capture in Adolescent Inpatients With Acute Suicidal Behavior

Impaired executive functions, modulated by the frontal lobes, have been suggested to be associated with suicidal behavior. The present study examines one of these executive functions, attentional control, maintaining attention to the task-at-hand. A group of inpatient adolescents with acute suicidal behavior and healthy controls were studied using a passively presented auditory optimal paradigm. This "optimal" paradigm consisted of a series of frequently presented homogenous pure tone "standards" and different "deviants," constructed by changing one or more features of the standard. The optimal paradigm has been shown to be a more time-efficient replacement to the traditional oddball paradigm, which makes it suitable for use in clinical populations. The extent of processing of these "to-be-ignored" auditory stimuli was measured by recording event-related potentials (ERPs). The P3a ERP component is thought to reflect processes associated with the capturing of attention. Rare and novel stimuli may result in an executive decision to switch attention away from the current cognitive task and toward a probe of the potentially more relevant "interrupting" auditory input. On the other hand, stimuli that are quite similar to the standard should not elicit P3a. The P3a has been shown to be larger in immature brains in early compared to later adolescence. An overall enhanced P3a was observed in the suicidal group. The P3a was larger in this group for both the environmental sound and white noise deviants, although only the environmental sound P3a attained significance. Other deviants representing only a small change from the standard did not elicit a P3a in healthy controls. They did elicit a small P3a in the suicidal group. These findings suggest a lowered threshold for the triggering of the involuntary switch of attention in these patients, which may play a role in their reported distractibility. The enhanced P3a is also suggestive of an immature frontal central executive and may provide a promising marker for early identification of some of the risk factors for some of the cognitive difficulties linked to suicidality.