Comparing suicide completion rates in bipolar I versus bipolar II disorder: A systematic review and meta-analysis.

BACKGROUND: Bipolar disorder (BD) has a high disease burden and the highest mortality risk in BD comes from suicide. Bipolar disorder type II (BD-II) has been described as a milder form of bipolar disorder; however, extant literature is inconsistent with this description and instead describe illness burden and notably suicidality comparable to persons with bipolar I disorder (BD-I). Towards quantifying the hazard of BD-II, herein we aim via systematic review and meta-analysis to evaluate the rates of completed suicide in BD-I and BD-II. METHOD: We conducted a literature search on PubMed, OVID (Embase, Medline) and PsychINFO databases from inception to June 30th, 2023, according to PRISMA guidelines. Articles were selected based on the predetermined eligibility criteria. A meta-analysis was performed, comparing the risk of completed suicide between individuals diagnosed with BD-I to BD-II. RESULTS: Four out of eight studies reported higher suicide completion rates in persons living with BD-II when compared to persons living with BD-I; however, two of the studies reported non-significance. Two studies reported significantly higher suicide completion rates for BD-I than BD-II. The pooled odds ratio of BD-II suicide rates to BD-I was 1.00 [95 % CI = 0.75, 1.34]. LIMITATIONS: The overarching limitation is the small number of studies and heterogeneity of studies that report on suicide completion in BD-I and BD-II. CONCLUSION: Our study underscores the severity of BD-II, with a risk for suicide not dissimilar from BD-I. The greater propensity to depression, comorbidity and rapid-cycling course reported in BD-II are contributing factors to the significant mortality hazard in BD-II.

Comparison of cognitive performance in first-episode drug-naïve schizophrenia, bipolar II disorder, and major depressive disorder patients after treatment.

BACKGROUND: Cognitive impairment is a recognized fundamental deficit in individuals diagnosed with schizophrenia (SZ), bipolar II disorder (BD II), and major depressive disorder (MDD), among other psychiatric disorders. However, limited research has compared cognitive function among first-episode drug-naïve individuals with SZ, BD II, or MDD. METHODS: This study aimed to address this gap by assessing the cognitive performance of 235 participants (40 healthy controls, 58 SZ patients, 72 BD II patients, and 65 MDD patients) using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) before and after 12 weeks of treatment in SZ, BD II, and MDD patients. To clarify, the healthy controls only underwent RBANS testing at baseline, whereas the patient groups were assessed before and after treatment. The severity of symptoms in SZ patients was measured using the Positive and Negative Syndrome Scale (PANSS), and depression in BD II and MDD patients was assessed using the Hamilton Depression Scale-24 items (HAMD-24 items). RESULTS: Two hundred participants completed the 12-week treatment period, with 35 participants dropping out due to various reasons. This group included 49 SZ patients, 58 BD II patients, and 53 MDD patients. Among SZ patients, significant improvements in immediate and delayed memory were observed after 12 weeks of treatment compared to their initial scores. Similarly, BD II patients showed significant improvement in immediate and delayed memory following treatment. However, there were no significant differences in RBANS scores for MDD patients after 12 weeks of treatment. CONCLUSIONS: In conclusion, the findings of this study suggest that individuals with BD II and SZ may share similar deficits in cognitive domains. It is important to note that standardized clinical treatment may have varying degrees of effectiveness in improving cognitive function in patients with BD II and SZ, which could potentially alleviate cognitive dysfunction.

Clinical distinctions in symptomatology and psychiatric comorbidities between misdiagnosed bipolar I and bipolar II disorder versus major depressive disorder.

BACKGROUND: To explore the demographic and clinical features of current depressive episode that discriminate patients diagnosed with major depressive disorder (MDD) from those with bipolar I (BP-I) and bipolar II (BP-II) disorder who were misdiagnosed as having MDD . METHODS: The Mini-International Neuropsychiatric Interview (MINI) assessment was performed to establish DSM-IV diagnoses of MDD, and BP-I and BP-II, previously being misdiagnosed as MDD. Demographics, depressive symptoms and psychiatric comorbidities were compared between 1463 patients with BP-I, BP-II and MDD from 8 psychiatric settings in mainland China. A multinomial logistic regression model was performed to assess clinical correlates of diagnoses. RESULTS: A total of 14.5% of the enrolled patients initially diagnosed with MDD were eventually diagnosed with BP. Broad illness characteristics including younger age, higher prevalence of recurrence, concurrent dysthymia, suicidal attempts, agitation, psychotic features and psychiatric comorbidities, as well as lower prevalence of insomnia, weight loss and somatic symptoms were featured by patients with BP-I and/or BP-I, compared to those with MDD. Comparisons between BP-I and BP-II versus MDD indicated distinct symptom profiles and comorbidity patterns with more differences being observed between BP-II and MDD, than between BP-I and MDD . CONCLUSION: The results provide evidence of clinically distinguishing characteristics between misdiagnosed BP-I and BP- II versus MDD. The findings have implications for guiding more accurate diagnoses of bipolar disorders.

The comparison of hot and cold executive functions in patients with bipolar II disorder, borderline personality disorder, and healthy individuals.

Background: Differential diagnosis of bipolar II disorder (BD-II) and borderline personality disorder (BPD) has always been challenging for clinicians due to symptoms' overlap. This study aimed to compare hot and cold executive functions (EFs) in BD-II patients, as well as BPD and healthy controls (HCs), in order to differentiate these two disorders. Methods: In the present study, 30 BD-II and 30 BPD patients undergoing the drug therapy with mood stabilizers, and 30 HC were examined using EFs evaluated tests. The data were then analyzed using ANOVA and Tukey post hoc test. Results: The BD-II Patients performed significantly less in all cold EFs than the HC. Also, BPD patients had meaningfully lesser performance compared to HC in all cold EFs except sustained attention. No significant difference was perceived between the two patient groups in the cold EFs. In BD-II patients, the risky decision-making as a hot EFs' component was not significantly different from HC; nevertheless, its amount was significantly higher in BPD than in the HC and BD-II patients. Conclusion: These findings underline the differences between the two mentioned disorders based on the hot EFs, which may indicate further disorder in the emotional information processing system among the BPD patients.

Correlation of potential diagnostic biomarkers (circulating miRNA and protein) of bipolar II disorder.

OBJECTIVES: We previously identified certain peripheral biomarkers of bipolar II disorder (BD-II) including circulating miRNAs (miR-7-5p, miR-142-3p, miR-221-5p, and miR-370-3p) and proteins (Matrix metallopeptidase 9 (MMP9), phenylalanyl-tRNA synthetase subunit beta (FARSB), peroxiredoxin 2 (PRDX2), carbonic anhydrase 1 (CA-1), and proprotein convertase subtilisin/kexin type 9 (PCSK9)). We try to explore the connection between these biomarkers. METHODS: We explored correlations between the peripheral levels of above circulating miRNAs and proteins in our previously collected BD-II (N = 96) patients and control (N = 115) groups. We further searched TargetScan and BioGrid websites to identify direct and indirect interactions between these protein-coding genes and circulating miRNAs. RESULTS: In the BD-II group, we identified significant correlations between the miR-221-5p and CA-1 (rho = -0.323, P = 0.001), FARSB (rho = 0.251, P = 0.014), MMP-9 (rho = 0.313, P = 0.002) and PCSK9 (rho = 0.252, P = 0.014). The miR-370-3p also significantly correlated with FARSB expression (rho = 0.330, P = 0.001) and PCSK9 expression (rho = 0.221, P = 0.031) in the BD-II group. Our findings were in line with the modulating axis identified from TargetScan and BioGrid, miR-221-5p/CA-1/MMP9 and miR-370-3p/FARSB/PCSK9, suggesting their association with BD-II. CONCLUSION: Our result supported that peripheral candidate miRNA and protein biomarkers may interact in BD-II. We concluded that miR-221-5p/CA-1/MMP9 and miR-370-3p/FARSB/PCSK9 axes might act a critical role in the pathomechanism of BD-II.

Differences in clinical presentation between newly diagnosed bipolar I and II disorders: A naturalistic study.

AIM: This naturalistic clinical study aims to investigate differences between newly diagnosed patients with bipolar type I (BDI) and bipolar type II (BDII) disorders in socio-demographic and clinical characteristics, affective symptoms, cognition, functioning and comorbidity with personality disorders. METHODS: The BD diagnosis and type were confirmed using the Schedules for Clinical Assessment in Neuropsychiatry. Affective symptoms were assessed with the Young Mania Rating Scale, the Hamilton Depression Rating Scale, the Major Depressive Index, and the Altman Self-Rating Mania Scale. Functional impairment was assessed with the Functional Assessment Short Test. Cognitive impairment was evaluated by the Screen for Cognitive Impairment in Psychiatry and the Cognitive Complaints in Bipolar Disorder Rating Assessment. Finally, comorbid personality disorders were assessed with the Standardized Assessment of Personality-Abbreviated Scale and structured interview Structured Clinical Interview for DSM-disorders. RESULTS: 383 newly diagnosed patients were included (BDI: n = 125; BDII: n = 258). Against expectations, we found no more depressive symptoms in BDII compared with BDI nor any differences in cognitive, childhood trauma or overall functional impairment. The only difference was lower occupational impairment in the BDII group. LIMITATIONS: The self-reported measures of cognitive difficulties and childhood trauma involved potential bias (recall or other). Despite BD being newly diagnosed a diagnostic delay was observed. CONCLUSION: Patients newly diagnosed with BDII and BDI had similar burdens of depressive symptoms and cognitive and overall functional impairment, however patients with BDI had lower occupational functioning. No statistically significant difference was found in prevalence of comorbid personality disorders between patients with BDI and BDII.

Transcranial Magnetic Stimulation in Bipolar II Disorder Treatment: A Case Report.

The objective of this case report is to describe and document the use of transcranial magnetic stimulation (TMS) to aid in the treatment of bipolar II disorder. A 35-year-old male with a past medical history of attention-deficit/hyperactivity disorder (ADHD), post-traumatic stress disorder (PTSD), severe depression, and bipolar II disorder was presented to an outpatient psychiatric clinic 1.5 years after his initial TMS treatment for TMS maintenance therapy. He reported feeling depressed, brain fogginess, loss of concentration, fatigue, and constant changes in moods. He had tried multiple antidepressants and antipsychotics, seen several therapists, and underwent electroconvulsive therapy in 2014 with no improvement. In August 2021, he underwent the standard TMS protocol with 36 treatments and noticed significant improvement in his symptoms. He followed up with his psychiatrist who placed him on quetiapine 400 mg, lurasidone 120 mg, topiramate 100 mg, Adderall 20 mg, Wellbutrin 150 mg, propranolol 20 mg, and Klonopin 0.5 mg for management. However, after starting these medications, he noticed a loss of concentration, not being able to think straight, fatigue, depression, and a change in moods. In January 2023, the patient underwent maintenance TMS treatment with theta bursts (TBS). The treatment protocol consisted of 10 sessions for 3 ½ minutes each, 20 trains, 10 bursts, and eight seconds between intervals. He completed his treatment and reported feeling great and like himself again. Two weeks following treatment, he reported that his brain fog had resolved, hypomanic episodes had lessened, and depressive moods had been occurring less often. Due to improvement, topiramate and lurasidone were discontinued and the patient will continue with monthly follow-ups to monitor his progress. TMS appears to be a promising treatment option for bipolar disorder.

Immediate visual reproduction negatively correlates with brain entropy of parahippocampal gyrus and inferior occipital gyrus in bipolar II disorder adolescents.

BACKGROUND: Brain entropy reveals complexity and irregularity of brain, and it has been proven to reflect brain complexity alteration in disease states. Previous studies found that bipolar disorder adolescents showed cognitive impairment. The relationship between complexity of brain neural activity and cognition of bipolar II disorder (BD-II) adolescents remains unclear. METHODS: Nineteen BD-II patients (14.63 ±1.57 years old) and seventeen age-gender matched healthy controls (HCs) (14.18 ± 1.51 years old) were enlisted. Entropy values of all voxels of the brain in resting-state functional MRI data were calculated and differences of them between BD-II and HC groups were evaluated. After that, correlation analyses were performed between entropy values of brain regions showing significant entropy differences and clinical indices in BD-II adolescents. RESULTS: Significant differences were found in scores of immediate visual reproduction subtest (VR-I, p = 0.003) and Stroop color-word test (SCWT-1, p = 0.015; SCWT-2, p = 0.004; SCWT-3, p = 0.003) between the two groups. Compared with HCs, BD-II adolescents showed significant increased brain entropy in right parahippocampal gyrus and right inferior occipital gyrus. Besides, significant negative correlations between brain entropy values of right parahippocampal gyrus, right inferior occipital gyrus and immediate visual reproduction subtest scores were observed in BD-II adolescents. CONCLUSIONS: The findings of the present study suggested that the disrupted function of corticolimbic system is related with cognitive abnormality of BD-II adolescents. And from the perspective temporal dynamics of brain system, the current study, brain entropy may provide available evidences for understanding the underlying neural mechanism in BD-II adolescents.

Comparison of the efficacy of venlafaxine and bupropion in the treatment of depressive episode in patients with bipolar II disorder.

Objective: Depressive disorders are common among those with bipolar disorder II (BD II) and may necessitate the use of antidepressants. Because of the lack of quality evidence, there is controversy about the use of antidepressants in BD II. The aim was to compare the efficacy of venlafaxine and bupropion in the treatment of depressive episode in BD II. Materials and Methods: This randomized triple-blind clinical trial study was conducted on patient with depressive episode of BD II (based on diagnostic and statistical manual of disorders [DSM-V] criteria) referred to the specialized clinic of Golestan Hospital. A total of 40 patients were randomly divided into two groups of receiving venlafaxine (75 mg/day) or bupropion (100 mg/day) for 4 weeks. At the end of the intervention, the effectiveness of treatment was assessed using the Hamilton Depression Rating Scale (HDRS). Results: The results of this study showed that the HDRS score before treatment (P = 0.43) and after treatment (P = 0.15) was not significantly different between the two groups. HDRS score in both groups significantly decreased after 4 weeks (P < 0.0001). Although the rate of decrease in depression score was more in venlafaxine than in bupropion, these differences were not significant (% 36.7 ± 21.8 vs. % 45.3 ± 17.9, P value = 0.17). Conclusion: Our study showed that short-term (4-weeks) treatments of venlafaxine and bupropion were equally effective and could be a safe and effective antidepressant monotherapy for BD II major depression. It is suggested that more studies be conducted with larger sample size and over longer periods of time in a multicenter manner.

The efficacy of lumateperone on symptoms of depression in bipolar I and bipolar II disorder: Secondary and post hoc analyses.

A recent Phase 3, randomized, double-blind, placebo-controlled study established that lumateperone 42-mg monotherapy significantly improved symptoms of depression in patients with bipolar depression. This manuscript reports prespecified secondary and post hoc efficacy analyses. Patients with bipolar I or bipolar II disorder experiencing a major depressive episode were randomized 1:1 to lumateperone 42 mg or placebo, administered orally once daily for 6 weeks. Prespecified analyses evaluated change from baseline to Day 43 in individual Montgomery-Åsberg Depression Rating Scale (MADRS) item scores in the modified intent-to-treat population (mITT) and bipolar I and bipolar II disorder subgroups. Post hoc analyses investigated the MADRS anhedonia factor and categorical shifts in MADRS item scores. In the mITT, there was significant improvement from baseline to Day 43 with lumateperone 42 mg compared with placebo for all 10 MADRS items; most MADRS items significantly improved in subgroups with bipolar I (9 items) and bipolar II disorder (8 items). A significantly higher proportion of patients receiving lumateperone compared with placebo shifted from baseline MADRS item score ≥4 to ≤2 at end of treatment in Reported Sadness, Reduced Sleep, Concentration Difficulties, Lassitude, Inability to Feel, and Pessimistic Thoughts. Lumateperone significantly improved the MADRS anhedonia factor from baseline to Day 43 compared with placebo in the mITT (effect size, -0.47) and subgroups with bipolar I (-0.36) and bipolar II disorder (-0.90). Lumateperone 42 mg treatment significantly improved depression symptoms compared with placebo, with consistent efficacy across a broad range of symptoms in people with bipolar I and bipolar II disorder.

Bipolar II Disorder: Understudied and Underdiagnosed.

Despite its inclusion as a distinct entity in APA's Diagnostic and Statistical Manual of Mental Disorders since 1994, bipolar II disorder remains a surprisingly neglected psychiatric condition. Understudied and underrecognized, bipolar II disorder is often misdiagnosed and misunderstood, even by experienced clinicians. As a result, patients typically experience symptoms for more than 10 years before receiving the correct diagnosis. Incorrect diagnosis leads to incorrect treatment, including overuse of monoaminergic antidepressant medications, with resultant declines in functioning and worse quality of life. Perhaps because of its underrecognition, treatment studies of bipolar II disorder are limited, and, too often, results of bipolar I disorder studies are applied to bipolar II disorder, with no direct evidence supporting this practice. Bipolar II disorder is an understudied and unmet treatment challenge in psychiatry. In this review, the authors provide a broad overview of bipolar II disorder, including differential diagnosis, course of illness, comorbid conditions, and suicide risk. The authors summarize treatment studies specific to bipolar II disorder, identifying gaps in the literature. This review reveals similarities between bipolar I and bipolar II disorders, including risks of suicide and predominance of depression over the course of illness, but also differences between the phenotypes in treatment response, for example, to antidepressant medications.

The clinical characterization of the adult patient with bipolar disorder aimed at personalization of management.

Bipolar disorder is heterogeneous in phenomenology, illness trajectory, and response to treatment. Despite evidence for the efficacy of multimodal-ity interventions, the majority of persons affected by this disorder do not achieve and sustain full syndromal recovery. It is eagerly anticipated that combining datasets across various information sources (e.g., hierarchical "multi-omic" measures, electronic health records), analyzed using advanced computational methods (e.g., machine learning), will inform future diagnosis and treatment selection. In the interim, identifying clinically meaningful subgroups of persons with the disorder having differential response to specific treatments at point-of-care is an empirical priority. This paper endeavours to synthesize salient domains in the clinical characterization of the adult patient with bipolar disorder, with the overarching aim to improve health outcomes by informing patient management and treatment considerations. Extant data indicate that characterizing select domains in bipolar disorder provides actionable information and guides shared decision making. For example, it is robustly established that the presence of mixed features - especially during depressive episodes - and of physical and psychiatric comorbidities informs illness trajectory, response to treatment, and suicide risk. In addition, early environmental exposures (e.g., sexual and physical abuse, emotional neglect) are highly associated with more complicated illness presentations, inviting the need for developmentally-oriented and integrated treatment approaches. There have been significant advances in validating subtypes of bipolar disorder (e.g., bipolar I vs. II disorder), particularly in regard to pharmacological interventions. As with other severe mental disorders, social functioning, interpersonal/family relationships and internalized stigma are domains highly relevant to relapse risk, health outcomes, and quality of life. The elevated standardized mortality ratio for completed suicide and suicidal behaviour in bipolar disorder invites the need for characterization of this domain in all patients. The framework of this paper is to describe all the above salient domains, providing a synthesis of extant literature and recommendations for decision support tools and clinical metrics that can be implemented at point-of-care.

Short Term Second-Generation Antidepressant Monotherapy in Acute Depressive Episodes of Bipolar II Disorder: A Systematic Review and Meta-Analysis.

Purpose: Bipolar II disorder (BD-II) has limited evidence-based treatment guidelines. The aim of this systematic review and meta-analysis was to estimate the efficacy and safety of second-generation antidepressant (SGAD) monotherapy in acute BD-II depression. Methods: A literature search was conducted from the database inception through March 2021. Only randomized controlled trials (RCTs) were included. Outcome measures included: response rates, treatment-emergent affective switch (TEAS) rates, discontinuation due to side-effects, and all-cause discontinuation. Risk ratio (RR) was calculated using the Mantel-Haenszel random effects model. Results: 3301 studies were screened, and 15 articles were selected for full-text review. Five studies met the inclusion criteria: Four double-blind RCTs (n = 533) and one open-label RCT (n = 83) were included. Two double-blind RCTs [n = 223, SGAD = 110 (venlafaxine = 65, sertraline = 45), lithium/control = 113] were included for meta-analysis. The response rate for SGAD monotherapy compared to lithium monotherapy were similar (RR = 1.44, 95% CI 0.78, 2.66). The TEAS rate for SGAD monotherapy was not significantly different from lithium monotherapy (p = 0.76). The discontinuation rate due to side-effects for SGAD monotherapy was significantly lower than lithium monotherapy with a RR = 0.32, 95% CI 0.11, 0.96, p = 0.04 but all-cause discontinuation rates were similar in both groups. Conclusions: Limited data suggests short-term efficacy of venlafaxine and sertraline monotherapy in patients with acute BD-II depression with good side effect tolerability and without significantly increased switch rate. There is an urgent need for RCTs investigating the role of SGAD monotherapy in short and long-term among patients with BD-II.

Comparison of Patterns of Non-suicidal Self-Injury and Emotion Dysregulation Across Mood Disorder Subtypes.

Introduction: Non-suicidal self-injury (NSSI) is frequently encountered in patients with mood disorders. Emotion dysregulation (ED), frequently observed in mood disorders, could be a major mediating factor in NSSI. The aim of this study was to explore differences in NSSI behavior and ED across mood disorder subtypes. The relationships between childhood trauma and NSSI and ED were also explored. Methods: A total of 191 patients with mood disorders were included in this study. The patterns of NSSI behavior and ED across patients with bipolar I disorder (BD-I), bipolar II disorder (BD-II), and major depressive disorder (MDD) were compared. Results: More than half (54%) of the subjects experienced NSSI. Patients with BD-II and MDD engaged in NSSI behavior more frequently than those diagnosed with BD-I. NSSI behaviors in patients with BD-II most commonly included cutting, whereas hitting behaviors were most common among other groups. Patients with BD-II and MDD reported more severe ED than those with BD-I. In the case of childhood trauma, those with BD-II and MDD reported greater emotional neglect than those with BD-I. Structural equation modeling revealed that ED mediated the association between childhood trauma and NSSI. Conclusion: BD-I was associated with less frequent NSSI behavior and less severe ED than BD-II and MDD. ED mediated the association between childhood trauma and NSSI. Promoting emotion regulation strategies could prevent NSSI behavior in patients with mood disorders.

Differences in mitochondrial DNA copy number between patients with bipolar I and II disorders.

Mitochondria play a critical role in energy metabolism. Genetic, postmortem brain, and brain imaging studies of bipolar disorder (BD) patients indicated that mitochondrial dysfunction might explain BD pathophysiology. Mitochondrial function can be indirectly evaluated by measuring mitochondrial DNA (mtDNA) copy numbers. We recruited 186 bipolar I disorder (BD1) and 95 bipolar II disorder (BD2) patients, and age- and sex-matched controls. MtDNA copy numbers in peripheral blood cells were measured via quantitative polymerase chain reaction. We explored parameters (including age and clinical features) that might affect mtDNA copy numbers. We found that BD1 patients had a lower mtDNA copy number than controls and that mtDNA copy number was negatively associated with the number of mood episodes. BD2 patients had a higher mtDNA copy number than controls. Thus, changes in mitochondrial function may influence BD pathophysiology. The opposite directions of the association with mtDNA copy number in BD1 and BD2 patients suggests that the difference in pathophysiology may be associated with mitochondrial function.

Deficits of social cognition in bipolar disorder: Systematic review and meta-analysis.

BACKGROUND: The association between impaired social cognition and bipolar disorder (BD) is well established. However, to our knowledge, there has not been a recent systematic review that characterizes disparate dimensions of social cognition in BD. Herein, this systematic review and meta-analysis aimed to synthesize the literature on core aspects of social cognition (i.e., Theory of Mind, emotion recognition, and social judgment) to identify potential areas of impairment. METHODS: Online databases (i.e., PubMed, Cochrane Libraries, PsycINFO) and Google Scholar were searched from inception to May 2021. Studies with populations ages ≥16 with DSM-IV or DSM-5 defined BD (I or II) either in a euthymic or symptomatic state were included. The risk of bias was measured using the ROBINS-1 tool, and the quality of the sources was evaluated using GRADE criteria. The results of the studies were quantitatively measured by synthesizing Hedge's g effect sizes through a random effects meta-analytic approach. RESULTS: A total of 29 studies were included in the final review (i.e., 12 studies on the Theory of Mind, 11 on emotion recognition, and 6 on social judgment). Overall, results demonstrated social cognition to be moderately impaired in individuals with BD (d = 0.59). The individual domains ranged in effect size (0.38 < d < 0.70), providing evidence for variation in impairment within social cognition. DISCUSSION: Individuals with BD exhibit clinically significant deficits in social cognition during euthymic and symptomatic states. Social cognition impairments in individuals with BD are an important therapeutic target for treatment discovery and development.

Plasma BDNF and Cytokines Correlated with Protein Biomarkers for Bipolar II Disorder.

We have previously identified five candidate proteins (matrix metallopeptidase 9 (MMP9), phenylalanyl-TRNA synthetase subunit beta (FARSB), peroxiredoxin 2 (PRDX2), carbonic anhydrase 1 (CA-1), and proprotein convertase subtilisin/kexin Type 9 (PCSK9)) as potential biomarkers for bipolar II disorder (BD-II). These candidate proteins have been associated with neuroprotective factors (BDNF) and inflammatory factors (cytokines, C-reactive protein (CRP), and tumor necrosis factor-α (TNF-α)). However, the correlations between these proteins with plasma BDNF and inflammatory factors remain unknown. We recruited a total of 185 patients with BD-II and 186 healthy controls. Plasma levels of candidate proteins, BDNF, cytokines (TNF-α, CRP, and interleukin-8 (IL-8)) were assessed from each participant. The correlations between levels of candidate proteins, BDNF, and cytokines were analyzed. In the BD-II group, we found that the level of FARSB was positively correlated with the BDNF level (r = 0.397, p < 0.001) and IL-8 (r = 0.320, p < 0.001). The CA-1 level positively correlated with IL-8 (r = 0.318, p < 0.001). In the control group, we found that the FARSB level positively correlated with the BDNF level (r = 0.648, p < 0.001). The CA-1 level positively correlated with TNF-α (r = 0.231, p = 0.002), while the MMP-9 level positively correlated with the CRP level (r = 0.227, p = 0.002). Our results may help in clarifying the underlying mechanism of these candidate proteins for BD-II.