Bipolar disorder (BD) is characterized by alternating episodes of mania or hypomania and depression, resulting in substantial psychosocial impairment. Despite its clinical importance, BD is frequently underrecognized or misdiagnosed as major depressive disorder (MDD) or other psychiatric conditions. This review aims to summarize current diagnostic criteria, key clinical differentiating features, and validated assessment tools in order to enhance diagnostic accuracy and facilitate earlier recognition in clinical practice.Current concepts: The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR), and the International Classification of Diseases, 11th Revision, define mania and hypomania by abnormal mood elevation accompanied by increased activity or energy. Bipolar I disorder requires the presence of at least one manic episode, whereas bipolar II disorder requires both hypomanic and major depressive episodes. Cyclothymic disorder and broader bipolar spectrum concepts emphasize subthreshold or atypical presentations that may be overlooked by categorical diagnostic systems. Structured and self-report instruments, including the structured clinical interview for DSM-5-TR, mood disorder questionnaire, hypomania checklist-32, bipolar spectrum diagnostic scale, and Young mania rating scale, play an important role in standardized assessment and longitudinal monitoring.Discussion and conclusion: Accurate diagnosis of BD requires integration of structured diagnostic interviews, standardized rating scales, collateral information, and longitudinal clinical observation. The differential diagnosis from MDD, borderline personality disorder, attention-deficit/hyperactivity disorder, and schizophrenia depends on careful evaluation of episode duration, illness course, and associated functional impairment. Future diagnostic approaches may benefit from dimensional and personalized models incorporating biomarkers, neuroimaging, and digital phenotyping.

Objective: This study aimed to develop a reliable and valid Mixed State Severity Index (MSSI) to assess mood instability in patients with mood disorders and determine cutoff scores. Methods: Twenty-one items were selected based on Koukopoulos’ criteria for mixed depressive episode, historically referred to as agitated depression, and Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision mixed features criteria. The MSSI was administered to 242 patients (major depressive disorder [n=92], bipolar disorder [BD] I [n=78], and BD II [n=72]) and 726 controls. Results: The MSSI demonstrated high internal consistency (α=0.78–0.90). Exploratory factor analysis revealed a stable four-factor structure. Based on receiver operating characteristic analysis, optimal cutoff scores were identified to distinguish mood disorder groups from controls, ranging from 19.5 to 27.5 depending on diagnosis. Conclusion The MSSI is a reliable and valid instrument for assessing the severity of mixed features in patients with mood disorders. The established cutoff scores enhance its clinical utility, providing robust diagnosis and treatment planning support.

Objectives: In this study, we aimed to compare the genetic architecture of schizophrenia (SCZ) and bipolar disorder (BD) in a Korean population by analyzing polygenic risk scores (PRS) derived from large-scale psychiatric disorder genome-wide association study data, based on genetic information collected from SCZ, BD, and healthy control groups. Methods: The study included 713 Korean patients with SCZ, 1,317 with BD, 526 healthy controls. Genotyping was performed using the Korean Biobank Array. PRS-continuous shrinkage method was used to calculate the PRS. Analysis of covariance (ANCOVA) was conducted to determine the association between SCZ or BD disorder and PRS after adjusting for sex. Results: ANCOVA revealed significant differences in PRS values by diagnosis for PRS for SCZ (F=215.281, p<0.001), PRS for BD (F=13.811, p<0.001), and PRS for major depressive disorder (F=6.042, p=0.002). Post-hoc analysis showed that PRS for SCZ was highest in SCZ, followed by BD, and healthy controls. PRS for BD was elevated in both BD and SCZ compared to healthy controls. Conclusion Our study revealed quantitative differences in genetic architecture between SCZ and BD compared to healthy controls, while also suggesting a shared genetic background between the two disorders.

Objective: This study aimed to elucidate the distinct response patterns exhibited by patients diagnosed with bipolar disorder (BD) and those with major depressive disorder (MDD) through the application of the short version of the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego Autoquestionnaire (TEMPS-A-SV). Methods: A total of 2,458 participants consisting of patients with MDD (n=288), BD (BD I, n=111; BD II, n=427), and control group (n=1,632) completed the TEMPS-A-SV. The response patterns of the participants were classified into distinct profiles using latent profile analysis. The study further examined the impact of covariates such as age, sex, and diagnostic group on derived latent profile memberships. Results: The following three latent profiles were identified: High Affective Temperament Group (17.86%), Low Affective Temperament Group (41.25%), and Middle Affective Temperament Group (40.89%). Compared with the patient group with MDD and BD, the control group was more likely to belong in the Low Affective Temperament Group, which showed a higher score on hyperthymic temperament than the Middle Affective Temperament Group. Furthermore, compared with the patients with BD, the MDD patients were more likely to be in the Low Affective Temperament Group rather than the Middle Affective Temperament Group. Conclusion These results indicate that different affective temperaments exist between patients with MDD and BD. Attempting to classify response patterns using the TEMPS-A-SV can help diagnose MDD and BD correctly.

Objective: Interpersonal sensitivity, characterized by a heightened awareness of others’ behavior and emotions, is linked to mood disorders. However, current literature lacks a comprehensive analysis of how some items of the Interpersonal Sensitivity Measure (IPSM) interrelate and contribute to the overall construct. This study constructed a network for interpersonal sensitivity symptomatology to identify core IPSM items in patients with mood disorders. Methods: The IPSM, a 36-item self-report scale, was utilized to evaluate interpersonal sensitivity symptoms in 837 participants (major depressive disorder [MDD], n=265; bipolar I disorder [BD I], n=126; and bipolar II disorder [BD II], n=446). We performed exploratory graph analysis, employing regularized partial correlation models to estimate the network structure. Centrality analysis identified core IPSM symptoms for each mood disorder group. Network comparison tests assessed structural differences between the MDD and BD subgroups. Results: Network analysis detected five communities. Item 10 (“I worry about being criticized for things that I have said or done”) showed the highest value in strength. Multiple items on “Interpersonal Worry/Dependency” and “Low Self-Esteem” showed high strength centrality. Network structure invariance and global strength invariance test results indicated no significant differences between the MDD and BD subgroups. Conclusion Our findings emphasize the importance of addressing “Interpersonal Worry/Dependency” and “Low Self-Esteem” in the IPSM network among mood disorder patients based on core items of the network. Additionally, targeted treatments and comprehensive strategies in this aspect could be crucial for managing mood disorders.

Objective: Mood instability (MI) is a clinically significant trait associated with psychiatric disorders. However, there are no concise measurements to evaluate MI. The initial Mood Instability Questionnaire-Trait (MIQ-T) was developed to fill this gap. The current study aimed to create a short form of MIQ-T (MIQ-T-SF) that measures MI with high validity and reliability in the Korean general population. Methods: Of the 59 items in the MIQ-T, 17 items were chosen for the MIQ-T-SF following the factor analysis process. In total, 540 participants completed the MIQ-T-SF. Cronbach’s alpha and McDonald’s omega were used to evaluate reliability. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to determine construct validity. Concurrent validity was confirmed via comparisons with Personality Assessment Inventory-Borderline Features Scale. Measurement invariance across gender and age groups was confirmed before analyzing differences in scores using Kruskal-Wallis test. Results: The MIQ-T-SF displayed expected correlations and high internal consistency (α=0.71–0.90, Ωt=0.72–0.92). Using EFA and CFA, a five-factor structure was confirmed. Measurement invariance was supported, and gender differences were observed. Conclusion The MIQ-T-SF is an accurate and reliable method to detect MI in the Korean general population. The study’s results offer new perspectives for future studies on MI.

Objective: Although the effects and safety of transcranial direct current stimulation (tDCS) treatment in depressive patients are largely investigated, whether the self-administration of tDCS treatment at patient’s home is comparable to clinic-based treatment is still unknown. Methods: In this single-arm, multi-center clinical trial, 61 patients with mild to moderate major depressive disorder were enrolled. tDCS treatment was delivered at the patient’s home once a day, 5 to 7 times a week for 6 weeks, and each session lasted for 30 minutes. The primary outcome was a total Beck-Depression Inventory-II score, and no concurrent antidepressants were used. Results: The remission rates in both Full-Analysis (FA) (n = 61) and Per-Protocol (PP) (n = 43) groups were statistically significant (FA: 57.4% [0.44−0.70], PP: 62.8% [0.47−0.77]; percent [95% confidence interval]). The degree of depression-related symptoms was also significantly improved in 2, 4, and 6 weeks after the treatment when compared with baseline. There was no significant association between treatment compliance and remission rate in both FA and PP groups. Conclusion These results suggest that acute treatment of patient-administered tDCS might be effective in improving the subjective feeling of depressive symptoms in mild to moderate major depressive disorder patients.

Objective: Mood disorder and borderline personality pathology (BPP) are frequently comorbid and relate to childhood trauma. We investigated the relationship between childhood trauma and BPP features in mood disorder patients versus controls. Methods: A total of 488 mood disorder patients, particularly major depressive disorder (MDD), bipolar I disorder (BD I), and bipolar II disorder (BD II), and 734 controls were included. We examined between-group BPP-related differences and correlated between BPP and childhood trauma using the Childhood Trauma Questionnaire-Short Form (CTQ) and the Personality Assessment Inventory–Borderline Features Scale. Results: BD II patients showed significantly higher BPP. Emotional abuse and neglect were prominently associated with BPP, while affective instability and negative relationships exhibited a stronger association with childhood trauma. We also found a positive relationship between childhood trauma and BPP in MDD, BD I, and BD II patients. Conclusion The findings of the present study imply that BPP features are more likely to be found in patients with BD II than BD I or MDD. Mood disorder patients with severe childhood trauma may have higher BPP features. Thus, further study of the relationship between childhood trauma and BPP features could improve the therapeutic approaches and help understand patients with mood disorders.

Objective: The Temperament Evaluation of Memphis, Pisa, Paris, and San Diego Autoquestionnaire (TEMPS-A) has been validated in more than 30 languages and is noted for its broad application in research and clinical settings. This study presents the first attempt to examine the reliability and validity of the TEMPS-A in Korea. Methods: A total of 540 non-clinical participants completed the Korean TEMPS-A, which was adapted from the original English version via a comprehensive translation procedure. Reliability was assessed using Cronbach’s α, and associations between temperaments were examined using Spearman’s correlation coefficient. Exploratory factor analysis (EFA) was performed, and differences in TEMPS-A scores between the gender- and age-based groups were examined using Kruskal-Wallis analysis. Results: The Korean TEMPS-A exhibited excellent internal consistency (0.70–0.91) and significant correlations between subscales. EFA resulted in a two-factor structure: Factor I (depressive, cyclothymic, irritable, and anxious) and Factor II (hyperthymic). Gender and age group differences were observed. Conclusion Overall, our results suggest that TEMPS-A is a reliable and valid measure of affective temperaments for the Korean population. This study opens new possibilities for further research on affective temperaments and their related traits.