1.Psychometric Properties of the Mixed State Severity Index for Patients With Mood Disorder
Woojae MYUNG ; Hyeona YU ; Hyo Shin KANG ; Daseul LEE ; Junwoo JANG ; Jakyung LEE ; Joohyun YOON ; Yun Seong PARK ; Hyun A RYOO ; Ye Rim KIM ; Kwang Ho PARK ; Chan Woo LEE ; Yoonjeong JANG ; Kimyoung KIM ; Nara LEE ; Sanghoon HONG ; Hong-Hee WON ; Tae Hyon HA ; Jungkyu PARK
Psychiatry Investigation 2026;23(1):106-117
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.
2.Association of Psychiatric Disorder Comorbidities With Global and Orbital Ablative Surgeries: A Real-World Retrospective Cohort Study
Sra JUNG ; Sung Joon CHO ; Jisang HAN
Psychiatry Investigation 2026;23(1):79-87
Objective:
To assess the incidence and risk of psychiatric disorders, including depression, anxiety, and trauma-related disorders, in individuals who underwent globe and orbital ablative surgeries compared to a matched control group.
Methods:
This retrospective cohort study used Korean National Health Insurance Service data. The cohort included 338,767 individuals, with 16,545 in the surgery group (orbital exenteration, enucleation, or evisceration, 2003–2021) and 322,222 matched controls. After exclusions, 12,965 patients were matched with 251,445 controls via propensity score matching. The cumulative incidence and risk of psychiatric disorders, including depression (F32.x, F34.0, F34.1), anxiety (F40.x, F41.x), and trauma-related disorders (F43.x), over three years post-surgery. Kaplan-Meier analysis assessed cumulative incidence, while Cox proportional hazards regression estimated adjusted hazard ratios (HRs) and 95% confidence intervals (CIs).
Results:
A total of 264,410 individuals (mean age, 54.4 years; 63.3% man) were included. The surgery group had significantly higher cumulative incidence of psychiatric disorders (log-rank p<0.001). The incidence rate ratio was 1.63 (95% CI, 1.52–1.75). Risk was greatest in younger individuals (incidence rate ratio, 2.15; 95% CI, 1.75–2.64) and men (1.77 vs. 1.48 in women). Higher comorbidities were associated with lower risk (HR: 0.91 in men, 0.90 in women), as was higher socioeconomic status (HR: 0.76 in men, 0.68 in women).
Conclusion
Globe and orbital ablative surgeries were associated with significantly increased psychiatric risk, particularly in younger men. Higher comorbidities and socioeconomic status appeared to mitigate this risk. Integrated mental health support should be considered in postoperative care.
3.Risk of Psychiatric Morbidity in People Living With Human Immunodeficiency Virus: A Population-Based Cohort Study
Tak Kyu OH ; Kyoung-Ho SONG ; Eunjeong HEO ; Hye Yoon PARK ; In-Ae SONG
Psychiatry Investigation 2026;23(1):38-47
Objective:
The incidence of psychiatric illnesses might be higher in individuals people living with human immunodeficiency virus (PLWH) than in individuals without human immunodeficiency virus (HIV). We aimed to investigate whether PLWH had different risks of psychiatric morbidities in comparison to non-HIV-infected individuals.
Methods:
This study included all PLWH in South Korea between January 1, 2017 and December 31, 2017. The control group, which had never been diagnosed with HIV, was selected using a 1:10 stratified random sampling technique, considering age and sex. The endpoint of this study was new diagnosis of psychiatric morbidities which were diagnosed from January 1, 2018 to December 31, 2022.
Results:
After conducting a 1:5 propensity score (PS) matching process, the final analysis comprised a group of 17,815 PLWH and 78,021 control subjects. In the PS-matched cohort, the incidence rate of psychiatric morbidity in PLWH was 5,677.7 per 100,000 per year, whereas that in the controls was 4,926.3 per 100,000 per year. In Cox regression in the PS-matched cohort, PLWH showed 17% (hazard ratio, 1.17; 95% confidence interval, 1.14–1.21; p<0.001) higher risk of psychiatric morbidity than controls. Specifically, PLWH showed higher risk of depression, mania, bipolar disorder, insomnia disorder, substance use disorder, and schizophrenia compared to controls.
Conclusion
PLWH had a greater likelihood of experiencing psychiatric morbidities compared to those without HIV in South Korea. Our research findings indicate the importance of public health policy in addressing the declining mental health of individuals living with HIV.
4.Risk of Psychiatric Disorders Following Carpal Tunnel Syndrome: A Nationwide Cohort Study
Youngoh BAE ; Chaeyoon KANG ; Hohyun JUNG ; Seung Won LEE
Psychiatry Investigation 2026;23(1):30-37
Objective:
Despite the suspected link between carpal tunnel syndrome (CTS)—a common neuropathy—and psychiatric issues, long-term evidence, especially in Asia, remains scarce. This study investigated the long-term incidence of depression, anxiety, somatoform, and sleep disorders after CTS diagnosis in a South Korean nationwide cohort.
Methods:
Using the Korean National Health Insurance Service cohort (2002–2013), newly diagnosed CTS patients (2004–2013) were identified following a 2-year washout period. Each CTS patient was propensity score-matched 1:10 with non-CTS controls based on demographics and health status. Cox proportional hazards regression yielded adjusted hazard ratios (aHRs) for incident depressive, anxiety, somatoform, and sleep disorders over up to 10 years of follow-up.
Results:
Compared to controls, CTS patients had significantly elevated risks for all outcomes: depressive disorders (aHR, 1.59; 95% confidence interval [CI], 1.45–1.74), anxiety disorders (aHR, 1.41; 95% CI, 1.31–1.52), somatoform disorders (aHR, 1.38; 95% CI, 1.23–1.55), and sleep disorders (aHR, 1.36; 95% CI, 1.25–1.49). Risk was notably higher in individuals aged <60 years for all disorders. Males showed higher risks for depression, anxiety, and sleep disorders, while females had a slightly higher risk for somatoform disorders.
Conclusion
This comprehensive, longitudinal study indicated that CTS is associated with an increased long-term risk of psychiatric disorders. The findings emphasize comprehensive management strategies that integrate mental health screening and interventions tailored to age and sex among patients with CTS.
5.Development of the Instrumental Activities of Daily Living Scale-Ability and Actual Performance: A New Measure for People With Schizophrenia
Psychiatry Investigation 2026;23(1):23-29
Objective:
The study was to develop the instrumental activities of daily living scale-ability and actual performance (IADL-AA) to assess the ability and actual performance constructs of instrumental activities of daily living (IADL).
Methods:
Eight experts reviewed the items of the IADL-AA. Additionally, 30 and 266 people with schizophrenia participated in cognitive interviews and validation analysis, respectively. Expert consultations and cognitive interviews were conducted to examine face validity and content validity, respectively. Construct validity was evaluated through Rasch analysis to ensure unidimensionality. Convergent validity was investigated using Pearson’s r, discriminative validity was examined through floor and ceiling effects, and internal consistency was assessed using Cronbach’s alpha (α).
Results:
The IADL-AA comprised 23 items showing the unidimensionality of each domain. The infit and outfit mean squares were 0.76–1.21 and 0.68–1.40, respectively. A moderate correlation was observed between ability and actual performance domains (r=0.63). No floor or ceiling effects were found for the two domains (0.0%–6.0% and 1.5%–3.0%, respectively). Cronbach’s α of the two domains was 0.83–0.90.
Conclusion
The IADL-AA demonstrates satisfactory psychometric properties, including face validity, content validity, construct validity, convergent validity, discriminative validity, and internal consistency. This measure can effectively identify the capacity and degree of independence of IADL function in people with schizophrenia.
6.Digital Monitoring of Micro- and Macro-Movement Regularity in Psychiatric Inpatients With Depression
Jaewook SHIN ; JungSun LEE ; Sung Woo JOO ; Hyeon Gyu PARK ; Hangsik SHIN ; Hamin LIM ; Ji Hyu PARK ; Sun Min KIM
Psychiatry Investigation 2026;23(1):11-22
Objective:
Depression involves mood-related behavioral changes typically monitored through subjective reports, which are limited by recall bias and low temporal resolution. Digital mental health tools offer objective, continuous monitoring, but prior studies have focused on outpatients subject to environmental variability. In this preliminary feasibility study, we examined psychiatric inpatients in a controlled setting to assess associations between behavioral regularity and depression severity, highlighting the clinical potential of digital phenotyping.
Methods:
Thirty-five adults from a closed psychiatric ward were recruited, and data from 10 inpatients with ≥7 days of valid monitoring were analyzed. Depression severity was assessed weekly using the Hamilton Depression Rating Scale (HAMD) and Dysfunctional Self-focus Attributes Scale, yielding 18 samples. Hourly accelerometer and location data from wearable devices and ward sensors were processed to generate digital phenotypes—interdaily stability (IS), intradaily variability (IV), ratio of IS to IV (ISV), entropy (EN), and normalized entropy (NE)—segmented into daytime and nighttime. Linear mixed models assessed group differences, and correlation and multiple regression examined associations with depression.
Results:
Patients with asymptomatic/mild depression showed significantly higher IS_day and ISV_day, and lower EN_night, and NE_night (all p<0.05). These four features correlated with HAMD after false discovery rate (all p<0.05) correction. A regression model including IS_day and NE_night explained 60.6% of HAMD variance (p<0.05).
Conclusion
Digital monitoring provides an objective and continuous method to assess depression severity. By capturing macro- and micro-level movement regularity across day and night in an inpatient environment, this approach offers practical relevance for psychiatric care. However, results should be considered preliminary due to the limited sample size.
8.Effects of Duration of Untreated Illness on Suicidal Ideation Among Patients With Panic Disorder
Ji Eun KIM ; Ji-Yoon HA ; Yerin BAE ; Hyun-Ju KIM ; Sang-Hyuk LEE
Psychiatry Investigation 2026;23(1):172-179
Objective:
Patients with panic disorder (PD) are approximately four times more likely than the general population to exhibit suicidal ideation (SI) and suicide attempts. Although prolonged duration of untreated illness (DUI) is a known risk factor for adverse outcomes in mood disorders, its impact on suicidality among patients with PD has not been well established. This study investigated whether prolonged DUI is associated with heightened SI among patients with PD, considering sociodemographic and clinical factors.
Methods:
A total of 804 patients with PD were recruited. DUI was defined as the time between symptom onset and the initiation of psychiatric treatment. Clinical assessments included the Scale for Suicide Ideation (SSI), Beck Depression Inventory-II (BDI-II), and Panic Disorder Severity Scale. Sociodemographic and clinical predictors of SI were examined using independent t-tests, Pearson’s correlations, and multiple regression analysis.
Results:
In patients with PD, the mean DUI was 41.56 months. Longer DUI was positively correlated with higher SSI total scores, along with greater depression severity. Gender women, unmarried status, and elevated BDI-II scores were significantly predicted higher SSI total scores. In the multiple regression model, prolonged DUI remained an independent predictor of SSI (B=0.116, p=0.012) after adjusting for other variables.
Conclusion
These findings indicate that delayed treatment contributes to increased suicidality in PD, beyond demographic and depressive risk factors. Therefore, early detection and timely intervention using treatment strategies that enhance awareness, improve the accessibility of psychiatric services, and provide social support may reduce DUI and mitigate suicide risk among patients with PD.
9.Health and Family Factors Predicting Suicidal Ideation Among Middle-Aged Korean Adults: An Explainable Machine Learning Approach
Hyeon-gyeong JO ; Hae-Young KIM ; Ki-Bong CHOI ; Young-Sun KIM ; Young-Bin SEO ; HoJung AHN ; Sunmi SONG ; Junesun KIM
Psychiatry Investigation 2026;23(1):164-171
Objective:
Research specifically targeting suicidal ideation (SI) in middle-aged populations remains limited. This study aimed to predict future and concurrent SI in middle-aged Korean adults by applying four machine learning (ML) models to a nationally representative longitudinal dataset.
Methods:
We analyzed data from 8,992 individuals aged 40–64 years who participated in the Korea Welfare Panel Study from the 7th (2011) to the 18th (2022) waves. Four ML algorithms were employed to develop the predictive models. The SHapley Additive exPlanations method was applied to enhance explainability.
Results:
Approximately half of the participants’ mean age was 49.3±8.2 years (range, 40–64 years) and 52.2% were male. The average annual SI rate between 2011 and 2022 was 2.8%±1.2%. Predictive performance for future SI was satisfactory, with area under the receiver operating characteristic curve (AUC) values of up to 0.806 (logistic regression, LR). Predictions for concurrent SI demonstrated AUC values of up to 0.907 (LR). Key predictors of future SI included subjective health status, satisfaction with family and spousal relationships, housing environment, and educational attainment. Concurrent SI was strongly associated with immediate stressors such as family violence and income dissatisfaction.
Conclusion
The ML models demonstrated good-to-excellent predictive performance for SI. These findings emphasize the importance of health, family, and socioeconomic factors, alongside mental health indicators in the prevention of SI among middle-aged adults. Building on these findings, tailored intervention strategies that comprehensively address multidimensional risk factors are essential for effective SI prevention.
10.Effectiveness of Acceptance and Commitment Therapy on Obsessive Beliefs Among Patients With Obsessive-Compulsive Disorder
Sang Won LEE ; Mina CHOI ; Seung Jae LEE
Psychiatry Investigation 2026;23(1):154-163
Objective:
Both acceptance and commitment therapy (ACT) and metacognitive therapy (MCT) for obsessive-compulsive disorder (OCD) target metacognition. In this context, ACT’s therapeutic effects on OCD are presumably reflected in the Obsessive Belief Questionnaire (OBQ), which incorporates significant metacognitive factors. However, most studies have investigated ACT’s effects on OCD symptoms rather than on obsessive beliefs.
Methods:
This study examined the relationship between ACT process measures—Acceptance and Action Questionnaire-II (AAQ-II) and Cognitive Fusion Questionnaire (CFQ)—and the OBQ following an 8-week group-format ACT (GACT) intervention among patients with OCD (GACT group, n=37; wait-list control group, n=42).
Results:
Significant reductions were observed in AAQ-II, CFQ, and OBQ scores after treatment. Changes in AAQ-II and CFQ (particularly in the former) were significantly associated with changes in the OBQ total and subscale scores. These measures accounted for 26% and 12% of the variance in the OBQ total score and OCD symptom scores, respectively. Among OBQ subscales, changes in AAQ-II and CFQ best accounted for the variance of perfectionism and intolerance of uncertainty (OBQ-PU), followed by importance and control of thoughts (OBQ-ICT).
Conclusion
Improvements in ACT process measures through GACT were more strongly linked to obsessive beliefs than to OCD symptoms, highlighting the role of obsessive beliefs—particularly OBQ-PU and OBQ-ICT—in ACT’s effectiveness for OCD.

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