Operational Status and Evidence Assessment of Community Mental Health Programs in Korea / 신경정신의학

Objectives@#This study analyzed the current state of community mental health programs in Korea to develop evidence-based criteria for these programs. @*Methods@#Seventy community mental health facilities nationwide were surveyed about the scope of their operated mental health programs. Details, including program structure, staff expertise, standardization, and quality management, of the 511 programs submitted by the facilities as their representative programs were also analyzed to evaluate their efforts for evidence-based practice. @*Results@#The average number of programs operated by community mental health welfare centers was 15.9. The most common programs were those related to serious mental illness (SMI), followed by child/adolescent mental health programs, early psychosis programs, and non-SMI adult mental health programs. In the case of community addiction management centers, there were 7.2 different addiction-related programs per center. Among the psychiatric rehabilitation facilities for SMI, the average number of programs for SMI was 13.1, with some programs for early psychosis. Of the 511 programs submitted as representative programs in their facilities, only 12.3% were judged to be good evidence-based programs. @*Conclusion@#More efforts by mental health professionals and governments are needed to implement evidence-based programs in Korea.

Health Insurance Issues and Future Prospects Related to Korean Mental Health Care: Adult Mental Health and Hospitalization Services / 신경정신의학

The landscape of mental health services in Korea has evolved due to changes in the payment system. Despite the increasing societal focus on mental health, challenges persist. In 2021, 3622695 patients received treatment for mental and behavioral disorders, but decreasing bed numbers in general hospitals and a shortage of psychiatry specialists posed significant hurdles. Although reimbursements for psychiatry remain modest compared to other medical fields, the proportion of expenses allocated to psychotherapy is rising steadily, indicating a growing demand for mental health services. The Korean psychiatric hospitalization system faces a critical juncture. Inadequate reimbursement rates have led to a reduction in the number of beds in general hospitals, compromising acute psychiatric care. Psychiatric hospitals also suffer from low reimbursements, resulting in substandard care environments. These issues exacerbate the societal challenge of acute mental illness and psychiatric emergencies. Despite the recent regulatory efforts, including facility standards, the underlying problem of a discriminatory payment system persists, disproportionately affecting those with medically insured mental illnesses. Although some positive systemic changes have occurred, establishing an effective acute care system for mental illness remains a distant goal. Additional measures are essential to address the disparities and inadequacies within the current mental health payment system and ensure equitable access to quality care for all individuals with mental health needs.

Characteristics of Comorbid Physical Disease in Patients With Severe Mental Illness in South Korea: A Nationwide Population-Based Study (2014-2019)

Objective@#The purpose of this study was to identify the associations of chronic physical disease between patients with severe mental illness (SMI) and the general population of South Korea. @*Methods@#This study was conducted with National Health Insurance Corporation data from 2014 to 2019. A total of 848,058 people were diagnosed with SMI in this period, and the same number of controls were established by matching by sex and age. A descriptive analysis was conducted on the sociodemographic characteristics of patients with SMI. Conditional logistic regression analysis was performed to identify the associations between comorbid physical disease in patients with SMI and those of the general population. SAS Enterprise Guide 7.1 (SAS Inc, Cary, NC, USA) were used to perform all statistical tests. @*Results@#The analysis revealed significant differences in medical insurance, income level, and Charlson Comorbidity Index weighted by chronic physical disease, between patients with SMI and the general population. Conditional logistic regression analysis between the two groups also revealed significant differences in eight chronic physical diseases except hypertensive disease. @*Conclusion@#This study confirmed the vulnerability of patients with SMI to chronic physical diseases and we were able to identify chronic physical disease that were highly related to patients with SMI.

Development of Mental Healthcare Model in Seoul

Objective@#To develop an integrated and comprehensive community-based mental healthcare model, opinions were collected on various issues from practitioners in mental health service institutions currently offering mental healthcare services in Seoul through a focus group interview, qualitative research method, and Delphi survey. @*Methods@#The focus group interview was conducted with six practitioners from mental health welfare centers and six hospital-based psychiatrists. A questionnaire of opinions on the mental healthcare model was filled by these practitioners and psychiatrists. A Delphi survey was additionally conducted with a panel of 20 experts from a community mental health welfare center and hospital-based psychiatrists. @*Results@#The focus group interview results showed the need for integrated community-based mental healthcare service and the need to establish a system for managing mental and physical health in an integrated manner. Based on the survey results, the current status of community-based mental healthcare services was investigated, and the direction of the revised model was established. The Delphi survey was then conducted to refine the revised model. @*Conclusion@#The present study presents the Seoul-type community-based mental healthcare model with integrated services between a psychiatric hospital with a mental health welfare center as well as combined mental and physical health services. This is ultimately expected to help people with mental illnesses live healthy lives by meeting their needs as community members.

Validation of the Patient Health Questionnaire–9 and Patient Health Questionnaire–2 in the General Korean Population

Objective@#The Patient Health Questionnaire–9 (PHQ-9) and PHQ-2 have not been validated in the general Korean population. This study aimed to validate and identify the optimal cutoff scores of the PHQ-9 and PHQ-2 in screening for major depression in the general Korean population. @*Methods@#We used data from 6,022 participants of the Korean Epidemiological Catchment Area Study for Psychiatric Disorders in 2011. Major depression was diagnosed according to the Korean Composite International Diagnostic Interview. Validity, reliability, and receiver operating characteristic curve analyses were performed using the results of the PHQ-9 and Euro Quality of life-5 dimension (EQ-5d). @*Results@#Of the 6,022 participants, 150 were diagnosed with major depression (2.5%). Both PHQ-9 and PHQ-2 demonstrated relatively high reliability and their scores were highly correlated with the “anxiety/depression” score of the EQ-5d. The optimal cutoff score of the PHQ-9 was 5, with a sensitivity of 89.9%, specificity of 84.1%, positive predictive value (PPV) of 12.6%, negative predictive value (NPV) of 99.7%, positive likelihood ratio (LR+) of 5.6, and negative likelihood ratio (LR-) of 0.12. The optimal cutoff score of the PHQ-2 was 2, with a sensitivity of 85.3%, specificity of 83.2%, PPV of 11.6%, NPV of 99.5%, LR+ of 5.1, and LR- of 0.18. @*Conclusion@#The PHQ-9 and PHQ-2 are valid tools for screening major depression in the general Korean population, with suggested cutoff values of 5 and 2 points, respectively.

Effectiveness of a Community-Based Intensive Case Management Model on Reducing Hospitalization for People With Severe Mental Illness in Seoul

Objective@#To overcome the limited effectiveness of standard case management services, the Seoul Intensive Case Management program (S-ICM) for patients with serious mental illnesses was introduced in 2017. This study aimed to evaluate its effectiveness in reducing the length of hospital stay. @*Methods@#Monitoring data from April 2019 to March 2020 were retrieved from the Seoul Mental Health Welfare Center. A total of 759 participants with serious mental illnesses were included. The average length of admission per month was compared between the pre-ICM (previous year) and during-ICM periods. For post-ICM observation subgroup, average length of admission per month was compared between pre-ICM, during-ICM, and post-ICM periods. To determine the relative contributions of risk factors for during-ICM and post-ICM admission, multivariate logistic regression analyses were performed. @*Results@#The average admission stay for pre-ICM period was significantly longer than that for during-ICM period (1.47 vs. 0.26 days). Among the predictors for during-ICM admission, pre-ICM psychiatric admission was the most important risk factor, followed by medical aid beneficiary and suicidal behavior. In the subgroup analysis of the post-ICM observation period, the pre-ICM, during-ICM, and post-ICM average admission stays were 1.45, 0.29, and 0.57 days/month, respectively. There was a significant difference in the average length of stay between the pre-ICM and during-ICM periods and between the pre-ICM and post-ICM periods. Post-ICM admission risks included pre-ICM admission, S-ICM duration <3 months, and chronic unstable symptoms. @*Conclusion@#The results suggest that the S-ICM effectively reduces psychiatric hospitalization duration, at least over a short-term period.

Development of a Seoul-Type Housing Service Model for People With a Mental Illness

Objective@#To establish and to promote the qualitative development of a housing service model in South Korea. @*Methods@#The questionnaire was collected through the housing needs survey and the focus group interview on the mental health professions. We enrolled 365 subjects from 63 places (community conversion facilities, cohabitation, cohabitation families, hospitals, psychiatric nursing homes) to answer the questionnaires. @*Results@#The survey result confirms the needs of people with a mental illness to be self-reliant, but it shows that the economic vulnerability is a hindrance. In addition, the most necessary factor for self-reliant living is to provide services that support daily living. Therefore, the study points out that a system that guarantees self-reliance must be added in order for the housing services to be distributed throughout local communities for the people with mental illness. @*Conclusion@#The study proposes the Seoul-type housing services model to replace the housing services that functions in a fragmented manner with the provision of an integrated services through a unified channel by establishing a housing support center (tentative name). This will ultimately help people with a mental illness to live a healthy life that meets their needs as community members.

The Psychological Burden of COVID-19Stigma: Evaluation of the Mental Health of Isolated Mild Condition COVID-19 Patients

Background@#The objective of this article is to assess the mental health issues of the mild condition coronavirus disease 2019 (COVID-19) patients admitted to a community treatment center (CTC) in Korea. @*Methods@#A total of 107 patients admitted to a CTC were included as the study population, and their mental health problems including depression (patient health questionnaire-9), anxiety (generalized anxiety disorder scale-7), post-traumatic stress disorder (PTSD) (PTSD checklist-5) and somatic symptoms (by patient health questionnaire-15) were evaluated every week during their stay. The stigma related to COVID-19 infection was evaluated with an adjusted version of the Middle East respiratory syndrome (MERS) stigma scale. @*Results@#During the first week of isolation, the prevalence of more-than-moderate depression was 24.3%, more-than-moderate anxiety was 14.9%, more-than-moderate somatic symptoms was 36.5% and possible PTSD was 5.6% of total population. For depression and anxiety, previous psychiatric history and stigma of COVID-19 infection were significant risk factors. For PTSD, previous psychiatric history and stigma of COVID-19 infection as well as total duration of isolation were found to be significant risk factors. Prevalence of depression, anxiety and possible PTSD remained similar across the four weeks of observations, though the prevalence of severe depression, increased after four weeks of stay. Somatic symptoms seemed to decrease during their stay. @*Conclusion@#The results suggest that social mitigation of COVID-19 related stigma, as well as care of patients with pre-existing mental health problems are important mental health measures during this crisis period. It is also important that clinical guidelines and public health policies be well balanced over the protection of the public and those quarantined to minimize the negative psychosocial consequences from isolation of the patients.

Annual Prevalence and Incidence of Schizophrenia and Similar Psychotic Disorders in the Republic of Korea: A National Health Insurance Data-Based Study

Objective@#We conducted this study to address the incidence and prevalence of schizophrenia and similar psychosis in South Korea with Health Insurance Review and Assessment (HIRA) database. @*Methods@#We used HIRA database, which includes diagnostic information of nearly all Korean nationals to collect number of cases with diagnosis of schizophrenia and schizophrenia-similar disorders (SSP), including schizophreniform, acute/transient psychotic disorders, schizoaffective disorders, and other/unspecific nonorganic psychosis (ICD-10 codes F20/23/25/28/29) between 2010 and 2015. The annual prevalence and incidence were calculated using the population data from the Korean Statistical Office. @*Results@#The 12-month prevalence of SSP of Korea between 2010 and 2015 were 0.48–0.66%. The 12-month prevalence of schizophrenia were 0.40–0.52%; The annual incidence rates (IR) of SSP between 2010 and 2015 were 118.8–148.7 per 100,000 person-year (PY). For schizophrenia, IR per 100,000 PY were 77.6–88.5 between 2010 and 2015. @*Conclusion@#The 12-month prevalence found in the present study was higher than that reported in community-based epidemiologic studies in South Korea but similar to those from other countries. The annual incidence of SSP and schizophrenia was found to steadily increase and was higher than that of other countries. The high incidence rate observed in the current study needs to be studied further.

Living Alone, Social Isolation and Depressive Disorder Among Community-Dwelling Older Adults in an Urban Community in Korea

Prevalence of Possible Depression and Post-traumatic Stress Disorder among Community Dwelling Adult Refugees and Refugee Applicants in South Korea

BACKGROUND: Because there has been a recent increase in refugee applications in Korea, the mental health of these refugees merits greater study. METHODS: We surveyed 129 refugees (including those in process of refugee application) and 121 migrant workers living in urban communities, using: the Patient Health Questionnaire-9 for depressive symptoms, the Impact Event Scale-Revised for post-traumatic stress disorder (PTSD) symptoms, and the health questionnaires used in 2016 Korean National Health and Nutrition Examination Survey (KNHANES). The majority of refugee subjects were from sub-Saharan Africa and Middle East. We compared the prevalence of possible depression and possible PTSD between refugees and migrant workers and refugees and age-gender matched samples from the KNHANES 2016. RESULTS: Frequency of suicidal planning during the last year was higher in the refugee group than Korean nationals, but frequency of suicidal attempt was not. High risk drinking was found in 0.8% of refugees, 6.6% of migrant workers and 27.2% of Korean nationals. Possible depression was present in 42.9% of refugee subjects, 33.3% of migrant workers, and 4.2% of Korean controls. Possible PTSD was present in 38.9% of refugees compared to 12.5% of migrant workers. Only major risk factor for depression among refugees was a traumatic event before entering Korea. CONCLUSION: Possible depression and PTSD are significantly more prevalent in refugees, compared to both migrant workers and Korean nationals. Prevalence rates are commensurate with refugee studies worldwide. Appropriate early screening and intervention schemes need to be developed for refugees entering Korea.

Decline in the Incidence of All-Cause and Alzheimer's Disease Dementia: a 12-Year-Later Rural Cohort Study in Korea

BACKGROUND: There has been no study on the time trends of dementia incidence in Korea. We report the 5-year incidence and its correlates of all-cause and Alzheimer's disease (AD) dementia, and compared our results with those of a 12-year-prior cohort study conducted in the same area. METHODS: A total of 751 community-dwelling older adults were followed up for a mean duration of 5.4 years. The age-, gender-, and educational attainment-specific incidence of all-cause and AD dementia were reported as cases per 1,000 person-years. We performed univariate and multivariate cox proportional hazard regression analyses to determine whether baseline sociodemographic, lifestyle, and clinical variables were associated with the risk of all-cause and AD dementia. A 12-year-prior cohort study was used for descriptive comparison to indicate the time trends of dementia incidence. RESULTS: The incidence rates were 16.2 and 13.0 cases per 1,000 person-years for all-cause and AD dementia, respectively. The baseline diagnosis of mild cognitive impairment increased the 5-year incidence of all-cause dementia by more than 4-fold. Old age and low baseline global cognitive function were noted as risk factors for both all-cause and AD dementia. CONCLUSION: Upon comparing the results with those from the earlier cohort study in Yeoncheon, the incidence of all-cause and AD dementia decreased by approximately 40% over 12 years; it has been mainly driven by the increase in the educational level of older adults. The declining time trends of incidence should be taken into account for estimating the future prevalence of dementia in Korea.

A Study on Factors Affecting Suicidal Tendency of the Elderly Living Alone on Care Services

OBJECTIVES: The high suicide rate has risen as a main concern in South Korea. Given the complexity of the mechanism resulting in complete suicide, studies targeting various populations are needed for broader understanding of its risk factors. This study aims to analyze the factors affecting the suicidal tendency in the population of the elderly living alone in Seoul depending on basic elderly-care services. METHODS: A total number of 415 people participated in the study. Home-visit interviews were administered by trained interviewers. Suicidal tendency was measured by the Korean version of mini international neuropsychiatric interview (K-MINI). Health-related quality of life was measured by a brief version of the World Health Organization Quality-of-life Scale (WHOQOL-BREF). Alcohol problem was assessed by the Korean version of the alcohol use disorders identification test (AUDIT-K). Among total subjects of 415 interviewees, the actual responses of 408 people were used for the final analysis. RESULTS: The result showed that the suicide risk was high in persons isolated from social support [odds ratio (OR) = 4.49], having depression (OR = 14.85), and having low quality of life (OR = 4.39). CONCLUSIONS: We found that social support, depression and health-related quality of life are associated with suicidal tendency in the elderly living alone on basic services. Our evidence will contribute to suicide prevention policy for the elderly living alone on care services.

Evaluation of a Functional Model of Acquired Capability for Suicide in a Nationwide Sample of Korean Adults

OBJECTIVE: We examined a functional model of acquired capability for suicide, which was elaborated from the “Interpersonal-Psychological Theory of Suicide”. METHODS: A total of 6,027 Korean community subjects were recruited from The Korean Epidemiologic Catchment Area study conducted in 2011. The subjects were assessed systematically using the Korean version of the Composite International Diagnostic Interview version 2.1, the Korean version of the Barratt Impulsiveness Scale, and the Korean version of the Mood Disorder Questionnaire. We used structural equation modeling to identify potential factors contributing to a suicide attempt. RESULTS: Most aspects of the model were supported by the data and “the short-term enhancer for the acquired capability for suicide” had direct effects on suicide attempts. However, the suicidal planning effects of “the short-term enhancer for the acquired capability for suicide” were eliminated by the rule of parsimony. CONCLUSION: The main finding was that “the short-term enhancer for the acquired capability for suicide” is relevant to suicide attempts when it's direct, indirect, and reciprocal effects are tested within a more complete system of relationships than found in existing studies. The implications of these findings are discussed with regard to future conceptual work and empirical research.

Efficacy of Case Management for the Community Dwelling Schizophrenia Patients : A 36-Month Prospective Follow-Up Study / 신경정신의학

OBJECTIVES: This study was conducted to observe a longitudinal course of patients with schizophrenia enrolled in a community mental health center (CMHC) in Seoul, Korea, and to evaluate the clinical efficacy of case management provided for them. METHODS: Study subjects, including 50 patients in a case-managed group, and 34 patients in the control group, were enrolled from a CMHC and followed up for 36 months. Annual length of hospitalization was compared between two groups by t-tests and time until hospitalization by Kaplan-Meier survival analysis. RESULTS: For the first year of observation, there was no significant difference in annual length of hospitalization between two groups (3.4 weeks vs. 2.9 weeks), but annual length of hospitalization of the case-managed group became significantly shorter for the second (1.7 weeks vs. 7.2 weeks) and third year (1.4 weeks vs. 7.8 weeks). In Kaplan-Meier survival analysis, no difference in time until hospitalization was observed between two groups, but time until hospitalization more than 3 months was significantly shorter in the control group. CONCLUSION: At least two years of case management was required to reduce the length of hospitalization. Reduction in length of hospitalization was achieved by preventing long-term hospitalization.

Steep Decrease of Gender Difference in DSM-IV Alcohol Use Disorder: A Comparison of Two Nation-wide Surveys Conducted 10 Years Apart in Korea

While decreasing trend in gender differences in alcohol use disorders was reported in Western countries, the change in Asian countries is unknown. This study aims to explore the shifts in gender difference in alcohol abuse (AA) and dependence (AD) in Korea. We compared the data from two nation-wide community surveys to evaluate gender differences in lifetime AA and AD by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Face-to-face interviews using the Composite International Diagnostic Interview (CIDI) were applied to all subjects in 2001 (n=6,220) and 2011 (n=6,022). Male-to-female ratio of odds was decreased from 6.41 (95% CI, 4.81-8.54) to 4.37 (95% CI, 3.35-5.71) for AA and from 3.75 (95% CI, 2.96-4.75) to 2.40 (95% CI, 1.80-3.19) for AD. Among those aged 18-29, gender gap even became statistically insignificant for AA (OR, 1.59; 95% CI, 0.97-2.63) and AD (OR, 1.18; 95% CI, 0.80-2.41) in 2011. Men generally showed decreased odds for AD (0.55; 95% CI, 0.45-0.67) and women aged 30-39 showed increased odds for AA (2.13; 95% CI 1.18-3.84) in 2011 compared to 2001. Decreased AD in men and increased AA in women seem to contribute to the decrease of gender gap. Increased risk for AA in young women suggests needs for interventions.

Prevalence and Correlates of DSM-IV Mental Disorders in South Korean Adults: The Korean Epidemiologic Catchment Area Study 2011

OBJECTIVE: The aim of this study was to estimate the prevalence and correlates of mental disorders in Korean adults. METHODS: Door to door household surveys were conducted with community residents aged 18-74 years from July 19, 2011, to November 16, 2011 (n=6,022, response rate 78.7%). The sample was drawn from 12 catchment areas using a multistage cluster method. Each subject was assessed using the Korean version of the World Health Organization Composite International Diagnostic Interview (CIDI) based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). RESULTS: Lifetime and 12-month prevalence estimates were as follows: alcohol use disorders, 13.4% and 4.4%, respectively; nicotine use disorders, 7.2% and 4.0%, respectively; anxiety disorders, 8.7% and 6.8%, respectively; and mood disorders, 7.5% and 3.6%, respectively. The prevalence rates of all types of DSM-IV mental disorders were 27.6% and 16.0%, respectively. Being female; young; divorced, separated, or widowed; and in a low-income group were associated with mood and anxiety disorders after adjustment for various demographic variables, whereas being male and young were associated with alcohol use disorders. Higher income was not correlated with alcohol use disorder as it had been in the 2001 survey. CONCLUSION: The rate of depressive disorders has increased since 2001 (the first national survey), whereas that of anxiety disorders has been relatively stable. The prevalence of nicotine and alcohol use disorders has decreased, and the male-to-female ratio of those with this diagnosis has also decreased.

Two Cases of Wernicke's Encephalopathy That Developed during Total Parenteral Nutrition in Colon Cancer Patients Treated with 5-Fluorouracil-based Chemotherapy / 대한소화기학회지

Wernicke's encephalopathy (WE) caused by thiamine deficiency is an acute neurological disorder. Clinically, the classic triad of WE consists of ophthalmoplegia, ataxia, and mental status changes. Thiamine deficiency is known to occur commonly in chronic alcoholic patients. Sometimes, it can occur in patients after gastrointestinal surgery and in those with malabsorption. In addition, patients undergoing renal dialysis, suffering from hyperemesis gravidarum, receiving total parenteral nutrition (TPN), and being treated with chemotherapeutic agents are also prone to develop thiamine deficiency. Herein, we report two cases of WE that developed following simultaneous 5-fluorouracil (5-FU) chemotherapy and TPN in colon cancer patients which was successfully treated with thiamine administration.

Prevalence, Work-Loss Days and Quality of Life of Community Dwelling Subjects with Depressive Symptoms

The nationwide prevalence of major depressive disorder in Korea is lower than most countries, despite the high suicide rate. To explain this unexpectedly low prevalence, we examined the functional disability and quality of life in community-dwelling subjects with significant depressive symptoms not diagnosable as depressive disorder. A total of 1,029 subjects, randomly chosen from catchment areas, were interviewed with the Center for Epidemiologic Studies Depression scale, Mini International Neuropsychiatric Interview, WHO Quality of Life scale, and the WHO Disability Assessment Schedule. Those with scores over 21 on the depression scale were interviewed by a psychiatrist for diagnostic confirmation. Among community-dwelling subjects, the 1-month prevalence of major depressive disorder was 2.2%, but the 1-month prevalence of depressive symptoms not diagnosable as depressive disorder was 14.1%. Depressive disorders were the cause of 24.7% of work loss days, while depressive symptoms not diagnosable as depressive disorder were the cause of 17.2% of work loss days. These findings support the dimensional or spectrum approach to depressive disorder in the community and might be the missing link between the apparent low prevalence of depressive disorder and high suicide rate in Korea.

The 12-Item General Health Questionnaire as an Effective Mental Health Screening Tool for General Korean Adult Population

OBJECTIVE: The 12-item General Health Questionnaire (GHQ-12) has been used extensively in various settings across different cultures. This study was conducted to determine the thresholds associated with optimum sensitivity and specificity for the GHQ-12 in Korean adults. METHODS: Data was acquired from a sample of 6,510 Korean adults, ages 18 to 64 years old, who were selected from the 2005 Census (2,581 men and 3,929 women). Participants completed the GHQ-12 and the Korean Composite International Diagnostic Interview (K-CIDI). Receiver Operating Characteristic (ROC) curve analysis was conducted. RESULTS: The mean GHQ-12 score for the total sample was 1.63 (SD 1.98). The internal consistency of the GHQ-12 was good (Cronbach's alpha=0.72). Results from the ROC curve indicated that the GHQ-12 yielded greater accuracy when identifying mood and anxiety disorders than when identifying all mental disorders as a whole. The optimal threshold of the GHQ-12 was either 1/2 or 2/3 point depending on the disorder, but was mainly 2/3. CONCLUSION: The Korean version of the GHQ-12 could be used to screen for individuals at high risk of mental disorders, namely mood and anxiety disorders.