Psychiatric comorbidity and causal disease models

Making meaning of multimorbidity and severe mental illness: A viewpoint

People living with severe mental illness, such as schizophrenia and bipolar affective disorder, frequently experience poorer physical health compared to those without mental illness. This issue has hitherto been approached through the disease-centred construct of comorbidity, where subsequent conditions are viewed as secondary to an 'index condition'. In contrast, this Viewpoint sets out to explain why multimorbidity, a patient-centred concept that instead refers to the coexistence of multiple chronic illnesses, is a more versatile and robust framework for tackling the issue of poor physical health in people with severe mental illness. In establishing this argument, this Viewpoint has sought to address three key areas. First, this article will discuss the epidemiology of both physical and psychiatric multimorbidity, with respect to how they manifest at greater frequency and at younger ages in people with severe mental illness. Second, the profound consequences of this multimorbidity burden will be explored, with respect to the 'three D's' of death (premature mortality), disability (functional impacts) and deficit (health-economic impacts). Finally, the utility of multimorbidity as a framework will be illustrated through a proposal for a three-dimensional multimorbidity construct composed of (1) quantity, (2) severity and (3) duration of an individual's chronic illnesses. Consequently, this Viewpoint aims to capture why it is necessary for modern psychiatry to grasp the concept of multimorbidity to facilitate holistic healthcare for people living with severe mental illness.

Anhedonia as a transdiagnostic symptom across psychological disorders: a network approach

BACKGROUND

Anhedonia is apparent in different mental disorders and is suggested to be related to dysfunctions in the reward system and/or affect regulation. It may hence be a common underlying feature associated with symptom severity of mental disorders.

METHODS

We constructed a cross-sectional graphical Least Absolute Shrinkage and Selection Operator (LASSO) network and a relative importance network to estimate the relationships between anhedonia severity and the severity of symptom clusters of major depressive disorder (MDD), anxiety sensitivity (AS), attention-deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD) in a sample of Dutch adult psychiatric patients (N = 557).

RESULTS

Both these networks revealed anhedonia severity and depression symptom severity as central to the network. Results suggest that anhedonia severity may be predictive of the severity of symptom clusters of MDD, AS, ADHD, and ASD. MDD symptom severity may be predictive of AS and ADHD symptom severity.

CONCLUSIONS

The results suggest that anhedonia may serve as a common underlying transdiagnostic psychopathology feature, predictive of the severity of symptom clusters of depression, AS, ADHD, and ASD. Thus, anhedonia may be associated with the high comorbidity between these symptom clusters and disorders. If our results will be replicated in future studies, it is recommended for clinicians to be more vigilant about screening for anhedonia and/or depression severity in individuals diagnosed with an anxiety disorder, ADHD and/or ASD.

A transdiagnostic network for psychiatric illness derived from atrophy and lesions

Psychiatric disorders share neurobiology and frequently co-occur. This neurobiological and clinical overlap highlights opportunities for transdiagnostic treatments. In this study, we used coordinate and lesion network mapping to test for a shared brain network across psychiatric disorders. In our meta-analysis of 193 studies, atrophy coordinates across six psychiatric disorders mapped to a common brain network defined by positive connectivity to anterior cingulate and insula, and by negative connectivity to posterior parietal and lateral occipital cortex. This network was robust to leave-one-diagnosis-out cross-validation and specific to atrophy coordinates from psychiatric versus neurodegenerative disorders (72 studies). In 194 patients with penetrating head trauma, lesion damage to this network correlated with the number of post-lesion psychiatric diagnoses. Neurosurgical ablation targets for psychiatric illness (four targets) also aligned with the network. This convergent brain network for psychiatric illness may partially explain high rates of psychiatric comorbidity and could highlight neuromodulation targets for patients with more than one psychiatric disorder.

Striatal connectopic maps link to functional domains across psychiatric disorders

Transdiagnostic approaches to psychiatry have significant potential in overcoming the limitations of conventional diagnostic paradigms. However, while frameworks such as the Research Domain Criteria have garnered significant enthusiasm among researchers and clinicians from a theoretical angle, examples of how such an approach might translate in practice to understand the biological mechanisms underlying complex patterns of behaviors in realistic and heterogeneous populations have been sparse. In a richly phenotyped clinical sample (n = 186) specifically designed to capture the complex nature of heterogeneity and comorbidity within- and between stress- and neurodevelopmental disorders, we use exploratory factor analysis on a wide range of clinical questionnaires to identify four stable functional domains that transcend diagnosis and relate to negative valence, cognition, social functioning and inhibition/arousal before replicating them in an independent dataset (n = 188). We then use connectopic mapping to map inter-individual variation in fine-grained topographical organization of functional connectivity in the striatum-a central hub in motor, cognitive, affective and reward-related brain circuits-and use multivariate machine learning (canonical correlation analysis) to show that these individualized topographic representations predict transdiagnostic functional domains out of sample (r = 0.20, p = 0.026). We propose that investigating psychiatric symptoms across disorders is a promising path to linking them to underlying biology, and can help bridge the gap between neuroscience and clinical psychiatry.

Another failure of the latent disease model? The case of compulsive sexual behavior disorder •

Recent debates have evolved regarding the classification/conceptualization of compulsive sexual behavior disorder (CSBD). Conclusions regarding an agreed upon CSBD model are hindered by reliance on the latent disease model. Competing biological-based frameworks are moving forward to replace latent disease classification more broadly but have been met with limited success. We suggest that CSBD researchers move towards developing dimensional, transtheoretical, process-based models. We further suggest additional research, particularly mixed methods and longitudinal studies. Finally, we request that federal funding bodies take a more active role in supporting CSBD research.

A network approach can improve eating disorder conceptualization and treatment

Eating disorders are severe mental illnesses with the second highest mortality rate of all psychiatric illnesses. Eating disorders are exceedingly deadly because of their complexity. Specifically, eating disorders are highly comorbid with other psychiatric illnesses (up to 95% of individuals with an eating disorder have at least one additional psychiatric illness), have extremely heterogeneous presentations, and individuals often migrate from one specific eating disorder diagnosis to another. In this Perspective, we propose that understanding eating disorder comorbidity and heterogeneity via a network theory approach offers substantial benefits for both conceptualization and treatment. Such a conceptualization, strongly based on theory, can identify specific pathways that maintain psychiatric comorbidity, how diagnoses vary across individuals, and how specific symptoms and comorbidities maintain illness for one individual, thereby paving the way for personalized treatment.

Measuring Integrated Novel Dimensions in Neurodevelopmental and Stress-Related Mental Disorders (MIND-SET): Protocol for a Cross-sectional Comorbidity Study From a Research Domain Criteria Perspective

BACKGROUND

It is widely acknowledged that comorbidity between psychiatric disorders is common. Shared and diverse underpinnings of psychiatric disorders cannot be systematically understood based on symptom-based categories of mental disorders, which map poorly onto pathophysiological mechanisms. In the Measuring Integrated Novel Dimensions in Neurodevelopmental and Stress-Related Mental Disorders (MIND-SET) study, we make use of current concepts of comorbidity that transcend the current diagnostic categories. We test this approach to psychiatric problems in patients with frequently occurring psychiatric disorders and their comorbidities (excluding psychosis).

OBJECTIVE

The main aim of the MIND-SET project is to determine the shared and specific mechanisms of neurodevelopmental and stress-related psychiatric disorders at different observational levels.

METHODS

This is an observational cross-sectional study. Data from different observational levels as defined in the Research Domain Criteria (genetics, physiology, neuropsychology, system-level neuroimaging, behavior, self-report, and experimental neurocognitive paradigms) are collected over four time points. Included are adult (aged ≥18 years), nonpsychotic, psychiatric patients with a clinical diagnosis of a stress-related disorder (mood disorder, anxiety disorder, or substance use disorder) or a neurodevelopmental disorder (autism spectrum disorder or attention-deficit/hyperactivity disorder). Individuals with no current or past psychiatric diagnosis are included as neurotypical controls. Data collection started in June 2016 with the aim to include a total of 650 patients and 150 neurotypical controls by 2021. The data collection procedure includes online questionnaires and three subsequent sessions with (1) standardized clinical examination, physical examination, and blood sampling; (2) psychological constructs, neuropsychological tests, and biological marker sampling; and (3) neuroimaging measures.

RESULTS

We aim to include a total of 650 patients and 150 neurotypical control participants in the time period between 2016 and 2022. In October 2021, we are at 95% of our target.

CONCLUSIONS

The MIND-SET study enables us to investigate the mechanistic underpinnings of nonpsychotic psychiatric disorders transdiagnostically. We will identify both shared and disorder-specific markers at different observational levels that can be used as targets for future diagnostic and treatment approaches.

Classifying major mental disorders genetically

Typically, mental disorders are defined and classified based on clinical symptoms and syndromes. Although clinically useful, current diagnostic systems for psychiatry cause concerns due to the lack of biological mechanisms. Deciphering the relationships among psychiatric traits according to their genetic basis may facilitate understanding the biological mechanisms of psychiatric disorders. Ten mental disorders were classified by genomic structural equation modeling (SEM), which leverages summary results of genome-wide association studies. Attention-deficit/hyperactivity disorder (ADHD), anorexia nervosa (AN), anxiety disorder (ANX), autism spectrum disorder (ASD), bipolar disorder (BD), major depressive disorder (MDD), obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), schizophrenia (SZ), and Tourette syndrome (TS) were included. The analysis indicates that they are genetically inter-correlated with one another and can be separated based on their general psychopathology. Most disorders have a close partner, forming pairs of traits; only TS is a relatively distinctive condition. At a higher level, MDD, ANX, ADHD, ASD, and PTSD cluster together, while OCD, AN, and TS cluster together. Together, the ten traits constitute a hierarchical classificatory system. This study allows inference of genetically determined classification of the ten mental disorders, which may biologically inform the current diagnostic framework and treatment regimens for mental disorders.

Multidimensional conceptualization of identity and psychopathology: Assessing mental health disparities from an intersectional and dimensional framework

Black, Indigenous, and People of Color (BIPOC) currently constitute 40% of the US population and will become the majority by 2045. Current mental health systems have not sufficiently accounted for disparities, inequities, and social determinants impacting BIPOC lives. We outline several advances that could improve mental health disparities research. Research on BIPOC requires mental health assessment accurately capturing multiple facets of one's identity, taking into account the complexities of multifaceted historical oppression. Assessing (personality) psychopathology in a dimensional and hierarchical manner could provide greater insight into mental health disparities between diverse identity individuals. We encourage studying moderators that are protective assets for BIPOC-such as resiliency and community factors-as opposed to deficit-dominant, category-based, and majority-dominant assessments.

[Introduction to the hierarchical taxonomy of psychopathology]

INTRODUCTION

In clinical practice, the usefulness of diagnosis based on the Diagnostic or Statistical Manual of Mental Disorders (DSM) or the International Classification of Diseases, 11th edition, appears essential from a clinical, research, epidemiological, administrative, economic and political level. However, such diagnostic systems have shortcomings in terms of validity, little consideration of comorbidities and strong intra-class heterogeneity. On a structural level, the operationalization of its criteria is based on a reliability which has been defined a posteriori and which does not lead to improving the validity of the diagnosis but rather to the reification of the diagnostic categories.

METHODS

First published in its current form in 2017, the Hierarchical Taxonomy of Psychopathology (HiTOP) constitutes a nosological alternative based on statistics. It conceptualizes psychopathology as a set of hierarchical dimensions, i.e. in "transdiagnostic" continua. The HiTOP is structured according to super-spectra, spectra, sub-factors, syndromes, components and symptoms. This comes from the current dimensional psychology and quantitative nosology. This article describes the basic principles of the HiTOP project and its potential to integrate into clinical and psychiatric research based on its advantages and limitations.

RESULTS

Unlike the DSM, which is descriptive and categorical, the HiTOP is first a dimensional classification. This dimensionality describes psychiatric phenomena on continua, each dimension providing a diagnostic continuum to situate a clinical patient. This dimensionality avoids the reification of categories and it limits the dichotomy between normal and pathological. In addition, HiTOP shows a hierarchical structure: vertical refinement of dimensions allows to circumvent the problem of comorbidities, proposes a new conception of etiopathogenic mechanisms, and improves management of care.

DISCUSSION

Thus, we provide an illustration of the applications of a dimensional and hierarchical classification in current clinical practice and scientific research, compared to traditional nosology. The challenges of the HiTOP arise in terms of validity, i.e. in the relation of dimensions with physiopathological mechanisms, in clinical terms, i.e. in the potential contribution of dimensions in relation to categories. Moreover, methodological challenges will be important given the inherent limitations of the HiTOP.

CONCLUSION

The HiTOP allows to examine the conceptualization of psychiatric disorders, the search for explanatory mechanisms, and treatment from another perspective for psychiatry.

Psychiatry in the Digital Age: A Blessing or a Curse?

Social distancing and the shortage of healthcare professionals during the COVID-19 pandemic, the impact of population aging on the healthcare system, as well as the rapid pace of digital innovation are catalyzing the development and implementation of new technologies and digital services in psychiatry. Is this transformation a blessing or a curse for psychiatry? To answer this question, we conducted a literature review covering a broad range of new technologies and eHealth services, including telepsychiatry; computer-, internet-, and app-based cognitive behavioral therapy; virtual reality; digital applied games; a digital medicine system; omics; neuroimaging; machine learning; precision psychiatry; clinical decision support; electronic health records; physician charting; digital language translators; and online mental health resources for patients. We found that eHealth services provide effective, scalable, and cost-efficient options for the treatment of people with limited or no access to mental health care. This review highlights innovative technologies spearheading the way to more effective and safer treatments. We identified artificially intelligent tools that relieve physicians from routine tasks, allowing them to focus on collaborative doctor-patient relationships. The transformation of traditional clinics into digital ones is outlined, and the challenges associated with the successful deployment of digitalization in psychiatry are highlighted.

ADHD Comorbid With Major Depression on Parents and Teachers Perceptions

Objective: Examine the Strengths and Difficulties Questionnaire (SDQ) responses of parents and teachers for children with ADHD comorbid with major depressive disorder (MDD), with an emphasis on determining how well the respondent groups' responses correlate, and how well the results obtained perform as predictors of clinical diagnosis. Method: The SDQ was completed by parents and teachers of (n = 215 participants, 7-12 years old) in ADHD, MDD, ADHD + MDD, and healthy control groups. Agreement between parent and teacher SDQs and their concordance with Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) diagnoses were assessed. Receiver operating characteristic (ROC) and Kappa concordance analyses were used to compare the groups with the health control group. Results: The comorbid group presented greater impairments than the ADHD, MDD, and control groups (p < .001). Conclusion: The presence of psychiatric comorbidity causes greater impairment for school children with ADHD. The SDQ has good sensitivity for detecting these children and correlates well with DSM diagnosis.

The Italian ICD-11 field trial: clinical utility of diagnostic guidelines for schizophrenia and related disorders

Background

The 11th revision of the International Classification of Diseases and Related Disorders (ICD-11) has been released. In order to test the clinical consistency and the clinical utility of the proposed guidelines the World Health Organization (WHO) has carried out the Ecological Implementation Field Studies in various countries. In this paper the results of the Italian field trials on the clinical utility of the ICD-11 diagnostic guideline concerning schizophrenia and related disorders will be presented.

Methods

In Italy, field trials have been carried out at the Department of Psychiatry of the University of Campania “L. Vanvitelli”. All patients showing any psychotic symptom and referring to the outpatient and inpatient units have been recruited. Patients were interviewed by two clinicians with whom they had not had any prior clinical contact. At the end of each interview, clinicians were asked to complete 12 questions about the clinical utility of the diagnostic guidelines as applied to each patient.

Results

Fourteen clinicians and 100 patients have been involved. The ICD-11 clinical guidelines were perceived as easy to use, with an adequate goodness of fit, clear and understandable and with an adequate level of details and specificity to describe the essential features of the diagnoses. Clinicians rated very positively their usefulness in describing the threshold between patient’s disorder and normality. Despite still very positive, the guidelines have been perceived as less useful to select a treatment, to assess patients’ prognosis and to communicate with other mental health professionals.

Conclusions

The 11th revision of the chapter on Mental, Behavioural and Neurodevelopmental Disorders has made substantive changes to the conceptualization of mental disorders which could have impacted on their reliability and clinical utility. Results of the Italian field studies, in line with those reported by the international sample, highlight that ICD-11 has been rated as highly clinically useful by participating clinician, more than the ICD-10. This could be considered a good reason to be optimistic about the implementation of the ICD-11 among global clinicians.

Trial registration The study has been approved by the Ethical Review Board of the University of Campania “L. Vanvitelli” (N. 416, 2016)

Childhood physical abuse and emotional neglect are specifically associated with adult mental disorders

Background: Childhood adversities and trauma (CAT) are associated with adult mental disorders. Nevertheless, although CAT of different domains mostly co-occurs, and co-morbidity is common, the associations between CAT and mental disorders, when taking these interrelations into account, are not well known.Aims: We aimed to study differential associations between the five core domains of CAT and current axis-I disorders, taking into consideration their interrelations.Methods: Four hundred and fifteen outpatients attending adult primary (n = 255) and psychiatric care (n = 160) were assessed with the Trauma and Distress Scale (TADS) and the Mini International Neuropsychiatric Interview (MINI). Associations between CAT core domains and diagnostic categories were examined by path analyses.Results: At least some infrequent experience of CAT (83.6%), mostly of neglect, and current mental disorders (49.4%), mostly depression, was frequent, as were co-morbidities and co-occurrence of CAT domains. Considering these interrelations in a path model of excellent fit, physical abuse predicted depressive, manic, psychotic and anxiety disorders, whereas emotional neglect predicted depressive, anxiety and substance misuse disorders.Conclusions: Of all five CAT core domains, physical abuse and emotional neglect had the strongest association with adult psychiatric disorders and might have transmitted earlier reported main effects of other CAT domains onto mental disorders.

Neuroimaging Studies in Patients With Mental Disorder and Co-occurring Substance Use Disorder: Summary of Findings

Introduction: More than half of psychiatric patients have comorbid substance use disorder (dual diagnosis) and this rate, confirmed by many epidemiological studies, is substantially higher compared to general population. Combined operation of self-medication mechanisms, common etiological factors, and mutually causative influences most likely accounts for comorbidity, which, despite its clinical prevalence, remains underrepresented in psychiatric research, especially in terms of neuroimaging. The current paper attempts to review and discuss all existing methodologically sustainable structural and functional neuroimaging studies in comorbid subjects published in the last 20 years. Methods: Performing a systematic PubMed/MEDLINE, Web of Science, and Cochrane databases search with predefined key-words and selection criteria, 43 structural and functional neuroimaging studies were analyzed. Results: Although markedly inconsistent and confounded by a variety of sources, available data suggest that structural brain changes are slightly more pronounced, yet not qualitatively different in comorbid patients compared to non-comorbid ones. In schizophrenia (SZ) patients, somewhat greater gray matter reduction is seen in cingulate cortex, dorsolateral prefrontal and frontotemporal cortex, limbic structures (hippocampus), and basal ganglia (striatum). The magnitude of structural changes is positively correlated to duration and severity of substance use, but it is important to note that at least in the beginning of the disease, dual diagnosis subjects tend to show less brain abnormalities and better cognitive functioning than pure SZ ones suggesting lower preexisting neuropathological burden. When analysing neuroimaging findings in SZ and bipolar disorder subjects, dorsolateral prefrontal, cingular, and insular cortex emerge as common affected areas in both groups which might indicate a shared endophenotypic (i.e., transdiagnostic) disruption of brain networks involved in executive functioning, emotional processing, and social cognition, rendering affected individuals susceptible to both mental disorder and substance misuse. In patients with anxiety disorders and substance misuse, a common neuroimaging finding is reduced volume of limbic structures (n. accumbens, hippocampus and amygdala). Whether this is a neuropathological marker of common predisposition to specific behavioral symptoms and drug addiction or a result from neuroadaptation changes secondary to substance misuse is unknown. Future neuroimaging studies with larger samples, longitudinal design, and genetic subtyping are warranted to enhance current knowledge on comorbidity.

Exploration of illness perception among patients with mental illness in a multi-ethnic Asian sample

Illness perceptions are beliefs that patients have about their illness. These beliefs play an important role in influencing their behaviour and outcomes. This study examined the factor structure and correlates of the Illness Perception Questionnaire Mental Health (IPQ-MH) among patients with mental illness in a multi-ethnic Asian sample. 400 participants with schizophrenia and other psychotic disorders, mood or anxiety disorder were recruited from a tertiary psychiatric institution and administered the IPQ-MH. Data on sociodemographic variables were also collected. A multi-factor structure was identified for the Identity, Structure and Cause subscale of the IPQ-MH. Age was consistently associated with a positive perception of illness across all three disorders; women had a more positive perception of schizophrenia and other psychotic disorders as compared to men while those of Indian ethnicity had a more negative perception of their mood disorder as compared to those of Chinese ethnicity. Those with lower education had a poorer understanding of their illness among those with mood disorder, and a poorer understanding of their illness and the effectiveness of treatment among those with anxiety disorder. The study identified specific groups which can be targeted through tailored and culturally relevant psychoeducational interventions to enhance their understanding and perception of mental illness.

Lifetime Depression, Other Mental Illness, and Smoking Cessation

Objectives In this study, we attempt to elucidate the relationship between lifetime mental illness (LMI), particularly a depression diagnosis, and smoking cessation. Methods Data were drawn from a previous study and include LMI, demographics, mood, and smoking cessation outcomes. We evaluated the relationship between multiple LMIs and smoking cessation at 7 months post-intervention, and depression in combination with another LMI. Results At 7 months, the adjusted odds of cessation for those with one LMI, including depression, were 0.74 (p = .102), and for those with 2+ LMIs, 0.69 (p = .037), both in comparison with participants who reported no history of LMI. Among those with 2+ LMIs, the adjusted odds of cessation for those with a depression diagnosis were 0.34 (p = .007) compared to those whose multiple LMIs did not include depression. Conclusions Among smokers seeking cessation treatment, those who had 2+ LMIs were at greater risk of relapse, an effect particularly marked in smokers with depression. This study adds to the literature examining the potential impact of LMI on smokers' ability to quit by considering the potential impact of 2+ LMIs and highlights the potential impact of depression as a risk factor for continued smoking.

Prediction, Understanding, and Medicine

What is medicine? One obvious answer in the context of the contemporary clinical tradition is that medicine is the process of curing sick people. However, this "curative thesis" is not satisfactory, even when "cure" is defined generously and even when exceptions such as cosmetic surgery are set aside. Historian of medicine Roy Porter argues that the position of medicine in society has had, and still has, little to do with its ability to make people better. Moreover, the efficacy of medicine for improving population health has been famously doubted by historians and epidemiologists. The curative thesis demands that we have mostly been stupid, duped, or staggeringly hopeful, given that medicine has not until recently offered more than a handful of effective cures. I suggest, in this article, that the core medical competence is neither to cure, nor to prevent, disease, but to understand and to predict it. I argue that this approach does a better job than the curative thesis at explaining why not all medicine is concerned with curative efforts and that it enjoys historical support from the ancient entanglement of prophecy and medicine and from the fact that medicine thrived for centuries with almost no effective cures and continues to thrive today in various forms that are mostly without curative efficacy. I suggest that this approach grounds a fairer approach to alternative, traditional, and other medical practices, as well as some fresh lessons for the development of mainstream medicine.

Personalized medicine in psychiatry

BACKGROUND

Personalized medicine is a model in which a patient's unique clinical, genetic, and environmental characteristics are the basis for treatment and prevention. Aim, method, and results: This review aims to describe the current tools, phenomenological features, clinical risk factors, and biomarkers used to provide personalized medicine. Furthermore, this study describes the target areas in which they can be applied including diagnostics, treatment selection and response, assessment of risk of side-effects, and prevention.

DISCUSSION AND CONCLUSION

Personalized medicine in psychiatry is challenged by the current taxonomy, where the diagnostic categories are broad and great biological heterogeneity exists within each category. There is, thus, a gap between the current advanced research prospects and clinical practice, and the current taxonomy is, thus, a poor basis for biological research. The discussion proposes possible solutions to narrow this gap and to move psychiatric research forward towards personalized medicine.

PSYCHIATRIC COMORBIDITY DOES NOT ONLY DEPEND ON DIAGNOSTIC THRESHOLDS: AN ILLUSTRATION WITH MAJOR DEPRESSIVE DISORDER AND GENERALIZED ANXIETY DISORDER

BACKGROUND

High rates of psychiatric comorbidity are subject of debate: To what extent do they depend on classification choices such as diagnostic thresholds? This paper investigates the influence of different thresholds on rates of comorbidity between major depressive disorder (MDD) and generalized anxiety disorder (GAD).

METHODS

Point prevalence of comorbidity between MDD and GAD was measured in 74,092 subjects from the general population (LifeLines) according to Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) criteria. Comorbidity rates were compared for different thresholds by varying the number of necessary criteria from ≥ 1 to all nine symptoms for MDD, and from ≥ 1 to all seven symptoms for GAD.

RESULTS

According to DSM thresholds, 0.86% had MDD only, 2.96% GAD only, and 1.14% both MDD and GAD (odds ratio (OR) 42.6). Lower thresholds for MDD led to higher rates of comorbidity (1.44% for ≥ 4 of nine MDD symptoms, OR 34.4), whereas lower thresholds for GAD hardly influenced comorbidity (1.16% for ≥ 3 of seven GAD symptoms, OR 38.8). Specific patterns in the distribution of symptoms within the population explained this finding: 37.3% of subjects with core criteria of MDD and GAD reported subthreshold MDD symptoms, whereas only 7.6% reported subthreshold GAD symptoms.

CONCLUSIONS

Lower thresholds for MDD increased comorbidity with GAD, but not vice versa, owing to specific symptom patterns in the population. Generally, comorbidity rates result from both empirical symptom distributions and classification choices and cannot be reduced to either of these exclusively. This insight invites further research into the formation of disease concepts that allow for reliable predictions and targeted therapeutic interventions.

Psychiatric comorbidity: fact or artifact?

The frequent occurrence of comorbidity has brought about an extensive theoretical debate in psychiatry. Why are the rates of psychiatric comorbidity so high and what are their implications for the ontological and epistemological status of comorbid psychiatric diseases? Current explanations focus either on classification choices or on causal ties between disorders. Based on empirical and philosophical arguments, we propose a conventionalist interpretation of psychiatric comorbidity instead. We argue that a conventionalist approach fits well with research and clinical practice and resolves two problems for psychiatric diseases: experimenter's regress and arbitrariness.

[Suicide Ideation Among Medical Students: Prevalence and Associated Factors]

INTRODUCTION

It is well documented that physicians have higher rates of suicide than the general population. This risk tends to increase even from the beginning of undergraduate training in medicine. There are few studies evaluating the frequency of suicidal behaviors in undergraduate medical students, particularly in Latin America.

OBJECTIVE

To determine the lifetime prevalence and the variables associated with suicidal ideation and suicide attempts in a sample of medical students from the city of Bucaramanga, Colombia.

MATERIALS AND METHODS

An analytical cross-sectional observational study was conducted to determine the lifetime prevalence of suicidal ideation and suicide attempts in a non-random sample of medical students enrolled in three medical schools in Bucaramanga. A self-administered questionnaire was voluntarily and anonymously answered by the participants. Validated versions of the CES-D and CAGE scales were used to assess the presence of depressive symptoms and problematic alcohol use, respectively. A multivariate logistic regression model was generated in order to adjust the estimates of variables associated with the outcome «suicidal ideation in life».

RESULTS

The study sample consisted of 963 medical students, of which 57% (n=549) of the participants were women. The average age was 20.3 years (SD=2.3 years). Having had at least one episode of serious suicidal ideation in their lifetime was reported by 15.7% (n=149) of the students, with 5% (n=47) of the students reported having made at least one suicide attempt. Having taken antidepressants during their medical training was reported by 13.9% (n=131) of the students. The variables associated with the presence of suicidal ideation in the logistic regression model were: clinically significant depressive symptoms (OR: 6.9, 95% CI; 4.54-10.4), history of illicit psychoactive substance use (OR 2.8, 95% CI; 1.6-4.8), and perception of poor academic performance over the past year (OR: 2.2, 95% CI; 1.4-3.6). The logistic regression model correctly classified 85% of the subjects with a history of suicidal ideation.

CONCLUSION

Suicidal ideation is a frequently occurring phenomenon in medical students. Medical schools need to establish screening procedures for early detection and intervention of students with emotional distress and suicide risk.