Genetic and environmental influences on obsessive-compulsive disorder

Unraveling the Boundaries, Overlaps, and Connections between Schizophrenia and Obsessive-Compulsive Disorder (OCD)

Schizophrenia (SCZ) and obsessive-compulsive disorder (OCD) typically have distinct diagnostic criteria and treatment approaches. SCZ is characterized by delusions, hallucinations, disorganized speech, and cognitive impairments, while OCD involves persistent, intrusive thoughts (obsessions) and repetitive behaviors (compulsions). The co-occurrence of these disorders increases clinical complexity and poses significant challenges for diagnosis and treatment. Epidemiological studies indicate a significant overlap, with prevalence rates of comorbid OCD in SCZ patients ranging from 12% to 25%, which is higher than in the general population. Etiological hypotheses suggest shared genetic, neurobiological, and environmental factors, with genetic studies identifying common loci and pathways, such as glutamatergic and dopaminergic systems. Neuroimaging studies reveal both overlapping and distinct neural abnormalities, indicating shared and unique neurobiological substrates. Environmental factors, like early life stressors and urbanicity, also contribute to the comorbidity. The overlapping clinical features of both disorders complicate diagnosis. Treatment approaches include combining SSRIs with antipsychotics and cognitive behavioral therapy (CBT). The complexity of SCZ and OCD comorbidity underscores the need for a dimensional, spectrum-based perspective on psychiatric disorders, alongside traditional categorical approaches, to improve diagnosis and treatment outcomes.

Mechanisms of pathogenesis and environmental moderators in preclinical models of compulsive-like behaviours

Obsessive-compulsive and related disorders (OCRD) is an emergent class of psychiatric illnesses that contributes substantially to the global mental health disease burden. In particular, the prototypical illness, obsessive-compulsive disorder (OCD), has a profoundly deleterious effect on the quality of life of those with lived experience. Both clinical and preclinical studies have investigated the genetic and environmental influences contributing to the pathogenesis of obsessive-compulsive and related disorders. Significant progress has been made in recent years in our understanding of the genetics of OCD, along with the critical role of common environmental triggers (e.g., stress). Some of this progress can be attributed to the sophistication of rodent models used in the field, particularly genetic mutant models, which demonstrate promising construct, face, and predictive validity. However, there is a paucity of studies investigating how these genetic and environmental influences interact to precipitate the behavioural, cellular, and molecular changes that occur in OCD. In this review, we assert that preclinical studies offer a unique opportunity to carefully manipulate environmental and genetic factors, and in turn to interrogate gene-environment interactions and relevant downstream sequelae. Such studies may serve to provide a mechanistic framework to build our understanding of the pathogenesis of complex neuropsychiatric disorders such as OCD. Furthermore, understanding gene-environment interactions and pathogenic mechanisms will facilitate precision medicine and other future approaches to enhance treatment, reduce side-effects of therapeutic interventions, and improve the lives of those suffering from these devastating disorders.

Relationship between gene-environment interaction and obsessive-compulsive disorder: A systematic review

BACKGROUND

Gene-environment interaction (G × E) refers to the change of genetic effects under the participation of environmental factors resulting in differences in genetic expression. G × E has been studied in the occurrence and development of many neuropsychiatric disorders, including obsessive-compulsive disorder (OCD).

AIM

A systematic review was conducted to investigate the role of G × E plays in OCD. This review explored the relationship between G × E and the susceptibility to OCD occurrence, disease progression, and treatment response.

METHODS

This systematic literature search was performed using Web of Science, PubMed, Cochrane Library, and CNKI. Seven studies were selected, which included seven genes (BDNF, COMT, MAO, 5-HTT, SMAD4, PGRN, and SLC1A1) polymorphisms, polygenic risk score (PRS), and two environmental factors (childhood trauma and stressful life events).

RESULTS

Information from this systematic review indicated that G × E increased the susceptibility to OCD, played a crucial role in the clinical characteristics, and had an inconsistent impact on treatment response of OCD.

FUTURE DIRECTIONS

The multi-omics studies and the inclusion of G × E in future GWAS studies of OCD should be drawn more attention, which may contribute to a deeper understanding of the etiology of OCD as well as guide therapeutic interventions for the disease.

Early Identification and Intervention in Pediatric Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a psychiatric disorder characterized by persistent thoughts with subsequent repetitive behaviors. Interventions that are effective for adult OCD cannot simply be generalized to pediatric OCD, since OCD in children and adolescents usually has a different clinical presentation, etiology and course from adult OCD. Delayed and inadequate treatment is associated with a worse prognosis, making the need for early identification and intervention in pediatric OCD very urgent. In this paper, we reflected on the current constraints that make early interventions for pediatric OCD unpromoted and reviewed the approaches with potential application for early identification and early intervention in pediatric OCD, categorized by three-level prevention stages corresponding to a clinical staging model. Since the etiology of pediatric OCD is still unclear, primary prevention is most lacking, and early interventions for pediatric OCD are currently focused on the secondary prevention stage, which aims to prevent the conversion of obsessive-compulsive symptoms into full-blown OCD; tertiary prevention mostly focuses on the alleviation of mild to moderate OCD, while interventions for co-morbidities are still in their infancy. We closed by considering the important research questions on this topic.

Sex matters: The impact of oxytocin on healthy conditions and psychiatric disorders

Oxytocin (OT) is involved in the regulation of physiological processes and emotional states, with increasing evidence for its beneficial actions being mediated by the autonomic and immune systems. Growing evidence suggests that OT plays a role in the pathophysiology of different psychiatric disorders. Given the limited information in humans the aim of this study was to retrospectively explore plasma OT levels in psychiatric patients, particularly focusing on sex-related differences, as compared with healthy controls. The patients studied here were divided into three groups diagnosed with obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD) or major depressive disorder (MDD). Plasma OT levels were significantly different between healthy men and women, with the latter showing higher values, while none of the three psychiatric groups showed sex-related differences in the parameters measured here. The intergroup analyses showed that the OT levels were significantly higher in OCD, lower in PTSD and even more reduced in MDD patients than in healthy subjects. These differences were also confirmed when gender was considered, with the exception of PTSD men, in whom OT levels were similar to those of healthy men. The present results indicated that OT levels were higher amongst healthy women than men, while a sex difference was less apparent or reversed in psychiatric patients. Reductions in sex differences in psychopathologies may be related to differential vulnerabilities in processes associated with basic adaptive and social functions.

Oxytocin: An Old Hormone, A Novel Psychotropic Drug And Possible Use In Treating Psychiatric Disorders

BACKGROUND

Oxytocin is a nonapeptide synthesized in the paraventricular and supraoptic nuclei of the hypothalamus. Historically, this molecule has been involved as a key factor in the formation of infant attachment, maternal behavior and pair bonding and, more generally, in linking social signals with cognition, behaviors and reward. In the last decades, the whole oxytocin system has gained a growing interest as it was proposed to be implicated in etiopathogenesis of several neurodevelopmental and neuropsychiatric disorders.

METHODS

With the main goal of an in-depth understanding of the oxytocin role in the regulation of different functions and complex behaviors as well as its intriguing implications in different neuropsychiatric disorders, we performed a critical review of the current state of art. We carried out this work through PubMed database up to June 2021 with the search terms: 1) "oxytocin and neuropsychiatric disorders"; 2) "oxytocin and neurodevelopmental disorders"; 3) "oxytocin and anorexia"; 4) "oxytocin and eating disorders"; 5) "oxytocin and obsessive-compulsive disorder"; 6) "oxytocin and schizophrenia"; 7) "oxytocin and depression"; 8) "oxytocin and bipolar disorder"; 9) "oxytocin and psychosis"; 10) "oxytocin and anxiety"; 11) "oxytocin and personality disorder"; 12) "oxytocin and PTSD".

RESULTS

Biological, genetic, and epigenetic studies highlighted quality and quantity modifications in the expression of oxytocin peptide or in oxytocin receptor isoforms. These alterations would seem to be correlated with a higher risk of presenting several neuropsychiatric disorders belonging to different psychopathological spectra. Collaterally, the exogenous oxytocin administration has shown to ameliorate many neuropsychiatric clinical conditions.

CONCLUSION

Finally, we briefly analyzed the potential pharmacological use of oxytocin in patient with severe symptomatic SARS-CoV-2 infection due to its anti-inflammatory, anti-oxidative and immunoregulatory properties.

Obsession and Maladaptive Search for Raison D'être: A Condition That May Harm Psychological Wellbeing

Being with raison d’être, or the meaning of living, usually has a positive effect on the psychological wellbeing of humans. The impact of an endeavor or desire to be with raison d’être on human wellbeing remains undetermined. This study investigated the potential impact of an obsession with raison d’être on human psychological wellbeing. A literature review revealed that only a limited number of studies have evaluated the relationship between attitudes toward raison d’être and psychological wellbeing. Some indicate that a pathological obsession with a self-oriented raison d’être, especially when the search is attempted via maladaptive ways, may eventually cause harm and distress to those who are the objects of obsession and the surrounding people. If obsessed people persist to preserve raison d’être in the community, they need to continuously demonstrate the advantage of their existence and differentiation from other members. As conceivable adaptive ways to search for raison d’être, people make efforts to enhance their talents, achieve certifications, be promoted, or dedicate themselves to volunteers. However, if these adaptive ways have failed, some obsessed people may change their processes to maladaptive ways, such as attacking or criticizing other members who are a threat to their satisfaction with raison d’être. Such maladaptive approaches in the community would harm both the obsessed and surrounding members. To date, the negative aspect of desiring for raison d’être has remained largely unevaluated. Research regarding the prevalence of pathologic obsession with raison d’être in the general population, its impact on human wellbeing, and treatability is warranted.

An Interdisciplinary Approach for Compulsive Behavior in Dogs: A Case Report

Compulsive disorder is a debilitating condition affecting both humans and animals, characterized by intrusive thoughts and recurring out-of-place behaviors. Among them, tail chasing might represent one of the most common traits in compulsive dogs. Herein, we reported the case of a 7-year-old intact male German Shepherd mixed-breed dog, presenting with tail chasing behavior. He underwent a first behavioral evaluation 1 year before (at the age of 6), when he injured himself with severe wounds at level of the tail and left thigh. To avoid any specific suffering and increase his physical health, of course, the study was carried out through an interdisciplinary approach, employing a veterinary behaviorist and a rehabilitating dog instructor. Three months after pharmacological treatment with fluoxetine and α-s1 casozepine, associated with a behavioral recovery program, the owner reported an improvement of compulsive events in his dog, in terms of intensity and frequency. Interestingly, over the following 3 months, the dog did not experience any new tail chasing episodes.

Serum Vitamins and Homocysteine Levels in Obsessive-Compulsive Disorder: A Systematic Review and Meta-Analysis

Vitamin and homocysteine (Hcy) alternations have been associated with psychiatric disorders. The aim of this meta-analysis was to assess the association of serum vitamin and Hcy levels with obsessive-compulsive disorder (OCD). Following PRISMA protocol, we used the databases including Scopus, PubMed, Google Scholar, and Web of Science with no time restriction. Data were pooled using a random-effects model and/or fixed-effects model to estimate the standard mean difference (SMD) for evaluation of the strength of association analyses. Our data showed a significant reduction in vitamin B12 (SMD = -0.58, 95% CI = -1.08 to -0.08, p = 0.02, I2 = 65%; pheterogeneity = 0.06), vitamin E (SMD = -0.89, 95% CI = -1.23 to -0.56, p < 0.00001, I2 = 23%; pheterogeneity = 0.26), and vitamin C (SMD = -1.40, 95% CI = -2.44 to -0.36, p = 0.008, I2 = 92%; pheterogeneity < 0.0001) in OCD patients. In addition, the findings showed significantly higher levels of Hcy (SMD = 1.11, 95% CI = [0.48, 1.75], p = 0.0006, I2 = 73%; ph = 0.02) in patients compared to controls. Also, our data showed that vitamin B9 and D levels are not associated with OCD (vitamin B9: SMD = -0.23, 95% CI = -1.01 to 0.55, p = 0.56, I2 = 88%; pheterogeneity < 0.0001; vitamin D: SMD = -0.63, 95% CI = -1.41 to 0.15, p = 0.11, I2 = 88%; pheterogeneity = 0.0002). Our findings support significant impacts of Hcy and vitamin B12, E, and C levels in OCD pathogenesis. This will be important for prevention and treatment of OCD. However, further studies are recommended to elucidate more accurate conclusions.

The Contagion of Psychopathology across Different Psychiatric Disorders: A Comparative Theoretical Analysis

Psychopathology is often studied and treated from an individual-centered approach. However, studies have shown that psychological distress is often best understood from a contextual, environmental perspective. This paper explores the literature on emotional contagion and symptom transmission in psychopathology, i.e., the complex ways in which one person's psychological distress may yield symptoms among others in his/her close environment. We argue that emotions, cognitions, and behaviors often do not stay within the borders of the individual, but rather represent intricate dynamic experiences that are shared by individuals, as well as transmitted between them. While this claim was comprehensively studied in the context of some disorders (e.g., secondary traumatization and the "mimicking" of symptoms among those close to a trauma survivor), it was very scarcely examined in the context of others. We aim to bridge this gap in knowledge by examining the literature on symptom transmission across four distinct psychiatric disorders: PTSD, major depression, OCD, and psychosis. We first review the literature on emotional contagion in each disorder separately, and then we subsequently conduct a comparative analysis highlighting the shared and differential mechanisms underlying these processes in all four disorders. In this era of transdiagnostic conceptualizations of psychopathology, such an examination is timely, and it may carry important clinical implications.

How do daily routines and situational factors affect the severity of obsessive-compulsive disorder?

BACKGROUND

Daily routine and situations may worsen, stabilise, or improve symptoms of obsessive-compulsive disorder (OCD). We investigated which factors OCD patients perceived to be related to the worsening of their OCD symptoms and their relationship to patients' OCD symptom severity.

METHODS

Seven-hundred and forty-two OCD patients completed the Yale-Brown Obsessive-Compulsive Scale as a measure of OCD symptom severity and the Yale OCD Natural History Questionnaire assessing perception of impact of environmental and routine factors on symptoms. We conducted univariate exploratory analyses and a multivariate regression.

RESULTS

Reporting of worsening OCD symptoms when having a meal (B = 0.093, p = 0.008), during hot weather (B = 0.153, p < 0.001) and while watching television (B = 0.080, p = 0.039) was associated with more severe OCD symptoms.

CONCLUSION

People with more severe OCD report symptom worsening while having a meal, when exposed to higher temperatures, and whilst watching television. While our study may be limited by its cross-sectional design (limiting inferences of causality) and analysis of broad (rather than specific) OCD symptoms, our findings point to a potential common biological abnormality that is disturbed by certain events in OCD. We present clinical implications of our findings and areas for further exploration.

Reduced DNA methylation of the oxytocin receptor gene is associated with obsessive-compulsive disorder

Background

Oxytocin is an important neuromodulator involved in cognition and socio-emotional processing that exerts its central activities via oxytocin receptors. Epigenetic alterations in the oxytocin receptor gene (OXTR) may be a molecular mechanism in the pathogenesis of obsessive-compulsive disorder (OCD). This study investigated the association between OXTR DNA methylation and the OCD status of a Korean population.

Results

Quantitative leukocyte DNA methylation levels of three cytosine-phosphate-guanine (CpG) sites in the 5′ untranslated region (UTR) of OXTR exon 2 and eight CpG sites within OXTR exon 3 were analyzed using the pyrosequencing method in 151 patients with OCD (including 45 drug-naïve patients) and 108 healthy controls. DNA methylation levels were compared between the groups using multiple analyses of covariance separately by sex after controlling for age and educational level. Patients with OCD showed significantly lower methylation levels at CpG1 and CpG2 sites on the UTR of OXTR exon 2 than those of healthy controls for both sexes. In a subset of 45 drug-naïve patients with OCD, the DNA methylation levels also remained significantly lower than those in the controls and their CpG1 methylation levels were significantly negatively associated with the ordering symptom dimension.

Conclusions

Our findings suggest that epigenetic OXTR alterations may affect the pathophysiology of OCD. The potential role of the oxytocin system in OCD development and treatment warrants further investigation.

Glutamate transporter gene polymorphisms and obsessive-compulsive disorder: A case-control association study

The etiology of obsessive-compulsive disorder (OCD) is largely unknown, but family, twin, neuroimaging, and pharmacological studies suggest that glutamatergic system plays a significant role on its underlying pathophysiology. We performed an association analysis of six Single Nucleotide Polymorphisms (SNPs) within SLC1A1 gene (rs12682807, rs2075627, rs3780412, rs301443, rs301430, rs301434) in a group of 199 patients and 200 healthy controls. Symptom profiles were evaluated using the Florida Obsessive-Compulsive Inventory (FOCI) and the Obsessive-Compulsive Inventory-Revised (OCI-R). SNPs were analyzed by Taqman® methodology (Thermo Fisher, Brazil). The genotype distributions were in Hardy-Weinberg equilibrium. The A-A-G (rs301434-rs3780412-rs301443) haplotype was twice as common in OCD as in controls (P = 0.02). We also found significant differences between male patients and controls for rs301443 in a dominant model (P = 0.04) and a protective effect of GG genotype of rs2072657 in women (P = 0.02). Regarding clinical characteristics, the G-A (rs301434-rs3780412) haplotype was almost twice more common in patients with vs. without hoarding (P = 0.04). Further analyses showed significant associations between hoarding and rs301434 (P = 0.04) and rs3780412 (P = 0.04) in women, both in a dominant model. A dominant effect was also observed on ordering dimension for rs301434 (P = 0.01, in women) and rs301443 (P = 0.04). Finally, the rs2072657 showed a recessive effect on neutralization (P = 0.04) and checking (P = 0.03, in men). These preliminary results demonstrated that the SLC1A1 may contribute to some extent the susceptibility to OCD and its symptoms. However, additional studies are still needed.

Vitamin B12, folic acid, homocysteine and vitamin D levels in children and adolescents with obsessive compulsive disorder

Obsessive compulsive disorder (OCD) is a complex disorder with a poorly understood aetiopathogenesis. One carbon metabolism that includes vitamin B12, folic acid and homocysteine has been investigated in many psychiatric disorders like OCD. In recent years, vitamin D has also been considered to contribute to many of these psychiatric disorders. In this study we investigated whether vitamin B12, homocysteine and vitamin D play a role in the aetiology of paediatric OCD. With this aim we compared 52 children and adolescent OCD patients with 30 healthy controls. The participants were tested for vitamin B12, folic acid, homocysteine and vitamin D levels and were evaluated with a sociodemographic form, state-trait anxiety inventory 1 and 2, Kovacs Depression Inventory and Yale-Brown Obsessive Compulsive Scale (Y-BOCS). As a result we found significantly lower levels of vitamin B12 and vitamin D and higher levels of homocysteine in the patient group compared to control group (p values for all three scores were <0.001), whereas there was no significant difference between groups in terms of folate levels (p=0.083). This demonstrates that one carbon metabolism and vitamin D deficiency can play a role in the aetiology of OCD.

Comorbidity variation in patients with obsessive-compulsive disorder according to symptom dimensions: Results from a large multicentre clinical sample

BACKGROUND

Obsessive-compulsive disorder (OCD) has a heterogeneous and complex phenomenological picture, characterized by different symptom dimensions and comorbid psychiatric disorders, which frequently co-occur or are replaced by others over the illness course. To date, very few studies have investigated the associations between specific OCD symptom dimensions and comorbid disorders.

METHODS

Cross-sectional, multicenter clinical study with 1001 well-characterized OCD patients recruited within the Brazilian Research Consortium on Obsessive-Compulsive and Related Disorders. The primary instruments were the Dimensional Yale-Brown Obsessive Compulsive Scale (DY-BOCS) and the Structured Clinical Interview for DSM-IV Axis I Disorders. Bivariate analyses between symptom dimensions and comorbidities were followed by logistic regression.

RESULTS

The most common comorbidities among participants (56.8% females) were major depression (56.4%), social phobia (34.6%), generalized anxiety disorder (34.3%), and specific phobia (31.4%). The aggressive dimension was independently associated with posttraumatic stress disorder (PTSD), separation anxiety disorder, any impulse-control disorder and skin picking; the sexual-religious dimension was associated with mood disorders, panic disorder/agoraphobia, social phobia, separation anxiety disorder, non-paraphilic sexual disorder, any somatoform disorder, body dysmorphic disorder and tic disorders; the contamination-cleaning dimension was related to hypochondriasis; and the hoarding dimension was associated with depressive disorders, specific phobia, PTSD, impulse control disorders (compulsive buying, skin picking, internet use), ADHD and tic disorders. The symmetry-ordering dimension was not independently associated with any comorbidity.

LIMITATIONS

Cross-sectional design; participants from only tertiary mental health services; personality disorders not investigated.

CONCLUSIONS

Different OCD dimensions presented some specific associations with comorbid disorders, which may influence treatment seeking behaviors and response, and be suggestive of different underlying pathogenic mechanisms.

Mild White Matter Changes in Un-medicated Obsessive-Compulsive Disorder Patients and Their Unaffected Siblings

Objective: Obsessive-compulsive disorder (OCD) is a common neuropsychiatric disorder with moderate genetic influences and white matter abnormalities in frontal-striatal and limbic regions. Inconsistencies in reported white matter results from diffusion tensor imaging (DTI) studies can be explained, at least partly, by medication use and between-group differences in disease profile and stage. We used a family design aiming to establish whether white matter abnormalities, if present in un-medicated OCD patients, also exist in their unaffected siblings.

Method: Forty-four OCD patients, un-medicated for at least the past 4 weeks, 15 of their unaffected siblings, and 37 healthy controls (HC) underwent DTI using a 3-Tesla MRI-scanner. Data analysis was done using tract-based spatial statistics (TBSS). Fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD) values were compared within seven skeletonised regions of interest (ROIs), i.e., corpus callosum, bilateral cingulum bundle, bilateral inferior longitudinal fasciculus/frontal-occipital fasciculus (ILF/FOF) and bilateral superior longitudinal fasciculus (SLF).

Results: Un-medicated OCD patients, compared with HC, had significantly lower FA in the left cingulum bundle. FA was trend-significantly lower in all other ROIs, except for the corpus callosum. Significant three-group differences in FA (and in RD at trend-significant level) were observed in the left cingulum bundle, with the unaffected siblings representing an intermediate group between OCD patients and HC.

Conclusions: OCD patients showed lower FA in the left cingulum bundle, partly driven by trend-significantly higher values in RD. Since the unaffected siblings were found to be an intermediate group between OCD patients and HC, this white matter alteration may be considered an endophenotype for OCD.

Anxiety and affective disorder comorbidity related to serotonin and other neurotransmitter systems: obsessive-compulsive disorder as an example of overlapping clinical and genetic heterogeneity

Individuals with obsessive-compulsive disorder (OCD) have also been shown to have comorbid lifetime diagnoses of major depressive disorder (MDD; rates greater than 70%), bipolar disorder (rates greater than 10%) and other anxiety disorders (e.g. panic disorder, post-traumatic stress disorder (PTSD)). In addition, overlap exists in some common genetic variants (e.g. the serotonin transporter gene (SLC6A4), the brain-derived neurotrophic factor (BDNF) gene), and rare variants in genes/chromosomal abnormalities (e.g. the 22q11 microdeletion syndrome) found across the affective/anxiety disorder spectrums. OCD has been proposed as a possible independent entity for DSM-5, but by others thought best retained as an anxiety disorder subtype (its current designation in DSM-IV), and yet by others considered best in the affective disorder spectrum. This review focuses on OCD, a well-studied but still puzzling heterogeneous disorder, regarding alterations in serotonergic, dopaminergic and glutamatergic neurotransmission in addition to other systems involved, and how related genes may be involved in the comorbidity of anxiety and affective disorders. OCD resembles disorders such as depression, in which gene × gene interactions, gene × environment interactions and stress elements coalesce to yield OC symptoms and, in some individuals, full-blown OCD with multiple comorbid disorders.

The Netherlands Obsessive Compulsive Disorder Association (NOCDA) study: design and rationale of a longitudinal naturalistic study of the course of OCD and clinical characteristics of the sample at baseline

In half of Obsessive Compulsive Disorder (OCD) patients the disorder runs a chronic course despite treatment. The factors determining this unfavourable outcome remain unknown. The Netherlands Obsessive Compulsive Disorder Association (NOCDA) study is a multicentre naturalistic cohort study of the biological, psychological and social determinants of chronicity in a clinical sample. Recruitment of OCD patients took place in mental health organizations. Its design is a six-year longitudinal cohort study among a representative clinical sample of 419 OCD patients. All five measurements within this six-year period involved validated semi-structured interviews and self-report questionnaires which gathered information on the severity of OCD and its co-morbidity as well as information on general wellbeing, quality of life, daily activities, medical consumption and key psychological and social factors. The baseline measurements also include DNA and blood sampling and data on demographic and personality variables. The current paper presents the design and rationale of the study, as well as data on baseline sample characteristics. Demographic characteristics and co-morbidity ratings in the NOCDA sample closely resemble other OCD study samples. Lifetime co-morbid Axis I disorders are present in the majority of OCD patients, with high current and lifetime co-morbidity ratings for affective disorders (23.4% and 63.7%, respectively) and anxiety disorders other than OCD (36% current and 46.5% lifetime).

Brain activation during response interference in twins discordant or concordant for obsessive compulsive symptoms

One of the core behavioral features associated with obsessive compulsive symptomatology is the inability to inhibit thoughts and/or behaviors. Neuroimaging studies have indicated abnormalities in frontostriatal and dorsolateral prefrontal - anterior cingulate circuits during inhibitory control in patients with obsessive compulsive disorder compared with controls. In the present study, task performance and brain activation during Stroop color-word and Flanker interference were compared within monozygotic twin pairs discordant for obsessive compulsive symptoms and between groups of pairs scoring very low or very high on obsessive compulsive symptoms, in order to examine the differential impact of non-shared environmental versus genetic risk factors for obsessive compulsive symptomatology on inhibitory control related functional brain activation. Although performance was intact, brain activation during inhibition of distracting information differed between obsessive compulsive symptom high-scoring compared to low-scoring subjects. Regions affected in the discordant group (e.g., temporal and anterior cingulate gyrus) were partly different from those observed to be affected in the concordant groups (e.g., parietal gyrus and thalamus). A robust increase in dorsolateral prefrontal activity during response interference was observed in both the high-scoring twins of the discordant sample and the high-scoring twins of the concordant sample, marking this structure as a possible key region for disturbances in inhibitory control in obsessive compulsive disorder.

Environmental effects on compulsive tail chasing in dogs

Obsessive Compulsive Disorder (OCD) is a neuropsychiatric disorder observed both in humans and animals. Examples of Canine Compulsive Disorder (CD) include excessive tail chasing (TC), light/shadow chasing and flank sucking. We performed a questionnaire survey to investigate the characteristics of compulsive (TC) and its possible associations with environmental correlates and personality in a pet population of 368 dogs from four dog breeds. We observed an early onset of TC at 3–6 months of age and a large variation in TC frequency in all breeds, with an overrepresentation of milder cases. Almost half of the TC dogs showed lowered responsiveness during bouts and displayed also other types of compulsions more often than the controls. Interestingly, dogs that received dietary supplements, especially vitamins and minerals, expressed less TC compared to dogs that did not receive any supplements. Neutered females had less TC, suggesting an influence of ovarian hormones on TC. Tail chasers were shyer and had separated earlier from their mothers than the controls. Finally, our genetic study did not find an association between TC and CDH2, a locus previously associated with the canine flank sucking compulsion. In conclusion, the early-onset and the variable nature of the repetitive behaviour, which is affected by environmental factors such as micronutrients, neutering and maternal care, share several similar components between canine and human compulsions and supports canine TC as a model for human OCD.

Stressful life events and obsessive-compulsive disorder: clinical features and symptom dimensions

The potential role of stressful life events (SLEs) in the genesis of obsessive-compulsive disorder (OCD) has been suggested by several authors, but whether the number or the severity or the type of SLEs preceding the onset of OCD has a triggering effect is unclear. Further, sociodemographic and clinical features of OCD preceded by SLEs, and the relationship between type of SLEs and type of obsessive-compulsive symptomatology remain mainly unexplored. The aims of this study were to compare the clinical features of OCD with and without SLEs preceding it and to examine the relationship between type of SLEs and OCD symptom dimensions. The number and type of SLEs which occurred before the onset of OCD were determined in 329 patients: the raters had to decide whether an occurrence 12 months before the onset of OCD would fit any of the 61 items on Paykel's list, and each event reported was carefully investigated in order to determine the exact time of occurrence. At least one event preceded the onset of OCD in 200 patients (60.8%), and this was significantly associated with female gender, abrupt onset of the disorder and somatic obsessions. Moreover, LogReg Analysis identified three specific traumatic events ("hospitalization of a family member", "major personal physical illness", "loss of personally valuable object") significantly associated with a symptom dimension (symmetry obsessions, repeating, ordering/arranging, counting, and checking compulsions). Additional evidence regarding the association among SLE-preceded OCD, female gender, somatic obsessions and symmetry/ordering symptoms should be obtained to advance the understanding of OCD.

Childhood Experiences and Adult Beliefs in Obsessive-Compulsive Disorder: Evaluating a Specific Etiological Model

Cognitive accounts of obsessive-compulsive disorder (OCD) propose that an individual’s early experiences contribute to the development of different belief domains, which in turn represent fertile ground for the development of the disorder (e.g., Salkovskis, Shafran, Rachman, & Freeston, 1999). This study examined the proximal relationship between specific, narrowly defined childhood experiences (CEs) and distinct adult OCD-related beliefs (Obsessive Beliefs Questionnaire-87 [OBQ-87]) through the self-reports of 83 participants with OCD and 213 unselected student participants. CEs variables were operationalized via theoretical groupings of items on an early experience questionnaire (QEE) relevant to distinct OBQ belief domains. These proximal relationships were assessed according to predictions from both a specific and a nonspecific vulnerability hypothesis. Correlational analyses were supportive of both but mostly of a nonspecific vulnerability model. Results are discussed regarding the understanding of the possible multideterministic pathways to OCD development.

Risk factors prospectively associated with adult obsessive-compulsive symptom dimensions and obsessive-compulsive disorder

BACKGROUND

Very few longitudinal studies have evaluated prospective neurodevelopmental and psychosocial risk factors for obsessive-compulsive disorder (OCD). Furthermore, despite the heterogeneous nature of OCD, no research has examined risk factors for its primary symptom dimensions, such as contamination/washing.

METHOD

Potential risk factors for symptoms or diagnosis of OCD in adulthood and for specific adult obsessive-compulsive (OC) symptom dimensions were examined in the Dunedin Study birth cohort. The presence of obsessions and compulsions and psychological disorders was assessed using the Diagnostic Interview Schedule (DIS) at ages 26 and 32 years. Individuals with a diagnosis of OCD at either age (n=36) were compared to both a healthy control group (n=613) and an anxious control group (n=310) to determine whether associations between a risk factor and an OCD diagnosis were specific.

RESULTS

Childhood neurodevelopmental, behavioral, personality and environmental risk factors were associated with a diagnosis of OCD and with OC symptoms at ages 26 and 32. Social isolation, retrospectively reported physical abuse and negative emotionality were specific predictors of an adult OCD diagnosis. Of note, most risk factors were associated with OC symptoms in adulthood and several risk factors predicted specific OCD dimensions. Perinatal insults were linked to increased risk for symmetry/ordering and shameful thoughts dimensions, whereas poor childhood motor skills predicted the harm/checking dimension. Difficult temperament, internalizing symptoms and conduct problems in childhood also predicted specific symptom dimensions and lower IQ non-specifically predicted increased risk for most dimensions.

CONCLUSIONS

The current findings underscore the need for a dimensional approach in evaluating childhood risk factors for obsessions and compulsions.

Psychopathological aspects of dopaminergic gene polymorphisms in adolescence and young adulthood

Dopamine hypotheses of several psychiatric disorders are based upon the clinical benefits of drugs affecting dopamine transporter or receptors, and have prompted intensive candidate gene research within the dopaminergic system during the last two decades. The aim of this review is to survey the most important findings concerning dopaminergic gene polymorphisms in attention deficit hyperactivity disorder (ADHD), Tourette syndrome (TS), obsessive compulsive disorder, and substance abuse. Also, genetic findings of related phenotypes, such as inattention, impulsivity, aggressive behavior, and novelty seeking personality trait are presented, because recent studies have applied quantitative trait measures using questionnaires, symptom scales, or other objective endophenotypes. Unfortunately, genetic variants with minor effects are problematic to detect in these complex inheritance disorders, often leading to contradictory results. The most consistent association findings relate to ADHD and the dopamine transporter and the dopamine D4 receptor genes. Meta-analyses also support the association between substance abuse and the D2 receptor gene. The dopamine catabolizing enzyme genes, such as monoamine oxidase (MAO) A and catechol-O-methyltransferase (COMT) genes, have been linked to aggressive behaviors.

Cognitive dysfunction in post-traumatic obsessive-compulsive disorder

OBJECTIVE

To investigate whether patients who develop obsessive-compulsive disorder (OCD) after posttraumatic stress disorder, i.e. post-traumatic OCD (PsT-OCD), display a distinctive neurocognitive pattern of dysfunction.

METHODS

Patients with PsT-OCD (n = 16), pre-traumatic OCD (PrT-OCD) (n = 18), non-traumatic OCD (NonT-OCD) (n = 67) and healthy controls (n = 17) had their performance compared on the following neuropsychological tests: the Wisconsin Card Sorting Test, the Iowa Gambling Task, the Wechsler Memory Scale Logical Memory, the Brief Visual Memory Test - Revised, and the Wechsler Abbreviated Scale for Intelligence.

RESULTS

Patients with OCD, as a group, were characterized by poor set-shifting abilities and impaired verbal and visuospatial memories. Impaired set-shifting abilities were found to correlate with the severity of obsessive-compulsive symptoms in all groups of patients with OCD, with the exception of PsT-OCD. Only patients with PsT-OCD were characterized by impaired visuospatial recognition, which was found to correlate with poor set-shifting abilities in this particular group of patients, but not in individuals with other types of OCD or in healthy controls.

CONCLUSIONS

Our study suggests that PsT-OCD is associated with a distinctive pattern of neurocognitive dysfunction, thus providing support for a different subtype of OCD.

Association between intracellular infectious agents and Tourette's syndrome

The underlying pathophysiological mechanisms in Tourette's syndrome (TS) are still unclear. Increasing evidence supports the involvement of infections, possibly on the basis of an altered immune status. Not only streptococci but also other infectious agents may be involved. This study investigates the association between the neurotrophic agents Chlamydia, Toxoplasma and TS. 32 patients with TS and 30 healthy matched controls were included. For each individual, IgA/IgG antibody titers against Chlamydia trachomatis/pneumoniae and Toxoplasma gondii were evaluated and analyzed with Fisher's exact test. We found a significantly higher rate of TS patients with elevated antibody titers against Chlamydia trachomatis (P = 0.017) as compared to controls. A trend toward a higher prevalence in the Tourette's group was shown for Toxoplasma (P = 0.069). In conclusion, within the TS patients a higher rate of antibody titers could be demonstrated, pointing to a possible role of Chlamydia and Toxoplasma in the pathogenesis of tic disorders. Because none of these agents has been linked with TS to date, a hypothesis is that infections could contribute to TS by triggering an immune response. It still remains unclear whether tic symptoms are partly due to the infection or to changes in the immune balance caused by an infection.

MRI study of the cavum septum pellucidum in obsessive-compulsive disorder

The cavum septum pellucidum (CSP), a putative marker of neurodevelopmental anomaly, has been associated with an increased risk of several psychiatric disorders. The purpose of this study was to evaluate the CSP in patients with obsessive-compulsive disorder (OCD) compared with healthy control subjects. Seventy-one patients with OCD and 71 healthy volunteers matched for age and sex were evaluated with magnetic resonance imaging. We evaluated the CSP using criteria employed in previous studies: presence of the CSP, length of the CSP, and overall size of the CSP, measured in five grades, ranging from grades 0 (no CSP) to 4 (severe CSP). We evaluated OCD symptom severity using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). The CSP presence was significantly greater in the OCD group (60.6%) than in control subjects (29.6%), and CSP size grade was significantly larger in the OCD group (chi(2) = 15.609, P = 0.004). CSP length showed no significant group difference. Among patients with OCD, those with a CSP had higher scores on the obsession subscale of the Y-BOCS than those without a CSP (Z = -2.358, P = 0.018), while they did not show significant difference from those without a CSP in the compulsion subscale of the Y-BOCS, age, duration of illness, or age at onset. These results indicate that neurodevelopmental alterations in midline structures might contribute to the pathogenesis of OCD.

Serum levels of brain-derived neurotrophic factor in drug-naïve obsessive-compulsive patients: a case-control study

BACKGROUND

There is lack of data regarding BDNF serum levels in patients with obsessive-compulsive disorder (OCD). The aims of the present study were: 1) to assess the serum BDNF content in a sample of drug-naïve patients with OCD and 2) to assess whether putative alterations in peripheral BDNF may be associated to OCD severity and clinical characteristics.

METHODS

Twenty-four drug-naïve patients with a principal diagnosis of OCD were recruited. In parallel, a control group of 24 unrelated volunteers matched for gender and age was enrolled. Serum BDNF levels were measured by ELISA method.

RESULTS

The results showed that BDNF levels were decreased in OCD patients when compared to controls (36.90+/-6.42 ng/ml versus 41.59+/-7.82 ng/ml; p=0.043). No correlations were evidenced between serum BDNF content and the severity of OCD symptoms measured as Y-BOCS scores or other clinical variables.

LIMITATIONS

The choice of drug-naïve patients with obsessive-compulsive disorder had limited the size of the sample and excluded the recruitment of patients with a severe symptomatology.

CONCLUSIONS

Our findings reveal for the first time in OCD patients a decrease in serum BDNF levels. These data corroborate the hypothesis of a dysfunction in the neurotrophin expression in the OCD pathogenetic mechanism and provide the rationale for further investigations directed to the identification of novel biomarkers and new therapeutic strategies for antiobsessional treatments.

The impact of trauma and post-traumatic stress disorder on the treatment response of patients with obsessive-compulsive disorder

Few case series studies have addressed the issue of treatment response in patients with obsessive-compulsive disorder (OCD) and comorbid post-traumatic stress disorder (PTSD), and there are no prospective studies addressing response to conventional treatment in OCD patients with a history of trauma (HT). The present study aimed to investigate, prospectively, the impact of HT or PTSD on two systematic, first-line treatments for OCD. Two hundred and nineteen non-treatment-resistant OCD outpatients were treated with either group cognitive-behavioral therapy (GCBT n = 147) or monotherapy with a selective serotonin reuptake inhibitor (SSRI n = 72). Presence of HT and PTSD were assessed at intake, as part of a broader clinical and demographical baseline characterization of the sample. Severity and types of OCD symptoms were assessed with the Yale-Brown Obsessive-Compulsive Scale (YBOCS) and the Dimensional YBOCS (DYBOCS), respectively. Depression and anxiety symptoms were measured with the Beck Depression Inventory (BDI) and the Beck Anxiety Inventory (BAI). Both treatments had 12-week duration. Treatment response was considered as a categorical [35% or greater reduction in baseline YBOCS scores plus a Clinical Global Impression-Improvement rating of better (2) or much better (1)] and continuous variable (absolute number reduction in baseline YBOCS scores). Treatment response was compared between the OCD + HT group versus the OCD without HT group and between the OCD + PTSD group versus the OCD without PTSD group. Parametric and non-parametric tests were used when indicated. Data on HT and PTSD were available for 215 subjects. Thirty-eight subjects (17.67% of the whole sample) had a positive HT (OCD + HT group) and 22 subjects (57.89% of the OCD + HT group and 10.23% of the whole sample) met full DSM-IV criteria for PTSD. The OCD + HT and OCD without HT groups presented similar response to GCBT (60% of responders in the first group and 63% of responders in the second group, p = 1.00). Regarding SSRI treatment, the difference between the response of the OCD + HT (47.4%) and OCD without HT (22.2%) groups was marginally significant (p = 0.07). In addition, the OCD + PTSD group presented a greater treatment response than the OCD without PTSD group when treatment response was considered as a continuous variable (p = 0.01). The age when the first trauma occurred had no impact on treatment response. In terms of specific OCD symptom dimensions, as measured by the DYBOCS, OCD treatment fostered greater reductions for the OCD + PTSD group than for the OCD without PTSD group in the scores of contamination obsessions and cleaning compulsions, collecting and hoarding and miscellaneous obsessions and related compulsions (including illness concerns and mental rituals, among others). The OCD + PTSD group also presented a greater reduction in anxiety scores than the OCD without PTSD group (p = 0.003). The presence of HT or PTSD was not related to a poorer treatment response in this sample of non-treatment-resistant OCD patients. Unexpectedly, OCD patients with PTSD presented a greater magnitude of response when compared with OCD without PTSD patients in specific OCD symptom dimensions. Future studies are needed to clarify if trauma and PTSD have a more significant impact on the onset and clinical expression of OCD than on the conventional treatment for this condition, and whether OCD stemming from trauma would constitute a subtype of OCD with a distinct response to conventional treatment.

The impact of trauma and post-traumatic stress disorder on the treatment response of patients with obsessive-compulsive disorder

Few case series studies have addressed the issue of treatment response in patients with obsessive-compulsive disorder (OCD) and comorbid post-traumatic stress disorder (PTSD), and there are no prospective studies addressing response to conventional treatment in OCD patients with a history of trauma (HT). The present study aimed to investigate, prospectively, the impact of HT or PTSD on two systematic, first-line treatments for OCD. Two hundred and nineteen non-treatment-resistant OCD outpatients were treated with either group cognitive-behavioral therapy (GCBT n = 147) or monotherapy with a selective serotonin reuptake inhibitor (SSRI n = 72). Presence of HT and PTSD were assessed at intake, as part of a broader clinical and demographical baseline characterization of the sample. Severity and types of OCD symptoms were assessed with the Yale-Brown Obsessive-Compulsive Scale (YBOCS) and the Dimensional YBOCS (DYBOCS), respectively. Depression and anxiety symptoms were measured with the Beck Depression Inventory (BDI) and the Beck Anxiety Inventory (BAI). Both treatments had 12-week duration. Treatment response was considered as a categorical [35% or greater reduction in baseline YBOCS scores plus a Clinical Global Impression-Improvement rating of better (2) or much better (1)] and continuous variable (absolute number reduction in baseline YBOCS scores). Treatment response was compared between the OCD + HT group versus the OCD without HT group and between the OCD + PTSD group versus the OCD without PTSD group. Parametric and non-parametric tests were used when indicated. Data on HT and PTSD were available for 215 subjects. Thirty-eight subjects (17.67% of the whole sample) had a positive HT (OCD + HT group) and 22 subjects (57.89% of the OCD + HT group and 10.23% of the whole sample) met full DSM-IV criteria for PTSD. The OCD + HT and OCD without HT groups presented similar response to GCBT (60% of responders in the first group and 63% of responders in the second group, p = 1.00). Regarding SSRI treatment, the difference between the response of the OCD + HT (47.4%) and OCD without HT (22.2%) groups was marginally significant (p = 0.07). In addition, the OCD + PTSD group presented a greater treatment response than the OCD without PTSD group when treatment response was considered as a continuous variable (p = 0.01). The age when the first trauma occurred had no impact on treatment response. In terms of specific OCD symptom dimensions, as measured by the DYBOCS, OCD treatment fostered greater reductions for the OCD + PTSD group than for the OCD without PTSD group in the scores of contamination obsessions and cleaning compulsions, collecting and hoarding and miscellaneous obsessions and related compulsions (including illness concerns and mental rituals, among others). The OCD + PTSD group also presented a greater reduction in anxiety scores than the OCD without PTSD group (p = 0.003). The presence of HT or PTSD was not related to a poorer treatment response in this sample of non-treatment-resistant OCD patients. Unexpectedly, OCD patients with PTSD presented a greater magnitude of response when compared with OCD without PTSD patients in specific OCD symptom dimensions. Future studies are needed to clarify if trauma and PTSD have a more significant impact on the onset and clinical expression of OCD than on the conventional treatment for this condition, and whether OCD stemming from trauma would constitute a subtype of OCD with a distinct response to conventional treatment.

Childhood neuropsychological deficits associated with adult obsessive-compulsive disorder

BACKGROUND

Existing neuropsychological studies of obsessive-compulsive disorder (OCD) are cross-sectional and do not provide evidence of whether deficits are trait-related (antecedent and independent of symptomatology) or state-related (a consequence, dependent on symptomatology).

AIMS

To investigate whether there are premorbid neuropsychological deficits associated with adult OCD.

METHOD

Longitudinal data were collected from participants of the Dunedin Multidisciplinary Health and Developmental study. Neuropsychological data collected at age 13 were linked with age 32 diagnosis of OCD.

RESULTS

The group who had OCD at age 32 differed significantly from the control group with no OCD on their performance at age 13 on neuropsychological tests of visuospatial, visuoconstructive and visuomotor skills, controlling for gender and socioeconomic status, but did not differ on tests of general IQ or verbal ability. Performance of the group with OCD on tests of executive functioning was mixed.

CONCLUSIONS

Individuals with OCD have premorbid impairment in visuospatial abilities and some forms of executive functioning, consistent with biological models of OCD.

Recent advances in the genetics of obsessive-compulsive disorder

This article reviews recent developments in understanding the genetic etiology of obsessive-compulsive disorder (OCD). Family studies provide further support for the familial aggregation of OCD. Genome-wide linkage studies indicate that specific chromosomal regions are linked to OCD. Moreover, results from recent molecular genetic studies suggest that several candidate genes are associated with OCD. However, specific genes causing OCD have not been conclusively identified, and the molecular pathogenesis of the disorder has not been elucidated. The search for genes is complicated by the clinical and etiologic heterogeneity of OCD, as well as the possibility of gene-gene and gene-environment interactions. Despite this complexity, further refinement of the phenotype and developments in molecular and statistical genetics hold promise for further deepening our genetic understanding of OCD in the future.

Genetics of anxiety and trauma-related disorders

Anxiety disorders are the most common psychiatric illnesses in the United States with approximately 30% of the population experiencing anxiety-related symptoms in their lifetime [Kessler RC, Berglund P, Demler O, Jin R, Merikangas KR, Walters EE (2005) Lifetime prevalence and age-of-onset distributions of Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) disorders in the National Comorbidity Survey Replication. Arch Gen Psychiatry 62:593-60]. Notably, a variety of studies have demonstrated that 30-40% of the variance contributing to these disorders is heritable. In the present review, we discuss the latest findings regarding the genetic and environmental influences on the development and symptomatology of anxiety disorders. Specific emphasis is placed on posttraumatic stress disorder (PTSD) due to its uniqueness as an anxiety disorder; its diagnosis is dependent on a precipitating traumatic event and its development appears to be mediated by both genetic and environmental contributions. The co-morbidity of anxiety disorders and the potential re-classification of anxiety disorders as part of DSM-V are reviewed given the potential impact on the interpretation and design of genetic investigations. Lastly, several keys to future genetic studies are highlighted. Thorough analyses of the gene by environment (GxE) interactions that govern one's vulnerability to anxiety disorder(s), the effectiveness of individual treatment strategies, and the severity of symptoms may lead to more effective prophylactic (e.g. social support) and treatment strategies.

BOLD response during visual perception of biological motion in obsessive-compulsive disorder : an fMRI study using the dynamic point-light animation paradigm

OBJECTIVE

Although research has shown that deficits in various cognitive functions may underlie obsessive-compulsive disorder (OCD), studies have not yet clarified the specificity and etiology of perception processing, particularly the perception of biological motion that is correlated with social cognition. We used functional magnetic resonance imaging (fMRI) to investigate neural activity associated with the perception of biological motion in OCD patients.

METHODS

The subjects were 15 patients with OCD and 15 age- and IQ-matched healthy volunteers. All subjects participated in a biological motion task in which they performed a one-back task signaling a repeated stimulus with a key press in each block condition to obligate attention to both types of stimuli.

RESULTS

The biological motion versus scrambled motion contrast revealed that both OCD patients and healthy controls exhibited increased activation of the superior and middle temporal gyrus, the regions implicated in processing of biological motion, which is consistent with previous studies. However, direct comparison between OCD subjects and healthy controls indicated that patients with OCD exhibited increased activation in the right superior and middle temporal gyrus and the left inferior temporal and fusiform gyrus, and reduced activation in the right postcentral gyrus (BA 40) compared to healthy subjects. OCD patients exhibited increased activation in the ventral visual system, including the inferior temporal and fusiform gyrus.

DISCUSSION

We observed a differential pattern of activity between OCD patients and healthy controls, indicating that OCD patients have functional differences related to the perception of biological motion. The differential activation between OCD patients and healthy subjects might contribute to the pathophysiological understanding of obsessive compulsive disorder.

Impact of substance-induced and general medical condition exclusion criteria on the prevalence of common mental disorders as defined by the CIDI

OBJECTIVES

It has been previously argued that the methodology used by the Composite International Diagnostic Interview version 2.1 to assess the substance-induced and general medical condition exclusion criteria are inadequate. As a result prevalence estimates generated from epidemiological studies using this interview may be underestimated. The purpose of the current study was to examine the substance-induced and general medical condition exclusion criteria in the Australian National Survey for Mental Health and Well-being and determine the impact that they have on prevalence estimates of the common mental disorders.

METHOD

Data from the 1997 Australian National Survey of Mental Health and Well-being were analysed. Frequencies were generated as an indication of how many respondents believed that their psychiatric symptoms were always due to a substance or general medical condition. New DSM-IV prevalence estimates were calculated ignoring the application of the substance-induced and general medical condition exclusion criteria and compared to standard DSM-IV prevalence estimates.

RESULTS

The effect of the substance-induced and general medical condition exclusion criteria on final prevalence rates were minimal, with approximately a 0.1% increase when the exclusions were ignored. This equates to a relative difference ranging from no difference for generalized anxiety disorder to an increase of 12% of the base prevalence estimate for agoraphobia.

CONCLUSIONS

In surveys that use the Composite International Diagnostic Interview version 2.1 the substance-induced and general medical condition exclusion criteria have a minor impact on determining final case definition in the majority of mental disorders.