The Diagnostic and Statistical Manual (4th ed. [DSM–IV]; American Psychiatric Association, 1994) distinction between clinical disorders on Axis I and personality disorders on Axis II has become increasingly controversial. Although substantial comorbidity between axes has been demonstrated, the structure of the liability factors underlying these two groups of disorders is poorly understood. The aim of this study was to determine the latent factor structure of a broad set of common Axis I disorders and all Axis II personality disorders and thereby to identify clusters of disorders and account for comorbidity within and between axes. Data were collected in Norway, through a population-based interview study (N = 2,794 young adult twins). Axis I and Axis II disorders were assessed with the Composite International Diagnostic Interview (CIDI) and the Structured Interview for DSM–IV Personality (SIDP–IV), respectively. Exploratory and confirmatory factor analyses were used to investigate the underlying structure of 25 disorders. A four-factor model fit the data well, suggesting a distinction between clinical and personality disorders as well as a distinction between broad groups of internalizing and externalizing disorders. The location of some disorders was not consistent with the DSM–IV classification; antisocial personality disorder belonged primarily to the Axis I externalizing spectrum, dysthymia appeared as a personality disorder, and borderline personality disorder appeared in an interspectral position. The findings have implications for a meta-structure for the DSM.

Cluster C PDs are moderately heritable. No evidence was found for shared environmental or sex effects. Common genetic and individual environmental factors account for a substantial proportion of the variance in AVPD and DEPD. However, OCPD appears to be largely etiologically distinct from the other two PDs. The results do not support the validity of the DSM-IV cluster C construct in its present form.

Background Twin data permit decomposition of comorbidity into genetically and environmentally derived correlations. No previous twin study includes all major forms of anxiety disorder. Aims To estimate the degree to which genetic and environmental risk factors are shared rather than unique to dimensionally scored panic disorder, generalised anxiety disorder, phobias, obsessive–compulsive disorder and post-traumatic stress disorder. Method Data obtained from 2801 young-adult Norwegian twins by means of the Composite International Diagnostic Interview were analysed with the Mx program. Results A multivariate common factor model fitted best. The latent liability to all anxiety disorders was substantially more heritable (54%) than the individual disorders (23% to 40%). Most of the genetic effect was common to the disorders. Genes contributed just over 50% to the covariance between liabilities. Conclusions The five anxiety disorders all share genetic and environmental risk factors. This has implications for the revision of the anxiety disorder section in DSM–V.

Objective. To evaluate the extent of and risk factors for bone loss in a population-based cohort of patients with rheumatoid arthritis (RA) receiving conventional health care.Methods. In a longitudinal study, clinical data were collected and bone mineral density (BMD) measurements were performed at baseline and after 2 years. Dual-energy x-ray absorptiometry was used for hip and spine BMD measurements. At baseline, patients received advice about lifestyle adjustments and calcium and vitamin D supplementation; during the followup period they were treated with antirheumatic and bonesparing drugs, according to clinical judgment.Results. After a mean ؎ SD of 2.2 ؎ 0.2 years, 366 (298 women, 68 men) of the 488 patients who were examined at baseline were reexamined. At that time, 47.9% were current users of corticosteroids and 37.0% were using antiresorptive drugs (hormone replacement therapy, bisphosphonates, or calcitonin). The mean BMD reduction was ؊0.64% in the femoral neck, ؊0.77% in the total hip, and ؊0.29% in the spine at L2-4. BMD was increased at all measurement sites in current users of antiresorptive drugs (0.16-1.64%) but was decreased in patients using calcium and vitamin D alone (؊1.99% to ؊1.39%) and in patients not using any osteoporosis treatment (؊1.20% to ؊0.43%). Conclusion. Results of this population-based, 2-year followup study indicate that adequate

Background The extent to which positive and negative indicators of mental health share etiological influences has been studied to a limited degree only. This study examines the genetic and environmental influences on association between liability to lifetime DSM-IV Major Depressive Disorder (MDD) and dispositional life satisfaction (LS). Methods Two-wave questionnaire data on LS (assessed 6 years apart) and lifetime MDD obtained by structured clinical interviews in a population-based sample of adult twins were analysed using structural equation modelling in Mx. Results The prevalence of lifetime MDD was estimated to be 11.1% and 15.8% in males and females, respectively. Individuals fulfilling the criteria for MDD reported significantly lower levels of LS. The co-variation in MDD and dispositional LS was found to be accounted for by genetic and unique environmental influences only. The phenotypic correlation was estimated to be 0.36, of which genetic influences accounted for 74% and environmental factors the remaining 26%. The correlation between genetic factors for MDD and LS was estimated to be −0.55 and the correlation between unique environmental factors to be −0.22. Heritability was estimated to 0.34 and 0.72 for MDD and LS, respectively. Limitations The sample consists of twins only and there are limitations associated with the twin design. Conclusions Whereas genetic influences on vulnerability to lifetime MDD are considerably shared with liability to (low) LS, environmental influences are more distinct. Thus, environmental factors associated with risk of MDD do not strongly impact on dispositional LS, and conversely, environmental factors influencing dispositional LS do not strongly buffer against MDD.