Associations between personality disorders and cannabis use and cannabis use disorder: a population-based twin study.

BACKGROUND AND AIMS: Individual differences in DSM-IV personality disorders (PDs) are associated with increased prevalence of substance use disorders. Our aims were to determine which combination of PDs trait scores best predict cannabis use (CU) and cannabis use disorder (CUD), and to estimate the size and significance of genetic and environmental risks in PD traits shared with CU and CUD. DESIGN: Linear mixed-effects models were used to identify PD traits for inclusion in twin analyses to explore the genetic and environmental associations between the traits and cannabis use. SETTING: Cross-sectional data were obtained from Norwegian adult twins in a face-to-face interview in 1999-2004 as part of a population-based study of mental health. PARTICIPANTS: Subjects were 1419 twins (µage  = 28.2 years, range = 19-36) from the Norwegian Institute of Public Health Twin Panel with complete PD and cannabis data. MEASUREMENTS: PD traits were assessed using DSM-IV criteria. Life-time CU and CUD were based on DSM-IV abuse and dependence criteria, including withdrawal and craving. FINDINGS: After adjusting for age and sex, antisocial [ß = 0.23, 95% confidence interval (CI) = 0.19-0.28] and borderline PDs (ß = 0.20, 95% CI = 0.14-0.26) were associated strongly with CU. Antisocial (ß = 0.26, 95% CI = 0.21-0.31) and borderline PDs (ß = 0.12, 95% CI = 0.06-0.18) were also linked strongly to CUD. Genetic risks in antisocial and borderline PD traits explained 32-60% of the total variance in CU and CUD. Dependent and avoidant PDs explained 11 and 16% of the total variance in CU and CUD, respectively. CONCLUSIONS: Individual differences in the liability to cannabis use and cannabis use disorder appear to be linked to genetic risks correlated with antisocial and borderline personality disorder traits.

The heritability of avoidant and dependent personality disorder assessed by personal interview and questionnaire.

OBJECTIVE: Personality disorders (PDs) have been shown to be modestly heritable. Accurate heritability estimates are, however, dependent on reliable measurement methods, as measurement error deflates heritability. The aim of this study was to estimate the heritability of DSM-IV avoidant and dependent personality disorder, by including two measures of the PDs at two time points. METHOD: Data were obtained from a population-based cohort of young adult Norwegian twins, of whom 8045 had completed a self-report questionnaire assessing PD traits. 2794 of these twins subsequently underwent a structured diagnostic interview for DSM-IV PDs. Questionnaire items predicting interview results were selected by multiple regression, and measurement models of the PDs were fitted in Mx. RESULTS: The heritabilities of the PD factors were 0.64 for avoidant PD and 0.66 for dependent PD. No evidence of common environment, that is, environmental factors that are shared between twins and make them similar, was found. Genetic and environmental contributions to avoidant and dependent PD seemed to be the same across sexes. CONCLUSION: The combination of both a questionnaire- and an interview assessment of avoidant and dependent PD results in substantially higher heritabilities than previously found using single-occasion interviews only.

Separation anxiety disorder in OCD.

BACKGROUND: A history of separation anxiety disorder (SAD) is frequently reported by patients with obsessive-compulsive disorder (OCD). The purpose of this study was to determine if there are clinical differences between OCD-affected individuals with, versus without, a history of SAD. METHODS: Using data collected during the OCD Collaborative Genetic Study, we studied 470 adult OCD participants; 80 had a history of SAD, whereas 390 did not. These two groups were compared as to onset and severity of OCD, lifetime prevalence of Axis I disorders, and number of personality disorder traits. RESULTS: OCD participants with a history of SAD were significantly younger than the non-SAD group (mean, 34.2 versus 42.2 years; P<.001). They had an earlier age of onset of OCD symptoms (mean, 8.0 versus 10.5 years; P<.003) and more severe OCD, as measured by the Yale-Brown Obsessive Compulsive Scale (mean, 27.5 versus 25.0; P<.005). In addition, those with a history of SAD had a significantly greater lifetime prevalence of agoraphobia (odds ratio (OR) = 2.52, 95% confidence interval (CI) = 1.4-4.6, P<.003), panic disorder (OR = 1.84, CI = 1.03-3.3 P<.04), social phobia (OR = 1.69, CI 1.01-2.8, P<.048), after adjusting for age at interview, age at onset of OCD, and OCD severity in logistic regression models. There was a strong relationship between the number of dependent personality disorder traits and SAD (adjusted OR = 1.42, CI = 1.2-1.6, P<.001). CONCLUSIONS: A history of SAD is associated with anxiety disorders and dependent personality disorder traits in individuals with OCD.

Using the family history method to distinguish relatives of patients with dependent personality disorder from relatives of controls.

It has long been established that some psychiatric disorders run in families, and as a result, the family history method has become an established part of clinical and research psychiatry. Although there is much literature on the Axis I disorders, there is relatively little on the personality disorders. There are now reports that dependent personality can run in families. This report demonstrates that a standardized family history method for the DSM-III personality disorder clusters can distinguish relatives of dependent personality disorder patients from relatives of normal controls on the anxious personality disorder cluster, but cannot distinguish them from relatives of a mixed anxiety/depression group who do not have personality disorders. Relatives of the mixed anxiety/depression group did show a different pattern from the relatives of the dependent personality disorder group when all three personality disorder clusters were examined. This is the first such finding reported in the literature. Implications for future research are discussed.

Avoidant and dependent personality traits in relatives of patients with panic disorder, patients with dependent personality disorder, and normal controls.

Psychiatric researchers have long wondered whether personality traits might predispose toward or be integral to Axis I illnesses. The question is difficult to address because acute illness can either create personality traits or distort their measurement. The present study bypassed that problem by examining personality traits in relatives of patients. Panic disorder, dependent personality disorder, and control subjects were the proband groups. A cluster of traits that appeared to reflect low social self-confidence combined with a desire for social interaction occurred significantly more often in relatives of patients in both groups.

Comparisons of males and females with DSM-III dependent personality disorder.

To determine whether DSM-III dependent personality disorder (PD) differed in males and females, 30 females and 11 males with this diagnosis were selected from a psychiatric outpatient population. Standardized measures of Axis I, Axis II, and family history were used. There were no differences in age or in the prevalence of Axis I or Axis II disorders in males and females, indicating that females were probably not misdiagnosed as having dependent PD. However, relatives of males had significantly more major depressive disorder and DSM-III anxious personality disorder cluster, while relatives of females had significantly more panic disorder. This may indicate different predisposing factors to dependent PD in males and females.