Svenn Torgersen

High interrater reliability for the structured clinical interview for DSM-III-R axis I (SCID-I)

The interrater reliability of the Structured Clinical Interview for DSM‐III‐R (SCID) was studied. Fifty‐four audiotaped SCID interviews were rated independently by 3 raters. The highest interrater agreements were observed for schizophrenia (0.94), major depressive disorder (0.93), dysthymia (0.88), generalized anxiety disorder (0.95), panic disorder (0.88), alcohol use disorder (0.96) and other psychoactive substance use disorder (0.85). The remaining diagnoses of mood and anxiety disorders obtained acceptable interrater agreement (0.70–0.80), with an exception for obsessive‐compulsive disorder (0.40). The poorest agreement was obtained for somatoform disorders (– 0.03). Lack of hierarchy in DSM‐III‐R allows for multiple Axis I diagnoses. Interrater reliability for multiple diagnoses was tested. Agreement was generally good for combinations of 2 diagnoses, and poorer when 3 diagnoses were combined. Our findings confirm that SCID yields highly reliable diagnoses. SCID is recommended for research on mental disorders.

The Structure of Genetic and Environmental Risk Factors for DSM-IV Personality Disorders: A Multivariate Twin Study

CONTEXT Although both genetic and environmental factors affect risk of individual personality disorders (PDs), we know little of how they contribute to the pattern of comorbidity between the PDs in the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) (DSM-IV). OBJECTIVE To clarify the structure of the genetic and environmental risk factors for the 10 DSM-IV PDs. DESIGN Assessment of PDs at personal interview and multivariate twin modeling with the Mx program. SETTING General community. PARTICIPANTS A total of 2794 young adult members of the Norwegian Institute of Public Health Twin Panel. Main Outcome Measure Number of endorsed criteria for the 10 DSM-IV PDs. RESULTS The best-fit multivariate twin model required 3 genetic and 3 individual-specific environmental factors and genetic and individual-specific factors unique to each PD. The first genetic factor had high loadings on PDs from all 3 clusters including paranoid, histrionic, borderline, narcissistic, dependent, and obsessive-compulsive. The second genetic factor had substantial loadings only on borderline and antisocial PD. The third genetic factor had high loadings only on schizoid and avoidant PD. Several PDs had substantial disorder-specific genetic risk factors. The first, second, and third individual-specific environmental factors had high loadings on the cluster B, A, and C PDs, respectively, with 1 exception: obsessive-compulsive PD loaded with cluster B and not cluster C PDs. CONCLUSIONS Genetic risk factors for DSM-IV PDs do not reflect the cluster A, B, and C typology. Rather, 1 genetic factor reflects a broad vulnerability to PD pathology and/or negative emotionality. The 2 other genetic factors are more specific and reflect high impulsivity/low agreeableness and introversion. Unexpectedly, the cluster A, B, and C typology is well reflected in the structure of environmental risk factors, suggesting that environmental experiences may be responsible for the tendency of cluster A, B, and C PDs to co-occur.

The relationship between DSM-III symptom disorders (Axis I) and personality disorders (Axis II) in an outpatient population

The relationship between symptom disorder and personality disorder according to DSM‐III was studied in 289 consecutive outpatients. It was observed that personality disorders occurred frequently among the chronic affective and anxiety disorders. The “dramatic” personality disorders were observed especially frequently among patients with cyclothymic disorder, and the “eccentric” personality disorders among patients with a diagnosis of dysthymic disorder, social phobia and agoraphobia. Dramatic personality disorder was also common among patients with simple phobia. As expected, a close correspondence was observed between social phobia, agoraphobia and avoidant personality disorder, between substance use disorder and borderline personality disorder, and between obsessive‐compulsive disorder and compulsive personality disorder. Even if a relationship was observed, it was not strong enough to warrant a combination of chronic symptom disorder diagnoses and personality disorder diagnoses.

A twin study of DSM-III-R anxiety disorders

The prevalence of anxiety disorders was studied in a sample of 20 monozygotic (MZ) and 29 dizygotic (DZ) co‐twins of anxiety disorder probands. A comparison group of co‐twins of 12 MZ and 20 DZ twin probands with other non‐psychotic mental disorders was also studied. All subjects were personally interviewed with the Structured Clinical Interview for DSM‐III‐R Axis I (SCID‐I). Panic disorder was significantly more prevalent in co‐twins of panic probands. Generalized anxiety disorder (GAD) was more prevalent in co‐twins of GAD probands with a history of mood disorder (NS). Post‐traumatic stress disorder was significantly more prevalent in co‐twins of anxiety probands and was more prevalent in MZ than in DZ co‐twins. The prevalences of social and simple phobia were equal in co‐twins of anxiety and comparison probands. For both panic disorder and generalized anxiety disorder the MZ:DZ concordance ratio was more than 2:1. The results support the hypothesis of a genetic contribution in the etiology of panic disorder, generalized anxiety disorder and post‐traumatic stress disorder. The hypothesis that simple and social phobia are mainly caused by environmental experiences was also supported.

Personality types and coping

Abstract In recent years, it has been well established that the basic personality factors of Neuroticism, Extraversion, and Conscientiousness are associated with stress experience and coping. However, little is known about their combined effects. To address this question, we studied eight personality types — unique combinations of Neuroticism, Extraversion, and Conscientiousness — in a sample of 683 university students. Participants reported daily hassles, positive and negative emotions, and coping strategies. The eight types related differentially to these measures. Types combining low Neuroticism with high Conscientiousness featured the most favourable profile of stress and coping, whereas types combining high Neuroticism with low Conscientiousness showed high vulnerability to stress and poor coping. The effects of Extraversion were more ambiguous and appeared to depend on the specific combinations of Neuroticism and Conscientiousness. The findings suggest that this typology represents a useful approach to addressing the question of how individuals with different combinations of personality traits experience and manage stress.

The borderline diagnosis III: identifying endophenotypes for genetic studies.

Although it is generally acknowledged that borderline personality disorder (BPD) has a complex, multifactorial etiology with interacting genetic and environmental substrates, the specific genetic underpinnings of this disorder have not been extensively investigated. Family aggregation studies suggest the heritability for BPD as a diagnosis, but the genetic basis for this disorder may be stronger for dimensions such as impulsivity/aggression and affective instability than for the diagnostic criteria itself. Family, adoptive, and twin studies also converge to support an underlying genetic component to the disorder. An endophenotypic approach to defining the genetics of this complex disorder may be called for. Twin studies in an epidemiologic, non-clinically ascertained sample using both diagnostic measures and laboratory measures that can be operationalized, including neuropsychologic, psychophysiologic, and operationalized behavioral tests, may be useful. Large-scale family studies of clinically ascertained samples with careful diagnostic demarcation and measurement of endophenotypes in probands and relatives may also prove to be a promising approach. The use of laboratory paradigms for measures of aggression and affective instability are discussed in the context of such endophenotypic approaches.

The determination of twin zygosity by means of a mailed questionnaire.

A mailed questionnaire dealing with similarity in childhood, and how often and by whom the twins were mixed up, was applied to 290 same-sex adult twin pairs. For about 75% of pairs ten genetic markers were analysed. The agreement in zygosity classification between questionnaire and blood typing was high. Irrespective of whether raw scores of discriminant function analysis was applied, the agreement was nearly 95%. When a decision tree was applied, the percentage rose to nearly 96%. Considering that probably four of the twin pairs were wrongly classified as MZ by genetic markers, the percentage rose to 96 and 98, respectively.

Who takes health risks? A probe into eight personality types

Ample research has shown that the basic personality factors of neuroticism, extraversion, and conscientiousness (or psychoticism) are important predictors of risky health behaviours. Yet, the findings are increasingly inconsistent. We propose that configurations of the basic personality factors, as represented by a typology, may yield clearer results. In a sample of 683 university students, smoking, consumption of alcohol and drugs, and risky sexual behaviour were examined among eight types. Findings showed that several types deviated significantly from the average with respect to risky health behaviours. Types with a configuration of low conscientiousness and either high extraversion (Impulsives, Hedonists) or high neuroticism (Insecures) were particularly inclined to engage in multiple, risky health behaviours. Conversely, types combining high conscientiousness with low extraversion (Sceptics, Brooders) abstained from risky behaviours. The findings suggest that the typology represents a useful approach to predicting risky health behaviours.

Twin concordance for DSM-III-R schizophrenia

The monozygotic (MZ)/dizygotic (DZ) concordance rates for schizophrenia and the relationship between schizophrenia and schizophrenic spectrum disorders were studied in a sample of 31 MZ and 28 DZ schizophrenic probands and their co‐twins. All subjects were personally interviewed with structured diagnostic instruments and classified according to DSM‐III‐R criteria. The concordance rates of 48% for MZ twins and 4% for DZ twins indicate a genetic transmission of DSM‐III‐R schizophrenia. In addition to the schizophrenic co‐twins, 3 MZ co‐twins had a nonaffective psychotic disorder, thus supporting the hypothesis that genes are involved in the development of Axis I schizophrenic spectrum disorders. Schizotypal and paranoid personality disorders were observed in both MZ and DZ co‐twins. These disorders may be familially related to schizophrenia, but a genetic relationship was not confirmed for the Axis II spectrum disorders. A substantial number of MZ co‐twins of schizophrenic probands had no mental disorder.

DSM-III symptom disorders (Axis I) and personality disorders (Axis II) in an outpatient population

Type and prevalence of Axis I and Axis II disorders (DSM‐III) were assessed in a sample of 298 consecutive psychiatric outpatients. The instruments used were SCID and SIDP. About half of the Axis I diagnoses consisted of different subgroups of depression. Most patients had more than one diagnosis, anxiety being the second most common disorder. Eighty one percent of the subjects met the criteria for a personality disorder diagnosis; half of them obtained more than one Axis II diagnosis. Personality disorder was more common among men than among women. Avoidant and dependent personality disorders constituted the most frequent diagnoses.