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Biomedical subjects

Svenn Torgersen

Publications and source records attributed to Svenn Torgersen.

At least 19 recordsLinked to original sources
PubMed2007

The heritability of cluster A personality disorders assessed by both personal interview and questionnaire.

BACKGROUND: Personality disorders (PDs) as assessed by questionnaires and personal interviews are heritable. However, we know neither how much unreliability of measurement impacts on heritability estimates nor whether the genetic and environmental risk factors assessed by these two methods are the same. We wish to know whether the same set of PD vulnerability factors are assessed by these two methods. METHOD: A total of 3334 young adult twin pairs from the Norwegian Institute of Public Health Twin Panel (NIPHTP) completed a questionnaire containing 91 PD items. One to 6 years later, 1386 of these pairs were interviewed with the Structured Interview for DSM-IV Personality (SIDP-IV). Self-report items predicting interview results were selected by regression. Measurement models were fitted using Mx. RESULTS: In the best-fit models, the latent liabilities to paranoid personality disorder (PPD), schizoid personality disorder (SPD) and schizotypal personality disorder (STPD) were all highly heritable with no evidence of shared environmental effects. For PPD and STPD, only unique environmental effects were specific to the interview measure whereas both environmental and genetic effects were found to be specific to the questionnaire assessment. For SPD, the best-fit model contained genetic and environmental effects specific to both forms of assessment. CONCLUSIONS: The latent liabilities to the cluster A PDs are highly heritable but are assessed by current methods with only moderate reliability. The personal interviews assessed the genetic risk for the latent trait with excellent specificity for PPD and STPD and good specificity for SPD. However, for all three PDs, the questionnaires were less specific, also indexing an independent set of genetic risk factors.

Adult↗
PubMed2006

Genetic and environmental influences on dimensional representations of DSM-IV cluster C personality disorders: a population-based multivariate twin study.

BACKGROUND: The DSM-IV cluster C Axis II disorders include avoidant (AVPD), dependent (DEPD) and obsessive-compulsive (OCPD) personality disorders. We aimed to estimate the genetic and environmental influences on dimensional representations of these disorders and examine the validity of the cluster C construct by determining to what extent common familial factors influence the individual PDs. METHOD: PDs were assessed using the Structured Interview for DSM-IV Personality (SIDP-IV) in a sample of 1386 young adult twin pairs from the Norwegian Institute of Public Health Twin Panel (NIPHTP). A single-factor independent pathway multivariate model was applied to the number of endorsed criteria for the three cluster C disorders, using the statistical modeling program Mx. RESULTS: The best-fitting model included genetic and unique environmental factors only, and equated parameters for males and females. Heritability ranged from 27% to 35%. The proportion of genetic variance explained by a common factor was 83, 48 and 15% respectively for AVPD, DEPD and OCPD. Common genetic and environmental factors accounted for 54% and 64% respectively of the variance in AVPD and DEPD but only 11% of the variance in OCPD. CONCLUSION: 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.

Adult↗
PubMed2006

Dimensional representations of DSM-IV cluster A personality disorders in a population-based sample of Norwegian twins: a multivariate study.

BACKGROUND: The 'odd' or 'Cluster A' personality disorders (PDs) - paranoid, schizoid and schizotypal PDs - were created in DSM-III with little empirical foundation. We have examined the relationship between the genetic and environmental risk factors for dimensional representations of these three personality disorders. METHOD: These personality disorders were assessed using the Structured Interview for DSM-IV Personality (SIDP-IV) in 1386 young adult twin pairs from the Norwegian Institute of Public Health Twin Panel. Using Mx, a single-factor independent pathway twin model was fitted to the number of endorsed criteria for the three disorders. RESULTS: The best-fit model included genetic and unique environmental common factors and genetic and unique environmental effects specific to each personality disorder. Total heritability was modest for these personality disorders and ranged from 21% to 28%. Loadings on the common genetic and unique environmental factors were substantially higher for schizotypal than for paranoid or schizoid PD. The proportion of genetic liability shared with all Cluster A disorders was estimated at 100, 43 and 26% respectively for schizotypal, paranoid and schizoid PDs. CONCLUSION: In support of the validity of the Cluster A construct, dimensional representations of schizotypal, paranoid and schizoid PD are all modestly heritable and share a portion of their genetic and environmental risk factors. No evidence was found for shared environmental or sex effects for these PDs. Schizotypal PD most closely reflects the genetic and environmental liability common to all three Cluster A disorders. These results should be interpreted in the context of the limited power of this sample.

Adult↗
PubMed2006

Mental illness in a rural area: a Norwegian psychiatric epidemiological study.

OBJECTIVES: Few epidemiological studies have compared less well-integrated urban areas with well-integrated rural areas with the same methods. The aim of this study was to explore the prevalence of mental disorder in a socially stable demographic western region of Norway and make comparison with previously observed prevalence figures of mental illness in Oslo, the capital of Norway. METHOD: A random sample of the 107,738 residents of Sogn and Fjordane, a western rural region of Norway, age 18-65 years, was drawn from the Norwegian Population Register. A total of 1,080 subjects, 63% of the original sample, were interviewed with the Composite International Diagnostic Interview. RESULTS: The mean age of the subjects was 39.2 years. The 12-month prevalence of mental illness was 16.5% and the lifetime prevalence was 30.9%. Simple phobia and social phobia had the highest 12-month prevalence whereas alcohol abuse and major depression had the highest lifetime prevalence. All mental disorders were more prevalent in women than in men, with the exception of alcohol and drug abuse. Severe psychopathology was found in 2.2% (12 month prevalence) and 5.1% (lifetime prevalence). These observations show that the 12-month and the lifetime prevalence of mental illness in this western area is approximately half the rate of figures observed for Oslo. CONCLUSION: Epidemiological figures for a western rural region of Norway showing 12-month and the lifetime prevalence of mental disorder are considerably lower than figures obtained in studies from the capital of Norway. However, the same basic pattern of mental illness can be observed in the rural as in the urban area of Oslo, with alcohol abuse/dependence and major depression being the most common disorders at both sites. The sex pattern is also the same with higher figures for women both in rural and urban areas with the exception of alcohol and drug abuse being higher in men.

Adolescent↗
PubMed2006

Social anxiety disorder in 11-12-year-old children: The efficacy of screening and issues in parent-child agreement.

OBJECTIVE: To investigate the level of diagnostic and discriminative accuracy of The Social Anxiety Scale for Children - Revised (SASC-R) for identifying social anxiety disorder (SAD) in a community-based sample of 11-12 year-old children. Parent-child diagnostic agreement was also examined. METHOD: A questionnaire including SASC-R and items on impulsive behavior was sent to a population based sample of children, born in 1992. A total of 2568 parents returned their questionnaires (rr: 70%), and 1297 (51%) consented to further participation. An index group [50 high-scoring children on social anxiety (SA-group)] and two contrast groups [(50 high-scoring children on impulsive behavior (Imp-group) and 50 low-scoring children on SA and Imp, (Ls-group)] were selected for participation. RESULTS: SAD was assigned 35 (23%) of 150 children; 28 (80%) from the SA-group; 7 (20%) from the Imp- group and 0 from the Ls-group. The SASC-R showed relatively high discriminative accuracy for SAD, but was also influenced by other diagnoses. Mother-child agreement was fair (kappa = 0.46), and mother-only diagnoses were frequent. Both child and parent information are important when diagnosing SAD in this age group.

Child↗
PubMed2005

Stability and prediction of schizophrenia from adolescence to adulthood.

Stability of schizophrenia diagnosis from adolescence to adulthood, antecedents of schizophrenia, and differences in developmental and behavioural histories between subjects with early onset schizophrenia (EOS) and with adult onset schizophrenia (AOS) were investigated in 145 adult subjects diagnosed with mental disorders in adolescence and re-diagnosed on the basis of medical records according to DSM-IV.A very high diagnostic stability schizophrenia was demonstrated at the 28-year follow-up. Several factors, including neurological adversities, delayed language development, low IQ, and congenital functional disability, differentiated significantly between schizophrenic subjects and non-schizophrenic subjects. Histories of concussion, physical abuse, parental divorce, and unstable familial context differentiated significantly between EOS and AOS subjects. Our findings support earlier evidence of schizophrenia being a chronic disorder with high diagnostic stability, and confirm the importance of neurological adversities, delayed language development, and low IQ as factors predictive of schizophrenia. Exploration of four case histories of AOS subjects delineates "pre-schizophrenic warning cluster" where combination of neurological adversities, temperamental problems, antisocial behaviour, preference for solitary play, and unstable family system constitute main factors.

Adolescent↗
PubMed2005

Behavioral genetics of personality.

Behavioral genetic personality research has moved from findings of genetic and environmental effects to new areas. Personality disorders have been included, children and adolescents studied, gender effects evaluated, and the importance of rater sources investigated. Recently, multivariate methods have been applied to disentangle the genetic and environmental latent structure, and investigate covariance in mental disorders. Perhaps the most exciting recent developments are the investigations of situation variables, the studies of how genotypes influence how individuals select themselves into situations and other form of gene-environment correlations, and how genotype moderates the effect of situations and circumstances on behavior (gene-environment interaction). In the future, we will learn how personality, partly determined by heredity, influences our entire lives. We will better understand what we experience, how we interpret the experiences and how to react to them effectively. We will learn how our mental lives develop while we interact with the environment, and we will broaden our understanding of which genes are coding for mental health and mental disorders.

Environment↗
PubMed2005

Quality of life and anxiety disorders: a population study.

The study of quality of life has increased in importance in the area of mental disorders during the last decade. The aim of the present study was to investigate the effect of specific anxiety disorders on specific quality of life indicators in the common population. More than 2000 individuals between 18 and 65 years old were studied by means of structured interviews. The results showed that social phobia and panic disorder within the past year and lifetime, and generalized anxiety disorder within the past year, had an independent effect on quality of life when controlling for a number of sociodemographic variables, somatic health, and other DSM-III-R Axis I mental disorders. Specific phobias and obsessive compulsive disorder had only a small effect, and agoraphobia showed no effect. The effect was strongest for self-realization and contact with friends, but anxiety disorders also influenced subjective well-being, social support, negative life events, contact with family of origin, and neighborhood quality.

Adolescent↗
PubMed2005

Continuities between emotional and disruptive behavior disorders in adolescence and personality disorders in adulthood.

OBJECTIVE: The purpose of this study was to quasiprospectively investigate continuities between emotional and disruptive behavior disorders in adolescence and personality disorders in adulthood. METHOD: One hundred thirty subjects (age: mean=43.2 years) who had been diagnosed with emotional and disruptive behavior disorders during adolescence (age: mean=14.6 years) and rediagnosed based on hospital records, according to DSM-IV, were interviewed with the Structured Interview for DSM-IV Personality to establish whether they suffered from personality disorders at the 28-year follow-up. RESULTS: Adolescents with disruptive behavior disorders were not more likely to have personality disorders in adulthood than adolescents with emotional disorders. Adolescents with disruptive behavior disorders were significantly more likely to have cluster B personality disorders at follow-up than adolescents with emotional disorders. Logistic regression analyses revealed that disruptive behavior disorders in females were significantly more strongly associated with a high risk of cluster B diagnoses at follow-up than in males. Emotional disorders were significant and independent predictors of cluster C personality disorders in women but not in men. Disruptive behavior disorders were a significant and independent predictor of antisocial personality disorders in men. CONCLUSIONS: These results support the view that personality disorders can be traced back to adolescent emotional and disruptive behavior disorders. The moderating effect of gender in cluster B and cluster C personality disorders suggests that sociocultural and biological factors may contribute to different adult outcomes in men and women with similar adolescent psychiatric disorders.

Adolescent↗
PubMed2004

Undue influence of weight on self-evaluation: a population-based twin study of gender differences.

OBJECTIVE: To explore the extent to which genetic and environmental factors contribute to liability to placing undue importance on weight as an indicator of self-evaluation and to determine whether differences exist across genders in the nature and magnitude of these effects. METHOD: Self-report data were collected on 8,045 same-sex and opposite-sex twins, aged 18-31 years, from a population-based registry of Norwegian twins. Structural equation modeling was utilized to estimate the relative contribution of genetic and environmental factors to liability for undue influence of weight on self-evaluation, allowing for gender-specific effects. RESULTS: Individual variation in undue influence of weight on self-evaluation was best explained by shared and individual environmental influences. No significant gender differences were found. Shared environmental factors accounted for 31% of the variance. DISCUSSION: These results raise the possibility that there may be distinct sources of familial resemblance for different symptoms of bulimia nervosa as codified in the 4th ed. of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1994).

Adolescent↗
PubMed2004

The role of stressful life events in the development of depressive symptoms in adolescence--a longitudinal community study.

Depressive symptoms were measured in a cohort of community-based adolescents (n = 163) at two time-points, with 1 year intervening. At Time 2, participants also answered a scale about past-year stressful life events. Depressive symptoms increased from Time 1 to Time 2, the effect being stronger for girls than for boys. Depressive symptoms were significantly correlated with concurrent measures of recent stressful life events, but this relationship disappeared after controlling for previous depressive symptoms. Rather, previous level of depressive symptoms predicted stressful life events. This demonstrates that a unidirectional model of stressful life events as the cause of depressive symptoms in adolescents is too simplistic.

Data Collection↗
PubMed2004

Genetic and environmental influences on the association between smoking and panic attacks in females: a population-based twin study.

BACKGROUND: Clinical and epidemiological studies have reported an association between lifetime cigarette-smoking and panic attacks. Several explanations for this relationship have been proposed, mostly focusing on direct causal pathways. The objective of this study was to investigate a hypothesis of shared vulnerability by examining whether panic attacks and cigarette-smoking share genetic or environmental liability factors. METHOD: Questionnaire data on 3172 female-female twins (1409 complete pairs), aged 18-31 years, from a population-based Norwegian twin registry, were used to calculate the correlation between genetic factors and the correlation between environmental factors that influence lifetime measures of panic attacks and daily smoking. RESULTS: The best-fitting biometrical twin model suggested that genetic factors influencing panic and smoking were uncorrelated. Shared or familial environmental factors were perfectly correlated, and accounted for 75 % of the association between the phenotypes. The correlation between individual environmental factors influencing the phenotypes was 0.25 (0.07-0.44). In the full model, the genetic correlation was 0.17 (0.00-1.00), and genetic and shared environmental factors respectively accounted for 18 % and 61 % of the co-variance between panic and smoking. CONCLUSION: The results suggest that panic attacks and lifetime smoking have few or no genetic liability factors in common. The shared environmental factors that influence the two phenotypes are identical. Liability to panic attacks in females appears to be more influenced by shared environmental factors than previously indicated by univariate studies.

Adolescent↗
PubMed2004

Building youths' resilience within a psychiatric outpatient setting: results from a pilot clinical intervention project.

The relevance of resilience research for clinical practice has not yet been established. In this intervention pilot study, the aim was to explore how group work based on enhancing the participants' creativity, self-efficacy, active coping, and sense of continuity could be utilized within a clinical context for adolescents with stressful background experiences. 31 participants and 24 parents completed pre-, post-, and 1-yr. follow-up assessments of the youths' behavior difficulties, as well as depression, positive life attitude, coping, and prosocial behavior. Apart from a drop in self-rated prosocial behavior, no significant treatment effects were found. Implications for clinical practice and research are indicated.

Adaptation, Psychological↗
PubMed2002

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.

Borderline Personality Disorder↗
PubMed2002

[Genetics and somatoform disorders].

The nosological status of somatoform disorders has long been unclear. Only with DSM-III in 1980 did the situation become more settled. This means that earlier theoretical speculation and empirical investigations are difficult to evaluate. It has not been possible to confirm empirically many psychoanalytic notions about environmental causes of somatoform disorders; however, Freud's emphasis on a genetic basis seems to be confirmed. Furthermore, genetic research suggests a certain connection between alcoholism and criminality on the one hand and somatization disorders on the other. This does not mean that manifest alcoholism and criminality is prevalent among people with somatoform disorders. Cultural, gender-specific barriers and environmental factors prevent much co-morbidity. It should, however, be noted that little research has been taking place over the last 25-30 years; we could hardly be said to be beginning to understand the interplay between genes and environment in the development of somatoform disorders.

Diseases in Twins↗
PubMed2002

Schizotypal personality disorder inside and outside the schizophrenic spectrum.

The concept of schizotypal personality disorder has been heavily discussed since its introduction into the official classification of mental disorders in DSM-III. The aim of this study was to investigate the difference between schizotypal personality disorder within and outside the genetic spectrum of schizophrenia. Schizotypals with and without schizophrenic cotwins and first-degree relatives were compared, with individuals with other mental disorders and no mental disorders as controls. It appeared that only inadequate rapport and odd communication were more pronounced among schizotypals within, compared to schizotypals outside the schizophrenic spectrum. Schizotypals outside the schizophrenic spectrum, however, scored higher than schizotypals inside the schizophrenic spectrum on ideas of reference, suspiciousness, paranoia, social anxiety, self-damaging acts, chronic anger, free-floating anxiety and sensitivity to rejection. Interestingly, the four last features are seldom observed among schizotypals inside the schizophrenic spectrum. Monozygotic non-schizophrenic cotwins of schizophrenics score high on inadequate rapport, odd communication, social isolation and delusions/hallucinations. Monozygotic non-schizophrenic cotwins of schizotypals outside the schizophrenic genetic spectrum score high on illusions, depersonalization, derealization and magical thinking. Negative schizotypal features appear to be inside the schizophrenic spectrum, while positive borderline-like features are outside having another genetic endowment.

Adult↗
PubMed2002

A case-control study of EAS child and parental temperaments in selectively mute children with and without a co-morbid communication disorder.

Clarification of sub-groups of children with selective mutism (SM) may enhance the understanding of symptom development. The present case-control study compares temperament characteristics applying EAS temperament survey in SM children with a co-morbid communication disorder (CoD), SM children without CoD and matched controls. Temperament characteristics in the parents are compared as well. The results show that SM children with CoD are characterized by more emotional stability and higher sociability than SM children without CoD. The parents of the SM children with CoD did not differ in temperament characteristics from the control parents. The parents of the SM children without CoD differed from the controls on the Distress, Fear and Activity scales. The study suggests different familial transmission in the two sub-groups of children with SM.

Case-Control Studies↗