Biomedical subjects

Kristian Tambs

Publications and source records attributed to Kristian Tambs.

At least 19 recordsLinked to original sources

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

Work factors and psychological distress in nurses' aides: a prospective cohort study.

BACKGROUND: Nurses' aides (assistant nurses), the main providers of practical patient care in many countries, are doing both emotional and heavy physical work, and are exposed to frequent social encounters in their job. There is scarce knowledge, though, of how working conditions are related to psychological distress in this occupational group. The aim of this study was to identify work factors that predict the level of psychological distress in nurses' aides. METHODS: The sample of this prospective study comprised 5076 Norwegian nurses' aides, not on leave when they completed a mailed questionnaire in 1999. Of these, 4076 (80.3 %) completed a second questionnaire 15 months later. A wide spectrum of physical, psychological, social, and organisational work factors were measured at baseline. Psychological distress (anxiety and depression) was assessed at baseline and follow-up by the SCL-5, a short version of Hopkins Symptom Checklist-25. RESULTS: In a linear regression model of the level of psychological distress at follow-up, with baseline level of psychological distress, work factors, and background factors as independent variables, work factors explained 2 % and baseline psychological distress explained 34 % of the variance. Exposures to role conflicts, exposures to threats and violence, working in apartment units for the aged, and changes in the work situation between baseline and follow-up that were reported to result in less support and encouragement were positively associated with the level of psychological distress. Working in psychiatric departments, and changes in the work situation between baseline and follow-up that gave lower work pace were negatively associated with psychological distress. CONCLUSION: The study suggests that work factors explain only a modest part of the psychological distress in nurses' aides. Exposures to role conflicts and threats and violence at work may contribute to psychological distress in nurses' aides. It is important that protective measures against violent patients are implemented, and that occupational health officers offer victims of violence appropriate support or therapy. It is also important that health service organisations focus on reducing role conflicts, and that leaders listen to and consider the views of the staff.

Adult↗

PubMed2006

Genetic and environmental contributions to depressive personality disorder in a population-based sample of Norwegian twins.

BACKGROUND: Depressive personality disorder (DPD) was introduced in DSM-IV as a new category requiring further study. The aim of this study was to estimate genetic and environmental contributions to DPD in a population-based twin sample, and include data on criteria performance, prevalence and diagnostic overlap. METHODS: Axis I and Axis II diagnoses were obtained by structured interviews in a population-based sample of 2794 young adult twins. Statistical analyses included correlation and factor analysis based on polychoric correlation coefficients, and diagnostic overlap applying adjusted odds ratios. Contributions from additive genetic and common and unique environmental influences to the liability to DPD were computed using structural equation modelling, applying a multiple threshold variable. RESULTS: Liability to DPD could best be explained by additive genetic and unique environmental factors, with heritability estimates of 49% (95% CI 0.41-0.57) in females and 25% (95% CI 0.12-0.40) in males. The best-fitting model indicated that some of the genes contributing to DPD differ between men and women. Chronbach's alpha was 0.87. 2.0% of participants fulfilled the criteria for DPD, and overlap was most pronounced for dysthymic disorder and avoidant personality disorder. LIMITATIONS: Low prevalence rates and subsequent inclusion of subthreshold criteria could have influenced parameter estimates, especially in males. CONCLUSIONS: DPD was almost twice as heritable in females as in males, comparable to previous studies on major depression. The proposed criteria showed good measurement properties, and DPD was not completely subsumed within any other disorder.

Adult↗

PubMed2006

Mental health in deaf adults: symptoms of anxiety and depression among hearing and deaf individuals.

Individuals with disabilities encounter practical and social problems beyond those experienced by nondisabled individuals. This extra burden may in turn increase the risk of developing mental health problems. The objective of this article is to disclose the mental health situation among deaf individuals compared to a control sample of hearing individuals. The analyses are based on two separate Norwegian postal surveys, one among the general population (1995-1997) and one among the deaf population (2001). A shortened version of the Hopkins Symptom Checklist was used to disclose the degree of mental distress among the respondents. Three questions common to the studies were analyzed to determine differences between the two groups. Analyses revealed that the deaf respondents showed significantly more symptoms of mental health problems than the hearing respondents. The results point to the need for focussing more attention on the mental health of deaf children and adults. Society must be made aware of the special risks that deaf children and adults encounter with respect to mental health.

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

Recurrent otitis media and tonsillitis: common disease predisposition.

OBJECTIVE: To estimate the relative contribution of genetic and environmental effects to the association between recurrent otitis media and recurrent tonsillitis. METHODS: Self-report questionnaire data from a population-based cohort of 9479 Norwegian twins born from 1967 to 1979. Recurrent otitis media and recurrent tonsillitis were main outcome measures. Structural equation modelling was used to fit alternative biometric models to the twin data and to estimate the relative contribution of genetic and environmental effects to the association between otitis media and tonsillitis. RESULTS: The lifetime prevalence was 11.7% (95% CI: 11.0-12.3) for recurrent tonsillitis and 11.2% (95% CI 10.5-11.9) for recurrent otitis media. Tetrachoric correlations were greater in monozygotic than in dizygotic twins in both males and females. A model specifying additive genetic effects and individual environmental effects for otitis media and tonsillitis and non-additive genetic effects for tonsillitis yielded the best fit. There was no evidence for sex differences in the genetic source or magnitude of the genetic effects. There was a substantial overlap in genetic factors influencing variation in liability to otitis media and tonsillitis. CONCLUSION: Common genetic factors contribute substantially to comorbidity between recurrent otitis media and recurrent tonsillitis.

Environment↗

PubMed2006

What mediates the inverse association between education and occupational disability from back pain?--A prospective cohort study from the Nord-Trøndelag health study in Norway.

Low education is consistently associated with an increased risk of back pain disability, but the underlying mechanisms for this relationship are poorly understood. In a seven-year prospective observational study of 38,426 employed men and women between 25 and 59 years in Norway, we investigated to what extent occupational class, working conditions and individual lifestyle mediated the effect of formal education on disability pensioning from back pain. Each additional year of formal education was associated with decreased risk for disability pensioning from back pain for both men [age adjusted Hazard Ratio (HR) 0.77; (95% Confidence Interval, 0.72-0.82)] and women [HR 0.76(0.71-0.82)]. Adjustment for occupational class and factors related to working conditions (authority to plan own work, physically demanding work, concentration and attention and job satisfaction) and individual lifestyle (smoking, body mass index, physical exercise and alcohol consumption) reduced the effect of education by 39% [HR 0.86(0.79-0.93)] for men and by 21% [HR 0.81(0.73-0.89)] for women. Working conditions contributed most to the explanation for men, while occupational class, working conditions and life style factors contributed equally for women. Subgroup analyses indicate small differences between full-time and part-time employees, while some differences were found between subcategories of back diseases. The study indicates that there is a strong and unexplained effect of education on back pain disability pensioning, which is not mediated by occupational class, working conditions or individual lifestyle.

Adult↗

PubMed2006

Illicit psychoactive substance use, abuse and dependence in a population-based sample of Norwegian twins.

BACKGROUND: Prior population-based twin studies from two Anglophonic countries with relatively high rates of drug use - the USA and Australia - suggest that genetic factors contribute substantially to individual differences in the use, abuse and dependence of illicit psychoactive substances. Would these results replicate in Norway, a Nordic country with a low prevalence of illicit drug use? METHOD: Lifetime use, abuse and dependence of five illicit drug categories (cannabis, stimulants, opiates, cocaine and psychedelics) were assessed at personal interview in 1386 complete young adult twin pairs ascertained from the Norwegian Institute of Public Health Twin Panel. Twin model fitting was performed using the Mx statistical package on three phenotypes: any lifetime use, endorsement of at least one DSM-IV symptom of abuse or dependence, and meeting DSM-IV criteria for abuse or dependence. RESULTS: Significant lifetime use of illicit substances (defined as use 10 or more times) was reported by only 6.4% of the sample. Meaningful analyses were possible for use of any substance and each of the five substances individually, but for symptoms or a diagnosis of abuse/dependence meaningful analyses were possible only for any substance and cannabis. Full twin models uniformly found twin resemblance to be due largely or entirely to genetic factors. Best-fit models for all analyses included only genetic and individual-specific environmental effects with heritability estimates ranging from 58% to 81%. CONCLUSION: In accord with prior results from the USA and Australia, genetic factors appear to play an important role in the etiology of use and abuse/dependence of illicit drugs in Norway.

Diseases in Twins↗

PubMed2006

Hearing loss induced by occupational and impulse noise: results on threshold shifts by frequencies, age and gender from the Nord-Trøndelag Hearing Loss Study.

The aim of the study was to compare the frequency-specific effects of noise on hearing acuity across the range 250-8000 Hz and the extent to which the patterns of frequency-specific threshold shifts differ between occupational noise and impulse noise. Pure-tone audiometry was administered to an adult general population sample with 51 975 subjects who also provided questionnaire information about noise exposure and other risk factors. Threshold shifts induced by life-long occupational noise and impulse noise (mostly shooting) were estimated separately in six age and sex groups for eight frequencies. Reported noise exposure, as well as observed threshold shifts, were moderate among women. Threshold shifts averaged over both ears among subjects in the higher 2% of exposure to occupational noise, reached 13 dB (3000 Hz, age 65 years + ) among men and were generally largest at 3000-4000 Hz. The shifts induced by impulse noise reached approximately 8 dB among men 45-64 years and men 65 years+. The effects of impulse noise were strongest at 3000-8000 Hz and varied little within this frequency range.

Adult↗

PubMed2006

Adolescent adjustment and well-being: effects of parental divorce and distress.

This study investigates the long-term effects of parental divorce on adolescent psychological adjustment and well-being, and to what extent the effects are accounted for by parental psychological distress. Data were collected among 8,984 Norwegian adolescents (13-19 years) and their parents. Outcome variables were symptoms of anxiety and depression, subjective well-being, and three areas of school problems. Parental divorce was found to be associated with both higher mean levels and larger variances in adolescent problems. Divorce and parental distress contributed independently to adolescent distress, supporting the notion of "double exposure" effects. The prevalence of adolescents with substantial distress symptoms was 14% among those with non-distressed non-divorced parents and 30% among those with divorced and distressed parents. In general effects remained when controlling for demographic factors. Long-term effects of divorce on symptoms of anxiety and depression were stronger among girls than among boys.

Adaptation, Psychological↗

PubMed2005

Is relatively young age within a school year a risk factor for mental health problems and poor school performance? A population-based cross-sectional study of adolescents in Oslo, Norway.

BACKGROUND: Several studies have shown that children who are relatively young within a school year are at greater risk for poorer school performance compared with their older peers. One study also reported that relative age within a school year is an independent risk factor for emotional and behavioral problems. The objective of this study was to test the hypothesis that relatively younger adolescents in the multiethnic population of Oslo have poorer school performance and more mental health problems than their relatively older classmates within the same school year. METHODS: This population-based cross-sectional study included all 10th-grade pupils enrolled in 2000 and 2001 in the city of Oslo. The participation rate was 88%. Of the 6,752 pupils in the study sample, 25% had a non-Norwegian background. Mental health problems were quantified using the abbreviated versions of Symptom Check List-25 (SCL-10) and the Strength and Difficulties Questionnaire (SDQ). Information on school performances and mental health problems were self-reported. We controlled for confounding factors including parental educational level, social support, gender, and ethnicity. RESULTS: The youngest one-third of pupils had significantly lower average school grades than the middle one-third and oldest one-third of their classmates (p < 0.001). Of the mental health problems identified in the questionnaires, the groups differed only on peer problems; the youngest one-third reported significantly more problems than the middle and oldest groups (p < 0.05). Age within a school year and gender showed significant interactions with total SDQ score, SDQ peer problems score, SDQ pro social score, and SCL-10 score. After stratifying for gender, the peer problem scores differed significantly between age groups only among boys. The SCL-10 score was significant, but only in girls and in the opposite direction to that expected, with the oldest pupils having significantly higher scores than the other two groups (p < 0.05). CONCLUSION: In adolescents from a multicultural city in Norway, relative age within a school year significantly influenced academic performance. In contrast to data from Great Britain, relative age within a school year was not an important risk factor for mental health problems in adolescents in Oslo.

Adolescent↗

PubMed2005

The reliability of self-reported childhood otitis media by adults.

OBJECTIVE: To estimate reliability of retrospective questionnaire data on childhood recurrent otitis media, and to identify factors influencing inconsistency in self-report. METHODS: Retrospective questionnaire data from a population-based sample of 4430 Norwegian twins who participated in two questionnaire surveys, 6 years apart, containing identical questions on otitis media. Main outcome measure was individual consistency in reporting of otitis media. The tetrachoric correlation and Cohen's Kappa were used to measure reliability. Inconsistent and consistent responders were compared on medical history and mental distress. The use of twin data made it possible to test whether inconsistent responders represent a group with intermediate levels of otitis media severity. RESULTS: The test-retest tetrachoric correlation was 0.82 and Kappa was 0.53. Inconsistency in response was not associated with mental distress, but related to reported number of otitis media episodes per year, use of medical services and history of ear surgery. CONCLUSION: Retrospective self-reported otitis media is a relatively reliable measure. The study suggests that reporting inconsistency is likely to be associated with less severe disease. The finding that reporting pattern is related to disease severity is in accordance with the proposed need for a uniform agreement on the definition of the term "recurrent otitis media" for research purposes.

Adult↗

PubMed2005

A comparison of genetic and environmental variance structures for asthma, hay fever and eczema with symptoms of the same diseases: a study of Norwegian twins.

BACKGROUND: We compared patterns of genetic and environmental influences on variation in liability for asthma, hay fever and eczema with those for symptoms of the same diseases, and determined how common sets of genes and environmental factors contribute to the relationship between diseases and symptoms among Norwegian twins. METHODS: Analyses were based on self-reported asthma, hay fever and eczema and symptoms of the same diseases among 3334 pairs of Norwegian twins aged 18-35 years. Structural equation modelling was conducted to estimate the genetic and environmental variance structures. RESULTS: For all diseases the concordances and the twin correlations were higher among monozygotic than among dizygotic twins. The results of the modelling confirmed that genetic effects were substantial for the diseases, and were more moderate for symptoms. The phenotypic correlation between disease and symptom was 0.67 for asthma and wheeze (a/w), 0.64 for hay fever and sneeze (hf/s), and 0.54 for eczema and itch (e/i). Decomposition of these correlations into genetic (G) and environmental (E) pathways revealed that G = 0.48 and E = 0.19 for a/w, G = 0.40 and E = 0.24 for hf/s, and G = 0.34 and E = 0.20 for e/i. For the diseases, the specific sources of genetic variance accounted for more variation than the specific environmental variance. Variance decomposition revealed that specific sources of variance were primarily explained by genetic effects for diseases and by environmental influences for symptoms. CONCLUSIONS: Genetic effects account for greater variation in reported diseases than symptoms. Co-occurrence of diseases and symptoms is mainly explained by genetic effects common to both phenotypes, but non-shared environment is also important.

Adult↗

PubMed2005

Adolescents with a childhood experience of parental divorce: a longitudinal study of mental health and adjustment.

**This is a prospective Norwegian study of a group of adolescents with an experience of parental divorce or separation (n=413) and a comparison group without this experience (n=1758). Mean age at T1 was 14.4 years and mean age at T2 was 18.4 years. Parental divorce was prospectively associated with a relative change in anxiety and depression, subjective well-being, self-esteem, and school problems. Considering boys separately, parental divorce was prospectively associated only with school problems. Among the girls, divorce was prospectively associated with all variables. The effect of divorce on relative change was partially mediated by paternal absence.

Adaptation, Psychological↗

PubMed2005

Heritability of recurrent tonsillitis.

OBJECTIVE: To estimate the relative contribution of genetic and environmental effects on the variance in the liability of recurrent tonsillitis. DESIGN: Retrospective questionnaire data from a population-based cohort. SETTING: Population-based data from Norway. PARTICIPANTS: A total of 9479 Norwegian twins born between January 1, 1967, and December 31, 1979, identified through the Medical Birth Registry of Norway. Main Outcome Measure Recurrent tonsillitis. RESULTS: The lifetime prevalence of recurrent tonsillitis was 11.7% (95% confidence interval, 11.0%-12.3%), with a significant predominance of female cases. The tetrachoric correlations for monozygotic twins were 0.71 for males and 0.60 for females. For dizygotic twins, the correlations were 0.12 for males, 0.14 for females, and 0.24 for dizygotic pairs of opposite sex. Structural equation modeling indicated that genetic effects explained 62% of the variation in the liability of recurrent tonsillitis. The remaining variance was attributed to individual environmental effects. There was no evidence of sex-specific genetic effects on the liability of recurrent tonsillitis. CONCLUSION: There is evidence for a substantial genetic predisposition for recurrent tonsillitis.

Adult↗

PubMed2005

Otoacoustic emissions in the general adult population of Nord-Trøndelag, Norway: III. Relationships with pure-tone hearing thresholds.

This study aims to describe the association between otoacoustic emissions (OAEs) and pure-tone hearing thresholds (PTTs) in an unscreened adult population (N =6415), to determine the efficiency by which TEOAEs and DPOAEs can identify ears with elevated PTTs, and to investigate whether a combination of DPOAE and TEOAE responses improves this performance. Associations were examined by linear regression analysis and ANOVA. Test performance was assessed by receiver operator characteristic (ROC) curves. The relation between OAEs and PTTs appeared curvilinear with a moderate degree of non-linearity. Combining DPOAEs and TEOAEs improved performance. Test performance depended on the cut-off thresholds defining elevated PTTs with optimal values between 25 and 45 dB HL, depending on frequency and type of OAE measure. The unique constitution of the present large sample, which reflects the general adult population, makes these results applicable to population-based studies and screening programs.

Adult↗

PubMed2005

Screened and unscreened hearing threshold levels for the adult population: results from the Nord-Trøndelag Hearing Loss Study.

This paper presents normative data of hearing threshold levels of a population screened with various criteria, as compared to unscreened population data. Computer-controlled pure-tone audiometry was administered to the adult population in Nord-Trøndelag County, Norway, during 1995-1997. The 51975 participants also provided questionnaire information about occupational and leisure noise exposure, previous ear infections, and head injury. While screening had little effect on the median hearing threshold levels of young adults, there was a substantial effect when screening men above 40 years of age for a history of noise exposure. Screening for known ear-related disorders and diseases resulted in small effects on the mean hearing threshold levels The median hearing thresholds of both the screened and the unscreened sample exceeded the age and sex specific thresholds specified by the ISO 7029.

Adult↗

PubMed2005

Resolving the genetic and environmental sources of the correlation between height and intelligence: a study of nearly 2600 Norwegian male twin pairs.

The main aim of this paper was to resolve the correlation between intelligence test scores and standing height into genetic and environmental components. Data on 1181 identical and 1412 fraternal twin pairs (all males) were retrieved by matching files from the Norwegian Army with twin registries. The data were analyzed by means of a structural equation model comprising latent genetic, shared environmental and nonshared environmental factors and correlations between them. A major part of the height--intelligence correlation was due to correlated shared environments (59% of the phenotypic height--intelligence correlation), but statistically significant effects of correlated genes and nonshared environments were also found (respectively 35% and 6% of the phenotypic correlation).

Adolescent↗