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Results for “Structural equation modeling”

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PubMed1999

Nightmares: familial aggregation and association with psychiatric disorders in a nationwide twin cohort.

We quantified the genetic influences affecting the liability to nightmares, and the association between nightmares and psychiatric disorders in a community-based sample. In 1990, 1,298 monozygotic (MZ) and 2,419 dizygotic (DZ) twin pairs aged 33-60 years responded to a questionnaire study in the Finnish Twin Cohort. Structural equation modeling was used to estimate genetic and environmental components of variance in the liability to nightmares. Records on hospitalization and long-term antipsychotic medication were used to estimate the period prevalence of serious psychiatric disorders. Nightmares were reported more frequently in females both in childhood and as adults. The correlation between occurrence in childhood and as adults was 0.69 in males and 0.71 in females. Polychoric correlations of occurrence within the twin pairs were 0. 45 in MZ and 0.21 in DZ pairs in childhood, and as adults 0.39 and 0. 18, respectively. The best fitting genetic model was that specifying additive genetic and unshared environmental effects. The estimated proportion of genetic effects in childhood was in males 44% (95% confidence interval [CI] 35-52%) and in females 45% (95% CI 38-52%) of the phenotypic variance. As adults the values were in males 36% (95% CI 27-44%) and in females 38% (95% CI 31-45%). Nightmare frequency and psychiatric disorders were linearly associated. Among those with the most frequent nightmares odds ratios (95% CI) were 3. 67 (2.48-5.42) for childhood and 5.87 (4.08-8.45) for adults compared with those never having nightmares. Nightmares are quite a stable trait from childhood to middle age. There are persistent genetic effects on the disposition to nightmares both in childhood and adulthood. Nightmares are significantly associated with psychiatric disorders.

Adult↗

PubMed1999

Genetic predisposition, environment and cancer incidence: a nationwide twin study in Finland, 1976-1995.

Twin studies integrate genetic and environmental (including physical environment and life-style) information by comparing monozygotic and dizygotic twins for the occurrence of disease. Our objectives were to compare cancer incidence in twins with national rates and to estimate both the probability that co-twins of affected twins may develop cancer and the importance of genetic predisposition and environment in cancer development. The nationwide record linkage of the Finnish Twin Cohort Study, the Finnish Cancer Registry and the Central Population Register allowed the follow-up of 12,941 same-sexed twin pairs for incident primary cancers from 1976 to 1995. Zygosity was determined by use of a validated questionnaire in 1975. Methods included calculation of standardized incidence ratios and concordances and fitting of structural equation models. A total of 1,613 malignant neoplasms occurred in the cohort. The overall cancer incidence among twins resembled that among the general population. Monozygotic co-twins of affected twins were at 50% higher risk than were dizygotic co-twins. Based on genetic modeling, inherited genetic factors accounted for 18% (95% confidence interval 4-32%) of the liability in inter-individual variation in the risk of overall cancer, while non-genetic factors shared by twins accounted for 7% (0-16%) and unique environmental factors for 75% (65-85%). Our results appear to exclude a contribution greater than one-third for genetic predisposition in the development of cancer in the general population, thus pointing to the earlier confirmed substantial role of environment.

Adult↗

PubMed1997

Peer, family, and motivational influences on drug treatment process and recidivism for probationers.

Treatment efforts appear to be effective in reducing crime among drug using individuals, but components of the treatment process associated with client improvement need to be identified. Furthermore, these elements of treatment may play an intermediate role in the connection between client background characteristics and later criminal activity. The current study examines a structural equation model including client perceptions of their drug related problems, peer deviance, and family dysfunction as influences upon the formation of therapeutic relationships during treatment and rearrests following treatment. Results showed therapeutic relationships were positively associated with recognition of drug related problems and negatively related to rearrest. Peer deviance also was positively related to rearrest.

Adolescent↗

PubMed1997

Genetic factors in the aetiology of mouth ulcers.

The aetiology of mouth ulcers is uncertain, and prior research has indicated both environmental and genetic factors. In this study, information on mouth ulcer incidence was collected for 290 twin pairs--127 monozygous (MZ) and 163 dizygous (DZ)--and their parents, a total of 1,160 people. Self-reported data on mouth ulcer incidence were available for the twins, and in each family the mother also reported on the mouth ulcer incidence in the twins, the twins' father, and herself. A structural equation model--combining a measurement model, a rater bias model, and a model including genetic and environmental influences--was used to explain variation in mouth ulcers. The fitted model explained the variation in a latent phenotype of mouth ulcer incidence for the twins in terms of an additive genetic factor (64%), a common environment factor (26%), and a specific environment factor (10%). The mothers' ratings showed a significant positive bias.

Bias↗

PubMed1997

The utility of locus of control for predicting adolescent substance use.

Structural equation modelling (SEM) was used to examine the utility of locus of control (LOC) for predicting adolescent substance use. As part of a larger three-wave cohort-sequential study (1983-1989), 155 secondary school-based adolescents completed questionnaires on substance use, personality characteristics, family/peer influences, and health behaviors. Latent variable indicators were developed from the Nowicki-Strickland Personal Reaction Survey and substance use survey items. LOC was a weak predictor of substance use. In two instances were relationships significant: (a) 7th grade LOC predicted 11th grade alcohol use; and, (b) 9th grade LOC correlated with 11th grade cannabis use. Small samples precluded analysis of gender and social class effects. SEM with panel data offers a methodological approach for examining the explanatory capability of LOC.

Adolescent↗

PubMed2000

Positive and negative outcomes of anger in early adolescents.

The purposes of this study were to examine symptom patterns and diminished general well-being as negative outcomes and vigor and change as positive outcomes of trait and state anger via two structural equation models. In a school auditorium, a convenience sample of 141 boys and girls, ages 12-14 years, responded to the Trait Anger Scale and the State Anger Scale and to instruments measuring general well-being, symptom patterns, vigor, and change. In the negative outcome model, results indicated that diminished general well-being and increased symptom patterns were outcomes of trait anger and state anger in early adolescents. In the positive outcome model, contrary to expectation, less vigor and less inclination to change were outcomes of trait anger in early adolescents, while state anger had no appreciable influence on the same variables. The findings suggest that anger, particularly trait anger, had a negative influence on the outcome variables studied.

Adolescent↗

PubMed2001

Perfectionism in women with binge eating disorder.

OBJECTIVE: This study examined self-oriented (SOP), socially prescribed (SPP), and other-oriented (OOP) perfectionism in 127 obese women with binge eating disorder (BED). METHOD: Relationships between eating disorder and general psychopathology variables and SOP, SPP, and OOP were assessed. Levels of SOP, SPP, and OOP in the BED sample were compared with those of 32 normal weight women with bulimia nervosa (BN) and 60 obese non-eating-disordered individuals (NED). Structural equation modeling (SEM) was used to test models of the maintenance of BED. RESULTS: Only SPP was significantly associated with eating disorder variables related to BED. All three groups demonstrated similar levels of SPP and OOP. BN and BED groups scored significantly higher than the NED group on SOP only. SEM resulted in two models with good fits. DISCUSSION: Further research is needed on the roles of SPP and SOP in BED and on weight and shape overconcern in BED maintenance models.

Adolescent↗

PubMed2001

Estimation of genetic and environmental components in colorectal and lung cancer and melanoma.

Cancer has predominant environmental and somatic causes but the assessment of hereditary (genetic) causes is difficult, except for highly penetrant single-gene causes. Family studies are only partially informative in this regard because family members share diet and life-styles. Twin studies have been classically used to disentangle the effects of heredity and environment on disease etiology. We estimate the genetic and environmental components in colorectal and lung cancer and melanoma by comparing cancer risks in family members. The Swedish Family-Cancer Database, comprising more than 6 million individuals, was used as the source of family and cancer data. Tetrachoric correlations were used to describe similarity in cancer liability among family members. Structural equation modelling was used to derive estimates of the importance of genetic and environmental effects. The estimated genetic component ranged from 10% in colon and colorectal cancer to 18% in melanoma. For lung cancer, the share was 14%. If assortative mating were important for liability to cancer, these heritability estimates may be an underestimation of the true genetic effects. Non-shared environmental effect was 67-68% in colorectal cancer and melanoma, and 71% in lung cancer. Shared and childhood environments were equally important in colorectal cancer and melanoma, whereas no childhood effect was observed for lung cancer.

Adolescent↗

PubMed2001

Widespread pain among 11-year-old Finnish twin pairs.

OBJECTIVE: To examine the prevalence of widespread musculoskeletal pain (WSP) symptoms in 11-year-old Finnish twins and to determine the relative role of genetic and environmental factors in the etiology of WSP. METHODS: Data on current pain items were collected from 1995 to 1998 from a national sample of Finnish families with 11-year-old twins born between 1984 and 1987. The presence of WSP was determined using a validated questionnaire method. Pairwise similarity was computed for 583 monozygotic (MZ) pairs, 588 same-sex dizygotic (DZ) pairs, and 618 opposite-sex DZ twin pairs. Variance components for genetic and environmental factors were estimated using biometric structural equation modeling techniques. RESULTS: The prevalence of WSP was 9.9%, with no sex difference. The majority of twin pairs with WSP were discordant. The tetrachoric correlations for male MZ (r = 0.38), male DZ (r = 0.37), female MZ (r = 0.59), female DZ (r = 0.54), and opposite-sex pairs (r = 0.43) showed little difference by zygosity. Female pairs were more concordant than male pairs among both MZ and DZ twins. Biometric model-fitting indicated that genetic factors did not account for the pattern of twin similarity. Among boys 35%, and among girls 56%, of the variation in liability to WSP could be attributed to shared familial environmental effects. The remainder was attributed to unshared environmental effects. CONCLUSION: Genetic factors seem to play at most a minor role in WSP in 11-year-old twins, and environmental factors shared by family members account for a substantial proportion of the variability in WSP.

Child↗

PubMed1995

Genetic, environmental, and phenotypic links between body mass index and blood pressure among women.

Greater relative weight is associated with higher blood pressure, but the reasons are unknown. The inability of current technology to induce sustained weight loss among overweight persons precludes experimental tests of whether this association is causal. We evaluated the degree to which the covariation between body mass index (BMI; kg/m2) and blood pressure (BP) among women is due to pleiotropic genetic factors, environmental factors, or phenotypic causation. The sample included 75 monozygotic (MZ) and 39 dizygotic (DZ) pairs of adult female twins. "BP" was calculated as the unit-weighted mean of systolic and diastolic. Data were analyzed through structural equation modeling. A model was specified stipulating that additive genetic effects (A) and unique environmental effects (E) each contributed to the covariance between BMI and BP, thus allowing for both pleiotropic and unique environmental influences on the covariance between BMI and BP. Dropping the pleiotropic influences significantly worsened the model (chi 2 = 4.62, df = 1, P = .032), suggesting significant pleiotropic effects. Dropping the environmental influences on the cross-phenotype covariance did not significantly worsen the model (chi 2 = 1.42, df = 1, P = .233). This indicates no significant effect of the environment on the covariance between BMI and BP. Finally, a model of phenotypic causation in which BMI directly influenced BP was fitted. This model provided the best single parameter explanation of the BP-BMI covariation. These data suggest that, among women, regardless of the source of variation, changes in BMI should lead to long-standing changes in BP.

Adult↗

PubMed2006

High heritability of fingertip arch patterns in twin-pairs.

The presence of an arch pattern on at least one fingertip has previously been suggested as an autosomal dominant trait with reduced penetrance, although the examination of pedigrees with this trait segregating is also consistent with major gene or multifactorial inheritance. We utilized fingerprints in 2,484 twin-pairs to estimate heritability for the presence of at least one fingertip arch pattern. The frequency of arches in the entire sample was 4.3% (2,175/50,850), 5.5% in females and 3.2% in males. There were 267 twin-pairs concordant for the presence of an arch on any finger. Structural equation modeling was performed to contingency table data for five groups (MZ male, MZ female, DZ male, DZ female, and unlike-sexed DZ). The best fitting model, which allowed for the prevalence of arches to differ between males and females, had a heritability of 91%. There was some evidence for small dominant genetic effects in females and shared environmental effects in males, although both were not significant. With such high heritability, the search for specific genes influencing the occurrence of fingertip arch patterns is justified.

Dermatoglyphics↗

PubMed2004

Do aggressive and non-aggressive antisocial behaviors in adolescents result from the same genetic and environmental effects?

Antisocial behavior (ASB) in adolescents can broadly be separated into two forms; aggressive and non-aggressive. Both are heritable and it has been suggested that aggressive ASB is more heritable. The extent to which genes contribute to the correlation between the two is unknown. Structural equation modeling was applied to a population-based twin sample of 258 twins pairs aged 11-18 to estimate the heritability of each form of ASB and to estimate the extent to which the phenotypic correlation was the consequence of shared genes and environmental factors. Non-shared environment and genetic factors substantially influenced both forms of ASB. The heritability of aggressive (but not non-aggressive) ASB was significantly higher in girls than in boys. Combining both sexes, a model in which the genetic effects on aggressive and non-aggressive ASB were identical could be rejected. Our results suggest a partial genetic overlap with a specific genetic effect contributing to the variance of aggressive ASB and a stronger genetic effect on aggression in females than in males.

Adolescent↗

PubMed1992

Genetic and environmental contributions to the variance of body height in a sample of first and second degree relatives.

Height was measured in a health screening of the population in Nord-Trøndelag, Norway. Correlations were computed for 24,281 pairs of spouses, 43,613 pairs of parents and offspring, 19,168 pairs of siblings, 1,318 pairs of grandparents and grandchildren, 1,218 cognate avuncular pairs, 849 noncognate avuncular pairs, 175 pairs of same-sexed twins, and smaller groups of other types of relatives. Fitting of structural equation models showed proportions of additive genetic variance of approximately 0.8 for both sexes and small sex-specific effects that probably reflect genetic dominance or environmental sibling effects. The correlations between parents and offspring were significantly lower in old than young cohorts, seeming to imply some kind of interaction effect between genes and environment.

Age Factors↗

PubMed1992

Psychological factors, immunologic activation, and disease activity in rheumatoid arthritis.

The purpose of this study was to use structural equation modeling techniques to examine potential interrelationships among psychological factors, immunologic activation, and disease activity in rheumatoid arthritis (RA). The subjects were 80 male patients with a diagnosis of classic or definite RA. Measures included the Beck Depression Inventory, the Arthritis Helplessness Index, and the Arthritis Impact Measurement Scales (AIMS) pain score. Joint counts and immunophenotypic analyses of peripheral blood lymphocytes also were collected. Path analysis showed that percentage of HLA-DR+ cells in the peripheral blood and helplessness were related to join count. In addition, joint count had an effect upon depression. Depression had an effect upon pain, but there was no reciprocal effect of pain upon depression. This study describes a preliminary path model of interrelationships among psychological factors, immunologic activation, and disease activity in RA.

Aged↗

PubMed2006

Importance of genetic influences on chronic widespread pain.

OBJECTIVE: To estimate the relative importance of genetic and environmental factors in chronic widespread pain, and to assess whether there are sex differences in the type or magnitude of these influences. METHODS: Data were collected from a national sample of twins > or = 42 years of age, all of whom were participants in the Swedish Twin Registry. The presence of chronic widespread pain was assessed via computer-assisted telephone interviews, which were conducted between 1998 and 2002, using the American College of Rheumatology criteria for fibromyalgia. No clinical examinations were performed. In preliminary analyses, probandwise concordance rates and tetrachoric correlations were calculated. Structural equation modeling was then performed to estimate additive genetic, shared environmental, and nonshared environmental sources of variability in susceptibility for the development of chronic widespread pain. RESULTS: Of 61,355 eligible twins, 44,897 individuals (73.2%) responded to the interview. Both members of 15,950 pairs responded to the items regarding pain symptoms; of these pairs, 4,170 were monozygotic, 5,881 were same-sex dizygotic, and 5,755 were opposite-sex dizygotic. The prevalence of chronic widespread pain was 4.1%, and the ratio of women to men was 3.3 to 1. Probandwise concordance rates and tetrachoric correlations suggested modest genetic influences for both women and men. Genetic and shared environmental influences explained approximately half of the total variance, with no indication of sex differences in either the type or magnitude of these influences. CONCLUSION: Individual differences in the likelihood of developing chronic widespread pain reflect modest genetic influences. There are no significant sex differences in the type or expression of the genes responsible for chronic widespread pain or in the magnitude of the relative importance of these influences on chronic widespread pain.

Chronic Disease↗

PubMed2005

Nipping psychopathy in the bud: an examination of the convergent, predictive, and theoretical utility of the PCL-YV among adolescent girls.

Over the last decade rates of violence among adolescent girls have increased. Within high-risk contexts, urgent calls for assessment options have resulted in the extension of adult and male-based instruments to adolescent females in spite of the absence of strong empirical support. The current study evaluates the downward extension of psychopathy within a population of female juvenile offenders (N=125). The convergent and predictive validity of the Psychopathy Checklist-Youth Version (PCL-YV) were evaluated within a structural equation modeling (SEM) framework. Results indicated that while a specific component of psychopathy, deficient affective experience, was related to aggression, the effect was negated once victimization experiences were entered into the models. In addition, PCL-YV scores were not predictive of future offending, while victimization experiences significantly increased the odds of re-offending. Implications for research, policy, and clinical practice are discussed.

Adolescent↗

PubMed2004

Quality of life and post trauma symptomatology in motor vehicle accident survivors: the mediating effects of depression and anxiety.

We examined the respective contributions of depression, anxiety, and post-trauma symptoms, as these factors reduce quality of life (QOL) in 111 individuals who had experienced a serious motor vehicle accident. Correlations and structural equation modeling were used to evaluate whether the severity of posttraumatic stress disorder symptoms influences QOL directly, and whether depression and anxiety mediated this relationship. Results indicated that post trauma symptomatology has a negative effect on QOL, which is mediated by depression and anxiety.

Accidents, Traffic↗

PubMed2007

Symptom severity and lifetime and prospective health service use among military veterans evaluated for PTSD.

We used structural equation modeling with 174 treatment-seeking military trauma survivors evaluated for posttraumatic stress disorder (PTSD) at a VA Medical Center PTSD clinic to examine relationships among lifetime mental health service use, PTSD symptom severity and medical problems (from self-report), as well as prospective (1-year) mental health and medical care use visit counts extracted from medical records. We discovered an adequate statistical fit to a hypothesized model of previous and prospective health service use, and current PTSD severity and health-related problems. Previous inpatient mental health treatment was significantly related to PTSD severity and prospective outpatient mental health use. However, PTSD severity was unrelated to prospective use of mental health or medical services. Health problems were related to prospective medical service use. Clinical and administrative implications in predicting health care use among trauma survivors are discussed.

Adult↗