The Nature and Origin of Common Phobic Fears

1979 ◽  
Vol 134 (4) ◽  
pp. 343-351 ◽  
Author(s):  
Svenn Torgersen
Keyword(s):  
Environmental Factors ◽  
Social Adjustment ◽  
Twin Study ◽  
Genetic Factors ◽  
Factor Analyses ◽  
Factors Affecting ◽  
Five Factors

SummaryBy means of a twin study an attempt was made to throw light upon the aetiology and nosology of phobic fears. Factor analyses revealed five factors, namely separation fears, animal fears, mutilation fears, social fears and nature fears. The study demonstrated that, apart from separation fears, genetic factors play a part in the strength as well as content of phobic fears. Environmental factors, affecting the development of dependence, reserve and neurotic traits generally, seemed also to be of some importance. It was further demonstrated that phobic fears were related to emotional and social adjustment and this was true to an even greater extent for separation fears.

Muscle Dissatisfaction and Muscle-Enhancing Substance Use: A Population-Based Twin Study in Young Adult Men

2006 ◽  
Vol 9 (3) ◽  
pp. 431-437 ◽  
Author(s):  
Anu Raevuori ◽  
Anna Keski-Rahkonen ◽  
Richard J. Rose ◽  
Aila Rissanen ◽  
Jaakko Kaprio
Keyword(s):  
Substance Use ◽  
Environmental Factors ◽  
Twin Study ◽  
Genetic Factors ◽  
Population Based ◽  
Tetrachoric Correlation ◽  
Polychoric Correlation ◽  
Adult Men ◽  
Genetic And Environmental Factors ◽  
Best Fit

AbstractIn the population-based FinnTwin16 study, proportions of genetic and environmental factors contributing to muscle dissatisfaction and muscle-enhancing substance use were assessed in 319 pairs of twin brothers: 141 monozygotic (MZ) and 178 dizygotic (DZ) pairs. In addition there were 86 twin individuals from pairs in which only one co-twin responded. Of all respondents, 30% experienced high muscle dissatisfaction. The corresponding proportion of muscle-enhancing substance use was 10%. The subjects were similar in age (23.8 years, 95% confidence interval [CI] 23.76–23.84), body mass index (23.7, 95% CI 23.5–23.9), and waist circumference (84.5 cm, 95% CI 83.7–85.2), independent of their muscle dissatisfaction or muscle-enhancing substance use status and independent of their zygosity. The MZ polychoric correlation for muscle dissatisfaction was .39 (95% CI .17–.58) and .27 for DZ pairs (95% CI .07–.46). The MZ tetrachoric correlation for muscle-enhancing substance use was .65 (95% CI .28–.87) and .56 for DZ pairs (95% CI .26–.78). The AE model, where additive genetic factors (A) accounted for 42% (95% CI .23–.59) and unique environmental factors (E) 58% (95% CI .41–.77) of the liability, provided the best fit for muscle dissatisfaction. The CE model, where common environmental factors (C) accounted for 60% (95% CI .37–.77) and unique environmental factors (E) 40% (95% CI .23–.63) of the liability, provided the best fit for muscle-enhancing substance use. Both genetic and unique (nonfamilial) environmental factors are involved in muscle dissatisfaction in the population. Nongenetic factors (both familial and non-familial) appear to best explain the use of muscle-enhancing substances.

scholarly journals Risk Factors Influencing Smoking Behavior: A Turkish Twin Study

2014 ◽  
Vol 17 (6) ◽  
pp. 563-573 ◽  
Author(s):  
Sevgi Yurt Öncel ◽  
Danielle M. Dick ◽  
Hermine H. Maes ◽  
Fazil Alıev
Keyword(s):  
Environmental Factors ◽  
Nicotine Dependence ◽  
Twin Study ◽  
Genetic Factors ◽  
Structural Equation Models ◽  
Environmental Influence ◽  
Smoking Behavior ◽  
Smoking Initiation ◽  
Smoking History ◽  
Shared Environmental Influence

Aim: In this study, we introduce the first twin study in Turkey, focusing on smoking behavior, and laying the foundation to register all twins born in Turkey for research purposes. Using Turkish twins will contribute to our understanding of health problems in the context of cultural differences. Materials and methods: We assessed 309 twin pairs (339 males and 279 females) aged between 15 and 45 years living in the Kırıkkale and Ankara regions of Turkey, and administered a health and lifestyle interview that included questions about smoking status and smoking history. We analyzed the data using descriptive statistics, t-tests, chi-square tests, and bivariate and multivariate clustered logistic regression. In addition, we fit bivariate Structural Equation Models (SEM) to determine contributions of latent genetic and environmental factors to smoking outcomes in this sample. Results: One hundred seventy-eight participants (28.8%) were identified as smokers, smoking every day for a month or longer, of whom 79.2% were males and 20.8% were females. Mean values for number of cigarettes per day and the Fagerstrom Test of Nicotine Dependence (FTND; Fagerstrom, 1978) score were higher in males than in females, and age of onset was earlier in males. There was a significant positive correlation between the FTND score and number of cigarettes smoked per day, and a significant negative correlation between both variables and age at onset of smoking. Our study showed that gender, presence of a smoking twin in the family, age, alcohol use, marital status, daily sports activities, and feeling moody all played a significant role in smoking behavior among twins. The twin analysis suggested that 79.5% of the liability to FTND was influenced by genetic factors and 20.5% by unique environment, while familial resemblance for smoking initiation was best explained by common environmental factors. Conclusions: Marked differences in the prevalence of smoking behavior in men versus women were observed for the Turkish population. Genetic analyses showed that common environmental factors primarily contributed to smoking initiation, while genetic factors explained a greater proportion of variance in liability to nicotine dependence. Our study shows higher heritability estimate of the FTND scores and higher shared environmental influence on smoking initiation for both males and females than reported in previous studies.

A Danish Twin Study of Schizophrenia

1969 ◽  
Vol 115 (526) ◽  
pp. 981-990 ◽  
Author(s):  
Margit Fischer ◽  
B. Harvald ◽  
M. Hauge
Keyword(s):  
Environmental Factors ◽  
Twin Study ◽  
Genetic Factors ◽  
Concordance Rate ◽  
High Concordance ◽  
Danish Twin

Previous studies on schizophrenia in twins have quite recently been reviewed in detail by Gottesman and Shields (1966a) and Shields (1968). The indications of concordance in different series are highly diverging, in monozygotic pairs ranging from near unity to zero. The high concordance rates found by Luxenburger (1928), Kallmann (1946) and Slater (1953) stress the importance of genetic factors in the aetiology of schizophrenia, whereas the low concordance rate in two recent Scandinavian twin series (Tienari, 1963; Kringlen, 1966) has given rise to the question whether special genetic or environmental factors prevail in some populations. It has, therefore, been found of interest to study schizophrenia in a Danish twin population.

scholarly journals Genetic Regulation of Growth in Height and Weight from 3 to 12 Years of Age: A Longitudinal Study of Dutch Twin Children

2007 ◽  
Vol 10 (2) ◽  
pp. 354-363 ◽  
Author(s):  
Karri Silventoinen ◽  
Meike Bartels ◽  
Daniëlle Posthuma ◽  
G. Frederiek Estourgie-van Burk ◽  
Gonneke Willemsen ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Genetic Factors ◽  
Molecular Genetic ◽  
Genetic Regulation ◽  
Genetic Correlations ◽  
Human Growth ◽  
Growth Period ◽  
Age Difference ◽  
Environmental Correlations ◽  
Factors Affecting

AbstractHuman growth is a complex and poorly understood process. We studied the effect of genetic and environmental factors on height and body mass index (BMI, kg/m2) based on maternal reports at 3, 4, 5, 7, 10 and 12 years of age in a large longitudinal cohort of Dutch twins (7755 complete twin pairs at age 3). Several multivariate variance component models for twins were fitted to the data using the Mx statistical package. The first-born twin was taller until age 10 and heavier until age 12 than the second-born co-twin. Heritability estimates were high for height (a2 = .58–.91) and BMI (a2 = .31–.82), but common and unshared environmental factors were also important. The phenotypic correlations across the ages for height and BMI were mainly explained by correlated additive genetic factors (ra = .77–.96 for height and .43–.92 for BMI), but common (rc = .40–.84 and .09–.78, respectively) and specific environmental correlations (re = .50–.81 and .42–.80, respectively) were also significant. Additive genetic factors decreased with increasing age difference for both height and BMI. However, the full Cholesky model, which does not make any assumptions regarding the underlying genetic structure, had the best fit. High genetic correlations across the ages, especially for height, may help further molecular genetic studies of human growth. Environmental factors affecting height and BMI during growth period are also important, and further studies are needed to identify these factors and test whether they interact with genetic factors.

A Twin study of Individuals with both Schizophrenia and Alcoholism

1985 ◽  
Vol 147 (1) ◽  
pp. 48-53 ◽  
Author(s):  
Kenneth S. Kendler
Keyword(s):  
Environmental Factors ◽  
Genetic Predisposition ◽  
Twin Study ◽  
Genetic Factors ◽  
Substantial Evidence

SummarySubstantial evidence suggests that genetic factors contribute to the aetiology of both schizophrenia and alcoholism, when they occur alone. To examine the role of genetic factors in schizophrenia and alcoholism when they occur together in the same individual, the frequency of both conditions was investigated in the co-twins of 34 monozygotic (MZ) and 47 dizygotic (DZ) index twins with a diagnosis of both schizophrenia and alcoholism. Both disorders alone were significantly more common in the MZ than in the DZ co-twins, suggesting that individuals suffering from schizophrenia and alcoholism have a genetic predisposition to both disorders, which is of the same nature as that which causes the two when they occur alone. In the co-twins of the MZ index twins, the diagnoses of schizophrenia and alcoholism were uncorrelated, indicating that the specific environmental factors of causal importance in the two disorders are not closely related.

SEM study of quartz grains from recent sediments: Western Iraq

1990 ◽  
Vol 48 (4) ◽  
pp. 860-861
Author(s):  
F. Al-Kufaishi
Keyword(s):  
Factor Loading ◽  
Fault System ◽  
Clay Material ◽  
Crustal Material ◽  
Factor Analyses ◽  
Five Factors ◽  
Sem Study ◽  
Recent Sediments ◽  
Quartz Grains ◽  
Positive Factor

Two localities (Al-Marij and Laik) were selected to investigate the type of Quartz Grains from crustal material formed by evaporation of waters discharged by springs in Hit area, western Iraq, Previous studies on the crustal material (1,2) showed that the water discharged by these springs are associated with Abu-Jir fault system which run parallel to the Euphrates river,Factor analyses of the crustal and soil materials (50 samples analysed for 16 variables)(2) showed five factors; the first factor includes SiO2, Al2O3 and TiO2 with positive factor loading, and CaO, L.O.I. with negative loading and hence lead to the conclusion that the distribution of these variables is a reflection of transported clay material.This study concentrates on the use of SEM to investigate the contribution of Quartz grains found in the crustal material on two selected sites.

Environmental factors affecting reproducibility of bioremediation field assays in Antarctica

2020 ◽  
Vol 169 ◽  
pp. 102915 ◽  
Author(s):  
L.M. Martínez Álvarez ◽  
L.A.M. Ruberto ◽  
J.M. Gurevich ◽  
W.P. Mac Cormack
Keyword(s):  
Environmental Factors ◽  
Factors Affecting
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