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Biomedical subjects

W R True

Publications and source records attributed to W R True.

At least 19 recordsLinked to original sources
PubMed2001

A twin study of generalized anxiety disorder symptoms, panic disorder symptoms and post-traumatic stress disorder in men.

Generalized anxiety disorder (GAD), panic disorder (PD) and post-traumatic stress disorder (PTSD) often co-occur. We investigated whether and to what degree genetic and environmental contributions overlap among symptoms of GAD, symptoms of PD and PTSD. Subjects were 3327 monozygotic and dizygotic male-male twin pair members of the Vietnam Era Twin Registry who participated in a 1992 telephone administration of the Diagnostic Interview Schedule Version 3 Revised (DIS3R). Genetic model fitting was performed to estimate the magnitude of genetic and environmental contributions to the lifetime co-occurrence of GAD symptoms, PD symptoms and PTSD. The liability for GAD symptoms was due to a 37.9% additive genetic contribution common to PD symptoms and PTSD. Liability for PD symptoms was due to a 20.7% additive genetic contribution common to GAD symptoms and PTSD, and a 20.1% additive genetic influence specific to PD symptoms. Additive genetic influences common to symptoms of GAD and PD accounted for 21.3% of the genetic variance in PTSD. Additive genetic influences specific to PTSD accounted for 13.6% of the genetic variance in PTSD. Remaining variance for all three disorders was due to unique environmental factors both common and specific to each phenotype. These results suggest that these disorders each have etiologically distinct components and also have significant genetic and unique environmental contributions in common.

Adult↗
PubMed2001

A twin study of the association between pathological gambling and antisocial personality disorder.

Many individuals with a history of pathological gambling (PG) also have a history of engaging in antisocial behaviors, and this has often been interpreted as a result of the former causing the latter. In a sample of 7,869 men in 4,497 twin pairs from the Vietnam Era Twin Registry, the authors examined (a) the association between PG and antisocial personality disorder (ASPD), (b) the extent to which PG might be differentially associated with childhood conduct disorder (CD) and adult antisocial behavior (AAB), and (c) the contribution of genetic and environmental factors to the association of PG with ASPD, CD, and AAB. PG was significantly associated with all 3 antisocial behavior disorders, and the association of PG with ASPD, CD, and AAB was predominantly explained by genetic factors. The results of this study suggest that the greater-than-chance co-occurrence of PG and antisocial behavior disorders is partially due to their sharing a common genetic vulnerability. The antisocial behavior observed among many individuals with PG probably cannot be interpreted as being simply a consequence of the PG.

Adult↗
PubMed2000

Genetic and environmental influences on posttraumatic stress disorder, alcohol and drug dependence in twin pairs.

We investigated whether and to what degree genetic and environmental contributions overlap among posttraumatic stress disorder (PTSD), alcohol dependence (AD) and drug dependence (DD). Subjects were 3304 monozygotic and dizygotic male-male twin pair members of the Vietnam Era Twin Registry who participated in 1992 telephone administration of the Diagnostic Interview Schedule Version 3 Revised (DIS-3R). Genetic model fitting was performed to estimate the magnitude of genetic and environmental contributions to the lifetime co-occurrence of DSM-III-R PTSD, AD and DD. The liability for PTSD was partially due to a 15.3% genetic contribution common to AD and DD and 20.0% genetic contribution specific to PTSD. Risk for AD was partially due to a 55.7% genetic contribution common to PTSD and DD. Genetic influences common to PTSD and AD accounted for 25.2% of the total risk for DD. Specific family environmental influence accounted for 33.9% of the total variance in risk for DD. Remaining variance for all three disorders was due to unique environmental factors both common and specific to each phenotype. These results suggest that PTSD, AD and DD each have etiologically distinct components and also have significant genetic and unique environmental contributions in common.

Adult↗
PubMed2000

Common genetic vulnerability for pathological gambling and alcohol dependence in men.

BACKGROUND: In comparison with alcohol dependence (AD), relatively little is known about the causes of pathological gambling (PG). Given the high rate of comorbidity between PG and AD, knowledge about the causes of AD may be applied to understanding those of PG. METHODS: Subjects were adult male twin pairs from the Vietnam Era Twin Registry. Lifetime histories of PG and AD were assessed by structured psychiatric telephone interview. The validity of a continuum of PG liability was tested to determine whether the causes of subclinical PG, or problem gambling, are quantitatively or qualitatively distinct from those of DSM-III-R PG disorder. Genetic model-fitting methods were used to quantify the extent to which the genetic and environmental risk for PG could be explained by the risk for AD. RESULTS: Tests of the continuity model of PG were all consistent with the hypothesis that subclinical PG and DSM-III-R PG disorder have many, perhaps all, of the same risk factors and thus differ quantitatively rather than qualitatively. Depending on the PG definition, between 12% and 20% of the genetic variation and between 3% and 8% of the nonshared environmental variation in the risk for PG were accounted for by the risk for AD. CONCLUSIONS: Subclinical PG, or problem gambling, may be a milder form of PG, rather than an etiologically distinct syndrome. Risk for AD accounts for a significant but modest proportion of the genetic and environmental risk for subclinical PG and DSM-III-R PG disorder.

Adult↗
PubMed2000

Self-Reported zygosity and the equal-environments assumption for psychiatric disorders in the Vietnam Era Twin Registry.

The equal-environments assumption (EEA) in twin studies of psychiatric disorders assumes that the family environment which contributes to risk for a disorder is equally correlated between monozygotic (MZ) and dizygotic (DZ) twin pairs. In a study of psychiatric disorders in female twins, Kendler and colleagues (1993) have demonstrated the utility of a test of the EEA which includes a specified family environmental factor defined by using measures of perceived zygosity. We tested the EEA assumption among 3155 male-male twin pair members of the Vietnam Era Twin Registry for the following DSM-III-R lifetime disorders: alcohol dependence, marijuana dependence, any illicit drug dependence, nicotine dependence, major depression, and posttraumatic stress disorder. The majority of MZ (81.6%; n = 1593) and DZ (90.2%; n = 1086) twin pairs agreed with the investigator's assigned zygosity. The best-fitting model for each of these disorders did not allow for a specified family environmental influence. These results support the usefulness of perceived zygosity in tests of the EEA. In male twin pairs, perceived zygosity has little impact on twin similarity for common psychiatric disorders.

Adult↗
PubMed2000

Heritability of self-reported health.

OBJECTIVE: To explore the contribution of genes and environmental factors to variation in a common measure (i.e., a five-point--excellent, very good, good, fair, and poor--Likert scale) of self-reported health. DATA SOURCES: Data were analyzed from 4,638 male-male twin pair members of the Vietnam Era Twin (VET) Registry who responded to a 1987 health survey. STUDY DESIGN: Varying models for the relationship between genetic and environmental influences on self-reported health were tested in an attempt to explain the relative contributions of additive genetic, shared and nonshared environmental effects, and health conditions reported since 1975 to perceived health status. DATA COLLECTION: A mail and telephone survey of health was administered in 1987 to VET Registry twins. PRINCIPAL FINDINGS: Variance component estimates under the best-fitting model included a 39.6 percent genetic contribution to self-reported health. In a model which included the effect of health condition, genes accounted for 32.5 percent and health condition accounted for 15.0 percent of the variance in self-reported health. The magnitude of the genetic contribution to perceived health status was not significantly different in a model with or without health condition. CONCLUSIONS: These data suggest over one-third of the variability of self-reported health can be attributed to genes. Since perceived health status is a major predictor of morbidity, mortality, and health services utilization, future analyses should consider the role of heritable influences on traditional health services variables.

Aged↗
PubMed1999

Interrelationship of genetic and environmental influences on conduct disorder and alcohol and marijuana dependence symptoms.

Data from the Vietnam Era Twin (VET) Registry were analyzed to explore the degree to which the same genetic and environmental factors contribute to childhood conduct disorder symptoms and to alcohol and marijuana dependence symptoms. Data on conduct disorder and alcohol and marijuana dependence were obtained from administration of the Diagnostic Interview Schedule to 1,856 monozygotic and 1,479 dizygotic male-male twin pair members of the VET Registry. Multivariate genetic models were compared to determine the genetic and environmental influences common and or specific to all three phenotypes. A full model that allowed for common genetic and environmental influences to all three phenotypes gave a good fit to the data, but the best fitting reduced model did not allow for a genetic influence on conduct disorder symptoms. Under the best fitting reduced model, genes explained 44.7% of the variance in risk for alcohol dependence symptoms. The genetic liability for symptoms of marijuana dependence was due to a 36.3% specific contribution and a 7.6% contribution from genes common with alcohol dependence symptoms. Family environmental contributions common to all three phenotypes explained 46.7%, 11.9%, and 21.3% of variance in risk for symptoms of conduct disorder, alcohol dependence, and marijuana dependence, respectively. Common family environmental factors contribute to risk of conduct disorder symptoms and alcohol and marijuana dependence symptoms. Common genetic influences contribute to risk of symptoms of alcohol dependence and marijuana dependence. While our findings suggest genes do not contribute to co-morbid conduct disorder symptoms, comparisons with other twin studies suggest that the role of genes in risk for conduct disorder remains uncertain.

Adult↗
PubMed1999

Sexual orientation and suicidality: a co-twin control study in adult men.

BACKGROUND: Several recent studies have found a higher lifetime prevalence of suicide attempts in homosexual males compared with heterosexual control subjects or population rates. These studies used either convenience samples, most without controls, or population-based samples in which confounding factors such as depression and substance abuse were not measured. METHODS: This study used twins from the population-based Vietnam Era Twin Registry, Hines, Ill. An analytic sample of 103 middle-aged male-male twin pairs from the registry was identified in which one member of the pair reported male sex partners after age 18 years while the other did not. Four lifetime symptoms of suicidality as measured by the Diagnostic Interview Schedule were analyzed: thoughts about death, wanting to die, thoughts about committing suicide, and attempted suicide. A composite measure of reporting at least one suicidality symptom was also assessed. RESULTS: Same-gender sexual orientation is significantly associated with each of the suicidality measures. Unadjusted matched-pair odds ratios follow: 2.4 (95% confidence interval [CI], 1.2 - 4.6) for thoughts about death; 4.4 (95% CI, 1.7 - 11.6) for wanted to die; 4.1 (95% CI, 2.1 - 8.2) for suicidal ideation; 6.5 (95% CI, 1.5 - 28.8) for attempted suicide; and 5.1 (95% CI, 2.4 - 10.9) for any of the suicidal symptoms. After adjustment for substance abuse and depressive symptoms (other than suicidality), all of the suicidality measures remain significantly associated with same-gender sexual orientation except for wanting to die (odds ratio, 2.5 [95% CI, 0.7 - 8.81). CONCLUSIONS: The substantially increased lifetime risk of suicidal behaviors in homosexual men is unlikely to be due solely to substance abuse or other psychiatric comorbidity. While the underlying causes of the suicidal behaviors remain unclear, future research needs to address the inadequacies in the measurement of both sexual orientation and suicidality in population-based samples.

Adult↗
PubMed1999

Common genetic vulnerability for nicotine and alcohol dependence in men.

BACKGROUND: Nicotine and alcohol dependence often occur together. We examined data from male twin pairs to determine whether there are genetic or environmental influences common to nicotine and alcohol dependence, and, if so, to estimate the magnitude and correlation of these influences. METHODS: Subjects were 3356 male-male twin-pair members of the Vietnam Era Twin Registry who participated in a 1992 telephone administration of the Diagnostic Interview Schedule Version 3 Revised. Genetic model fitting was performed to estimate the magnitude and correlation of genetic and environmental contributions to lifetime nicotine and alcohol dependence. RESULTS: The heritability of nicotine dependence was 60.3% (95% confidence interval [CI], 55.4%-65.2%); that of alcohol dependence, 55.1% (95% CI, 49.7%-60.5%). The best-fitting model for the co-occurrence of lifetime nicotine and alcohol dependence included a substantial genetic correlation between both disorders (r = 0.68; 95% CI, 0.61-0.74) and a modest unique environmental correlation (r = 0.23; 95% CI, 0.14-0.32). CONCLUSIONS: These data suggest a common genetic vulnerability to nicotine and alcohol dependence in men. This common genetic influence may partially explain the clinical and epidemiological observations that alcoholics are often dependent smokers.

Adult↗
PubMed1999

Sociodemographic and health status characteristics with prostate cancer screening in a national cohort of middle-aged male veterans.

OBJECTIVES: To characterize variables associated with obtaining prostate cancer screening in a nonclinical, nationally distributed, middle-aged male population. METHODS: Telephone interviews were administered to 2652 individual members of the Vietnam Era Twin Registry in 1992 and 1995. Dependent variables were self-report measures of having had a digital rectal examination (DRE) and/or a prostate-specific antigen (PSA) test in the past 5 years. Independent variables were current measures of age, household income, education, race, insurance, source of care, and lifetime measures of physical condition, psychiatric illness, and alcohol and nicotine dependence. RESULTS: Thirty-five percent of the sample reported having had a PSA and DRE within the past 5 years. Prevalence of obtaining either a PSA or DRE varied with age, income, education, and race. Subjects with a regular source of care, a regular physician, and health insurance reported higher rates of having had a DRE or PSA and DRE. Persons with a physical or psychiatric illness reported more screening. A multiple regression model revealed that having a regular source of care, having a regular physician, physical illness, psychiatric illness, minority status, higher income, and age predicted having had some form of screening. CONCLUSIONS: A substantial portion of middle-aged men have had both a PSA and DRE performed at least once in the preceding 5 years. It may be possible to further improve prostate cancer screening participation by directing educational programs at men who are not in contact with the healthcare system. If the PSA and DRE screening guidelines that are finally adopted discourage screening among low-risk men younger than age 50, educational programs that emphasize age screening criteria may be warranted.

Health Status↗
PubMed1999

Genetic and environmental influences on transitions in drug use.

Genetic and environmental factors influence drug abuse, but abuse represents the culmination of a sequence of events. Different levels of use may have different determinants and these determinants may differ across drug types. Approximately 3200 male-male twin pairs from the Vietnam Era Twin Registry were interviewed by telephone. Data were obtained regarding exposure to six categories of illicit drugs, initiation of use, continuation of use, regular usage, and diagnosis of drug abuse/dependence. Genetic, common environmental, and unique environmental influences on transitions of drug involvement, defined as movement from one level of drug use to the next, were investigated. Marijuana had the highest conditional probability for the transition from exposure to use, from use to use more than five times, and from use more than five times to regular use. The rate of transition to regular use of heroin was higher than the rate for amphetamine, cocaine, sedatives, and psychedelics. Cocaine had the highest conditional probability for the transition from regular use to abuse/dependence. Significant genetic influences were observed for a number of transitions in marijuana, amphetamine, and cocaine usage.

Adult↗
PubMed1999

The heritability of alcoholism symptoms: "indicators of genetic and environmental influence in alcohol-dependent individuals" revisited.

There is consistent evidence from twin and adoption studies implicating genetic factors in the etiology of alcoholism, yet few studies have examined the role of genetic influences on individual symptoms of alcoholism. In a previous study of 113 male twins, Johnson et al. (1996a) identified 7 alcoholism symptoms that were more "genetic" and 14 that were more "environmental" (that is, non-genetic) in their etiology by examining symptom concordances among monozygotic and dizygotic twin pairs. The present study represents an attempt to replicate the results of this previous study and extend them by estimating the contribution of genetic factors to the variation in liability for different alcoholism symptoms. Subjects were 3356 male twin pairs from the Vietnam Era Twin Registry. Lifetime histories of alcoholism symptoms were assessed by a structured psychiatric telephone interview. The results of the previous study were not replicated. The correlations between symptom classifications as genetic and non-genetic in the present and previous study were nonsignificant and ranged from -0.27 to 0.11. However, within the present study the correlation between symptom classifications as genetic and non-genetic was statistically significant across random split-half subsamples (r = 0.59); nine alcoholism symptoms were consistently classified as genetic and six symptoms as non-genetic in their etiology. Model-fitting analyses applied to different alcoholism symptoms yielded heritability estimates ranging from 0.03 to 0.53 with broad and overlapping confidence intervals around these estimates, ranging from 0.00 to 0.65. The results of this study highlight the difficulty of identifying more or less heritable phenotypes in twin research, and suggest that it may not be possible to identify specific alcoholism symptoms that are more genetic in their etiology than others. Nevertheless, there appears to be potentially important variation in the relative magnitude of genetic influences for individual alcoholism symptoms, and exploring these differences may lead to further insights into the nosology and etiology of alcohol-related problems.

Adult↗
PubMed1999

The impact of sociodemographics, comorbidity and symptom recency on health-related quality of life in alcoholics.

OBJECTIVE: To obtain estimates of the relationship between alcoholism and health-related quality of life (HRQL) in twin pairs discordant for alcohol dependence. METHOD: In 1995, 1,258 male-male twin pair members of the Vietnam Era Twin Registry (total Registry N = 7.375 pairs) were administered a modified Medical Outcomes Study 36 Item Short Form (SF-36) and the Diagnostic Interview Schedule (DIS) to obtain measures of HRQL and a DSM-III-R criteria lifetime diagnosis of alcohol dependence. Mean within pair differences on eight separate SF-36 subscales were calculated for 436 remitted (no alcohol symptoms in the past 5 years) alcohol-dependent discordant twin pairs and for 194 recent (at least one alcohol symptom in the past 5 years) alcohol-dependent discordant pairs before and after adjustment for covariates. Covariates included lifetime physical illness, lifetime psychiatric disorders, lifetime drug dependence, lifetime nicotine dependence, current marital status, current income and severity. RESULTS: In the unadjusted analysis remitted alcoholic twins compared to their nonalcoholic co-twins reported significantly lower mean scores for six of eight SF-36 subscales. Recent alcoholic twins, compared to their nonalcoholic co-twins, reported significantly lower mean scores for all of the SF-36 subscales. However, after simultaneous adjustment for all covariates, no SF-36 subscale mean, except "vitality" among recent alcoholic twins, was significantly different between alcoholic twins and their nonalcoholic co-twins. CONCLUSIONS: Differences in HRQL between alcoholic and nonalcoholic co-twins is due to covariation from physical and psychiatric problems, drug and nicotine dependence, marital status, income and severity.

Adult↗
PubMed1998

Familial influences on gambling behavior: an analysis of 3359 twin pairs.

BACKGROUND: Pathological gambling is becoming an increasing problem in the United States as the number of legalized gambling establishments grows. To examine vulnerability to pathological gambling, we estimated the familial contributions (i.e. inherited factors and/or experiences shared by twin siblings during childhood) to DSM-III-R pathological gambling symptoms and disorder. METHODS: Data were obtained from a telephone interview performed in 1991-92 utilizing the Diagnostic Interview Schedule Version III-Revised. Interviews were administered to 6718 members of the nationally distributed Vietnam Era Twin Registry of male-male monozygotic and dizygotic twin pairs who served in the military during the Vietnam era. RESULTS: Inherited factors explain between 35% (95% CI: 28%, 42%) and 54% (95% CI: 39%, 67%) of the liability for the five individual symptoms of pathological gambling behavior that could be estimated statistically. In addition, familial factors explain 56% (95% CI: 36%, 71%) of the report of three or more symptoms of pathological gambling and 62% (95% CI: 40%, 79%) of the diagnosis of pathological gambling disorder (four or more symptoms). CONCLUSIONS: Familial factors have an important influence on risk for pathological gambling behavior. The increasing access to legalized gambling is likely to result in a higher prevalence of pathological gambling behavior among individuals who are more vulnerable because of familial factors.

Adult↗
PubMed1998

Long-term reliability and validity of alcoholism diagnoses and symptoms in a large national telephone interview survey.

The long-term reliability and validity of telephone lay interview assessments of alcoholism were examined in the context of a large national community-based survey of over 8,000 male Vietnam era veterans. A subsample of 146 men was interviewed twice by telephone using the same structured interview an average of 15 months apart to evaluate the long-term reliability of alcoholism symptoms and diagnoses. In addition, a search of Department of Veterans Affairs patient treatment files of inpatient hospitalizations between 1970 and 1993 yielded a subsample of 89 interviewed men with a past discharge diagnosis of alcohol dependence. The test-retest reliability of alcohol abuse and alcohol dependence diagnoses was good, with kappa coefficients of 0.74 and 0.61, respectively. The reliability of individual alcoholism symptoms was fair to good, with kappas of 0.46 to 0.67. Ninety-six percent of individuals identified by Department of Veterans Affairs patient treatment files as having an alcohol dependence diagnosis were correctly diagnosed by the telephone interview. The results of the present study provide additional evidence for the long-term reliability and validity of lifetime alcoholism diagnoses, and suggest that the reliability and validity of telephone interview assessments of alcoholism are as good as that of an in-person interview. Telephone administration of structured psychiatric interviews appears to be an attractive alternative to in-person interviewing for gathering information about alcoholism and alcohol-related problems.

Adult↗
PubMed1997

Genetic and environmental contributions to healthcare need and utilization: a twin analysis.

OBJECTIVE: An exploratory study to examine the genetic and environmental influences on healthcare-seeking behavior for four health conditions (high blood pressure, mental health problems, joint disorders, and hearing problems). DATA SOURCES: Data collected from 3,602 male-male twin pair members of the Vietnam Era Twin (VET) Registry. STUDY DESIGN: Varying models for the relationship between genetic and environmental influences on health condition liability and on treatment use were tested in an attempt to explain the relative contributions of additive genetic, common, and unique environmental effects to health condition and treatment use. DATA COLLECTION: A mail and telephone survey of general health status was administered in 1987 to VET Registry twins. PRINCIPAL FINDINGS: Variance component estimates under the best-fitting model for the genetic component ranged from 24 percent to 52 percent for the condition status and from 42 percent to 56 percent for treatment-seeking behavior. CONCLUSIONS: Utilization models that consider only environmental parameters will leave a large percentage of variability unexplained. Familial patterns have an impact not only on disease susceptibility but also on healthcare utilization, thereby having lifelong implications for social and fiscal constraints placed on the healthcare system. Thus, explanatory models for healthcare utilization behavior should consider the contribution of genetic factors in the decision to seek and use health services.

Adult↗
PubMed1997

How do genes influence marijuana use? The role of subjective effects.

This study investigated determinants of the subjective effects of marijuana and the relationship of subjective effects to marijuana use. Subjects were 8169 twins drawn from the Vietnam Era Twin Registry. Subjects who used marijuana more than five times (n = 2513) reported whether they experienced each of 23 subjective reactions. Factor analysis identified a positive (pleasant) reaction factor and a negative (unpleasant) reaction factor. Both factors were related to duration and frequency of use. Pairs in which both members used marijuana more than five times (MZ = 352 pairs; DZ = 255 pairs) were examined to assess determinants of subjective effects. Approximately one-quarter of the variance in each factor was determined by additive genetic influences; the remaining variance was determined by environmental factors that are not shared by members of a twin pair. The shared or family environment had no detectable influence on either subjective reaction factor.

Adult↗