Showing papers by "Tracey D. Wade published in 2000"

Anorexia nervosa and major depression: shared genetic and environmental risk factors.

Abstract: OBJECTIVE: The authors sought to derive heritability estimates for anorexia nervosa and to explore the etiology of the comorbid relationship between anorexia nervosa and major depression. METHOD: They applied bivariate structural equation modeling to a broad definition of anorexia nervosa and lifetime major depression as assessed in a population-based sample of 2,163 female twins. RESULTS: Anorexia nervosa was estimated to have a heritability of 58% (95% confidence interval=33%–84%). The authors were unable to completely rule out a contribution of shared environment. The comorbidity between anorexia nervosa and major depression is likely due to genetic factors that influence the risk for both disorders. CONCLUSIONS: Although the study was limited by the small number of affected twins, the results suggest that genetic factors significantly influence the risk for anorexia nervosa and substantially contribute to the observed comorbidity between anorexia nervosa and major depression.

Twin studies of eating disorders: A review

Abstract: Objective Twin methodology has been used to delineate etiological factors in many medical disorders and behavioral traits including eating disorders. Although twin studies are powerful tools, their methodology can be arcane and their implications easily misinterpreted. Method The goals of this study are to (a) review the theoretical rationale for twin studies; (b) provide a framework for their interpretation and evaluation; (c) review extant twin studies on eating disorders; and (d) explore the implications for understanding etiological issues in eating disorders. Discussion On the basis of this review, it is not possible to draw firm conclusions regarding the precise contribution of genetic and environmental factors to anorexia nervosa. Twin studies confirm that bulimia nervosa is familial and reveal significant contributions of additive genetic effects and of unique environmental factors in liability to bulimia nervosa. The magnitude of the contribution of shared environment is less clear, but in the studies with the greatest statistical power, it appears to be less prominent than additive genetic factors. © 2000 by John Wiley & Sons, Inc. Int J Eat Disord 27: 1–20, 2000.

The relationship between social support and major depression: cross-sectional, longitudinal, and genetic perspectives.

Abstract: Although social support (SS) is associated with risk for major depression (MD), we are uncertain of the extent to which a) low SS increases risk for MD, b) MD lowers SS, or c) both variables reflect a common genetic liability. Using two waves of interview data on female twin pairs from a population-based registry, we examine the cross-sectional and longitudinal association of eight dimensions of perceived SS and MD. Risk for MD in the last year was inversely associated with supportive spouse and relative relationships, and directly associated with problems in these relationships (e.g., too many demands, criticism, tension, and disagreements). Significant cross-time associations were seen only for spousal variables. The history of MD in one twin significantly predicted low relative and spouse support, and relative and friend problems, in her co-twin (MZ > DZ pairs). The relationship between SS and MD in women is complex and due to at least the three separate mechanisms outlined above that operate to varying degrees in different dimensions of SS.

Absence of interactions between social support and stressful life events in the prediction of major depression and depressive symptomatology in women.

Abstract: Background. While high levels of social support (SS) are associated with a decreased risk for major depression (MD) or less depressive symptomatology, and stressful life events (SLEs) have a substantial causal relationship with MD, uncertainty remains as to whether a main-effect or a buffering model best explains the nature of the relationship among SS, MD and SLEs. Method. Using two waves of interview data on 2163 female twin pairs from a population-based twin registry, and discrete time survival analysis with both logistic and linear regression models, we examine the ability of interactions between eight dimensions of SS and 16 categories of stressful life events to predict MD onset and levels of depressive symptomatology. Results. In the presence of a significant effect of a SLE on MD (β [ges ] 1·00), we found evidence for seven interactions out of a possible 93, of which none involved buffering effects. Similarly, examination of depressive symptomatology detected a total of two interactions (both buffering) out of possible 28. We found no evidence, beyond what would be expected by chance, for the existence of buffering effects where either MD or depressive symptomatology was used as the dependent variable. Conclusions. There is little evidence to suggest the presence of the buffering effect of social support in the face of adverse life events for women. We suggest that it is important to use alternative models (multiplicative and additive) to examine data, to investigate the match between stressors and social resources, and to investigate fully whether detected interactions actually represent a buffering effect.

The genetic epidemiology of parental discipline.

Abstract: Background. Previous studies of parental discipline have identified little influence of heritability on parental control, and some influence of gene–environment correlations, shared environment and child temperament.Method. Using interview data from 2003 female twins from a population-based twin registry and 1472 of their parents, we examined reports of parental discipline from four perspectives: (1) father and mother reporting separately on the type of discipline they provided for their offspring; (2) each twin reporting on the type of discipline they received from their parents; (3) each parent reporting on the discipline provided by their spouse; and, (4) each twin reporting on the discipline they provided for their own offspring. Using factor analysis and univariate structural equation modelling, we examined the structure of parental discipline, and the genetic and environmental influences thereon.Results. The seven discipline items yielded two factors, physical discipline and limit setting, which were moderately positively correlated. Parents perceived discipline as largely a common environmental experience for the twins, whereas the twins indicated that discipline was influenced by unique environmental factors and the genotype of the child. Twins as parents indicated no influence of shared environment on discipline, with the majority of influence accounted for by non- shared environment and parental genotype.Conclusions. Parents recall providing similar discipline to their children, whereas children emphasize the differences in parental discipline. Sources of individual variation in parental discipline vary according to which family member report is examined. In total, parental discipline is partially influenced by the genotype of both the parent and child, and by environmental factors shared by the twins and unique to the individual.

The relation between risk factors for binge eating and bulimia nervosa: a population-based female twin study.

Abstract: This study investigated the differential risk factors for the initiation of binge eating and the transition from binge eating to bulimia nervosa. Women from a population-based twin registry (850 complete pairs) were assessed with respect to specific measured variables (including demographics, religiosity, lifetime psychopathology, current symptomatology, and personality) and latent genetic and environmental variables. Because of the relative rarity of bulimia nervosa, statistical power was low, but findings suggested considerable overlap between the genetic risk factors for the development of binge eating and the genetic risk factors for the transition from binge eating to bulimia nervosa. Genetic risk factors for binge eating and bulimia nervosa may be largely similar, whereas nonshared environment may be important in influencing the risk for bulimia nervosa once binge eating is initiated.

Assessing the relevance of the hopelessness theory of depression to women with disordered eating.

Abstract: Objective The aim of this study was to investigate the relevance of the hopelessness theory of depression to women with partial-syndrome eating disorders. Method Three groups of women, one meeting criteria for eating disorders not otherwise specified (EDNOS), one with major depression, and a control group, completed the Balanced Attributional Style Questionnaire, the Eating Disorders Examination Questionnaire, and the Beck Depression Inventory. Results Once levels of depression were controlled, all three groups differed significantly with respect to their attributional style for bad events, with the depressed group showing the greatest tendency to attribute the causes of negative life events to internal factors. However, with respect to the attributional style for good events, the depressed and control group displayed similar styles of attribution, whereas the EDNOS group showed a significantly more dysfunctional style, being more likely to attribute positive events to external factors. Discussion These findings are discussed in terms of their implications for specific therapeutic interventions with disordered eating. © 2000 by John Wiley & Sons, Inc. Int J Eat Disord 28: 113–119, 2000.

Reliability of lifetime history of bulimia nervosa: Comparison with major depression

Abstract: Background Previous studies have found that the reliability of the lifetime prevalence of bulimia nervosa is low to moderate. However, the reasons for poor reliability remain unknown. Aims We investigated the ability of a range of variables to predict reliability, sensitivity, and specificity of reporting of both bulimia nervosa and major depression. Method Two interviews, approximately 5 years apart, were completed with 2163 women from the Virginia Twin Registry. Results After accounting for different base rates, bulimia nervosa was shown to be as reliably reported as major depression. Consistent with previous studies of major depression, improved reliability of bulimia nervosa reporting is associated with more severe bulimic symptomatology. Conclusions Frequent binge eating and the presence of salient behavioural markers such as vomiting and laxative misuse are associated with more reliable reporting of bulimia nervosa. In the absence of the use of fuller forms of assessment, brief interviews should utilise more than one prompt question, thus increasing the probability that memory of past disorders will be more successfully activated and accessed.