Comparative efficacy and acceptability of psychological interventions for the treatment of adult outpatients with anorexia nervosa: a systematic review and network meta-analysis

BACKGROUND

No consistent first-option psychological interventions for adult outpatients with anorexia nervosa emerges from guidelines. We aimed to compare stand-alone psychological interventions for adult outpatients with anorexia nervosa with a specific focus on body-mass index, eating disorder symptoms, and all-cause dropout rate.

METHODS

In this systematic review and network meta-analysis, we assessed randomised controlled trials about stand-alone pharmacological or non-pharmacological treatments of adult outpatients with anorexia nervosa, defined according to standardised criteria, with data for at least two timepoints relating to either body-mass index or global eating disorder psychopathology. We searched Cochrane CENTRAL, CINAHL, MEDLINE, and PsychINFO for published and unpublished literature from inception until March 20, 2020. The primary outcomes were the change in body mass index and clinical symptoms, and the secondary outcome was all-cause dropout rate, which were all assessed for treatment as usual, cognitive behavioural therapy (CBT), Maudsley anorexia treatment for adults, family-based treatment, psychodynamic-oriented psychotherapies, a form of CBT targeting compulsive exercise, and cognitive remediation therapy followed by CBT. Global and local inconsistencies for the network meta-analysis were measured, and CINeMA was used to assess the confidence in evidence for primary outcomes. The protocol is registered in PROSPERO (CRD42017064429).

FINDINGS

Of 14 003 studies assessed for their title and abstract, 16 (0·1%) randomised controlled trials for psychological treatments were included in the systematic review, of which 13 (0·1%) contributed to the network meta-analysis, with 1047 patients in total (of whom 1020 [97·4%] were female). None of the interventions outperformed treatment as usual in our primary outcomes, but the all-cause dropout rate was lower for CBT than for psychodynamic-oriented psychotherapies (OR 0·54, 95% CI 0·31-0·93). Heterogeneity or inconsistency emerged only for a few comparisons. Confidence in the evidence was low to very low.

INTERPRETATION

Compared with treatment as usual, specific psychological treatments for adult outpatients with anorexia nervosa can be associated with modest improvements in terms of clinical course and quality of life, but no reliable evidence supports clear superiority or inferiority of the specific treatments that are recommended by clinical guidelines internationally. Our analysis is based on the best data from existing clinical studies, but these findings should not be seen as definitive or universally applicable. There is an urgent need to fund new research to develop and improve therapies for adults with anorexia nervosa. Meanwhile, to better understand the effects of available treatments, participant-level data should be made freely accessible to researchers to eventually identify whether specific subgroups of patients are more likely to respond to specific treatments.

FUNDING

Flinders University, National Institute for Health Research Oxford Health Biomedical Research Centre.

Changes in genetic and environmental influences on disordered eating between early and late adolescence: a longitudinal twin study

BACKGROUND

We investigated the genetic and environmental contributions to disordered eating (DE) between early and late adolescence in order to determine whether different sources of heritability and environmental risk contributed to these peak times of emergence of eating disorders.

METHOD

Adolescent female twins from the Australian Twin Registry were interviewed over the telephone with the Eating Disorder Examination (EDE). Data were collected at 12-15 and 16-19 years (wave 1: N = 699, 351 pairs; wave 3: N = 499, 247 pairs). Assessments also involved self-report measures related to negative life events and weight-related peer teasing.

RESULTS

Unstandardized estimates from the bivariate Cholesky decomposition model showed both genetic influences and non-shared environmental influences increased over adolescence, but shared environmental influences decreased. While non-shared environmental sources active at ages 12-15 years continued to contribute at 16-19 years, new sources of both additive genetic and non-shared environmental risk were introduced at ages 16-19 years. Weight-related peer teasing in early-mid adolescence predicted increases of DE in later adolescence, while negative life events did not.

CONCLUSIONS

Two-thirds of the heritable influence contributing to DE in late adolescence was unique to this age group. During late adolescence independent sources of genetic risk, as well as environmental influences are likely to be related in part to peer teasing, appear key antecedents in growth of DE.

Prevention Across the Spectrum: a randomized controlled trial of three programs to reduce risk factors for both eating disorders and obesity

BACKGROUND

A randomized controlled trial of three school-based programs and a no-intervention control group was conducted to evaluate their efficacy in reducing eating disorder and obesity risk factors.

METHOD

A total of 1316 grade 7 and 8 girls and boys (mean age = 13.21 years) across three Australian states were randomly allocated to: Media Smart; Life Smart; the Helping, Encouraging, Listening and Protecting Peers (HELPP) initiative; or control (usual school class). Risk factors were measured at baseline, post-program (5 weeks later), and at the 6- and 12-month follow-ups.

RESULTS

Media Smart girls had half the rate of onset of clinically significant concerns about shape and weight than control girls at the 12-month follow-up. Media Smart and HELPP girls reported significantly lower weight and shape concern than Life Smart girls at the 12-month follow-up. Media Smart and control girls scored significantly lower than HELPP girls on eating concerns and perceived pressure at the 6-month follow-up. Media Smart and HELPP boys experienced significant benefit on media internalization compared with control boys and these were sustained at the 12-month follow-up in Media Smart boys. A group × time effect found that Media Smart participants reported more physical activity than control and HELPP participants at the 6-month follow-up, while a main effect for group found Media Smart participants reported less screen time than controls.

CONCLUSIONS

Media Smart was the only program to show benefit on both disordered eating and obesity risk factors. Whilst further investigations are indicated, this study suggests that this program is a promising approach to reducing risk factors for both problems.

Training mental health nurses to provide motivational interviewing on an inpatient eating disorder unit

This study examined whether: (1) brief training in motivational interviewing (MI) can prepare mental health nurses (MHNs) to provide MI to patients; and (2) this MI impacts on patients with respect to premature discharge. Six MHNs on an inpatient eating disorder unit were trained in MI, and their treatment adherence and competence were evaluated at post-training and 2-month follow-up. Premature discharge was examined by comparing a 3-month period in 2009 before MI administration with 2010 when MI was being administered. MHNs significantly improved their MI adherence and competence. Satisfaction with the training was high as was patient satisfaction with MI. Premature discharge rates significantly decreased. Brief training in MI is sufficient to significantly increase competency and adherence in the practice of MI by MHNs, which may in turn be effective in improving patients' treatment adherence by reducing premature discharge rates. Future research will need to utilize a randomized controlled design in order to further investigate these findings.

Evaluating the impact of cancer on complementary and alternative medicine use, distress and health related QoL among Australian women: a prospective longitudinal investigation

OBJECTIVES

While several cross-sectional studies have examined psychological correlates of complementary and alternative medicine (CAM) use and cancer, few prospective longitudinal investigations have been reported. This study examined whether CAM use moderated distress and quality of life (HRQoL) from pre- to post-cancer.

DESIGN

A prospective longitudinal national cohort design.

SETTING

Participants were 718 mid-aged women from the Australian longitudinal study on women's health who did not have cancer at survey 1, but who subsequently developed cancer. For each participant, three waves of data were extracted: the wave prior to diagnosis ('pre'), at diagnosis ('cancer'), and after cancer ('post').

MAIN OUTCOME MEASURES

CAM use was measured by the question 'in the past 12 months have you consulted an alternative health practitioner'. Distress was measured by perceived stress (PSS) and depression (CES-D 10), HRQoL was measured by physical and mental health functioning (SF-36).

RESULTS

CAM use significantly moderated the change over time in stress [F(561)=3.09, p=0.04], depression [F(494)=3.14, p=0.04], but not HRQoL. CAM-users were significantly more stressed than non-users pre-cancer (p<0.05), but there were no significant differences at subsequent surveys. CAM-users were significantly less depressed post-cancer compared to non-users (p<0.05).

CONCLUSIONS

Findings indicated that CAM users may be more psychologically vulnerable than non-users with respect to stress, with CAM acting as an effective psychological, but not HRQoL, intervention.

Undue influence of weight and shape: is it distinct from body dissatisfaction and concern about weight and shape?

BACKGROUND

Three cognitive constructs are risk factors for eating disorders: undue influence of weight and shape, concern about weight and shape, and body dissatisfaction (BD). Undue influence, a diagnostic criterion for eating disorders, is postulated to be closely associated with self-esteem whereas BD is postulated to be closely associated with body mass index (BMI). We understand less about the relationships with concern about weight and shape. The aim of the current investigation was examine the degree of overlap across these five phenotypes in terms of latent genetic and environmental risk factors in order to draw some conclusions about the similarities and differences across the three cognitive variables.

METHOD

A sample of female Australian twins (n=1056, including 348 complete pairs), mean age 35 years (S.D.=2.11, range 28-40), completed a semi-structured interview about eating pathology and self-report questionnaires. An independent pathways model was used to investigate the overlap of genetic and environmental risk factors for the five phenotypes.

RESULTS

In terms of variance that was not shared with other phenotypes, self-esteem emerged as being separate, with 100% of its variance unshared with the other phenotypes, followed by undue influence (51%) and then concern (34%), BD (28%) and BMI (32%).

CONCLUSIONS

In terms of shared genetic risk, undue influence and concern were more closely related than BD, whereas BMI and BD were found to share common sources of risk. With respect to environmental risk factors, concern, BMI and BD were more closely related to each other than to undue influence.

An investigation of temperament endophenotype candidates for early emergence of the core cognitive component of eating disorders

BACKGROUND

This study was designed to investigate potential temperament endophenotypes for clinically significant importance of shape and weight.

METHOD

Seven temperament risk factors for eating disorders and the Eating Disorder Examination were assessed in 699 female twins aged 12-15 years. Each variable was evaluated against the following endophenotype criteria: associated with illness in the general population; found in non-affected family members at a higher rate than in the general population; and, heritable.

RESULTS

All seven variables were significantly associated with clinically significant importance of shape and weight, while thin-ideal internalization, ineffectiveness, body dissatisfaction and sensitivity to punishment were found at significantly elevated levels in non-affected twins, when controlling for sister's temperament score. These four variables had genetic correlations with importance of shape and weight, ranging from 0.48 to 0.95.

CONCLUSIONS

Future research should evaluate the stability of the identified endophenotypes and their utility for predicting significant growth in importance of shape and weight, and also whether different endophenotypes emerge when the importance of weight and shape reaches its peak in adolescents, around 15 to 16 years of age.

Shared and unique risk factors between lifetime purging and objective binge eating: a twin study

BACKGROUND

Objective binge eating (OBE) and self-induced vomiting (SIV) occur and co-occur across a range of eating disorders but the extent to which the risk factors for these two behaviours overlap is unclear. Examination of this overlap was the focus of the current report.

METHOD

A population of female Australian twins (n=1002), mean age 35 years (s.d.=2.11, range 28-40), participated in three waves of data collection and were assessed for lifetime disordered eating with a semi-structured interview at wave 3 and a self-report questionnaire at wave 1; risk factors were assessed via a self-report at waves 1 and 3.

RESULTS

Non-shared environmental influences were the largest contributor to the variance of both OBE and SIV, with a more modest contribution of genetic influences. Between 5% and 14% of the environmental risk factors for OBE and SIV were shared and 27-100% of genetic risk factors were shared. SIV initiation was predicted by higher neuroticism and novelty seeking and lower maternal and paternal care, whilst lower levels of perceived paternal care, higher lifetime BMI, and a wider BMI range predicted OBE initiation. Retrospective correlates associated with both SIV and OBE onset were parental comments about weight, whilst higher levels of parental conflict, expectations and criticism was associated with OBE onset only.

CONCLUSIONS

The substantial extent of non-overlap between risk factors for SIV and OBE suggests that each of these behavioural disturbances warrants future investigation in its own right, not only when they occur in conjunction with each other.

The genetic epidemiology of body attitudes, the attitudinal component of body image in women

BACKGROUND

There were four purposes of the current study, including the investigation of the: (i) adequacy of a multidimensional measure of body image; (ii) genetic and environmental epidemiology of this measure; (iii) shared variance between genetic and environmental risk factors for body mass index (BMI) and body image; and (iv) Equal Environment Assumption (EEA) as it related to body attitudes.

METHOD

Six types of body attitudes, as measured by the Body Attitudes Questionnaire (BAQ) and reported by 894 complete female-female twin pairs (mean age 32.35 years, S.D. = 41.8) from the Australian Twin Registry, were analysed.

RESULTS

Confirmatory factor analysis of the BAQ supported the adequacy of the measure. Additive genetic and unique environmental influences best accounted for the variance of all six of the BAQ subscales. The relationship between BMI and body attitudes was primarily due to shared genes rather than environment but the majority of genetic and environmental effects on body attitudes were independent of BMI, with the exception of the Feeling Fat subscale, which shared 53% of its genetic risk factors with BMI. One violation of the EEA was suggested, namely similarity of childhood treatment influenced similarity on Lower Body Fatness subscale.

CONCLUSIONS

Findings support the notion that: (i) body image is a multidimensional concept; (ii) it is relatively independent of BMI; and (iii) both genetic and non-shared environment are influential determinants of body attitudes.

Investigation of quality of the parental relationship as a risk factor for subclinical bulimia nervosa

OBJECTIVE

Previous literature suggests a link between the quality of the parental relationship and disordered eating in offspring. We investigated the relationship between offspring pyschopathology and the parental relationship using a population-based twin registry that contained 766 complete twin pairs.

METHOD

We used reports of twin lifetime psychopathology from the twins and quality of parental relationship and parental lifetime psychopathology from both parents.

RESULTS

Poorer quality of the marital relationship predicted the presence of subclinical bulimia nervosa (SBN) using both mother's (odds ratio [OR] = 0.83, 95% confidence interval [CI]: 0.71-0.97) and father's (OR = 0.78, 95% CI: 0.62-0.97) reports. It also predicted the presence of generalized anxiety disorder (GAD) and alcohol dependence. SBN was still strongly predicted by the marital relationship when parental psychopathology was included as a covariate.

DISCUSSION

These results are supportive of the notion that a conflictual and distant marital relationship can, at least partially, act as an environmental risk factor for SBN.

Relating body mass index to figural stimuli: population-based normative data for Caucasians

OBJECTIVE

To establish body mass index (BMI) norms for standard figural stimuli using a large Caucasian population-based sample. In addition, we sought to determine the effectiveness of the figural stimuli to identify individuals as obese or thin.

DESIGN

All Caucasian twins born in Virginia between 1915 and 1971 were identified by public birth record. In addition, 3347 individual twins responded to a letter published in the newsletter of the American Association of Retired Persons (AARP). All adult twins (aged 18 and over) from both of these sources and their family members were mailed a 16 page 'Health and Lifestyle' questionnaire.

SUBJECTS

BMI and silhouette data were available on 16 728 females and 11 366 males ranging in age from 18-100.

MEASUREMENTS

Self-report information on height-weight, current body size, desired body size and a discrepancy score using standard figural stimuli.

RESULTS

Gender- and age-specific norms are presented linking BMI to each of the figural stimuli. Additional norms for desired body size and discrepancy scores are also presented. Receiver operating curves (ROC) indicate that the figural stimuli are effective in classifying individuals as obese or thin.

CONCLUSIONS

With the establishment of these norms, the silhouettes used in standard body image assessment can now be linked to BMI. Differences were observed between women and men in terms of desired body size and discrepancy scores, with women preferring smaller sizes. The figural stimuli are a robust technique for classifying individuals as obese or thin.

The influence of genetic and environmental factors in estimations of current body size, desired body size, and body dissatisfaction

The objective was to investigate the genetic epidemiology of figural stimuli. Standard figural stimuli were available from 5,325 complete twin pairs: 1,751 (32.9%) were monozygotic females, 1,068 (20.1%) were dizygotic females, 752 (14.1%) were monozygotic males, 495 (9.3%) were dizygotic males, and 1,259 (23.6%) were dizygotic male-female pairs. Univariate twin analyses were used to examine the influences on the individual variation in current body size and ideal body size. These data were analysed separately for men and women in each of five age groups. A factorial analysis of variance, with polychoric correlations between twin pairs as the dependent variable, and age, sex, zygosity, and the three interaction terms (age x sex, age x zygosity, sex x zygosity) as independent variables, was used to examine trends across the whole data set. Results showed genetic influences had the largest impact on the individual variation in current body size measures, whereas non-shared environmental influences were associated with the majority of individual variation in ideal body size. There was a significant main effect of zygosity (heritability) in predicting polychoric correlations for current body size and body dissatisfaction. There was a significant main effect of gender and zygosity in predicting ideal body size, with a gender x zygosity interaction. In common with BMI, heritability is important in influencing the estimation of current body size. Selection of desired body size for both men and women is more strongly influenced by environmental factors.

A comparison of family functioning, temperament, and childhood conditions in monozygotic twin pairs discordant for lifetime bulimia nervosa

OBJECTIVE

The authors investigated differences between twins in nine pairs of female monozygotic twins in the Australian Twin Registry who were discordant for lifetime bulimia nervosa.

METHOD

The twins affected and unaffected by lifetime bulimia nervosa were compared on self-report measures, including a measure of parental bonding, four measures of temperament, and six early-childhood medical conditions.

RESULTS

No twins had current bulimia nervosa, and there was no difference in weight or eating status between the affected and unaffected twins. The affected twins reported significantly lower self-esteem and less warmth but more overprotection by their mothers during childhood.

CONCLUSIONS

Although limited by the small number of discordant twin pairs and the inability to detect causal relationships, these results suggest that environmental influences that promote low self-esteem may also increase the risk for bulimia nervosa. These temperamental differences may explain the discrepancies in parenting or perceived parenting.

Parent, child, and social correlates of parental discipline style: a retrospective, multi-informant investigation with female twins

BACKGROUND

The type of parental discipline used in families appears to be related to parental characteristics, child temperament, and aspects of the social context. Within these three areas, we examine specific correlates of parental discipline (namely, limit setting and physical discipline) using a multiple informant model.

METHOD

Using interview data from 2003 female twins from a population-based twin registry and 1472 of their parents, we examined retrospective reports of parental discipline from three perspectives. First, father and mother reporting separately on the type of discipline they provided for their offspring; second, each twin reporting on the type of discipline they received from their parents; and third, each parent reporting on the discipline provided by their spouse. Using a mixed model regression, we examined the impact on parental discipline of 25 potential predictor variables, as reported by parents, from three domains: social context, parental factors, and childhood vulnerability factors.

RESULTS

There was a great deal of overlap between the independent variables for the two types of discipline in the areas of child vulnerability factors and family relationships, with similar effect sizes for child disobedience, teenage rebelliousness, and family discord. However, the profiles of parental characteristics associated with each type of discipline were quite different. Greater use of physical discipline was associated with less parental warmth, a higher incidence of parental lifetime generalised anxiety disorder, and more frequent religious attendance. Greater use of limit setting was associated with more years of parental education, younger age, and greater parental extroversion and authoritarianism.

CONCLUSIONS

Parental characteristics, child temperament, and social context may all contribute to the frequency of discipline used in families, but parental characteristics may be most influential in determining the type of discipline used.

Integrating workplace exposure databases for occupational medicine services and epidemiologic studies at a former nuclear weapons facility

We outline methods for integrating epidemiologic and industrial hygiene data systems for the purpose of exposure estimation, exposure surveillance, worker notification, and occupational medicine practice. We present examples of these methods from our work at the Rocky Flats Plant--a former nuclear weapons facility that fabricated plutonium triggers for nuclear weapons and is now being decontaminated and decommissioned. The weapons production processes exposed workers to plutonium, gamma photons, neutrons, beryllium, asbestos, and several hazardous chemical agents, including chlorinated hydrocarbons and heavy metals. We developed a job exposure matrix (JEM) for estimating exposures to 10 chemical agents in 20 buildings for 120 different job categories over a production history spanning 34 years. With the JEM, we estimated lifetime chemical exposures for about 12,000 of the 16,000 former production workers. We show how the JEM database is used to estimate cumulative exposures over different time periods for epidemiological studies and to provide notification and determine eligibility for a medical screening program developed for former workers. We designed an industrial hygiene data system for maintaining exposure data for current cleanup workers. We describe how this system can be used for exposure surveillance and linked with the JEM and databases on radiation doses to develop lifetime exposure histories and to determine appropriate medical monitoring tests for current cleanup workers. We also present time-line-based graphical methods for reviewing and correcting exposure estimates and reporting them to individual workers.

Characteristics of monozygotic twins discordant for bulimia nervosa

OBJECTIVE

We studied monozygotic (MZ) twins who were discordant for bulimia nervosa in order to identify environmental factors that could have contributed to the expression of bulimia nervosa in only one member of these genetically identical twin pairs.

METHOD

Female twin pairs from the Virginia Twin Registry were identified. One twin met DSM-III-R criteria for bulimia nervosa (excluding the frequency and duration criterion) and the co-twin either reported some symptoms of bulimia nervosa but never met full diagnostic criteria (n = 20 pairs) or reported no symptoms of bulimia nervosa (n = 10). We compared the twins on demographic, developmental, personality, and psychiatric dimensions using self- and maternal report.

RESULTS

Affected twins were more likely to report lifetime generalized anxiety disorder and were described by their mothers as more anxious and fearful as children. They also had significantly lower mastery, optimism, and self-esteem, and significantly greater obsessive and compulsive symptoms than their unaffected co-twins. Affected twins recalled greater discord in their families but viewed their parents as more warm toward them than toward their unaffected co-twin.

DISCUSSION

Given that MZ twins are genetically identical and share a common family background, differences between them must be attributable to unique environmental factors. Although it is difficult to disentangle predisposing risk factors from sequelae of psychiatric illness in a retrospective co-twin control design, the affected twins were perceived to have been more anxious as children by their mothers-possibly reflecting a predisposing trait. More extensive interviews are required to determine the nature of environmental events that contribute to the expression of the observed personality, behavioral, anxious, and eating-related traits in the affected twins.

The genetic epidemiology of parental discipline

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.

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

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 2,163 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 (beta > or = 100), 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.

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

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.

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

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.

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

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.

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

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.

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

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

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.

Time lines and computer-based visual editing: new techniques for assessing exposure in epidemiologic studies

We describe a time-line-based methodology for collecting exposure data for epidemiologic studies and for processing these data for statistical analysis with readily available software for the personal computer. The four components to this approach are: (1) collecting data in a memory-enhancing time-line format; (2) entering data from time lines into a computer database and editing them; (3) making a quantitative estimate of exposure, intake, or dose for each exposure event; and (4) creating analysis datasets by 'slicing' the quantified time lines based on desired exposure intervals or disease latent periods. Compared with fixed-format interviews, time-line-based interviews help subjects organize remembered events, thereby reducing confusion. They do not restrict responses to predetermined categorical exposure responses. The time-line methodology also facilitates the collection of supplementary data necessary for computing doses for complex exposures and the packaging of quantified exposures into analysis datasets for any time period of interest.

Computer-generated time lines for visualizing and editing epidemiological and biomedical data

Most biomedical data have a temporal dimension. Time-line displays spatialize this dimension and help the viewer comprehend large sets of complex data. If we add ways for users to selectively expand the details of data visible on a time line, even more information can be organized and accessed. Design issues for this kind of display include: how to display time scales that are often wider than the physical display space; how to display events with brief duration; how to display data for two or more events that overlap in time; how to manage the display of data details; how to allow database editing from a time line; and how to facilitate time-based analytical techniques. We describe a time-line display system that addresses each of these issues, and show how it can be used to organize data for an epidemiological study of parental radiation exposure and childhood leukemia. We also suggest further refinements of the time line technique for other biomedical applications.

Finding temporal patterns--a set-based approach

We created an inference engine and query language for expressing temporal patterns in data. The patterns are represented by using temporally-ordered sets of data objects. Patterns are elaborated by reference to new objects inferred from original data, and by interlocking temporal and other relationships among sets of these objects. We found the tools well-suited to define scenarios of events that are evidence of inappropriate use of prescription drugs, using Medicaid administrative data that describe medical events. The tools' usefulness in research might be considerably more general.

Using smoothing splines to make inferences about the shape of gas-exchange curves

Respiratory gas-exchange data from progressive exercise tests are typically interpreted by visual inspection. Attempts to objectify such interpretation have applied particular parametric models which limit the measures which can be studied and the inferences which can be made. We use a known spline-smoothing procedure which fits a continuous curve to such data, yielding confidence intervals for the curve and for its first and second derivatives. Rules can be made which use the derivatives to infer features of a curve's shape and to relate features from different curves in the same data set. In this way complex interpretations can be made objective, so that they may be adequately tested.