Childhood body mass index and development of eating disorder traits across adolescence

Differential genetic associations between dimensions of eating disorders and alcohol involvement in late adolescent twins

BACKGROUND

Twin studies have demonstrated shared genetic and environmental effects between eating disorders and alcohol involvement in adults and middle adolescents. However, fewer studies have focused on late adolescents or investigated a wide range of eating disorder dimensions and alcohol involvement subscales in both sexes. We examined genetic and environmental correlations among three eating disorder dimensions and two alcohol involvement subscale scores in late adolescent twins using bivariate twin models.

METHODS

Participants were 3568 female and 2526 male same-sex twins aged 18 years old from the Child and Adolescent Twin Study in Sweden. The Eating Disorder Inventory-2 (EDI) assessed the drive for thinness, bulimia, and body dissatisfaction. Alcohol involvement was assessed with the Alcohol Use Disorder Identification Test consumption (AUDIT-C) and problem (AUDIT-P) subscales.

RESULTS

Only phenotypic and twin correlations in female twins met our threshold for twin modeling. The proportion of total variance for each trait accounted for by additive genetic factors ranged from 0.50 to 0.64 in female twins, with the rest explained by nonshared environmental factors and measurement error. Shared environmental factors played a minimal role in the variance of each trait. The strongest genetic correlation (ra ) emerged between EDI bulimia and AUDIT-P (ra  = 0.46, 95% confidence interval: 0.37, 0.55), indicating that the proportion of genetic variance of one trait that was shared with the other trait was 0.21. Nonshared environmental correlations between eating disorder dimensions and alcohol involvement ranged from 0.03 to 0.13.

CONCLUSIONS

We observed distinct patterns of genetic and environmental effects for co-occurring eating disorder dimensions and alcohol involvement in female vs. male twins, supporting sex-specific treatment strategies for late adolescents with comorbid eating disorders and alcohol use disorder. Our findings emphasize the importance of assessing family history of multiple eating disorder dimensions while treating late adolescents with problematic alcohol use, and vice versa, to improve detection and treatment.

Prevention of eating disorders: 2021 in review

This review of 19 prevention-related publications in Eating Disorders during 2021 is framed by four models: (1) Mental Health Intervention Spectrum: health promotion → types of prevention → case identification/referral → treatment; (2) the prevention cycle: rationale and theory, shaped by critical reviews → clarifying risk and protective factors → program innovation and feasibility studies → efficacy and effectiveness research → program dissemination; (3) links between disordered eating (DE) and eating disorders (EDs); and (4) Kraemer and Jacobi's criteria for variable, causal risk factors (RFs). Twelve articles demonstrated the strengths and limitations of cross-sectional investigations of RFs for DE and EDs: five explored the role of trauma in activating genetic and psychological RFs (e.g., anxiety and experiential avoidance), while five suggest other variables meriting further evaluation: ergogenic supplement use, "feeling fat," internalized weight bias, food insecurity, and compulsive exercising. One article presents a pilot program that reduced risk factors in a high-risk group: professional ballerinas. Implications of the absence of efficacy, effectiveness, dissemination, and advocacy studies, along with the need to develop tailored programs for various high-risk groups, are discussed.

Risk factors and temporal patterns of disordered eating differ in adolescent boys and girls: Testing gender-specific appearance anxiety models

Adolescent dieting and disordered eating (DE) are risks for clinical eating disorders. In this five-wave longitudinal study, we tested gender-specific models linking early risk factors to temporal patterns of DE, considering appearance anxiety as a mediator. Participants were 384 Australian students (age 10 to 13; 45% boys) who reported their purging and skipping meals, experience with appearance-related teasing, media pressure, and appearance anxiety. Parents reported pubertal maturation and height/weight was measured. Gender differences in temporal patterns of DE were found and predictive models were tested using latent-variable growth curve and path models. Boys’ DE was generally stable over time; girls showed stability in purging but an average increase in skipping meals. Peer teasing, media pressure, and pubertal maturation were associated with more elevated initial DE in girls, and pubertal maturation was associated with a steeper increase in DE. For boys, body mass index had a direct positive association with DE. Appearance anxiety was associated with more DE, but there was only one significant indirect effect via anxiety, which was for boys’ pubertal maturation. Findings support the dominant role of social interactions and messages, as well as pubertal maturation, for girls’ DE and the prominence of physical risk factors for explaining boys’ DE.

Disordered Eating Behaviors and 15-year Trajectories in Body Mass Index: Findings From Project Eating and Activity in Teens and Young Adults (EAT)

PURPOSE

Disordered eating behaviors are prevalent among adolescents. Understanding how these behaviors link to body mass index (BMI) across different stages of development and over an extended period may provide insight for designing interventions around eating and weight. This study had two objectives: (1) to assess the distribution of disordered eating behaviors and develop a global score of disordered eating behaviors among adolescents and (2) to examine the association between the number of disordered eating behaviors in adolescence and BMI trajectory over 15 years.

METHODS

Project Eating and Activity in Teens and Young Adults (EAT), a longitudinal study of weight-related health and behavior comprising four waves (EAT-I to EAT-IV), measured seven disordered eating behaviors (importance of weight and shape, frequent dieting, extreme unhealthy weight control behaviors, overeating, distress about overeating, loss of control while overeating, and frequency of overeating and loss of control) at baseline (N = 1,230, ages 11 to 18 years, 1998-1999). These behaviors were summed to create a disordered eating behavior score. BMI was self-reported at all four waves (up to age 27-33 years at EAT-IV). Repeated measures with random slope and intercept examined the association between disordered eating behaviors and BMI trajectories over 15 years.

RESULTS

At baseline, 50.7% and 33.7% of females and males endorsed disordered eating behaviors. Throughout 15 years of follow-up, sociodemographic-adjusted BMI was higher among adolescents who engaged in disordered eating behaviors. The association remained significant after further adjustment for baseline BMI (p < .05).

CONCLUSIONS

Among adolescents, regardless of the type of disordered eating behaviors, engagement in disordered eating behavior predicted higher BMI in a dose-response fashion.

Weight trajectories and disordered eating behaviours in 11- to 12-year-olds: A longitudinal study within the Danish National Birth Cohort

OBJECTIVE

To examine how childhood weight trajectories are associated with disordered eating behaviours (DEBs) in early adolescence.

METHODS

Self-reports on DEBs (fasting, purging, and binge eating) were obtained from 18,337 children in the 11-year follow-up of the Danish National Birth Cohort. For this population, birth register information on gestational age and birth weight was categorized into the following: small, appropriate, and large for gestational age. Prospective parent-reported height and weight data at child ages 1 and 7 years were dichotomized using standardized cut-offs into non-overweight and overweight. A 12-category weight trajectory variable was created, and the associations between weight trajectory and DEBs were estimated using logistic regression.

RESULTS

In total, 7.0% 11- to 12-year olds reported DEBs. Compared with children born appropriate for gestational age and being non-overweight at age 1 and 7 years, children born small for gestational age and who were overweight at age 1 and 7 years had a very high risk of disordered eating (OR 7.00; CI [2.57, 19.40]). The statistical analyses revealed, however, that overweight at age 7 years was the main contributor and independently of trajectory increased the risk of disordered eating at age 11-12 years significantly (OR 3.16 CI [2.73, 3.65]).

CONCLUSION

Overweight not in the first year of life, but at age 7 years was more predictive for DEBs.

Why is premorbid BMI consistently elevated in clinical samples, but not in risk factor samples, of individuals with eating disorders?

Body image disturbance is widely viewed as contributing to the development and maintenance of disordered eating. Yet this perspective is not inconsistent with the possibility that elevated premorbid BMIs also increase the risk of developing eating disorders. Research examining whether actual body size may play a role in eating disorder development reveals a curious pattern of findings. Few prospective risk factor studies conducted with community-based samples found a relationship between premorbid BMI and subsequent eating disorder pathology whereas retrospective research conducted with clinical samples indicates a consistent pattern of elevated premorbid BMIs relative to population norms or control groups. This study documents these disparate findings, considers potential explanations for them and proposes further study of premorbid BMI as a factor contributing to the psychopathology of eating disorders, particularly among those who come to the attention of treatment providers.