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1.  Interactions between genotype and depressive symptoms on obesity 
Behavior genetics  2009;39(3):296-305.
Depression and Genetic variation in serotonin and monoamine transmission have both been associated with Body Mass Index (BMI), but their interaction effects are not well understood. We examined the interaction between depressive symptoms and functional polymorphisms of serotonin transporter (SLC6A4) and monoamine oxidase A (MAOA) on categories of BMI.
Participants were from the National Longitudinal Study of Adolescent Health. Multiple logistic regression was used to investigate interactions between candidate genes and depression on risk of obesity (BMI≥30) or overweight + obese combined (BMI≥25).
Males with an MAOA active allele with high depressive symptoms were at decreased risk of obesity (OR, 0.22; 95% CI, 0.06 – 0.78) and overweight + obesity (OR, 0.48; 95% CI, 0.26 – 0.89). No similar effect was observed among females.
These findings highlight that the obesity-depression relationship may vary as a function of gender and genetic polymorphism, and suggest the need for further study.
PMCID: PMC2884968  PMID: 19337825
2.  Interactions Between MAOA Genotype and Receipt of Public Assistance: Predicting Change in Depressive Symptoms and Body Mass Index 
Response to stress is determined in part by genetically-influenced regulation of the monoamine system. We examined the interaction of a stressor (receipt of public assistance) and a gene regulating the monoamine system (MAOA) in the prediction of change in adolescent depressive symptoms and body mass index (BMI). Participants were drawn from the National Longitudinal Study on Adolescent Health (AddHealth) genetically-informative subsample. We focused on males due to the fact that males only have one MAOA allele. Growth curve analyses were conducted to assess the association between public assistance, MAOA allele, and their interaction and the intercept and slope of depressive symptoms and BMI. The results indicated that among males, MAOA allele type interacted with receipt of public assistance in the prediction of rate of change in both depressive symptoms and BMI from early adolescence through early adulthood. Males with the short MAOA allele whose families received public assistance tended to experience increased growth in depressive symptoms and BMI. Implications of the findings for understanding the relations among stress, physiology, and development are discussed.
PMCID: PMC3178327  PMID: 21949471
3.  Dopamine Polymorphisms and Depressive Symptoms Predict Foods Intake: Results from a Nationally Representative Sample 
Appetite  2011;57(2):339-348.
Depression and variation in dopamine related genes have both independently been associated with food consumption. Depressive symptoms could synergistically interact with genetic variation to influence food intake. We examined the interaction between high depressive symptoms and functional polymorphisms of dopamine transportor (SLC6A3), monoamine oxidase A (MAOA), dopamine receptor D2 (DRD2) and dopamine receptor D4 (DRD4) on intake of high-calorie sweet, high-calorie non-sweet, and low-calorie foods in the National Longitudinal Study of Adolescent Health (Add Health). Multivariate linear regression analyses were used to examine main effects of gene and depression symptoms and their interaction (genotype-by-high depression symptoms) on food categories. Applying a false discovery rate criterion for multiple comparisons indicated a statistically significant interaction for females with high depressive symptoms and the SLC6A3 gene, such that those with the SLC6A3 10/10 allele reported greater intake of high-calorie sweet foods than their counterparts high in depressive symptoms with the SLC6A3 any 9 allele (LS mean 10/10 allele = 2.5, SE = .13; LS mean any 9 allele = 1.8, SE = .13, p<.05). These findings highlight that the relationship between depression and food intake may vary as a function of genetic polymorphism. Further research is needed to confirm these findings.
PMCID: PMC3156384  PMID: 21672565
Adolescent; Diet; Dopamine; Depression
4.  The Influence of Five Monoamine Genes on Trajectories of Depressive Symptoms across Adolescence and Young Adulthood 
Development and psychopathology  2012;24(1):267-285.
The influence of five monoamine candidate genes on depressive symptom trajectories in adolescence and young adulthood were examined in the Add Health genetic sample. Results indicated that, for all respondents, carriers of the DRD4 5-repeat allele were characterized by distinct depressive symptom trajectories across adolescence and early adulthood. Similarly, for males, individuals with the MAOA 3.5-repeat allele exhibited unique depressive symptom trajectories. Specifically, the trajectories of those with the DRD4 5-repeat allele were characterized by rising levels in the transition to adulthood, while their peers were experiencing a normative drop in depressive symptom frequency. Conversely, males with the MAOA 3.5-repeat allele were shown to experience increased distress in late adolescence. An empirical method for examining a wide array of allelic combinations was employed, and false discovery rate methods were used to control the risk of false positives due to multiple testing. Special attention was given to thoroughly interrogate the robustness of the putative genetic effects. These results demonstrate the value of combining dynamic developmental perspectives with statistical genetic methods to optimize the search for genetic influences on psychopathology across the life course.
PMCID: PMC3515661  PMID: 22293009
5.  A Preliminary Analysis of Interactions Between Genotype, Retrospective ADHD Symptoms, and Initial Reactions to Smoking in a Sample of Young Adults 
Nicotine & Tobacco Research  2011;14(2):229-233.
Initial reactions to cigarettes predict later regular smoking. Symptoms of attention deficit hyperactivity disorder (ADHD) have also been shown to increase smoking risk and may moderate the relationship between genotype and smoking. We conducted an exploratory study to assess whether ADHD symptoms interact with genetic variation to predict self-reported initial reactions to smoking.
Participants were a subsample of 1,900 unrelated individuals with genotype data drawn from the National Longitudinal Study of Adolescent Health (Add Health), a nationally representative sample of adolescents followed from 1995 to 2002. Linear regression was used to examine relationships among self-reported ADHD symptoms, genotype, and self-reported initial reactions to cigarettes (index scores reflecting pleasant and unpleasant reactions).
Polymorphisms in the DRD2 gene, SLC6A4 gene, and among males, the MAOA gene interacted with retrospective reports of ADHD symptoms in predicting pleasant initial reaction to cigarettes. Polymorphisms in the CYP2A6 gene and, among females, the MAOA gene interacted with retrospective reports of ADHD symptoms in predicting unpleasant initial reaction to cigarettes. No main effect for any of these polymorphisms was observed nor were any interactions with DRD4 and DAT genes.
These findings suggest that genotypes associated with monoamine neurotransmission interact with ADHD symptoms to influence initial reactions to cigarette smoking. Given that an initial pleasant reaction to cigarettes increases risk for lifetime smoking, these results add to a growing body of literature that suggests that ADHD symptoms increase risk for smoking and should be accounted for in genetic studies of smoking.
PMCID: PMC3265740  PMID: 21778150
Behavior genetics  2010;40(4):495-504.
The transition between adolescence and young adulthood is a developmentally sensitive time where children are at an increased risk for becoming overweight and developing obesity. Twin studies have reported that body mass index [BMI] is highly heritable, however, it remains unclear whether the genetic influences are sex-limited and whether non-additive genetic influences contribute to body mass index [BMI] during these ages. In the current report, we examined self-reported data on BMI in same [n= 2744] and opposite-sex [n = 1178] siblings participating in the National Longitudinal Study on Adolescent Health [Add Health]. To investigate whether the same or different genes contributed to BMI for both sexes, we fit quantitative sex-limited genetic models to three waves of data collection. At each of the three Waves of assessment, models that included additive genetic, individual-specific environment, and no sex-limited genetic influences fit the data most parsimoniously. Heritable effects on BMI at each of the three Waves were large for both sexes and ranged between 0.75 and 0.86. While genetic contributions across the ages were highly correlated, longitudinal analyses indicated that the relevant individual-specific environmental influences on BMI in adolescence and young adulthood change sizably. These results underscore the importance of understanding early genetic influences on BMI and highlight the role environmental experiences have at later ages when new genetic influences appear to make a small contribution to individual variation in BMI.
PMCID: PMC2989725  PMID: 20087641
7.  Association between Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms and obesity and hypertension in early adulthood: A population-based study 
To examine associations between attention-deficit/hyperactivity disorder (ADHD) symptoms, obesity and hypertension in young adults in a large population-based cohort.
Design, Setting, and Participants
The study population consisted of 15,197 respondents from the National Longitudinal Study of Adolescent Health, a nationally representative sample of adolescents followed from 1995 – 2009 in the United States. Multinomial logistic and logistic models examined the odds of overweight, obesity, and hypertension in adulthood in relation to retrospectively reported ADHD symptoms. Latent curve modeling was used to assess the association between symptoms and naturally occurring changes in body mass index (BMI) from adolescence to adulthood.
Linear association was identified between the number of inattentive (IN) and hyperactive/impulsive (HI) symptoms and waist-circumference, BMI, diastolic blood pressure, and systolic blood pressure (all ps for trend < .05). Controlling for demographic variables, physical activity, alcohol use, smoking, and depressive symptoms, those with 3 or more HI or IN symptoms had the highest odds of obesity (HI 3+ OR, 1.50; 95% CI, 1.22-2.83; IN 3+ OR, 1.21; 95% CI, 1.02-1.44) compared to those with no HI or IN symptoms. HI symptoms at the 3+ level were significantly associated with a higher OR of hypertension (HI 3+ OR, 1.24; 95% CI 1.01-1.51; HI continuous OR, 1.04; 95% CI 1.00-1.09), but associations were non-significant when models were adjusted for BMI. Latent growth modeling results indicated that compared to those reporting no HI or IN symptoms, those reporting more 3 or symptoms had higher initial levels of BMI during adolescence. Only HI symptoms were associated with change in BMI.
Self-reported ADHD symptoms were associated with adult BMI and change in BMI from adolescence to adulthood, providing further evidence of a link between ADHD symptoms and obesity.
PMCID: PMC3391591  PMID: 20975727
attention-deficit/hyperactivity disorder; obesity; hypertension; young adult; risk factors
8.  US Trends in Body Mass in Adolescence and Young Adulthood, 1959–2002 
This study examined trends in body mass index (BMI) during the transition from adolescence to young adulthood by sex and race using national data from the US spanning over forty years from 1959–2002. While prior research has investigated BMI trends separately in childhood/adolescence or adulthood, this study uniquely focused on the transition to adulthood ages (12–26 years) to identify the emergence of the obesity epidemic during this critical life-stage.
Data came from multiple waves and cross-sections of data from four nationally representative surveys: National Health and Nutrition Examination Survey (NHANES); National Longitudinal Study of Adolescent Health (Add Health); National Health Interview Survey (NHIS); and National Longitudinal Surveys of Youth (NLSY79 and NLSY97). The analysis tracked age trends in BMI by time period, which allowed for the examination of how BMI changed during the transition to adulthood and whether the patterns of change varied by period. Data best suited for trend analysis were identified. Age trends in BMI by sex and race were graphed and regression analysis was used to test for significant differences in the trends using NHANES and Add Health.
BMI increased sharply in the adolescent ages beginning in the 1990s and among young adults around 2000. This age pattern of BMI increase was more dramatic among females and blacks, particularly black females.
BMI increases during the transition to adulthood and these increases have grown larger over time. Obesity prevention efforts should focus on this high risk transition period, particularly among minority populations.
PMCID: PMC3228354  PMID: 22098770
adolescence; transition to adulthood; obesity; BMI trends
9.  The Relationship between Asthma and Obesity in Urban Early Adolescents 
Asthma and obesity, which have reached epidemic proportions, impact urban youth to a great extent. Findings are inconsistent regarding their relationship; no studies have considered asthma management. We explored the association of obesity and asthma-related morbidity, asthma-related health care utilization, and asthma management in urban adolescents with uncontrolled asthma. We classified 373 early adolescents (mean age=12.8 years; 82% Hispanic or Black) from New York City public middle schools into 4 weight categories: normal (body mass index [BMI]<85th percentile); overweight (85th percentile≤BMI<95th percentile); obese (95th percentile≤BMI<97th percentile); and very obese (BMI≥97th percentile). We compared sample obesity prevalence to national estimates, and tested whether weight categories predicted caregiver reported asthma outcomes, adjusting for age and race/ethnicity. Obesity prevalence was 37%, with 28% of the sample being very obese; both rates were significantly higher than national estimates. We found no significant differences in asthma-related health care utilization or asthma management between weight categories, and a few differences in asthma-related morbidity. Relative to normal weight and obese youth, overweight youth had higher odds of never having any days with asthma-related activity limitations. They also had higher odds of never having asthma-related school absences compared with obese youth. Overweight youth with asthma-related activity limitations had more days with limitations compared with normal weight youth. Overweight, but not obese youth, missed more school due to asthma than normal weight youth. Overweight and obesity prevalence was very high in urban, Hispanic, and Black adolescents with uncontrolled asthma, but not strongly associated with asthma-related morbidity, asthma-related health care utilization, or asthma management practices.
PMCID: PMC3429276  PMID: 22970423
10.  The influence of three genes on whether adolescents use contraception, United States 1994-2002 
Population studies  2011;65(3):253-271.
In a further contribution to recent investigations of the relevance of genetic processes for demographic outcomes, we investigate genetic associations with whether adolescents use contraception. Using data from the National Longitudinal Study of Adolescent Health, we find that variants in the dopamine transporter gene DAT1, the dopamine receptor gene DRD2, and the monoamine oxidase gene MAOA are associated with unprotected sexual intercourse. Consistent with previous analyses of these data, the genotypes DRD2*A1/A2, DRD2*A2/A2, DAT1*9R/10R, and MAOA*2R/ are associated with higher odds of unprotected sexual intercourse than other genotypes at these loci. The DRD2 associations apply to both men and women, whereas the other associations apply to women only. These results are robust to controls for population stratification by continental ancestry, do not vary by contraceptive type, and are consistent with previous research showing that these genetic variants are associated with higher rates of impulsivity.
PMCID: PMC3716578  PMID: 21916669
adolescents; contraception; genetics; DRD2; DAT1; MAOA
11.  Developmental trajectories of overweight and obesity of US youth through the life course of adolescence to young adulthood 
To detect subgroups with different risks at different ages to develop overweight and obese during the adolescence–young adulthood period.
Accelerated longitudinal design and developmental trajectory analysis were used. The likelihoods to become overweight (body mass index [BMI] >25 kg/m2) and obese (BMI >30 kg/m2) were assessed across the life course from the ages of 12 to 28 years.
Adolescent participants aged 12–17 years (n = 4119) identified in the National Longitudinal Survey of Youth 1997 at baseline were followed up to 2008.
Seven overweight risk groups (WG) were detected for male and female samples respectively, of which five were closely related to each of the following five periods: (a) middle-school ages (19.7% and 12.6% for male and female, respectively), (b) high-school ages (11.4% and 13.6%, respectively), (c) college ages (12.6% and 9.1%, respectively), (d) post-college ages (11.8% and 10.0%, respectively), and (e) work–family-formation ages (11.0% and 12.9%, respectively); two were nonperiod-specific groups: a permanent low-risk group for both sexes (27.3% for male, 36.4% for female), a growing-risk group for males (6.2%), and a self-limiting risk group for females (5.4%, with the likelihood increasing with age, which peaked at the age of 21 years, and then declined). Likewise, six obesity risk groups (OG) were detected, of which four corresponded to the first four high-risk WG groups. The risk groups were relatively independent of race and educational attainment.
Findings of this study imply that five risk groups for weight gain like five consecutive “tests” exist from middle-school period to work-and-family formation. Failure to pass any of these tests in the life course could lead to overweight or obese status. Further research needs to study life-course-specific factors and mechanisms for more effective weight control.
PMCID: PMC3915891  PMID: 24600285
developmental trajectory; overweight; obesity; adolescents and young adults; life course; United States
12.  Adolescent Obesity, Change in Weight Status and Hypertension; Racial/Ethnic Variations 
Hypertension  2012;61(2):290-295.
We sought to determine whether change in weight status between adolescence and young adulthood was associated with the risk of developing hypertension among adolescents and whether gender and racial/ethnic group differences existed in the National Longitudinal Study of Adolescent Health. The sample was restricted to participants who self-identified as African-American, Hispanic or White Non-Hispanic (N=8543). Height and weight were measured in adolescence (mean 16yrs), and again in adulthood (mean 29yrs). We categorized the participants weight into four groups: stayed normal weight; gained weight (normal weight in adolescence and obese in adulthood); lost weight (overweight/obese in adolescence non-obese in adulthood); chronically overweight/obese. Hypertension was defined as measured systolic blood pressure of at least 140mmHg or diastolic blood pressure of at least 90mmHG measured in adulthood, or use of antihypertensive medications. A higher risk of hypertension was noted for all gender and racial/ethnic groups who became obese in adulthood. Furthermore, those who were chronically overweight/obese were at higher risk of hypertension for all groups with odds ratios ranging from 2.7 in Hispanic men to 6.5 in Hispanic women. Except for African-American men, those who lost weight during follow up had no significant increased risk compared to those who maintained normal weight. Overall, there was an increased risk of hypertension for those who gained weight in adulthood and among those who remained obese from adolescence to young adulthood. These data give further evidence for prevention strategies that begin earlier in life to reduce or delay the onset of chronic disease in young adults.
PMCID: PMC3938160  PMID: 23248147
obesity; blood pressure; adolescence; hypertension; life course; racial/ethnic disparities
13.  Overweight in Adolescence Can Be Predicted at Age 6 Years: A CART Analysis in German Cohorts 
PLoS ONE  2014;9(3):e93581.
To examine, whether overweight in adolescents can be predicted from the body mass index (BMI) category, at the age of 6, the mother's education level and mother's obesity and to quantify the proportion of overweight at the age of 14 that can be explained by these predictors.
Pooled data from three German cohorts providing anthropometric and other relevant data to a total of 1 287 children. We used a classification and regression tree (CART) approach to identify the contribution of BMI category at the age of 6 (obese: BMI>97th percentile (P97); overweight: P90P90) at the age of 14.
While 4.8% [95%CI: 3.2;7.0] of 651 boys and 4.1% [95%CI: 2.6;6.2] of 636 girls with a BMIP97 (similar results for girls). BMI≥P75 at the age of 6 explained 63.5% [95%CI: 51.1;74.5]) and 72.0% [95%CI: 60.4;81.8] of overweight/obesity at the age of 14 in boys and girls, respectively.
Overweight/obesity in adolescence can be predicted by BMI category at the age of 6 allowing for parent counselling or risk guided interventions in children with BMI≥P75, who accounted for >2/3 of overweight/obesity in adolescents.
PMCID: PMC3968156  PMID: 24676281
14.  Health Behaviors of the Young Adult U.S. Population: Behavioral Risk Factor Surveillance System, 2003 
Preventing Chronic Disease  2007;4(2):A25.
Health-risk behaviors such as eating poorly, being physically inactive, and smoking contribute to the leading causes of morbidity and mortality in the United States and are often established during adolescence and young adulthood. The objectives of this study were to characterize the health-risk behaviors of young adults (aged 18–24 years) using a large population-based survey of Americans and to determine if behaviors of this group differ by weight category, as assessed by body mass index (BMI).
Prevalence estimates for selected health-risk behaviors were calculated for respondents aged 18 to 24 years to the 2003 Behavioral Risk Factor Surveillance System (BRFSS). Respondents were categorized by BMI, and comparisons between sex and race and ethnicity were made within the overweight and obese categories.
More than three quarters (78.4%) of respondents consumed fewer than five fruits and vegetables per day, 43.2% reported insufficient or no physical activity, 28.9% were current smokers, 30.1% reported binge drinking, and 11.9% reported frequent mental distress. One quarter (26.1%) of respondents were overweight, and 13.6% were obese. Of obese young adults, 67.2% reported that they currently were trying to lose weight; however, only 24.3% reported having received professional advice to lose weight. More obese women (34.2%) than obese men (16.7%) reported having received professional advice to lose weight. Only 19.1% of obese non-Hispanic white respondents had received professional advice to lose weight compared with 28.0% of obese Hispanic respondents and 30.6% of obese non-Hispanic black respondents.
Many young adults engage in unhealthy behaviors, and differences exist in health-risk behaviors by BMI category and specifically by sex and race and ethnicity within BMI categories. The transition from adolescence to adulthood may be an opportune time for intervening to prevent future chronic disease.
PMCID: PMC1893124  PMID: 17362616
15.  The prevalence of physical, sexual and mental abuse among adolescents and the association with BMI status 
BMC Public Health  2012;12:840.
Studies among adults show an association between abuse and Body Mass Index (BMI) status. When an aberrant BMI status as a consequence of abuse is already prevalent in adolescence, early detection and treatment of abuse might prevent these adolescents from developing serious weight problems and other long-term social, emotional and physical problems in adulthood. Therefore, this study investigated the prevalence of physical, sexual and mental abuse among adolescents and examined the association of these abuse subtypes with BMI status.
In total, data of 51,856 secondary school students aged 13–16 who had completed a questionnaire on health, well-being and lifestyle were used. BMI was classified into four categories, underweight, normal weight, overweight and obesity. Adolescents reported if they had ever been physically, sexually or mentally abused. Crude and adjusted General Estimation Equation (GEE) analyses were performed to investigate the association between abuse subtypes and BMI status. Analyses were adjusted for ethnicity and parental communication, and stratified for gender and educational level.
Eighteen percent of the adolescents reported mental abuse, 7% reported sexual abuse, and 6% reported physical abuse. For underweight, overweight and obese adolescents these percentages were 17%, 25%, and 44%; 7%, 8%, and 16%; and 6%, 8%, 18% respectively. For the entire population, all these subtypes of abuse were associated with being overweight and obese (OR=3.67, 1.79 and 1.50) and all but sexual abuse were associated with underweight (OR=1.21 and 1.12). Stratified analyses showed that physical and sexual abuse were significantly associated with obesity among boys (OR=1.77 and 2.49) and among vocational school students (OR=1.60 and 1.69), and with underweight among girls (OR=1.26 and 0.83).
Mental abuse was reported by almost half of the obese adolescents and associated with underweight, overweight and obesity. Longitudinal analyses are recommended to explore the causality of and the mechanisms explaining this association between abuse and overweight.
PMCID: PMC3507854  PMID: 23033819
Abuse; Weight; Overweight; Obesity; Adolescents
16.  A gene × gene interaction between DRD2 and DRD4 is associated with conduct disorder and antisocial behavior in males 
Antisocial behaviors are complex polygenic phenotypes that are due to a multifactorial arrangement of genetic polymorphisms. Little empirical research, however, has been undertaken that examines gene × gene interactions in the etiology of conduct disorder and antisocial behavior. This study examined whether adolescent conduct disorder and adult antisocial behavior were related to the dopamine D2 receptor polymorphism (DRD2) and the dopamine D4 receptor polymorphism (DRD4).
A sample of 872 male participants from the National Longitudinal Study of Adolescent Health (Add Health) completed self-report questionnaires that tapped adolescent conduct disorder and adult antisocial behavior. DNA was genotyped for DRD2 and DRD4.
Multivariate regression analysis revealed that neither DRD2 nor DRD4 had significant independent effects on conduct disorder or antisocial behavior. However, DRD2 interacted with DRD4 to predict variation in adolescent conduct disorder and in adult antisocial behavior.
The results suggest that a gene × gene interaction between DRD2 and DRD4 is associated with the development of conduct disorder and adult antisocial behavior in males.
PMCID: PMC1913922  PMID: 17587443
17.  ‘Do I care?' Young adults' recalled experiences of early adolescent overweight and obesity: a qualitative study 
Individual behaviour change to reduce obesity requires awareness of, and concern about, weight. This paper therefore describes how young adults, known to have been overweight or obese during early adolescence, recalled early adolescent weight-related awareness and concerns. Associations between recalled concerns and weight-, health- and peer-related survey responses collected during adolescence are also examined.
Qualitative semi-structured interviews with young adults; data compared with responses to self-report questionnaires obtained in adolescence.
A total of 35 participants, purposively sub-sampled at age 24 from a longitudinal study of a school year cohort, previously surveyed at ages 11, 13 and 15. Physical measures during previous surveys allowed identification of participants with a body mass index (BMI) indicative of overweight or obesity (based on British 1990 growth reference) during early adolescence. Overall, 26 had been obese, of whom 11 had BMI⩾99.6th centile, whereas 9 had been overweight (BMI=95th–97.9th centile).
Qualitative interview responses describing teenage life, with prompts for school-, social- and health-related concerns. Early adolescent self-report questionnaire data on weight-worries, self-esteem, friends and victimisation (closed questions).
Most, but not all recalled having been aware of their overweight. None referred to themselves as having been obese. None recalled weight-related health worries. Recollection of early adolescent obesity varied from major concerns impacting on much of an individual's life to almost no concern, with little relation to actual severity of overweight. Recalled concerns were not clearly patterned by gender, but young adult males recalling concerns had previously reported more worries about weight, lower self-esteem, fewer friends and more victimisation in early adolescence; no such pattern was seen among females.
The popular image of the unhappy overweight teenager was not borne out. Many obese adolescents, although well aware of their overweight recalled neither major dissatisfaction nor concern. Weight-reduction behaviours are unlikely in such circumstances.
PMCID: PMC3572401  PMID: 22450852
qualitative study; obese; adolescent; awareness; concern; dissatisfaction
18.  Association of a serotonin transporter gene (SLC6A4) 5-HTTLPR polymorphism with body mass index categories but not type 2 diabetes mellitus in Mexicans 
Genetics and Molecular Biology  2012;35(3):589-593.
The serotonergic system has been hypothesized to contribute to the biological susceptibility to type 2 diabetes mellitus (T2DM) and body-mass index (BMI) categories. We investigate a possible association of 5-HTTLPR polymorphism (L and S alleles) in the promoter region of the serotonin transporter gene (SLC6A4) with the development of T2DM and/or higher BMI by analyzing a sample of 138 individuals diagnosed with T2DM and 172 unrelated controls from the Mexican general population. In the total sample genotypes were distributed according to Hardy-Weinberg equilibrium, and S allele frequency was 0.58. There was no statistical association between 5-HTTLPR polymorphism and the development of T2DM in this Mexican population sample (p = 0.12). Nevertheless, logistic regression analysis of the L allele and increased BMI disclosed an association, after adjusting for age, sex and T2DM (p = 0.02, OR 1.74, 95% CI: 1.079–2.808).
PMCID: PMC3459407  PMID: 23055796
SLC6A4 gene; 5-HTTLPR polymorphism; type 2 diabetes mellitus; body mass index
19.  Deviant Peer Affiliation and Antisocial Behavior: Interaction with Monoamine Oxidase A (MAOA) Genotype 
Although genetic and environmental factors are separately implicated in the development of antisocial behavior (ASB), interactive models have emerged relatively recently, particularly those incorporating molecular genetic data. Using a large sample of male Caucasian adolescents and young adults from the National Longitudinal Study of Adolescent Health (Add Health), the association of deviant peer affiliation, the 30-base pair variable number tandem repeat polymorphism in promoter region of the monoamine oxidase-A (MAOA) gene, and their interaction, with antisocial behavior (ASB) was investigated. Weighted analyses accounting for over-sampling and clustering within schools as well as controlling for age and wave suggested that deviant peer affiliation and MAOA genotype were each significantly associated with levels of overt ASB across a 6-year period. Only deviant peer affiliation was significantly related to covert ASB, however. Additionally, there was evidence suggestive of a gene-environment interaction (G × E) where the influence of deviant peer affiliation on overt ASB was significantly stronger among individuals with the high-activity MAOA genotype than the low-activity genotype. MAOA was not significantly associated with deviant peer affiliation, thus strengthening the inference of G × E rather than gene-environment correlation (rGE). Different forms of gene-environment interplay and implications for future research on ASB are discussed.
PMCID: PMC3066389  PMID: 21152968
Antisocial behavior; Longitudinal; Deviant peer affiliation; Gene–environment interaction
20.  Body Mass Index, Obesity, and Prevalent Gout in the United States in 1988–1994 and 2007–2010 
Arthritis care & research  2013;65(1):127-132.
To determine the association and prevalence of gout among overweight, obese and morbidly obese segments of the US population.
Among participants (age 20 and older) of the National Health and Nutrition Examination Surveys, in 1988–1994 and 2007–2010, gout status was ascertained by self-report of a physician-diagnosis. BMI was examined in categories of <18.5, 18.5–24.9, 25–29.9, 30–34.9, and ≥35 kg/m2 and as a continuous variable. The cross-sectional association of BMI category with gout status was adjusted for demographic and obesity-related medical disorders.
In the US, the crude prevalence of gout was 1–2% among participants with a normal BMI (18.5–24.9 kg/2), 3% among overweight participants, 4–5% with class I obesity, and 5–7% with class II or class III obesity. The adjusted prevalence ratio comparing the highest to a normal BMI category was 2.46 (95% CI: 1.44, 4.21) in 1988–1994, and 2.21 (95% CI: 1.50, 3.26) in 2007–2010. Notably, there was a progressively greater prevalence ratio of gout associated with successively higher categories of BMI. In both survey periods, for an average American adult standing 1.76m (5 feet, 9 inches), a 1 unit higher BMI, corresponding to 3.1 kg (~6.8 lbs) greater weight, was associated with a 5% greater prevalence of gout, even after adjusting for serum uric acid (P < 0.001).
Healthcare providers should be aware of the elevated burden of gout among both overweight and obese adults, applicable to both women and men, and observed among non-Hispanic White, non-Hispanic Black and Mexican Americans in the US.
PMCID: PMC3482278  PMID: 22778033
21.  Being Overweight Modifies the Association Between Cardiovascular Risk Factors and Microalbuminuria in Adolescents 
Pediatrics  2008;121(1):37-45.
The goal was to determine the association between cardiovascular risk factors and microalbuminuria in a nationally representative sample of adolescents and to determine whether being overweight modifies this association.
We analyzed cross-sectional data from the National Health and Nutrition Examination Survey(1999–2004) for 2515 adolescents 12 to 19 years of age. Cardiovascular risk factors included abdominal obesity, impaired fasting glucose, diabetes mellitus, insulin resistance, high triglyceride levels, low high-density lipoprotein cholesterol levels, hypertension, smoking, and the metabolic syndrome. Microalbuminuria was defined as a urinary albumin/creatinine ratio of 30 to 299 mg/g in a random morning sample. Overweight was defined as BMI of ≥95th percentile, according to the Centers for Disease Control and Prevention 2000 growth charts.
Microalbuminuria was present in 8.9% of adolescents. The prevalence of microalbuminuria was higher among nonoverweight adolescents than among overweight adolescents. The median albumin/creatinine ratio decreased with increasing BMI z scores. The association of microalbuminuria with cardiovascular risk factors differed according to BMI category. Among nonoverweight adolescents, microalbuminuria was not associated with any cardiovascular disease risk factor except for overt diabetes mellitus. Among overweight adolescents, however, microalbuminuria was associated with impaired fasting glucose, insulin resistance, hypertension, and smoking, as well as diabetes mellitus.
For the majority of adolescents, microalbuminuria is not associated with cardiovascular risk factors. Among overweight adolescents, however, microalbuminuria is associated with cardiovascular risk factors. The prognostic importance of microalbuminuria in overweight and nonoverweight adolescents with regard to future cardiovascular and renal disease needs to be defined in prospective studies conducted specifically in children.
PMCID: PMC3722048  PMID: 18166555
adolescents; obesity; cardiovascular risk factors; metabolic syndrome; albuminuria; epidemiology; National Health and Nutrition Examination Survey; Centers for Disease Control and Prevention
22.  Obesity in the Transition to Adulthood: Predictions across Race-Ethnicity, Immigrant Generation, and Sex 
With longitudinal data we traced how race, ethnic, and immigrant disparities in body mass index (BMI) change over time as adolescents (ages 11–19) transition to young adulthood (ages 20–28).
We used growth curve modeling to estimate the pattern of change in BMI from adolescence through the transition to adulthood.
All participants in the study were residents of the United States enrolled in high school or junior high school during the 1994–95 school year.
We used nationally representative data on 20,000+ adolescents interviewed at Wave I (1994–95) of Add Health, followed in Wave II (1996) and Wave III (2001–02) when the sample was in early adulthood.
Main Exposure(s)
Exposures of interest include race-ethnicity, immigrant generation, and sex.
Main Outcome Measure(s)
Our main outcome measure is BMI.
Findings indicate significant differences in both the level and change in BMI across age by sex, race-ethnicity, and immigrant generation. Females, second and third generation immigrants, and Hispanics and blacks experience more rapidly increasing BMI as adolescents age into young adulthood. Increases in BMI are relatively lower for males, first generation immigrants, and whites and Asians.
Disparities in BMI and percent overweight and obese widen with age as adolescents leave home and begin independent lives as young adults in their 20s.
PMCID: PMC2788784  PMID: 19884593
23.  Predicting waist circumference from body mass index 
Being overweight or obese increases risk for cardiometabolic disorders. Although both body mass index (BMI) and waist circumference (WC) measure the level of overweight and obesity, WC may be more important because of its closer relationship to total body fat. Because WC is typically not assessed in clinical practice, this study sought to develop and verify a model to predict WC from BMI and demographic data, and to use the predicted WC to assess cardiometabolic risk.
Data were obtained from the Third National Health and Nutrition Examination Survey (NHANES) and the Atherosclerosis Risk in Communities Study (ARIC). We developed linear regression models for men and women using NHANES data, fitting waist circumference as a function of BMI. For validation, those regressions were applied to ARIC data, assigning a predicted WC to each individual. We used the predicted WC to assess abdominal obesity and cardiometabolic risk.
The model correctly classified 88.4% of NHANES subjects with respect to abdominal obesity. Median differences between actual and predicted WC were − 0.07 cm for men and 0.11 cm for women. In ARIC, the model closely estimated the observed WC (median difference: − 0.34 cm for men, +3.94 cm for women), correctly classifying 86.1% of ARIC subjects with respect to abdominal obesity and 91.5% to 99.5% as to cardiometabolic risk.
The model is generalizable to Caucasian and African-American adult populations because it was constructed from data on a large, population-based sample of men and women in the United States, and then validated in a population with a larger representation of African-Americans.
The model accurately estimates WC and identifies cardiometabolic risk. It should be useful for health care practitioners and public health officials who wish to identify individuals and populations at risk for cardiometabolic disease when WC data are unavailable.
PMCID: PMC3441760  PMID: 22862851
24.  Underweight, Overweight and Obesity Among Zaboli Adolescents: A Comparison Between International and Iranians’ National Criteria 
Obesity and overweight are the major health problems in Iran. The aim of this study was to determine the prevalence of overweight and obesity among adolescents living in Zabol settled in Sistan va Baluchistan, one of economically underprivileged provinces in South Eastern of Iran, based on four different definitions.
This cross-sectional study was accomplished among a sample of 837 Zaboli adolescents (483 males; 354 females) aged 11-15 years. Anthropometric measurements including weight and height were measured and body mass index (BMI) was calculated. Sex-specific BMI-for-age reference data of the Iranian national data, Centers for Disease Control data (CDC 2000), International Obesity Task Force data (IOTF) and recent World Health Organization (WHO) data was used to define overweight and obesity.
Mean age of the studied population was 13.14 year. Underweight was prevalent among almost 18.7% and 18.4% of adolescents by the use of WHO 2007 and CDC 2000 cut-off points. The prevalence rates reached 25.8% and 27.2% by IOTF and Iranian national criteria, respectively. The highest prevalence of overweight was obtained by IOTF cut-points (10.8%) followed by CDC 2000 criteria (9.4%), WHO 2007 (8.8%) while national Iranian cut-points resulted in the lowest prevalence (2.4%). 7.5% of the studied population were found to be obese by WHO 2007 definition, while this rate was 2.2%, 3.4% and 1.5% by IOTF, CDC 2000 and national Iranian cut-points.
Almost all definitions revealed coexistence of underweight, overweight, and obesity among Zaboli adolescents. Huge differences exist between different criteria. To understand the best appropriate criteria for Iranian adolescents, future studies should focus on the predictability of obesity-related co-morbidities by these criteria.
PMCID: PMC3733182  PMID: 23930162
Adolescents; body mass index; Iran; obesity; overweight; prevalence; Zabol
25.  Weight Status in Childhood as a Predictor of Becoming Overweight or Hypertensive in Early Adulthood 
Obesity research  2005;13(1):163-169.
To assess the extent to which weight status in childhood or adolescence predicts becoming overweight or hypertensive by young adulthood.
Research Methods and Procedures
We conducted a prospective study of 314 children, who were 8 to 15 years old at baseline, and were followed up 8 to 12 years later. Weight, height, and blood pressure were measured by trained research staff. Incident overweight was defined as BMI ≥ 25 kg/m2 among participants who had not been overweight as children.
More male subjects (48.3%) than female subjects (23.5%) became overweight or obese between their first childhood visit and the young adult follow-up (p < 0.001). Being in the upper one half of the normal weight range (i.e., BMI between the 50th and 84th percentiles for age and gender in childhood) was a good predictor of becoming overweight as a young adult. Compared with children with a BMI <50th percentile, girls and boys between the 50th and 74th percentiles of BMI were ~5 times more likely [boys, odds ratio (OR) = 5.3, p = 0.002; girls, OR = 4.8, p = 0.07] and those with a BMI between the 75th and 84th percentiles were up to 20 times more likely (boys, OR = 4.3, p = 0.02; girls, OR = 20.2, p = 0.001) to become overweight. The incidence of high blood pressure was greater among the male subjects (12.3% vs. 1.9%). Compared with boys who had childhood BMI below the 75th percentile, boys between the 75th and 85th percentiles of BMI as children were four times more likely (OR = 3.6) and those at above the 85th percentile were five times more likely (OR = 5.1) to become hypertensive.
High normal weight status in childhood predicted becoming overweight or obese as an adult. Also, among the boys, elevated BMI in childhood predicted risk of hypertension in young adulthood.
PMCID: PMC1989681  PMID: 15761176
BMI; children; overweight; incidence; hypertension

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