Courtney E. Walls

Characteristics of Screen Media Use Associated With Higher BMI in Young Adolescents

OBJECTIVES: This study investigates how characteristics of young adolescents’ screen media use are associated with their BMI. By examining relationships between BMI and both time spent using each of 3 screen media and level of attention allocated to use, we sought to contribute to the understanding of mechanisms linking media use and obesity. METHODS: We measured heights and weights of 91 13- to 15-year-olds and calculated their BMIs. Over 1 week, participants completed a weekday and a Saturday 24-hour time-use diary in which they reported the amount of time they spent using TV, computers, and video games. Participants carried handheld computers and responded to 4 to 7 random signals per day by completing onscreen questionnaires reporting activities to which they were paying primary, secondary, and tertiary attention. RESULTS: Higher proportions of primary attention to TV were positively associated with higher BMI. The difference between 25th and 75th percentiles of attention to TV corresponded to an estimated +2.4 BMI points. Time spent watching television was unrelated to BMI. Neither duration of use nor extent of attention paid to video games or computers was associated with BMI. CONCLUSIONS: These findings support the notion that attention to TV is a key element of the increased obesity risk associated with TV viewing. Mechanisms may include the influence of TV commercials on preferences for energy-dense, nutritionally questionable foods and/or eating while distracted by TV. Interventions that interrupt these processes may be effective in decreasing obesity among screen media users.

Food Insecurity and Increased BMI in Young Adult Women

Food insecurity has been associated with weight status in children and adults although results have been mixed. We aimed to identify whether food insecurity was associated with BMI in young adults and whether this association differed by gender and was modified by food stamp use and the presence of children in the home. Cross‐sectional data from wave 4 (2007–2008) of the National Longitudinal Study of Adolescent Health were analyzed. Multiple linear regression was used to investigate the association between food insecurity and BMI in gender stratified models of young adult women (n = 7,116) and men (n = 6,604) controlling for age, race/ethnicity, income, education, physical activity, smoking, alcohol use, the presence of children in the home, and food stamp use in young adulthood and/or adolescence. Food insecurity was more common in young adult women (14%) than young adult men (9%). After controlling for a variety of individual variables, food insecure women had a BMI that was on average 0.9 kg/m2 units higher than women who were food secure. This difference in BMI persisted after controlling for recent or past food stamp use and was not different among women with or without children in the household. No relationship was found between food insecurity and BMI in young adult men. Providers should inquire about food insecurity, especially when treating obesity, and policy initiatives should address the role of access to healthy food in those facing food insecurity.

Real-time, contextual intervention using mobile technology to reduce marijuana use among youth: A pilot study

We evaluated the feasibility, acceptability, and potential efficacy of MOMENT, an intervention to reduce youth marijuana use that combines brief motivational enhancement therapy with mobile self-monitoring and responsive messaging. At baseline, primary care patients ages 15-24 who used marijuana frequently (at least 3 times per week) completed a recall assessment, then 1 week of mobile momentary and daily reports on use-related factors. For the intervention, youth participated in two motivational enhancement therapy sessions, during which they identified their top-3 social and emotional triggers for use and discussed healthy ways to manage them. They then completed two weeks of mobile reports. Upon reporting a top-3 trigger for use, desire to use, or recent use, they received a message supporting self-efficacy and prompting consideration of coping strategies. Generalized estimating equations examined changes in momentary-, daily-, and individual-level measures on 3-month recall and mobile assessments. Twenty-seven youth (M=19.2 years, 70% female) enrolled; there were 377-677 momentary and 50-106 daily reports per study phase. Participants reported reading the messages and finding them motivating, being comfortable with participation, and not experiencing the study as burdensome. Although proportion of momentary reports of being in a top-3 trigger context did not change (36%-43%), marijuana desire in a top-3 trigger context and marijuana use after top-3 trigger exposure decreased over the study (p<.0001 and p=.03, respectively). Daily- and individual-level measures showed similar, non-significant, improvements. The MOMENT intervention appears feasible, well-accepted, and potentially efficacious for youth who use marijuana frequently.

Sexual Orientation and Bias in Self‐Reported BMI

Our objective was to determine if sexual orientation groups differ in accuracy of BMI (kg/m2) calculated from self‐reported height and weight and if weight status modifies possible differences. Using gender‐stratified multiple linear regression to analyze Wave III of the National Longitudinal Study of Adolescent Health (n = 12,197), we examined the association of sexual orientation with BMI calculated from self‐reported height and weight (self‐reported BMI), controlling for BMI calculated from objectively measured height and weight (objectively measured BMI) as well as demographic, health, and behavioral variables. We tested for effect modification of the relationship between sexual orientation and self‐reported BMI by objectively measured BMI. The population underestimated their BMI (females: β = 0.87, P < 0.001; males = 0.86, P < 0.001). Sexual orientation groups differed little in their accuracy of reporting; only gay males had significant underreporting (β = −0.37, P = 0.038) relative to their heterosexual peers. We found no evidence of effect modification of the relationship of sexual orientation and self‐reported BMI by objectively measured BMI. With the exception of gay males, sexual orientation groups are consistent in their underreporting of BMI thus providing confidence in most comparisons of weight status based on self‐report. Self‐reporting of weight and height by gay males may exaggerate the differences in BMI between gay and heterosexual males.

Substance Use, Sexual Intercourse, and Condom Nonuse Among Depressed Adolescents and Young Adults

PURPOSE To examine daily- and event-level associations of substance use with occurrence of sex and condom nonuse among depressed youth. METHODS Depressed, sexually active outpatients aged 15-22 years reported alcohol use, marijuana use, and sex on a personal digital assistant for 2 weeks. If they reported sex, participants indicated partner type and condom use. Data were analyzed for participants who reported both substance use and sex events (N = 39) using generalized estimating equations. Daily-level models compared the likelihood of sex and of condom nonuse between days on which participants did or did not use substances. Event-level models examined the likelihood of sex in the 2, 6, and 12 hours after substance use and the likelihood of condom nonuse if substances were used in the preceding 2, 6, and 12 hours. RESULTS Participants reported 307 sex events (180 unprotected) and 391 substance use events on 572 days. Substance use was associated with increased odds of sex on the same day, but not after adjusting for weekend. Depressed youth were less likely to have sex within 2 hours after substance use and more likely to have sex within 12 hours after marijuana use. There was no main effect of substance use on condom nonuse; however, there was a significant interaction such that on weekdays, condom nonuse was less likely when substances were used within 6 hours before sex. CONCLUSIONS The findings from this small, predominantly female sample suggest that contextual factors, not intoxication, influence associations of substance use with sexual behavior in depressed youth.

Individual and contextual predictors of severity of marijuana use events among young frequent users.

This study used momentary sampling to characterize marijuana events among young frequent users and determine contextual and individual predictors of use severity. Medical clinic outpatients aged 15-24 who used marijuana at least twice a week completed a baseline assessment, then used a handheld computer to report marijuana use at 4-6 signal-prompted times per day and before/after use for 2 weeks. Reports assessed event characteristics (when, with whom, where, how, why, how much, how high). Timestamps identified time, weekend, and duration for each event. Generalized estimating equations tested associations of individual and event-specific contextual characteristics with hits/event, duration, and high. Forty-one youth completed 3868 momentary reports; 40 (98%) reported at least one marijuana use event (N=432 events; M=10.5/participant) and thus provided data for these analyses. Marijuana was most commonly used with other people (74% of events), at home (58%), via blunt (66%), and for social or enhancement reasons (86%). Most events (62%) occurred on weekdays; use was least likely in the morning (8%). Most events involved 6 or more hits (81%). Mean high was 5.2 (out of 8). Of events with start and end times (n=250), mean duration was 46.8 min. Poor mental health and use with a blunt or a bong, in the morning or evening, and on the weekend were associated with 6 or more hits/event. Female gender was associated with greater event duration. Poor mental health predicted higher high. Among youth who used it frequently, marijuana was used in a variety of contexts, with diversity in method, dose, and duration. Contextual factors appeared to predict marijuana dose for a given event, while individual characteristics were more predictive of high and duration.

The context of desire to use marijuana: momentary assessment of young people who frequently use marijuana.

Drawing on factors identified in the literature, this study explored in-the-moment associations of social, emotional, and temporal contexts and perceived marijuana availability with desire to use the drug, using momentary sampling methodology with young people who frequently use marijuana. Forty-one adolescent/young adult medical outpatients aged 15 to 24 years who reported using marijuana at least twice a week completed 2,912 brief questionnaires on a handheld computer in response to signals emitted at random four to six times a day for 2 weeks. The questionnaires assessed, for the moment when signaled, desire to use marijuana, location, companionship, perceived ease of getting marijuana (availability), positive affect, and negative affect. Participants reported any desire to use marijuana on 1,528 reports (55%). Companionship, perceived availability, and positive affect were independently associated with having any desire to use marijuana. Once desire to use marijuana was present, time of day, positive affect, and negative affect were independently associated with strength of desire. By collecting data in real time, in real life, this study highlights the importance of examining and intervening on emotional, environmental, and temporal contexts for youth who frequently use marijuana in order to reduce their desire to use the drug.

Malnutrition and Hemodynamic Status in Adolescents Hospitalized for Anorexia Nervosa

OBJECTIVE To determine the effects of malnutrition on hemodynamic status of adolescents hospitalized for anorexia nervosa. DESIGN Longitudinal observational study. SETTING Tertiary care pediatric hospital. Patients Thirty-eight adolescents with anorexia nervosa, aged 13 to 21 years, with a mean (SD) body mass index (calculated as weight in kilograms divided by height in meters squared) of 15.9 (1.8). Intervention Subjects received standard care, including bed rest and graded nutritional therapy. A subsample of subjects (n=19) returned 11 to 57 weeks following hospitalization for a second cardiac evaluation. MAIN OUTCOME MEASURES Results from a 15-lead electrocardiogram, echocardiogram, treadmill stress test, and spinal bone mineral density measurement. RESULTS On admission, 26 subjects (68%) had sinus bradycardia. Bradycardia was less common in participants with a longer duration of illness (P=.04). Left ventricle mass was lower than predicted for age (Z score<-1.0) in 11 subjects (31%). Exercise tolerance was normal by all measures. Both heart rate and QT interval were predictors of spinal bone mineral density. In those who returned for follow-up, absolute measures of left ventricle mass did not change (P=.27). However, the corresponding Z scores declined over time (mean [SD] change, -0.9 [1.3]; P=.02). CONCLUSIONS In acutely malnourished adolescents with anorexia nervosa, few truly pathologic cardiac findings were identified. Sinus bradycardia was observed in most cases. Mild reductions in left ventricle mass and left ventricle function were seen both at baseline and at follow-up, suggesting early sparing of cardiac muscle in the face of moderate malnutrition as well as a relative delay of cardiac muscle restoration. The association of hemodynamic status with altered spinal bone mineral density emphasizes the range of systems affected by malnutrition in anorexia nervosa.

Racial/ethnic differences in accuracy of body mass index reporting in a diverse cohort of young adults

Surveillance data describing the weight status of the US population often rely on self-reported height and weight, despite likely differences in reporting accuracy by demographics. Our objective was to determine if there were racial/ethnic differences in accuracy of self-reported body mass index (BMI) in a diverse nationally representative sample of young people. Using data from Wave III (data collected in 2001–2002) of the National Longitudinal Study of Adolescent Health when respondents were aged 18–26, we used gender-stratified multivariable linear regression models to examine the association of race/ethnicity and self-reported BMI controlling for measured BMI while also adjusting for factors known to be associated with weight self-perception. Black males and females (bFemale=0.45, confidence interval (CI): 0.19, 0.71; bMale=0.34, CI: 0.17, 0.51) and Hispanic females (bFemale=0.30, CI: 0.08, 0.52) and Native American males (bNative American=0.87, CI: 0.15, 1.58) reported higher BMIs than their similarly weighted White peers, leading to more accurate BMI reporting in these groups at higher BMIs. Caution should be taken in interpreting results from studies relying on self-reported BMI, as they may exaggerate racial/ethnic differences in weight status.

The association of body mass index and externally perceived attractiveness across race/ethnicity, gender, and time.

PURPOSE Being perceived by others as unattractive is associated with negative health and social consequences. Overweight individuals may be more likely to be perceived by others as unattractive, thereby further endangering their well-being. Our objective was to determine whether body mass index (BMI) was associated with perceptions by others regarding attractiveness and whether this relationship was similar across race/ethnicity, gender, and time. METHODS We analyzed Waves I and III of the National Longitudinal Study of Adolescent Health, a nationally representative longitudinal study of adolescents. We used participant gender- and race/ethnicity-stratified multinomial logistic regression to examine the association between BMI and interviewer-rated attractiveness (1 = unattractive, 2 = average, 3 = attractive, 4 = very attractive) controlling for participant age, household income, and maternal education. RESULTS BMI was positively associated with risk of being categorized as unattractive (relative to very attractive) by the interviewer in black (Wave I: relative risk ratio [RRR] = 1.26, CI: 1.18, 1.33; Wave III: RRR = 1.14, CI: 1.08, 1.20), Hispanic (Wave I: RRR = 1.23, CI: 1.11, 1.36; Wave III: RRR = 1.22, CI: 1.12, 1.34), and white (Wave I: RRR = 1.25, CI: 1.19, 1.32; Wave III: RRR = 1.22, CI: 1.17, 1.28) females in both waves of data collection. Only in African American females, the risk of being rated unattractive with increasing BMI declined significantly between waves (p = .00018). Trends were similar in males, although the magnitude of risk was smaller and nonsignificant in most groups. CONCLUSIONS Interviewers were more likely to rate those with higher BMIs as unattractive; this finding was similar across gender and racial/ethnic groups with few exceptions and was stable across time.