Adolescent substance use initiation and long-term neurobiological outcomes: insights, challenges and opportunities.

The increased frequency of risk taking behavior combined with marked neuromaturation has positioned adolescence as a focal point of research into the neural causes and consequences of substance use. However, little work has provided a summary of the links between adolescent initiated substance use and longer-term brain outcomes. Here we review studies exploring the long-term effects of adolescent-initiated substance use with structural and microstructural neuroimaging. A quarter of all studies reviewed conducted repeated neuroimaging assessments. Long-term alcohol use, as well as tobacco use were consistently associated with smaller frontal cortices and altered white matter microstructure. This association was mostly observed in the ACC, insula and subcortical regions in alcohol users, and for the OFC in tobacco users. Long-term cannabis use was mostly related to altered frontal cortices and hippocampal volumes. Interestingly, cannabis users scanned more years after use initiation tended to show smaller measures of these regions, whereas those with fewer years since initiation showed larger measures. Long-term stimulant use tended to show a similar trend as cannabis in terms of years since initiation in measures of the putamen, insula and frontal cortex. Long-term opioid use was mostly associated with smaller subcortical and insular volumes. Of note, null findings were reported in all substance use categories, most often in cannabis use studies. In the context of the large variety in study designs, substance use assessment, methods, and sample characteristics, we provide recommendations on how to interpret these findings, and considerations for future studies.

Neural Tracking of Perceived Parent, but Not Peer, Norms Is Associated with Longitudinal Changes in Adolescent Attitudes about Externalizing Behaviors.

Adolescents' perceptions of parent and peer norms about externalizing behaviors influence the extent to which they adopt similar attitudes, yet little is known about how the trajectories of perceived parent and peer norms are related to trajectories of personal attitudes across adolescence. Neural development of midline regions implicated in self-other processing may underlie developmental changes in parent and peer influence. Here, we examined whether neural processing of perceived parent and peer norms in midline regions during self-evaluations would be associated with trajectories of personal attitudes about externalizing behaviors. Trajectories of adolescents' perceived parent and peer norms were examined longitudinally with functional neuroimaging (n = 165; ages 11-16 years across three waves; 86 girls, 79 boys; 29.7% White, 21.8% Black, 35.8% Latinx, 12.7% other/multiracial). Behavioral results showed perceived parent norms were less permissive than adolescents' own attitudes about externalizing behaviors, whereas perceived peer norms were more permissive than adolescents' own attitudes, effects that increased from early to middle adolescence. Although younger adolescents reported less permissive attitudes when they spontaneously tracked perceived parent norms in the ventromedial and medial pFCs during self-evaluations, this effect weakened as they aged. No brain-behavior effects were found when tracking perceived peer norms. These findings elucidate how perceived parent and peer norms change in parallel with personal attitudes about externalizing behaviors from early to middle adolescence and underscore the importance of spontaneous neural tracking of perceived parent norms during self-evaluations for buffering permissive personal attitudes, particularly in early adolescence.

Maternal high-fat diet-induced microbiota changes are associated with alterations in embryonic brain metabolites and adolescent behaviour.

The developing central nervous system is highly sensitive to nutrient changes during the perinatal period, emphasising the potential impact of alterations of maternal diet on offspring brain development and behaviour. A growing body of research implicates the gut microbiota in neurodevelopment and behaviour. Maternal overweight and obesity during the perinatal period has been linked to changes in neurodevelopment, plasticity and affective disorders in the offspring, with implications for microbial signals from the maternal gut. Here we investigate the impact of maternal high-fat diet (mHFD)-induced changes in microbial signals on offspring brain development, and neuroimmune signals, and the enduring effects on behaviour into adolescence. We first demonstrate that maternal caecal microbiota composition at term pregnancy (embryonic day 18: E18) differs significantly in response to maternal diet. Moreover, mHFD resulted in the upregulation of microbial genes in the maternal intestinal tissue linked to alterations in quinolinic acid synthesis and elevated kynurenine levels in the maternal plasma, both neuronal plasticity mediators related to glutamate metabolism. Metabolomics of mHFD embryonic brains at E18 also detected molecules linked to glutamate-glutamine cycle, including glutamic acid, glutathione disulphide, and kynurenine. During adolescence, the mHFD offspring exhibited increased locomotor activity and anxiety-like behaviour in a sex-dependent manner, along with upregulation of glutamate-related genes compared to controls. Overall, our results demonstrate that maternal exposure to high-fat diet results in microbiota changes, behavioural imprinting, altered brain metabolism, and glutamate signalling during critical developmental windows during the perinatal period.

Weekly links among irritability and suicidal thoughts and behaviors in high-risk youth.

BACKGROUND: Previous studies demonstrate a link between irritability and suicidal thoughts and behaviors (STBs) in youth samples. However, they have mostly assessed irritability in community samples and as a largely dispositional (i.e. trait-like) construct. Thus, it remains unclear to what extent links between irritability and STBs reflect within-person processes of elevated risk in clinically meaningful time periods. METHODS: The present study used clinical data from 689 adolescents aged 12-19 years attending a total of 6,128 visits at a specialty Intensive Outpatient Program for depressed and suicidal youth to examine patterns in weekly assessments of irritability and STBs throughout treatment, including associations among trends and fluctuations departing from these trends via multilevel structural equation modeling. Youth completed self-report measures of irritability, depression, and STBs weekly as part of standard IOP clinical care. RESULTS: Overall, two-thirds of variance in weekly irritable mood was accounted for by between-person differences and the remaining portion by weekly fluctuations. After controlling for depression, during weeks when youth were more irritable they experienced increased STBs. Rates of change in irritability and STBs tended to track together at early stages of treatment, but these effects were generally accounted for by depression severity. CONCLUSIONS: Our results suggest that although changes in STBs are best accounted for by depression, irritability can be understood as a specific, proximal risk factor for youth STBs that exacerbates youth STBs in clinically informative timeframes above and beyond depression.

Reduced prosocial motivation and effort in adolescents with conduct problems and callous-unemotional traits.

BACKGROUND: Prosocial behaviours - acts that benefit others - are of crucial importance for many species including humans. However, adolescents with conduct problems (CP), unlike their typically developing (TD) peers, demonstrate markedly reduced engagement in prosocial behaviours. This pattern is particularly pronounced in adolescents with CP and high levels of callous-unemotional traits (CP/HCU) who are at increased risk of developing psychopathy in adulthood. While a substantial amount of research has investigated the cognitive-affective mechanisms thought to underlie antisocial behaviour, much less is known about the mechanisms that could explain reduced prosocial behaviours in adolescents with CP. METHODS: Here we examined the willingness to exert effort to benefit oneself (self) and another person (other, prosocial condition) in children with CP/HCU, CP and lower levels of CU traits (CP/LCU) and their TD peers. The task captured both prosocial choices, and actual effort exerted following prosocial choices, in adolescent boys aged 11-16 (27 CP/HCU; 34 CP/LCU; 33 TD). We used computational modelling to reveal the mechanistic processes involved when choosing prosocial acts. RESULTS: We found that both CP/HCU and CP/LCU groups were more averse to initiating effortful prosocial acts than TD adolescents - both at a cognitive and at a behavioural level. Strikingly, even if they chose to initiate a prosocial act, the CP/HCU group exerted less effort following this prosocial choice than other groups. CONCLUSIONS: Our findings indicate that reduced exertion of effort to benefit others may be an important factor that differentiates adolescents with CP/HCU from their peers with CP/LCU. They offer new insights into what might drive low prosocial behaviour in adolescents with CP, including vulnerabilities that may particularly characterise those with high levels of CU traits.

Do traumatic events and substance use co-occur during adolescence? Testing three causal etiologic hypotheses.

BACKGROUND: Why do potentially traumatic events (PTEs) and substance use (SU) so commonly co-occur during adolescence? Causal hypotheses developed from the study of posttraumatic stress disorder (PTSD) and substance use disorder (SUD) among adults have not yet been subject to rigorous theoretical analysis or empirical tests among adolescents with the precursors to these disorders: PTEs and SU. Establishing causality demands accounting for various factors (e.g. genetics, parent education, race/ethnicity) that distinguish youth endorsing PTEs and SU from those who do not, a step often overlooked in previous research. METHODS: We leveraged nationwide data from a sociodemographically diverse sample of youth (N = 11,468) in the Adolescent Brain and Cognitive Development Study. PTEs and substance use prevalence were assessed annually. To account for the many pre-existing differences between youth with and without PTE/SU (i.e. confounding bias) and provide rigorous tests of causal hypotheses, we linked within-person changes in PTEs and SU (alcohol, cannabis, nicotine) across repeated measurements and adjusted for time-varying factors (e.g. age, internalizing symptoms, externalizing symptoms, and friends' use of substances). RESULTS: Before adjusting for confounding using within-person modeling, PTEs and SU exhibited significant concurrent associations (ßs = .46-1.26, ps < .05) and PTEs prospectively predicted greater SU (ßs = .55-1.43, ps < .05) but not vice versa. After adjustment for confounding, the PTEs exhibited significant concurrent associations for alcohol (ßs = .14-.23, ps < .05) and nicotine (ßs = .16, ps < .05) but not cannabis (ßs = -.01, ps > .05) and PTEs prospectively predicted greater SU (ßs = .28-.55, ps > .05) but not vice versa. CONCLUSIONS: When tested rigorously in a nationwide sample of adolescents, we find support for a model in which PTEs are followed by SU but not for a model in which SU is followed by PTEs. Explanations for why PTSD and SUD co-occur in adults may need further theoretical analysis and adaptation before extension to adolescents.

Mapping potential pathways from polygenic liability through brain structure to psychological problems across the transition to adolescence.

BACKGROUND: We used a polygenic score for externalizing behavior (extPGS) and structural MRI to examine potential pathways from genetic liability to conduct problems via the brain across the adolescent transition. METHODS: Three annual assessments of child conduct problems, attention-deficit/hyperactivity problems, and internalizing problems were conducted across across 9-13 years of age among 4,475 children of European ancestry in the Adolescent Brain Cognitive DevelopmentSM Study (ABCD Study®). RESULTS: The extPGS predicted conduct problems in each wave (R2 = 2.0%-2.9%). Bifactor models revealed that the extPRS predicted variance specific to conduct problems (R2 = 1.7%-2.1%), but also variance that conduct problems shared with other measured problems (R2 = .8%-1.4%). Longitudinally, extPGS predicted levels of specific conduct problems (R2 = 2.0%), but not their slope of change across age. The extPGS was associated with total gray matter volume (TGMV; R2 = .4%) and lower TGMV predicted both specific conduct problems (R2 = 1.7%-2.1%) and the variance common to all problems in each wave (R2 = 1.6%-3.1%). A modest proportion of the polygenic liability specific to conduct problems in each wave was statistically mediated by TGMV. CONCLUSIONS: Across the adolescent transition, the extPGS predicted both variance specific to conduct problems and variance shared by all measured problems. The extPGS also was associated with TGMV, which robustly predicted conduct problems. Statistical mediation analyses suggested the hypothesis that polygenic variation influences individual differences in brain development that are related to the likelihood of conduct problems during the adolescent transition, justifying new research to test this causal hypothesis.

Food insecurity and adolescent impulsivity: The mediating role of functional connectivity in the context of family flexibility.

Adolescent food insecurity is a salient adversity hypothesized to affect neural systems associated with increased impulsive behavior. Family environments shape how adverse experiences influence development. In this study, hypotheses were tested regarding the conjoint effects of food insecurity and family flexibility on impulsivity via alterations in connectivity between regions within the salience and central executive networks. Such alterations are reflected in resting-state functional connectivity (rsFC) metrics between the anterior insula (AI) and the middle frontal gyrus (MFG). Hypotheses were tested in a longitudinal moderated mediation model with two waves of data from 142 adolescents (Time 1 [T1] Mage = 12.89, SD = 0.85; Time 2 [T2] Mage = 15.01, SD = 1.07). Data on past-year household food insecurity, family flexibility, and rsFC were obtained at T1. Impulsivity was self-reported by the adolescent at T1 and T2. Findings revealed that high T1 left-to-left rsFC between the AI and MFG was associated with increased impulsivity at T2. The interaction of family flexibility and food insecurity was associated with AI and MFG rsFC. In the context of low family flexibility, food insecurity was linked to high levels of AI and MFG rsFC. Conversely, in the context of optimal family flexibility, food insecurity was associated with low levels of AI and MFG rsFC. Conditional indirect analysis suggests that the links among food insecurity, rsFC, and impulsive behavior depend on family flexibility. RESEARCH HIGHLIGHTS: Adolescent food insecurity was associated with anterior insula and middle frontal gyrus connectivity only at certain levels of family flexibility. High family flexibility attenuated the link between food insecurity and neural connectivity, while low levels of family flexibility increased this risk. High left anterior insula and left middle frontal gyrus connectivity was associated with increased impulsivity 1 year later.

Adolescence and the next generation.

Adolescent growth and social development shape the early development of offspring from preconception through to the post-partum period through distinct processes in males and females. At a time of great change in the forces shaping adolescence, including the timing of parenthood, investments in today's adolescents, the largest cohort in human history, will yield great dividends for future generations.

Do adolescents use choice to learn about their preferences? Development of value refinement and its associations with depressive symptoms in adolescence.

Independent decision making requires forming stable estimates of one's preferences. We assessed whether adolescents learn about their preferences through choice deliberation and whether depressive symptoms disrupt this process. Adolescents aged 11-18 (N = 214; participated 2021-22; Female: 53.9%; White/Black/Asian/Mixed/Arab or Latin American: 26/21/19/9/8%) rated multiple activities, chose between pairs of activities and re-rated those activities. As expected, overall, participants uprated chosen and downrated unchosen activities (dz = .20). This value refinement through choice was not evident in younger participants but emerged across adolescence. Contrary to our predictions, depressive symptoms were associated with greater value refinement. Despite this, more depressed adolescents reported lower value certainty and choice confidence. The cognitive processes through which choice deliberation shapes preference develop over adolescence, and are disrupted in depression.

Nighttime Texting on Social Media, Sleep Parameters, and Adolescent Sadness: A Mediation Analysis.

OBJECTIVES: The use of social media during bedtime has increased in the past years among adolescents, contributing to disturbed sleep quality, which could potentially be related to emotional problems. This study aimed to analyze the mediation effects of sleep parameters on the relationship between NightTime Texting (NTT) on social media and adolescent sadness. METHODS: We used a cross-sectional study and evaluated a total of 1464 Swedish students aged 15-17 (55.7% girls) to examine their frequency of NTT on social media, sleep parameters, and adolescent sadness. Bivariate and mediation analyses were performed. RESULTS: Approximately 60% (n = 882) of adolescents engaged in nighttime instant messaging, with 37% (n = 330) reporting texting every night. Higher frequency of NTT was significantly associated with later bedtimes (η2 > 0.12), extended weekend wake-up times (η2 = 0.07), increased social jetlag (η2 = 0.07), and reduced sleep duration on schooldays (η2 = 0.10). Multicategorical parallel mediation analyses revealed that sleep duration on schooldays had an indirect effect on the relationship between both Occasional NTT (a11b1 = 0.05, p < .05) and Daily NTT (a21b1 = 0.12, p < .05) with sadness. Mediation effects were not moderated by gender (p > .05), however, the association between Occasional NTT and higher sadness was significantly linked to boys (t = 2.72; p = .007). CONCLUSIONS: Findings showed a large percentage of adolescents engaging in nighttime social media use with worse quality of sleep, and underlined sleep duration on schooldays as a mediator associated with emotional problems in adolescents. These insights can aid in developing strategies for healthier habits to address the misuse of social media and prevent related health problems.

Cultural Values Influence the Developmental Trajectory of Resistance to Social Influence Over the Course of Adolescence.

The opinions of peers are among the most potent factors influencing human decision-making. Research conducted in Western societies suggests that individuals become more resistant to peer influence from late adolescence to adulthood. It is unknown whether this developmental trajectory is universal across cultures. Through two cross-national studies, we present consistent self-report and behavioral evidence for culturally distinct developmental trajectories of resistance to peer influence (RPI). Our findings from the US samples replicated prior findings that reported increasing RPI. Yet, data from the Chinese participants were better fitted using a nonlinear model, displaying a U-shaped trajectory with lowest RPI levels at around 20 years old. In contrast to the long-held belief that increasing RPI from adolescence to early adulthood is a universal developmental trait, we propose that this developmental trajectory may depend on cultural context.

"Nobody Here Likes Her"-The Impact of Parental Verbal Threat Information on Children's Fear of Strangers.

Parental verbal threat (vs. safety) information about strangers may induce fears of these strangers in adolescents. In this multi-method experimental study, utilizing a within-subject design, parents provided standardized verbal threat or safety information to their offspring (N = 77, Mage = 11.62 years, 42 girls) regarding two strangers in the lab. We also explored whether the impact of parental verbal threat information differs depending on the social anxiety levels of parents or fearful temperaments of adolescents. Adolescent's fear of strangers during social interaction tasks was assessed using cognitive (fear beliefs, attention bias), behavioral (observed avoidance and anxiety), and physiological (heart rate) indices. We also explored whether the impact of parental verbal threat information differs depending on the social anxiety levels of parents or fearful temperaments of adolescents. The findings suggest that a single exposure to parental verbal threat (vs. safety) information increased adolescent's self-reported fears about the strangers but did not increase their fearful behaviors, heart rate, or attentional bias. Furthermore, adolescents of parents with higher social anxiety levels or adolescents with fearful temperaments were not more strongly impacted by parental verbal threat information. Longitudinal research and studies investigating parents' naturalistic verbal expressions of threat are needed to expand our understanding of this potential verbal fear-learning pathway.

[Non-suicidal self-injurious behaviors in adolescence Role of frontline practitioners]. / Comportements autodommageables sans intention suicidaire à l'adolescence. Rôle des intervenant-e-s en première ligne.

Non-suicidal self-injury (NSSI) is an increasing mental health issue among adolescents. General practitioners and pediatricians play a crucial role in detecting, evaluating, and managing these behaviors. This article aims to provide recommendations for the first line surrounding the young person, such as the appropriate stance to adopt and the use of a safety plan, for effectively managing NSSI patients. It takes into account the often-present interpersonal hypersensitivity in these patients and includes strategies for working with families and within a multidisciplinary network.

Les comportements autodommageables sans intention suicidaire (NSSI, non-suicidal self-injury) sont un problème de santé mentale en augmentation chez les adolescents. Les généralistes et pédiatres jouent un rôle crucial dans la détection, l'évaluation et la prise en charge de ces comportements. Cet article donne des recommandations, surtout pour les services non spécialisés, telles la posture à tenir et l'utilisation d'un plan de sécurité, pour une prise en charge appropriée des patients NSSI, en tenant compte de l'hypersensibilité interpersonnelle souvent présente chez ces patients, et en incluant des stratégies pour le travail avec les familles et en réseau.

Onset of substance use: Deviant peer, sex, and sympathetic nervous system predictors.

We evaluated whether the association between deviant peer affiliation and onset of substance use is conditional upon sex and sympathetic nervous system (SNS) reactivity as measured by pre-ejection period (PEP). Community-sampled adolescents (N = 251; M = 15.78 years; 53% female; 66% White, 34% Black) participated in three waves. PEP reactivity was collected during a mirror star-tracer stress task. Alcohol, marijuana, tobacco, or any substance use, as well as binge drinking and sexual activity involving substance use were outcomes predicted by affiliation with deviant peers and two- and three-way interactions with sex and PEP reactivity. Probability of substance use increased over time, but this was amplified for adolescents with greater deviant peer affiliation in conjunction with blunted PEP reactivity. The same pattern of results was also found for prediction of binge drinking and sexual activity involving substance use. Findings are discussed in the context of biosocial models of adolescent substance use and health risk behaviors.

Distrust Moderates the Effect of Deviant Peer Affiliation on Increased Externalizing in Adolescents.

Deviant peer affiliation predicts externalizing behavior in adolescence, but no research explores how having negative or suspicious expectations of others (i.e., distrust) may evoke or buffer against the relationship between deviant peer affiliation and externalizing behavior. The current study used data across two timepoints to investigate the impact of deviant peer affiliation and distrust on externalizing behavior 3 years later and whether race/ethnicity moderated this relationship. The sample consisted of 611 adolescents from the Project on Human Development in Chicago Neighborhoods Study (48% male; Mage = 15.5 years, SD = 1.6; 17% White; 34% Black; 49% Hispanic). Higher levels of distrust buffered against the influence of deviant peer affiliation on externalizing behaviors. Further, this buffering was evident in Black compared to White adolescents. Understanding externalizing behavior warrants considering the intersection between the person and their environment.

A 4-year longitudinal neuroimaging study of cognitive control using latent growth modeling: developmental changes and brain-behavior associations.

Despite theoretical models suggesting developmental changes in neural substrates of cognitive control in adolescence, empirical research has rarely examined intraindividual changes in cognitive control-related brain activation using multi-wave multivariate longitudinal data. We used longitudinal repeated measures of brain activation and behavioral performance during the multi-source interference task (MSIT) from 167 adolescents (53% male) who were assessed annually over four years from ages 13 to 17 years. We applied latent growth modeling to delineate the pattern of brain activation changes over time and to examine longitudinal associations between brain activation and behavioral performance. We identified brain regions that showed differential change patterns: (1) the fronto-parietal regions that involved bilateral insula, bilateral middle frontal gyrus, left pre-supplementary motor area, left inferior parietal lobule, and right precuneus; and (2) the rostral anterior cingulate cortex (rACC) region. Longitudinal confirmatory factor analyses of the fronto-parietal regions revealed strong measurement invariance across time implying that multivariate functional magnetic resonance imaging data during cognitive control can be measured reliably over time. Latent basis growth models indicated that fronto-parietal activation decreased over time, whereas rACC activation increased over time. In addition, behavioral performance data, age-related improvement was indicated by a decreasing trajectory of intraindividual variability in response time across four years. Testing longitudinal brain-behavior associations using multivariate growth models revealed that better behavioral cognitive control was associated with lower fronto-parietal activation, but the change in behavioral performance was not related to the change in brain activation. The current findings suggest that reduced effects of cognitive interference indicated by fronto-parietal recruitment may be a marker of a maturing brain that underlies better cognitive control performance during adolescence.

Effects of cannabis exposure in the prenatal and adolescent periods: Preclinical and clinical studies in both sexes.

Cannabis is the most commonly used illicit drug among adolescents and young adults, including pregnant women. There is substantial evidence for a significant association between prenatal cannabis exposure and lower birth weight in offspring, and mixed results regarding later behavioural outcomes in the offspring. Adolescent cannabis use, especially heavy use, has been associated with altered executive function, depression, psychosis and use of other drugs later in life. Human studies have limitations due to several confounding factors and have provided scarce information about sex differences. In general, animal studies support behavioural alterations reported in humans and have revealed diverse sex differences and potential underlying mechanisms (altered mesolimbic dopaminergic and hippocampal glutamatergic systems and interference with prefrontal cortex maturation). More studies are needed that analyse sex and gender influences on cannabis-induced effects with great clinical relevance such as psychosis, cannabis use disorder and associated comorbidities, to achieve more personalized and accurate treatments.

Adherence to index-based dietary patterns in childhood and BMI trajectory during the transition to adolescence: the EPOCH study.

BACKGROUND: In the United States, one in five adolescents are obese. Index-based dietary patterns are measures of the overall diet that have the potential to serve as valuable obesity risk stratification tools. However, little is known about the association between adherence to index-based dietary patterns in childhood and BMI during the transition from childhood to adolescence. OBJECTIVE: To prospectively examine the relationship between adherence to three index-based dietary patterns in childhood and BMI trajectory during the transition to adolescence. METHODS: The study included 581 children enrolled in a Colorado prospective cohort study conducted between 2006 and 2015. Dietary intake was assessed with the Block Kids Food Frequency Questionnaire at age 10 years. Scores were calculated for the Healthy Eating Index-2010 (HEI-2010), the alternate Mediterranean (aMED) diet, and the Dietary Approaches to Stop Hypertension (DASH) diet. Weight and height were assessed via anthropometry at two research visits (ages 10 and 16 years), with interim clinical measurements extracted from Kaiser Permanente medical records. Separate mixed models were used to assess the association between each diet index score and BMI over a 6-year period. Models were stratified by sex and adjusted for age, race/ethnicity, income, and exposure to gestational diabetes. RESULTS: Median (IQR) number of BMI assessments was 14 (10-18). Among girls, for every ten-unit increase in HEI-2010 score, there was an average 0.64 kg/m2 decrease (p = 0.007) in BMI over time, after adjustment for covariates. Among girls, there was no association between BMI and aMED (ß = -0.19, p = 0.24) or DASH (ß = 0.28, p = 0.38). Among boys, there was no statistically significant association between BMI and HEI-2010 (0.06, p = 0.83), aMED (0.07, p = 0.70), or DASH (0.42, p = 0.06). CONCLUSIONS: Efforts to prevent adolescent obesity could benefit from considering the degree of adherence to federal dietary guidance, as assessed by the HEI, in the period preceding adolescence, especially among girls.

Association of dietary intake, physical activity, and sedentary behaviours with overweight and obesity among 282,213 adolescents in 89 low and middle income to high-income countries.

BACKGROUND: Adolescent overweight and obesity are well documented in high-income countries (HICs). They are also emerging as a global public health concern in low-and middle-income countries (LMICs), yet there is a lack of reliable, national-level data to inform policies and interventions. This study aimed to estimate the prevalence of overweight and obesity and assess associated lifestyle risk factors amongst school-going adolescents in LMICs as well as HICs. METHODS: A total of 282,213 samples were drawn from 89 LMICs and HICs in the 'latest Global School-based Student Health Survey' of school children, aged 11-17 years, during 2003 to 2015, in the six World Health Organisation (WHO) regions. The prevalence of adolescent overweight and obesity were estimated using the WHO BMI-for-age growth standards. A multinomial logistic regression model was employed to estimate the adjusted (age and sex) association of food patterns, physical activity, and sedentary behaviours with adolescent overweight and obesity. RESULTS: The pooled prevalence of overweight and obesity amongst adolescents was 10.12%, and 4.96%, respectively, ranging from 2.40% in Sri Lanka to 29.08% in Niue for overweight and 0.40% in Sri Lanka to 34.66% in the Cook Islands for obesity. Overweight and obesity were associated with unhealthy dietary intake and lifestyles including respectively fast-food intake (adjusted relative risk ratio, RRR = 1.09; 95% CI: 1.05-1.12 and RRR = 1.32; 95% CI: 1.26-1.38), a high level of carbonated soft drinks consumption (RRR = 1.19; 1.12-1.24 and RRR = 1.28; 1.18-1.38), a low level of physical activity (RRR = 1.11; 1.06-1.17 and 1.20; 1.12-1.28), and high level of sedentary behaviours (RRR = 1.33; 1.27-1.39 and RRR = 1.73; 1.63-1.84). Adolescents who consumed vegetables at least two times per day had a lower risk of overweight (22%) and obesity (17%) than those who did not consume vegetables per day. CONCLUSIONS: Adolescent overweight and obesity represent a global public health problem and can possibly track into adult weight status and morbidity. School-based obesity prevention that promotes environmental and policy changes related to healthy dietary practices and active living are urgently needed to curb the trend.