Non-shared environments and discordance of obesity in adolescent siblings

描述（由申请人提供）：青少年中超重/肥胖的患病率增加了3倍，因此了解为什么这么多青少年变得超重的机制很重要。体重正常的青少年可能在面对肥胖经历时更好地调节能量摄入和消耗，或者较少受到来自社会（父母和同伴）影响的肥胖压力。不一致兄弟姐妹方法控制了平均50%的遗传变异，是确定正常体重和超重/肥胖兄弟姐妹是否经历非共同行为反应和/或暴露于肥胖环境的理想设计。如果假定的非共同经历与肥胖的不一致有关，那么兄弟姐妹之间的经历差异相对于家庭之间将会很大。本研究研究了不和谐兄弟姐妹的能量平衡行为（正常饮食、体育活动、久坐），以及可能导致兄弟姐妹体重行为差异的关键非共同经历，从而研究了他们在肥胖方面的不和谐。不共享的饮食行为可能是兄弟姐妹肥胖不一致的主要危险因素。因此，需要研究的一组风险因素是兄弟姐妹对饮食模式的不同反应，即对外部饮食线索的敏感性增加和对内部饱腹感线索的敏感性降低。影响能量平衡行为的非共享经历发生在社会影响的背景下。因此，第二组需要测试的风险因素是社会对饮食和活动的影响，这些影响发生在家庭内部（父母通过问卷对饮食和活动的影响）和外部（同伴通过饮食回忆对饮食的影响和通过生态瞬间分析对身体活动的影响）。将研究48对同性青春期兄弟姐妹（24对男孩和女孩，年龄在13至17岁之间），每个性别中有相同数量的对（n=12），包括体重较轻的正常青少年（BMI <70百分位）和年龄较大的超重/肥胖青少年（BMI bbb85百分位），或年龄较小的超重/肥胖青少年和年龄较大的正常体重青少年。鉴于青少年独特的发育阶段，他们对肥胖经历的暴露和对这些经历的反应可能与儿童或成人不同，但关于青少年肥胖机制的实验研究很少。具体目的是利用班级内相关性来确定青少年不协调的兄弟姐妹在能量平衡行为方面的相似性（目的：1a）。平时吃的东西，1b。体育活动，1c。久坐行为)，非共享饮食经历(目标：2a。增加进食线索反应，2b。降低内部饱腹感线索敏感性)，以及非共享社会对饮食和活动的影响（Aim 3a）。父母的影响)和外界（目标3b）。家庭的同辈影响。这项研究将为青少年肥胖的机制以及为什么青少年在肥胖的环境中变得超重提供重要的信息。

DESCRIPTION (provided by applicant): The prevalence of overweight/obesity in youth has increased 3-fold, so it is important to understand the mechanisms of why so many adolescents are becoming overweight. Normal weight youth may either better regulate energy intake and expenditure in the face of obesigenic experiences or experience fewer obesigenic pressures from social (parent and peer) influences. The discordant sibling methodology controls for an average of 50 percent of genetic variability and is an ideal design for determining whether normal weight and overweight/obese siblings experience non-shared behavioral responsivity and/or exposures to obesigenic environments. If a putative non-shared experience is associated with discordance in obesity then variability in the experience within siblings will be large relative to between families. This research studies the energy balance behaviors (usual eating, physical activity, sedentary) of discordant siblings and key putative non-shared experiences contributing to sibling differences in weight behaviors and thus their discordance in adiposity. Non-shared eating behaviors are likely primary risk factors for the discordance in sibling adiposity. Thus, one set of risk factors to be studied is differential sibling responsiveness to eating paradigms that test increased sensitivity to external eating cues and reduced sensitivity to internal satiety cues. Non-shared experiences affecting energy balance behaviors occur within the context of social influences. Thus, the second set of risk factors to be tested is social influences on eating and activity that occur within (parent influences on eating and activity, via questionnaires) and outside (peer influences on eating via dietary recalls and on physical activity via ecological momentary analysis) the family. 48 same- sex biologic adolescent sibling pairs (24 pairs of boys and girls, age 13 to 17 years) will be studied with an equal number of pairs (n=12) within each sex consisting of a younger-normal weight (BMI <70th percentile) and an older-overweight/obese (BMI > 85th percentile) adolescent, or of a younger-overweight/obese and an older- normal weight adolescent. Given the unique developmental stage of adolescence, their exposure to obesigenic experiences and responsivity to those experiences are likely different than for children or adults, but there are few experimental studies of the mechanisms of obesity in adolescents. The specific aims are to use intraclass correlations to determine adolescent discordant sibling resemblances for energy balance behaviors (Aims: 1a. usual eating, 1b. physical activity, 1c. sedentary behaviors), non-shared eating experiences (Aims: 2a. increased eating cue responsivity, 2b. reduced internal satiety cue sensitivity), and non-shared social influences on eating and activity within (Aim 3a. parent influences) and outside (Aim 3b. peer influences) of the family. This research will provide important information on the mechanisms of adolescent obesity and why youth are becoming overweight in our obesigenic environment.