Non-shared environments and discordance of obesity in adolescent siblings

描述(申请人提供)：青少年超重/肥胖的流行程度增加了3倍，因此了解为什么这么多青少年超重的机制是很重要的。正常体重的年轻人在面对顺从的经历时，可能会更好地调节能量摄入和支出，或者感受到较少的社会(父母和同龄人)影响的顺从压力。不协调的兄弟姐妹方法控制了平均50%的遗传变异性，是确定正常体重和超重/肥胖兄弟姐妹是否经历非共同的行为反应和/或暴露在顺从环境中的理想设计。如果假定没有分享的经历与肥胖的不和谐有关，那么兄弟姐妹之间的经历相对于家庭之间的差异将很大。这项研究研究了不和谐兄弟姐妹的能量平衡行为(日常饮食、体育活动、久坐不动)，以及导致兄弟姐妹体重行为差异的关键假设经验，从而导致他们肥胖的不协调。不分享饮食行为可能是导致兄弟姐妹肥胖的主要危险因素。因此，需要研究的一组风险因素是兄弟姐妹对进食的不同反应模式，这些模式测试了对外部进食线索的敏感度增加，对内在饱腹感线索的敏感度降低。影响能量平衡行为的非共同经历发生在社会影响的背景下。因此，第二组要测试的风险因素是对饮食和活动的社会影响，这些影响发生在家庭内部(通过问卷调查，父母对饮食和活动的影响)和外部(通过饮食回忆对饮食的同伴影响，通过生态瞬时分析对身体活动的影响)。48对同性生物青少年兄弟姐妹(24对男孩和女孩，年龄在13到17岁之间)将被研究，每个性别中有12对(n=12)，其中包括一个较年轻的正常体重(BMI&lt；70%)和一个较大的超重/肥胖(BMI&gt；85%)青少年，或一个较年轻的超重/肥胖青少年和一个较大的正常体重青少年。考虑到青春期独特的发育阶段，他们对顺从经历的接触和对这些经历的反应可能与儿童或成年人不同，但关于青少年肥胖机制的实验研究很少。具体目标是使用组内相关性来确定青少年能量平衡行为中不和谐的兄弟姐妹相似性(目标：1A.平时吃，1b.体力活动，1c.久坐行为)、不分享进食经历(目标：2a。增加进食提示的响应度，2b。减少内部饱腹感(提示敏感性)，以及不分享对饮食和内部活动的社会影响(目标3a)。父母影响)和外部(目标3b。同龄人的影响)。这项研究将为青少年肥胖的机制以及为什么青少年在我们顺应的环境中变得超重提供重要信息。

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.