Eagleton Sally G, Temple Jennifer L, Keller Kathleen L, Marini Michele E, Savage Jennifer S
Department of Nutritional Sciences, College of Health and Human Development, The Pennsylvania State University, University Park, PA, United States.
Center for Childhood Obesity Research, College of Health and Human Development, The Pennsylvania State University, University Park, PA, United States.
Front Psychol. 2021 Apr 30;12:653762. doi: 10.3389/fpsyg.2021.653762. eCollection 2021.
The relative reinforcing value (RRV) of food measures how hard someone will work for a high-energy-dense (HED) food when an alternative reward is concurrently available. Higher RRV for HED food has been linked to obesity, yet this association has not been examined in low-income preschool-age children. Further, the development of individual differences in the RRV of food in early childhood is poorly understood. This cross-sectional study tested the hypothesis that the RRV of HED (cookies) to low-energy-dense (LED; fruit) food would be greater in children with obesity compared to children without obesity in a sample of 130 low-income 3- to 5-year-olds enrolled in Head Start classrooms in Central Pennsylvania. In addition, we examined individual differences in the RRV of food by child characteristics (i.e., age, sex, and reward sensitivity) and food security status. The RRV of food was measured on concurrent progressive-ratio schedules of reinforcement. RRV outcomes included the last schedule reached (breakpoint) for cookies (cookie Pmax) and fruit (fruit Pmax), the breakpoint for cookies in proportion to the total breakpoint for cookies and fruit combined (RRV cookie), and response rates (responses per minute). Parents completed the 18-item food security module to assess household food security status and the Behavioral Activation System scale to assess reward sensitivity. Pearson's correlations and mixed models assessed associations between continuous and discrete child characteristics with RRV outcomes, respectively. Two-way mixed effects interaction models examined age and sex as moderators of the association between RRV and Body Mass Index z-scores (BMIZ). Statistical significance was defined as < 0.05. Children with obesity (17%) had a greater cookie Pmax [ (1, 121) = 4.95, = 0.03], higher RRV cookie [ (1, 121) = 4.28, = 0.04], and responded at a faster rate for cookies [ (1, 121) = 17.27, < 0.001] compared to children without obesity. Children with higher cookie response rates had higher BMIZ ( = 0.26, < 0.01); and RRV cookie was positively associated with BMIZ for older children (5-year-olds: = 2.40, = 0.02) and boys ( = 2.55, = 0.01), but not younger children or girls. The RRV of food did not differ by household food security status. Low-income children with obesity showed greater motivation to work for cookies than fruit compared to their peers without obesity. The RRV of HED food may be an important contributor to increased weight status in boys and future research is needed to better understand developmental trajectories of the RRV of food across childhood.
食物的相对强化值（RRV）衡量的是当同时存在另一种奖励时，一个人为高能量密度（HED）食物付出努力的程度。HED食物的RRV较高与肥胖有关，但这种关联尚未在低收入学龄前儿童中得到研究。此外，人们对幼儿期食物RRV个体差异的发展了解甚少。这项横断面研究检验了一个假设：在宾夕法尼亚州中部参加“启智计划”课堂的130名低收入3至5岁儿童样本中，与无肥胖儿童相比，肥胖儿童对低能量密度（LED；水果）食物的HED（饼干）RRV会更高。此外，我们还根据儿童特征（即年龄、性别和奖励敏感性）以及粮食安全状况，研究了食物RRV的个体差异。食物的RRV是通过同时进行的渐进比率强化程序来测量的。RRV结果包括达到的最后一个程序（断点），即饼干（饼干Pmax）和水果（水果Pmax）的断点，饼干断点占饼干和水果总断点之和的比例（RRV饼干）以及反应率（每分钟反应次数）。家长们完成了18项粮食安全模块以评估家庭粮食安全状况，并完成了行为激活系统量表以评估奖励敏感性。皮尔逊相关性分析和混合模型分别评估了连续和离散儿童特征与RRV结果之间的关联。双向混合效应交互模型将年龄和性别作为RRV与体重指数z评分（BMIZ）之间关联的调节因素进行了检验。统计学显著性定义为P<0.05。与无肥胖儿童相比，肥胖儿童（17%）的饼干Pmax更高[F(1, 121)=4.95，P=0.03]，RRV饼干更高[F(1, 121)=4.28，P=0.04]，且对饼干的反应速度更快[F(1, 121)=17.27，P<0.001]。饼干反应率较高的儿童BMIZ也较高（r=0.26，P<0.01）；RRV饼干与年龄较大的儿童（5岁儿童：r=2.40，P=0.02）和男孩（r=2.55，P=0.01）的BMIZ呈正相关，但与年龄较小的儿童或女孩无关。食物的RRV在家庭粮食安全状况方面没有差异。与无肥胖的同龄人相比，肥胖的低收入儿童表现出为饼干而不是水果努力工作的更大动力。HED食物的RRV可能是男孩体重增加的一个重要因素，未来需要进行更多研究以更好地了解儿童期食物RRV的发展轨迹。
