Development of the Highly Processed Food Withdrawal Scale for Children

Journal Pre-proof Development of the Highly Processed Food Withdrawal Scale for Children Lindsey Parnarouskis, Erica M. Schulte, Julie C. Lumeng, AshleyN. Gearhardt PII:

S0195-6663(19)30795-0

DOI:

https://doi.org/10.1016/j.appet.2019.104553

Reference:

APPET 104553

To appear in:

Appetite

Received Date: 15 July 2019 Revised Date:

2 December 2019

Accepted Date: 7 December 2019

Please cite this article as: Parnarouskis L., Schulte E.M., Lumeng J.C. & Gearhardt A., Development of the Highly Processed Food Withdrawal Scale for Children, Appetite (2020), doi: https://doi.org/10.1016/ j.appet.2019.104553. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Ltd.

Running head: DEVELOPMENT OF THE HIGHLY PROCESSED FOOD WITHDRAWAL SCALE FOR CHILDREN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

Development of the Highly Processed Food Withdrawal Scale for Children Lindsey Parnarouskis1, Erica M. Schulte1, Julie C. Lumeng2,3,4, Ashley N. Gearhardt1 1

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Department of Psychology, University of Michigan, Ann Arbor, MI, USA Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA 3 Department of Pediatrics, University of Michigan Medical School, Ann Arbor, MI, USA 4 Department of Nutritional Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA

Corresponding Author: Lindsey Parnarouskis, B.S. Department of Psychology, University of Michigan 2261 East Hall 530 Church Street Ann Arbor, Michigan 48105 [email protected] (703) 508-7407

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Abstract Introduction: Highly processed foods (with added fats and/or refined carbohydrates) may trigger an addictive-like process, including withdrawal when these foods are reduced. Withdrawal is marked by affective, cognitive, and physical symptoms that may hinder dietary change. A recently developed scale of highly processed food withdrawal in adults (ProWS) provides evidence for this construct. Children commonly consume highly processed foods, but no measures currently exist to examine highly processed food withdrawal in children. The purpose of this study was to develop a measure (ProWS-C) to assess for signs of highly processed food withdrawal in children. Methods: Parents who had recently attempted to reduce their child’s highly processed food consumption were recruited through an online crowdsourcing platform. 304 parents (56.9% mothers) reported on their 3-11-year-old children (63.8% male). The ProWS-C was designed to reflect parents’ observations of child behavior. Internal consistency and validity were evaluated using the Dimensional Yale Food Addiction Scale Version 2.0 for Children (dYFAS-C 2.0.), Children’s Food Neophobia Scale-Modified (CFNS), and body mass index (BMI) silhouettes. Results: Exploratory factor analysis revealed a one-factor structure with 21 items (α=0.94). The ProWS-C demonstrated convergent validity with more child food addiction symptoms (r=.55, p<.001) and higher child BMI (r=.24, p<.001) and discriminant validity with child food neophobia (r=-.10, p=.08). The ProWS-C was associated with less success in reducing child highly processed food intake independent of child addictive-like eating and BMI (p=.001). Discussion: The ProWS-C provides preliminary evidence for highly processed food withdrawal in children and appears to be a psychometrically sound tool for assessing parent-reported withdrawal symptoms in children. Illuminating specific challenges families face when reducing highly processed foods may improve parents’ ability to help their children make sustainable dietary changes.

Keywords: Child eating behavior, food addiction, diet change

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Introduction Childhood obesity is a significant public health problem. Obesity, once established, often tracks into later childhood (Nader et al., 2006) and adulthood (Freedman, Khan, Dietz, Srinivasan, & Berenson, 2001) and increases risk for illnesses, such as cardiovascular disease and diabetes (Lloyd, Langley-Evans, & McMullen, 2010). Although multiple factors contribute to obesity risk, excess consumption of highly processed foods (i.e., foods with added fats and/or refined carbohydrates) is a major contributor to obesity (Kant, 2003; Monteiro, Levy, Claro, de Castro, & Cannon, 2011). By age 4, highly processed foods (e.g., cakes, cookies, and other grain-based desserts) are the top ranked dietary source of energy for American children (Reedy & Krebs-Smith, 2010). In the United States, one-third of children eat 6 or more highly processed foods a day (Kant, 2003), and children who eat more highly processed foods also tend to eat fewer healthier, nutrient-rich foods like fruits and vegetables (Kant & Graubard, 2003). Thus, obesity prevention and treatment interventions in both children and adults usually emphasize the reduction of highly processed food intake (Shai et al., 2008; Spear et al., 2007). However, cutting down on these foods is challenging for most people, including parents trying to manage their children’s dietary intake, which is reflected in very high attrition rates for pediatric weight management programs (ranging from 27% to 73%) (Jeffery et al., 2000; Skelton & Beech, 2011; Young, Northern, Lister, Drummond, & O'Brien, 2007). Illuminating the specific challenges parents and children face when trying to reduce highly processed foods may be a key factor in improving parents’ ability to help their children make sustainable dietary changes. Highly processed foods, or ingredients in these foods (e.g., added sugar), more powerfully engage reward-related systems (e.g., mesolimbic dopamine, endogenous opioids) in the brain relative to minimally processed foods like whole fruits, vegetables, and grains (Burger, 2017; DiFeliceantonio et al., 2018; Volkow, Wise, & Baler, 2017). Highly processed food consumption is often driven by the desire to experience pleasure or to cope with negative affect, rather than a homeostatic need for calories (Lowe & Butryn, 2007). There is growing evidence that these highly rewarding foods may be capable of triggering addictive-like responses, such as intensive cravings, tolerance and diminished control over consumption, for some individuals (Gearhardt, Corbin, & Brownell, 2016; Meule & Kübler, 2012). Withdrawal is one symptom of addiction that has received little empirical attention in the context of highly processed foods. In substance use disorders, withdrawal is defined as the adverse affective, cognitive, and physical effects of stopping or reducing use of a substance following a period of heavy and prolonged use (American Psychiatric Association, 2013). When a person uses a substance heavily over a period of time, the body adapts by altering physiological and neural systems to counteract the effects of the drug. When the person stops or reduces their use of the substance, the body becomes dysregulated, and withdrawal symptoms typically emerge within the first 24-hours and peak 2-5 days after the initial reduction (Koob & Le Moal, 2001). Physical withdrawal symptoms (e.g., nausea, tremors, seizures) can be particularly dangerous and even deadly for some substances (e.g., alcohol, opioids) (Koob & Le Moal, 1997). However, affective withdrawal symptoms (e.g., irritability, cravings, anxiety, anhedonia) are more universally experienced across substance use disorders (Koob & Le Moal, 2001) and may be especially risky for relapse (Connors, Maisto, & Donovan, 1996). Among active users, early indicators of acute withdrawal (e.g., restlessness in tobacco withdrawal) may motivate them to continue consumption in order to avoid the effects of

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cutting down or stopping (Koob & Le Moal, 1997). If highly processed foods are also capable of triggering a withdrawal-like syndrome, this could be a major obstacle faced by parents and children when trying to make positive diet changes. Animal models provide compelling support for the construct of withdrawal from highly processed foods (or ingredients in these foods). Rats that are given access to a sugar-rich diet exhibit indicators of withdrawal (e.g., increased anhedonia, anxiety-like behaviors, and motivation to seek out sugar-rich foods) when these foods are removed from the diet, which remit when they regain access to sugar (Colantuoni et al., 2002; Cottone, Sabino, Steardo, & Zorrilla, 2009; Iemolo et al., 2012). For rats consuming high levels of sugar, administration of an opioid antagonist (i.e., naloxone) triggers an opioid-like withdrawal response marked by anxiety, teeth chattering, forepaw tremor, and head shakes (Colantuoni et al., 2002). Anxiety has also been observed in rats withdrawing from a high-fat diet (Sharma, Fernandes, & Fulton, 2013). Thus, there is evidence from animal models that the removal of highly processed food from the diet can trigger withdrawal-like symptoms. There is also a small but growing body of evidence for highly processed food withdrawal in humans. The Yale Food Addiction Scale (YFAS) is a self-report measure of food addiction that adapts the diagnostic criteria for substance use disorders to the context of highly processed foods (Gearhardt et al., 2016). The YFAS assesses withdrawal symptoms via questions such as, “When I cut down on or stopped eating certain foods, I had physical symptoms like headache or fatigue” and “When I cut down on or stopped eating certain foods, I felt irritable, nervous, or sad.” In community samples, 18.5-29.7% of adults endorse at least one YFAS withdrawal question (Gearhardt et al., 2016; Hauck, Weiss, Schulte, Meule, & Ellrott, 2017) with higher endorsement rates of 26-54.9% in more clinical samples with overweight/obesity or binge eating disorder (Gearhardt et al., 2012; Meule, Hermann, & Kübler, 2015). Although the withdrawal questions in the YFAS indicate some people experience a withdrawal-like syndrome when trying to cut down on highly processed foods, it is important to understand the full range of indicators of withdrawal. To address this gap in the literature, the Highly Processed Food Withdrawal Scale (ProWS) was recently developed to more specifically operationalize and measure withdrawal symptoms associated with cutting down on highly processed foods (Schulte, Smeal, Lewis, & Gearhardt, 2018). The ProWS is a self-report measure that was based on existing measures of drug withdrawal and consists of 29 items that assess a range of affective (e.g., cravings, negative affect), cognitive (e.g., difficulty concentrating), and physical (e.g., headaches) withdrawal symptoms that may occur when individuals cut down on highly processed foods (Schulte et al., 2018). The ProWS demonstrated excellent psychometric properties, including convergent validity with addictive-like eating and weight cycling (i.e., losing and regaining 20 pounds or more), discriminant validity with dietary restraint, and incremental validity in predicting weight cycling and decreased dieting success over and above addictive-like eating and body mass index (BMI) (Schulte et al., 2018). Further, the intensity of core withdrawal symptoms (feeling down, feeling irritable, feeling tired, and having cravings) peaked 2-5 days after cutting down on highly processed foods, which mirrors the time course of drug withdrawal symptoms (Schulte et al., 2018).

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Cutting down on highly processed foods may also lead to a withdrawal-like syndrome in children. Over half of overweight and obese children in a qualitative study endorsed heightened urges and cravings consistent with withdrawal when cutting down on highly processed foods (Pretlow, 2011) and 18.9% of children in a community sample met the threshold for the withdrawal symptom on the YFAS for children (YFAS-C) (Gearhardt, Roberto, Seamans, Corbin, & Brownell, 2013). However, there is currently no validated measure to specifically assess highly processed food withdrawal in children. It is critical to understand the full range of affective, cognitive, and physical symptoms experienced by children when reducing highly processed foods, as this may represent a key obstacle parents face when helping their children make dietary changes. The purpose of the current study was to adapt the ProWS to develop a measure to assess for signs of highly processed food withdrawal in children. Specifically, we developed a developmentally appropriate parent-report version of the ProWS that assesses children’s behaviors reflective of adverse affective, cognitive, and physical experiences following the reduction of highly processed foods. The psychometric properties of the Highly Processed Food Withdrawal Scale for Children (ProWS-C) were then tested in a sample of 304 parents with children aged 3-11. This study utilized parent-report measures of their child’s behavior and selfreport measures of parent behavior to examine the following hypotheses: Hypothesis 1: Consistent with the adult ProWS, an exploratory factor analysis of the ProWS-C will show a one-factor structure with good internal consistency between items. Hypothesis 2: The content validity of the ProWS-C will be demonstrated by the severity of withdrawal-like symptoms peaking within the first few days following reduction of highly processed foods, mirroring the time course typically observed in substance use disorders and highly processed food withdrawal in adults (Budney, Moore, Vandrey, & Hughes, 2003; Hughes, 2007; McGregor et al., 2005; Schulte et al., 2018; Sellers & Kalant, 1976). Hypothesis 3: The ProWS-C will show convergent validity by significantly correlating with related constructs of child food addiction symptoms and BMI. Child food addiction will be examined as greater symptoms of addiction are associated with greater experiences of withdrawal in the substance use disorder literature (Weinberger, Desai, & McKee, 2010). BMI will be investigated as higher BMI is associated with greater highly processed food withdrawal in adults (Schulte et al., 2018) and higher BMI has been associated with addictive-like eating in children (Schiestl & Gearhardt, 2018). Hypothesis 4: The ProWS-C will show discriminant validity through a weaker association with the related but distinct construct of child food neophobia (i.e., fear of trying new foods). Children with food neophobia generally prefer a narrower range of foods, many of which are less healthy (e.g., French fries, chicken tenders) (Russell & Worsley, 2008). Thus, dietary change that introduces a greater variety of healthy options and restricts access to preferred unhealthy foods may be particularly challenging for children with high food neophobia due to mechanisms other than withdrawal (i.e., fear of new foods, limited variety). Thus, this study will aim to establish discriminant validity by evaluating whether ProWS-C scores are distinct from food neophobia.

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Hypothesis 5: Consistent with the adult ProWS, the ProWS-C will show incremental validity by accounting for differences in parent-reported success at changing their child’s diet, over and above child food addiction and BMI.

Methods Ethical Approval All research procedures were approved by the University of Michigan Health Sciences and Behavioral Sciences Institutional Review Board (IRB). Study Design This was a cross-sectional psychometric validation study. Participants were recruited through Amazon Mechanical Turk (MTurk), an online recruiting service which allows researchers to recruit participant samples that are often similar or more representative of the United States population than convenience samples (Berinsky, Huber, & Lenz, 2012; Paolacci & Chandler, 2014). Participants accessed the survey using a link provided on MTurk. Following informed consent, participants were directed to the survey, which was designed and administered using Qualtrics software (Qualtrics, 2019). Participants were required to live in the United States and were able to complete the survey from any location that was convenient for them. Participants The ProWS-C was examined in parents who reported having at least one child between 3 and 11 years old and who had attempted to reduce that child’s highly processed food consumption in the last year (n = 304). Three years was chosen as the lower age limit because this is when children typically become capable of asking for specific foods and verbally expressing symptoms assessed by the ProWS-C (i.e., complaining of headaches and stomachaches). Children also typically eat a wide range of foods (including HP foods) by three years of age, as compared to younger children (Reedy & Krebs-Smith, 2010). The upper age limit was set to 11 years old because adolescent children have more autonomy over their eating behaviors and less parental oversight, which may reduce the validity of parent report (Finkelstein, Hill, & Whitaker, 2008). The participant pool was limited to participants living in the United States, and participants were compensated $0.75 for survey completion. Participants responded to a posting inviting them to participate in a “survey on parents' experiences feeding their children.” Participants (n=640) responded to the initial survey, and were excluded from participation if they did not have a child under 18 years old (n = 67), did not have a child between 3 and 11 years old (n = 200), or had not tried to reduce the amount of “junk food” their child ate in the last year (n = 16). The term “junk food” was used throughout the surveys, as it is a colloquial term for highly processed foods that could be easily understood by participants. Participants were also excluded from analyses if they provided incorrect responses to any of 3 “catch questions,” designed to

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assess data quality (e.g. “Who was the first president of the United States,” (n = 53). All measures were completed by the parent on both themselves and one of their children. Parents with multiple children between 3-11 years old were asked to report on their youngest child within that age range.

Measures Development of the ProWS-C. The 21 questions included in the ProWS-C were chosen based on symptoms of withdrawal observed in substance use disorders and the adult ProWS, which are categorized under affective (i.e., sadness, irritability), cognitive (i.e. difficulty concentrating), and physical domains (i.e. headaches, fatigue) (Koob & Le Moal, 2001). The ProWS-C is designed to measure symptoms that fall within each of these domains, as detailed in Table 1. Affective symptoms were emphasized in the ProWS-C as affective symptoms of withdrawal are the most consistently demonstrated across substance use disorders (Koob & Le Moal, 2001) and the most predictive of relapse (Connors et al., 1996). The adult ProWS was adapted from rating scales designed to measure withdrawal in substance use disorders, including the Wisconsin Smoking Withdrawal Scale (Welsch et al., 1999) and Cannabis Withdrawal Scale (Allsop, Norberg, Copeland, Fu, & Budney, 2011). These scales were selected for this purpose because nicotine and cannabis withdrawal emphasize withdrawal symptoms that are most universally experienced across substance use disorders (e.g., craving, irritability) (Schulte et al., 2018). The ProWS-C assesses for many of the symptoms assessed in the adult ProWS, including irritability, anxiety, depressive symptoms, craving, difficulty concentrating, and trouble sleeping. However, developmental considerations were also taken into account when adapting the ProWS-C for use with children. Symptoms of irritability were emphasized in the affective domain, as children often express depressive symptoms and other affective dysfunction through increased irritability (Leibenluft & Stoddard, 2013). Oppositionality is not typically considered a symptom of withdrawal in substance use disorders, but was included in the ProWS-C, as oppositionality can be an indicator of depressive symptoms in children (Boylan, Vaillancourt, & Szatmari, 2012). Given that the ProWS-C was designed to reflect parent report, items were also adapted to reflect parents’ observations of children’s behavior rather than the child’s subjective experience (“complained of headaches,” vs “had headaches”). All items were reviewed by a board certified developmental-behavioral pediatrician (J.C.L.) to ensure they were appropriate for parent-report of children’s behavior. The format of the ProWS-C mirrored the adult ProWS (Schulte et al., 2018), but the framing of the ProWS-C was shifted such that parents are asked to rate their child’s change in each symptom on a Likert scale from less than usual to a lot more than usual, following their most recent attempt to cut down on their child’s “junk food” consumption. The ProWS-C has an 8th grade Flesch-Kinkaid reading level, which suggests its appropriateness for use with adults (Kincaid, Fishburne, Rogers, & Chissom, 1975). All items were rated on a Likert scale from 1 (less than usual) to 4 (a lot more than usual), and the measure was scored by adding responses to each item to create a composite score.

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Table 1. ProWS-C Symptom Domains Symptom Domain

Affective

Substance Use Disorder Withdrawal Symptom

How the ProWS-C Assesses the Symptom

Irritability

Was irritable Threw tantrums Was cranky Got in arguments with me Got in arguments with others Was easily annoyed Lost his or her temper

Anxiety

Seemed stressed out

Depressive Symptoms

Seemed down or sad Didn’t seem like him or herself

Oppositionality1

Craving

Cognitive

Physical

316 317 318 319 320 321 322 323 324

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Acted up (e.g., wouldn’t listen to directions) Broke rules (e.g., got in trouble for breaking rules at home or school) Tried to sneak junk food (e.g., sneaking into kitchen to get junk food without me knowing) Bought junk food themselves (e.g., at school or from a vending machine) Had other people get them junk food (such as other caregivers, friends) Repeatedly asked for junk food Whined for junk food

Difficulty concentrating

Had difficulty paying attention

Fatigue2

Seemed tired or seemed to have low energy

Headaches

Complained of headaches

Nausea

Complained of stomachaches

Notes: 1.Oppositionality is not typically observed as a symptom of withdrawal in substance use disorders and was not included in the adult ProWS, but may indicate negative affect in children (Boylan et al., 2012); 2. Fatigue was represented as sleep difficulties (e.g., restless sleep) in the adult ProWS, but parents may not be able to directly observe their child’s sleep quality. Thus, fatigue was used in the ProWS-C. All other substance use disorder withdrawal symptoms were assessed in both the adult and child versions of the ProWS. All items were rated on a Likert scale from 1 (less than usual) to 4 (a lot more than usual), and the measure was scored by adding responses to each item to create a composite score.

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Time course. In order to assess the time course of symptom severity, parents were asked immediately following the ProWS-C, “When were the changes in your child the worst during your attempt to cut down on their junk food consumption?” Parents were asked to choose one of the following response options: “Day 1, Days 2-3, Days 4-5, Days 6-7, Within Week 2, Within Weeks 3-4, Within Month 2, and Within Months 3-4.” Success and duration of diet change attempt. In order to assess parents’ perceived success at reducing their child’s highly processed food consumption, parents rated their agreement with the statement, “I was successful in reducing the amount of junk food my child eats,” on a four-point Likert scale from “strongly disagree” to “strongly agree.” The average success rating was 3.15 (SD = 0.64), which corresponded to a rating of “somewhat agree.” To assess how long parents were able to reduce their child’s highly processed food consumption, parents were asked, “What was the longest period of time you were successful in cutting down on your child's junk food in the past year?” Reported duration ranged from 1-3 days to 6 or more months, with the average parent reporting a duration of 3-4 weeks. Other measures of child behavior. Dimensional Yale Food Addiction Scale Version 2.0 for Children (dYFAS-C 2.0.) The dimensional Yale Food Addiction Scale Version 2.0 for Children (dYFAS-C 2.0) is a 16-item scale developed to assess symptoms of food addiction (e.g., loss of control, cravings, tolerance) in children (Schiestl & Gearhardt, 2018). The dYFAS-C 2.0 has been found to have appropriate psychometric properties for assessing food addiction in community samples of children (Schiestl & Gearhardt, 2018). Due to a clerical error, one question was omitted from the dYFAS-C 2.0 (Question 2: “My child kept eating certain foods even though they were not hungry.”) Thus, the final total score consisted of the total of 15 responses. Items were scored on a five-point Likert scale from 0, “never,” to 4, “always.” Total scores could range from 0 to 60, with higher scores indicating more food addiction pathology. The average score on the dYFAS-C 2.0 was 33.77 (SD=13.78) and the measure demonstrated excellent internal consistency in this sample (α = .95). BMI silhouettes. Given concerns about the accuracy of parent-reported weight and height for young children, parents were asked to select a two-dimensional (2-D) picture that best represented their child’s body (Eckstein et al., 2006). 2-D rating scales are shown to moderately correlate with measured BMI in children (Eckstein et al., 2006; Warschburger & Kroller, 2009). Thus, we used the silhouettes as a proxy for child BMI (adiposity). There were six sets of BMI silhouettes, based on the child’s reported sex and age: both a male and female version for ages 34, 5-6, and 7-11. Each set contained seven silhouettes of a child, in order from smallest to largest, coded as 1-7 for analysis. BMI silhouettes were not recorded for children whose sex was marked as “other” (n = 2) or “prefer not to respond” (n = 2), as BMI silhouettes presented depended on reported child sex. The average BMI rating was 3.76 (SD = 1.88) on the seven-point scale. Children’s Food Neophobia Scale-Modified (CFNS). The Children’s Food Neophobia Scale-Modified (CFNS) is a 10-item scale designed to measure parent’s perceptions of their child’s fear of trying new foods (Russell, Worsley, & Behavior, 2008). Items were scored on a Likert scale from 1, “strongly agree” to 7, “strongly disagree.” Items were summed to generate a

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total score, for a possible range from 10 to 70, with higher scores indicating greater food neophobia. The average score on the CFNS was 39.6 (SD = 11.79) and the measure demonstrated good internal consistency in this sample (α = .89). Data Analytic Plan All statistical analyses were performed using IBM SPSS Statistics, Version 25. All measures were reviewed for normality and outliers prior to analyses described below. None were detected. Missing data were addressed with stepwise deletion, as described below. Associations between ProWS-C scores and demographic variables were examined using correlations for continuous variables (age, education level). Due to the low sample size of parents who chose not to report their child’s sex (n = 2) or chose “other” for their child’s sex (n = 2), these children were coded as missing and excluded from these analyses. Due to the low sample size of participants in each non-White racial category and Hispanic participants, race and ethnicity were recoded as dichotomous variables (White/non-White and Hispanic/non-Hispanic). Children whose parent chose not to identify the child’s race (n = 1) or ethnicity (n = 18) were coded as missing and excluded from these analyses. Independent samples t-tests were used to investigate differences for these dichotomized variables (sex, race, ethnicity). Hypothesis 1: The Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy was used to determine the proportion of variance in the ProWS-C that was explained by underlying factors, indicating the appropriateness of factor analysis (Kaiser, 1974). KMO values between 0.8 and 1.0 indicate adequate sampling. Bartlett’s test of sphericity was used to determine the appropriateness of a factor analysis to analyze the structure of the ProWS-C (Snedecor & Cochran, 1989). A significant Bartlett value (p < 0.05) indicates the appropriateness of factor analysis. Exploratory Factor Analysis (EFA) was conducted to assess the structure of the ProWSC. Principal axis factoring was used as the factor extraction method and oblique rotation was used to account for interitem correlations (Costello & Osborne, 2005). Internal consistency of the resulting factor structure was measured using Cronbach’s α. Cronbach's α is considered acceptable between 0.7 and 0.8, good between 0.8 and 0.9, and excellent when it exceeds 0.9 (Bernstein & Nunnally, 1994; Streiner, 2003). Hypothesis 2: Content validity was examined by calculating frequencies of the timeframe during which parents reported their children’s withdrawal-like symptoms were “the worst,” to evaluate the most commonly reported timeframe for peak withdrawal symptom intensity. Hypothesis 3: Convergent validity was assessed by computing correlations between ProWS-C total scores and dYFAS-C 2.0 scores. The dYFAS-C 2.0 also assesses withdrawal symptoms. Thus, to avoid overinflating the association between addictive-like eating (as assessed by the dYFAS-C 2.0) and the ProWS-C, we removed the withdrawal questions from the dYFAS-C 2.0 prior to all analyses. Associations between ProWS-C total scores and child BMI silhouettes were also examined using correlations.

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Hypothesis 4: Discriminant validity was evaluated by examining the correlation between the ProWS-C total score and the CFNS total score. Hypothesis 5: Incremental validity was examined using hierarchical linear regression with parent-reported success at restricting the child’s highly processed food consumption and length of most successful diet change attempt as dependent variables. In both regression models, dYFAS-C 2.0 scores (with withdrawal questions removed) and child BMI silhouettes were entered in step one, and ProWS-C score was added in step two.

Results Parents included in analyses (n = 304) identified as 56.9% female, 42.8% male, and 0.3% preferred not to identify their sex. Parents were aged 19 – 56 (M = 34.25, SD = 6.76). 71.4% identified as White, 16.4% as Black/African-American, 5.9% as Asian, 2.6% as American Indian or Alaskan Native, 2.6% as other, and 1% preferred not to report their race; 84.9% identified as not Hispanic/Latino, 9.2% identified as Hispanic/Latino, and 5.9% preferred not to report their ethnicity. Educational level ranged from less than high school to an advanced degree with the majority of participants having completed a bachelor’s degree (44.7%). The cohort of children on which parents reported was 63.8% male, 34.9% female, 0.7% other, and 0.7% parents preferred not to report their child’s sex. Children were aged 3 – 11 (M = 6.46, SD = 2.52). 69.1% of children were identified as White, 16.4% as Black/African-American, 5.9% as Asian, 5.3% as other, 2.3% as American Indian or Alaskan Native, and 0.3% preferred not to report their child’s race; 82.6% identified their child as not Hispanic/Latino, 11.5% identified their child as Hispanic/Latino, and 5.9% preferred not to report their child’s ethnicity.

Hypothesis 1: Factor Structure and Internal Consistency of the ProWS-C Bartlett's test of sphericity demonstrated the appropriateness of factor analysis (χ2=3765.85, p < 0.001) and the Kaiser-Meyer-Olkin (KMO) index indicated excellent sampling adequacy (KMO=0.95). EFA revealed three factors with an eigenvalue >1, which has been suggested as one method of determining factor structure (Kaiser, 1960). However, the scree plot indicted that the “break” was indicative of a one-factor solution that accounted for 48.59% of the variance. All items loaded strongly onto the one-factor solution (factor loadings > 0.5) (see Table 2), so no items were removed from the scale (Osborne, Costello, & Kellow, 2008). Thus, the final version of the scale contained 21 items that exhibited excellent internal consistency (α=0.94). See Table 2 for the questions and factor loadings for the ProWS-C. Table 2 Items on the ProWS-C and factor loadings. Item

Factor Loading

DEVELOPMENT OF THE HIGHLY PROCESSED FOOD WITHDRAWAL SCALE FOR CHILDREN Was irritable Threw tantrums Tried to sneak junk food (e.g., sneaking into kitchen to get junk food without me knowing) Bought junk food themselves (e.g., at school or from a vending machine) Had other people get them junk food (such as other caregivers, friends) Repeatedly asked for junk food Whined for junk food Seemed down or sad Didn't seem like him or herself Was cranky Acted up (e.g., wouldn't listen to directions) Broke rules (e.g., got in trouble for breaking rules at home or school) Got in arguments with me Got in arguments with others (other caregivers, teachers, siblings, friends) Seemed stressed out Was easily annoyed Lost his or her temper Seemed tired or seemed to have low energy Had difficulty paying attention Complained of headaches Complained of stomachaches 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476

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.71 .66 .58 .55 .57 .52 .63 .76 .75 .72 .77 .69 .71 .70 .76 .71 .80 .71 .71 .59 .63

Instructions: “Please answer the following questions based on what you noticed about your child's behavior during the last time you tried to cut down on your child's junk food consumption. When I tried to cut down on my child's junk food consumption, my child....” ProWS-C scores ranged from 21 to 126 with a mean of 49.98 (SD = 20.04). ProWS-C scores were not associated with child age (r = -0.01, p = 0.89). It also did not significantly differ by sex (t(298) = 0.63, p = 0.53, d = 0.07). ProWS-C scores were associated with child race, such that non-White children had higher ProWS-C scores than White children. ProWS-C scores were associated with child ethnicity such that Hispanic children had higher ProWS-C scores than nonHispanic children (see Table 3). Table 3 Means, standard deviations, p-values and Cohen’s d for sex, racial and ethnic differences in ProWS-C scores. Variable

ProWS-C Total Score Mean (SD)

t (df)

p

d

Male

50.66 (20.30)

0.63 (298)

0.53

0.07

Female

49.14 (19.77) -2.33 (301)

0.02

0.28

Child Sex

Child Race White

48.29 (18.68)

DEVELOPMENT OF THE HIGHLY PROCESSED FOOD WITHDRAWAL SCALE FOR CHILDREN Non-white

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54.06 (22.38)

Child Ethnicity

477 478 479 480 481 482 483 484

Hispanic

56.80 (23.28)

Non-Hispanic

48.95 (19.72)

2.16 (284)

0.03

0.36

Hypothesis 2: Content Validity of the ProWS-C The symptoms assessed by the ProWS-C were reported as being “the worst” on days 2–3 (reported by 40.1% of parents, n =122). Figure 1 shows the number of parents that reported changes in their child were “the worst” at each time point.

Parents Reporting Peak Intensity

Time Course of Parent-reported ProWS-C Symptoms 140 120 100 80 60 40 20 0

Day 1

Days 2-3

Days 4-5

Days 6-7

Withink Week 2

Within Within Within Weeks 3-4 Month 2 Months 3-4

Time Following Start of Diet Change

485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501

Figure 1. Time Course of Parent-reported ProWS-C Symptoms

Hypothesis 3: Convergent Validity of the ProWS-C Consistent with predictions for convergent validity, ProWS-C scores were positively associated with higher dYFAS-C 2.0 food addiction symptoms (r = 0.55, p < 0.001) and higher BMI silhouette rating (r = 0.24, p < 0.001). Hypothesis 4: Discriminant Validity of the ProWS-C Discriminant validity was supported, as ProWS-C scores were not significantly associated with CFNS food neophobia scores (r = -0.10, p = 0.08). Hypothesis 5: Incremental Validity of the ProWS-C

DEVELOPMENT OF THE HIGHLY PROCESSED FOOD WITHDRAWAL SCALE FOR CHILDREN 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547

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In the model with parent-reported success at changing the child’s diet as the outcome, dYFAS-C 2.0 (t(297) = -1.63, β = -0.10, p = 0.12) and BMI silhouettes (t(297) = -1.03, β = 0.06, p = 0.31) were not significantly associated with self-reported success in step one of the hierarchical regression model, accounting for 1.5% of the variance (R2 = 0.02, F(2,297) = 2.25, p = 0.11). In step two, ProWS-C was significantly associated with self-reported success (t(296) = 4.71, β = -0.32, p < 0.001), accounting for an additional 6.9% of the variance (R2 = 0.07, F(3,296) = 8.99, p < 0.001). In the model with longest successful diet change attempt as the outcome, dYFAS-C 2.0 (t(297) = -5.06, β = -0.29, p < 0.001) was significantly associated with length of successful attempt in step one of the hierarchical regression model but BMI silhouettes (t(297) = -0.31, β = 0.02, p = 0.76) were not, with both variables accounting for 8.4% of the variance (R2 = 0.08, F(2,297) = 13.65, p < 0.001). In step two, ProWS-C was significantly associated with length of successful attempt (t(296) = -3.32, β = -0.22, p = 0.001), accounting for an additional 3.3% of the variance (R2 = 0.03, F(3,296) = 13.08, p < 0.001). Discussion The aim of the current study was to develop a developmentally appropriate assessment tool (ProWS-C) to evaluate affective, cognitive, and physical symptoms of withdrawal in response to parental restriction of “junk food” consumption in children. In a sample of 304 parents of children aged 3 to 11, this study found evidence that the ProWS-C is a psychometrically sound tool to assess withdrawal symptoms in response to parental restriction of highly processed foods in children. Higher ProWS-C scores are associated with clinically relevant factors, such as lower parent-reported success at and shorter duration of restricting their children’s highly processed food consumption. Each of our hypotheses regarding the psychometric properties and validity were supported, as detailed below. As with the adult ProWS (Schulte et al., 2018) the ProWS-C demonstrated a one-factor solution and good internal consistency, suggesting that HP food withdrawal in children is a single unified construct. The current study also supported the content validity of the ProWS-C, as the reported time course in which withdrawal-like symptoms peaked was consistent with that reported in the adult ProWS and other addictive substances (Budney et al., 2003; Hughes, 2007; Schulte et al., 2018). Specifically, symptoms peak around days 2-3 after restricting children’s “junk food” intake and symptoms steadily diminish over the next few weeks. Thus, the early stages of dietary change appear to be a key period to address the affective, cognitive and physical symptoms of withdrawal in children. The current study also provided evidence that the ProWS-C has convergent validity with theoretically associated constructs. Of the parent-reported child variables assessed, the ProWS-C was most strongly associated with children’s other symptoms of addictive-like eating (Schiestl & Gearhardt, 2018). This is consistent with highly processed food withdrawal in adults, which is associated with overall symptoms of addictive-like eating (Schulte et al., 2018). The connection between withdrawal and other symptoms of addiction is also observed in substance use disorders, in which people who are more strongly addicted to a substance experience stronger withdrawal symptoms when the substance is reduced (Weinberger et al., 2010). Similar to adults

DEVELOPMENT OF THE HIGHLY PROCESSED FOOD WITHDRAWAL SCALE FOR CHILDREN 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592

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(Schulte et al., 2018), children with higher BMI also had more withdrawal-like symptoms. Excess body weight tracks into adulthood and is associated with health issues such as cardiovascular disease and diabetes (Lloyd et al., 2010). Thus, the current study suggests that highly processed food withdrawal may be particularly relevant for children who may be at the greater risk for negative weight-related consequences. The ProWS-C was not significantly associated with food neophobia, thus exhibiting discriminant validity from this construct. Food neophobia, or the fear of trying new foods, is common in children and is considered a barrier to children eating more nutrient-dense and fiberrich foods like fruits and vegetables (Dovey, Staples, Gibson, & Halford, 2008). The lack of association between the ProWS-C and food neophobia suggests that the ProWS-C is not merely detecting the difficulty children with high food neophobia may experience when they have reduced access to preferred foods. Highly processed food withdrawal and food neophobia appear to be distinct constructs that should both be considered when investigating barriers to child diet change. Food neophobia tends to decrease as children age (Cooke & Wardle, 2005), but highly processed food withdrawal was not associated with child age in this sample. Thus, highly processed food withdrawal may represent a more long-lasting barrier to child diet change. Incremental validity was demonstrated by the significant association of the ProWS-C with less parent-reported success and shorter duration of success at changing their child’s diet above and beyond child food addiction symptoms (excluding withdrawal symptoms) and BMI. Thus, the demonstration of incremental validity in the current study supports the psychometric validity of highly processed food withdrawal and suggests it provides unique information for predicting child diet change success. This also consistent with the substance use disorder literature, in which greater withdrawal symptoms are strongly associated with relapse (Becker, 2008; Zhou et al., 2009). The current research has important clinical implications. Attrition rates in pediatric weight loss studies are very high, with 27-73% of participants dropping out, mostly in the first few weeks of treatment (Skelton & Beech, 2011). Although attrition is recognized as a problem in the pediatric weight loss literature, little attention has been paid to the obstacles that arise early in the process of dietary change. The current study finds that affective, cognitive, and physical symptoms of withdrawal emerge for children within days of parents restricting highly processed foods and this makes it more difficult for parents to maintain dietary change. Thus, clinical interventions that seek to limit the impact of the symptoms of highly processed food withdrawal may be key to keeping families engaged in treatment and improving their ability to sustain healthy eating patterns over time. Addressing highly processed food withdrawal symptoms will likely also be important outside of the treatment clinic. The vast majority (95.7%) of parents who responded to this survey on feeding behaviors reported trying to reduce their child’s “junk food” consumption in the last year. It is unlikely that all of these parents engaged in supervised clinical treatment, but instead attempted to improve their child’s diet on their own. Thus, many parents may benefit from strategies to minimize the impact of affective, cognitive, and physical withdrawal symptoms that may emerge when they attempt to reduce their child’s highly processed food intake outside of professional supervision.

DEVELOPMENT OF THE HIGHLY PROCESSED FOOD WITHDRAWAL SCALE FOR CHILDREN 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638

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Interventions from the substance use disorder field may be relevant to reducing the impact of highly processed food withdrawal in children. In substance use disorder treatment, psychoeducation about withdrawal symptoms can increase treatment adherence by helping clients understand the discomfort is temporary and motivating them to maintain abstinence past the peak withdrawal period (Katz et al., 2011). Similarly, it may be helpful for parents to receive psychoeducation about the time course of symptoms of highly processed food withdrawal. In substance use disorder treatment, clients are often taught strategies to regulate emotions and manage craving (e.g., mindful breathing, identifying triggers for craving) prior to a quit attempt, to help them successfully cope with withdrawal symptoms (Dimeff & Linehan, 2008; McHugh, Hearon, & Otto, 2010; Witkiewitz, Bowen, & Donovan, 2011). In the context of dietary change, these strategies are either not included at all or are integrated into treatment after the quit attempt has already begun and withdrawal may already be occurring (Aparicio, Canals, Arija, De Henauw, & Michels, 2016). The current research suggests that teaching parents strategies to deal with highly processed food withdrawal symptoms, particularly before highly processed food is reduced, may be important to improving the success of diet change attempts. For example, parents may learn to help their children identify antecedents to highly processed food cravings and “ride the craving wave” with distraction techniques, or use joint parent-child cognitive reframing, in which the parent helps the child reinterpret a situation so that it is no longer negative (Boutelle et al., 2011; Morris et al., 2011). As a psychometrically sound, developmentally appropriate measurement tool, the ProWS-C represents a critical first step in advancing our understanding of highly processed food withdrawal in children. Nevertheless, the essential next step to evaluating the construct of highly processed food withdrawal is to evaluate whether the ProWS-C is associated with established biological and behavioral indicators of withdrawal (e.g., cortisol dysfunction, neural cue reactivity) when highly processed foods are reduced (George, Le Moal, & Koob, 2012; Volkow, Koob, & Baler, 2015). Further, there are also developmental challenges to conducting this work. No child-specific measures of withdrawal currently exist, as exposure to addictive substances and the emergence of withdrawal symptoms typically occurs later in development (i.e., adolescence, adulthood) (Johnston et al., 2019). Yet, exposure to highly processed food occurs very early in development with children consuming a significant proportion of calories from highly processed foods by the age of two (Reedy & Krebs-Smith, 2010). If highly processed foods are capable of triggering addictive processes, this would result in the emergence of withdrawal symptoms at much earlier ages than traditional addictive substances. This is particularly concerning, as children have less well-developed executive functioning and emotion regulation capacities (Aldwin, Skinner, Zimmer-Gembeck, & Taylor, 2011; De Luca & Leventer, 2010). Thus, even if the withdrawal symptoms are comparably mild relative to traditional drugs of abuse, it may still negatively impact children’s ability to function. Given that the majority of research on withdrawal has occurred in older samples, there may be developmental specificity to the presentation of withdrawal symptoms in younger children. In the current study, child-specific signs of negative affect, such as oppositional behaviors, were integrated into the ProWS-C. However, it will be important to investigate other ways that withdrawal symptoms may present differently in childhood. There are methodological constraints to consider when interpreting the results of this study. Because parents are consistently inaccurate at reporting their young children’s height and

DEVELOPMENT OF THE HIGHLY PROCESSED FOOD WITHDRAWAL SCALE FOR CHILDREN 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684

17

weight (Rietmeijer‐Mentink, Paulis, van Middelkoop, Bindels, & van der Wouden, 2013), this study used BMI silhouettes which have been validated for this purpose (Eckstein et al., 2006). Direct measurement of height, weight, and other measures of children’s body composition will strengthen future studies. It remains unclear whether the symptoms assessed by the ProWS-C are specific to the reduction of highly processed foods or if they reflect the changes children experience when access to any rewarding stimulus (e.g., friends, toys) is restricted. If the behaviors assessed by the ProWS-C emerge in a similar manner when non-addictive stimuli are restricted, higher ProWS-C scores may be assessing temperamental differences rather than withdrawal processes. To examine this distinction in the food domain, future studies may compare ProWS-C scores in children who have reduced their highly processed food consumption and children who have reduced familiar and rewarding foods that are not expected to be addictive (do not have high amounts of added fat and refined carbohydrates). There was potential for recall bias, as the survey asked parents to report on a diet change attempt within the last year. The attempt may have occurred within the last week or up to one year prior, which likely caused variation in parent’s ability to accurately remember their child’s behavior during that time. Future work would benefit from asking about more specific, more recent timeframes or using the ProWS-C during a known diet change attempt. The questions about parents’ perceived level of diet change success and duration of success did not explicitly instruct parents to think of a particular restriction attempt, or a particular time frame. Therefore, parents may have thought about different diet change attempts when answering each of these questions, potentially including attempts before the previous year. Although measuring the ProWS-C in real time will be most informative, future retrospective recall studies should explicitly detail the diet change attempt under examination in each question. Although the parent-report design of the ProWS-C provides one important perspective on children’s behavior, it is ideal to elicit reports on children’s behavior from multiple vantage points (i.e., self-report in older children, other caregivers, and teachers). Developing these versions of the ProWS-C is an important future direction. Although MTurk allows researchers to recruit study samples that are more representative than community samples, this study sample was not representative of the United States population, in a few key ways. The sample reflected a much higher proportion of participants with at least a bachelor’s degree, a smaller proportion of Hispanic or Latino participants, and an overrepresentation of male children (United States Census Bureau, 2018). Thus, further research with larger and more representative samples (particularly with regard to education level) is needed to determine generalizability of the ProWS-C. The association of the ProWS-C with child race and ethnicity raise questions about the measurement invariance of the ProWS-C across demographic groups. Future work should evaluate this in a larger and more diverse sample of parents and children. The age range of the children included in the study (3-11 years old) reflects a relatively wide range of physical, cognitive, and emotional development, ranging from preschool to middle childhood (Davies, 2010). Thus, important differences may exist with regard to the experience and expression of highly processed food withdrawal in children of different age groups. We conducted an exploratory analysis to determine whether convergent, discriminant, and incremental validity of the ProWS-C differed by age group (see Supplemental Materials). The ProWS-C appears to operate similarly across the sampled age range. However, the association between the ProWS-C and BMI silhouettes, and the incremental validity of the

DEVELOPMENT OF THE HIGHLY PROCESSED FOOD WITHDRAWAL SCALE FOR CHILDREN 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702

18

ProWS-C for determining parent-reported length of successful diet change attempt became trend-level when the data were median split by age. Further research with adequately powered samples of children of various ages is needed to confirm the utility of ProWS-C across childhood periods. The continued morbidity associated with childhood obesity and the extremely high attrition rates for pediatric weight loss studies highlight the urgency for a more nuanced understanding of barriers to child diet change. The food addiction model has the potential to inform our approach to childhood obesity by illuminating the underlying addictive processes (including withdrawal) that may keep parents and children in a cycle of attempting and failing at improving their eating habits. The ProWS-C is the first psychometrically sound and developmentally appropriate measure of the affective, cognitive, and physical withdrawal symptoms that children may experience when trying to cut down on highly processed foods. Importantly, children with higher scores on the ProWS-C have less success in improving their diet. The ProWS-C provides a strong foundation for numerous avenues of important research into the presentation, mechanisms, and implications of highly processed food withdrawal in children. This study represents a crucial step toward improving parents’ ability to help their children eat healthier diets and reduce their risk for negative diet-related health outcomes.

DEVELOPMENT OF THE HIGHLY PROCESSED FOOD WITHDRAWAL SCALE FOR CHILDREN 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746

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DEVELOPMENT OF THE HIGHLY PROCESSED FOOD WITHDRAWAL SCALE FOR CHILDREN 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838

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