Neurobehavioral Plasticity to Regular Sugar-Sweetened Beverage Intake: An fMRI Experiment

The proposed project will examine the strength, specificity and persistence of neurobehavioral adaptions that occur in the initial period of repeated consumption of a branded sugar sweetened beverage (SSB).

The proposed project addresses critical gaps in the understanding of the strength, specificity and persistence of neurobehavioral adaptions that occur in the initial period of repeated consumption of a branded sugar sweetened beverage (SSB). Half of Americans consume SSBs on any given day. Regular SSB intake is considered a contributing factor to excess energy intake, weight gain, and obesity, which impacts 70% of Americans. A contributing factor to repeated SSB consumption is sugar intake causes the release of dopamine (DA) and opioids in the striatum, providing positive reinforcement. As such, multiple brain-based models of food reward-driven obesity have been proposed, largely focusing on the striatum and executive functioning. These brain-based models of obesity have elucidated risk factors for overconsumption of high-sugar foods; however, data supporting these competing models rely heavily on observational studies in small samples. Importantly, previous reports from the investigators lab and others directly implicate eating behavior patterns as a vital contributor to aberrant neurobehavioral responses to food stimuli. However, without experimental evidence, there are fundamental gaps in the investigators knowledge about the neurobehavioral adaptations that occur as an individual begins to regularly consume a SSB prior to weight change. As observational data suggest, it is also crucial to examine individual difference factors that may exacerbate or protect against adaptations associated with regular SSB intake, as well as whether these adaptions are specific.

nutrition, obesity, weight gain, sugar, sugar sweetened beverage, dopamine, neurobehavioral adaptation

Stratified randomization techniques will be used to distribute: 1) male & females, 2) those with a BMI > 26.1 & those with a BMI < 26.1, and 3) regular SSB consumers (> 1/day; 12 fl oz) & low or non-SSB consumers equally across the 2 experimental conditions (SSB vs. unsweetened beverage) and then to the two flavors within each experimental condition. BMI of 26.0 was selected as it is the midpoint of inclusion criteria 18 < BMI < 34.

One quarter of the group to receive black cherry and orange flavored beverage with added sugar for 3 weeks. MRIs will be performed before starting and then after 3 weeks of daily beverage consumption wherein participants will be presented with visual stimuli of two beverage logos, one representing a water solution and another representing the assigned beverage. Each 1-second presentation signals impending delivery of 3 mL of the associated beverage via a plastic mouthpiece during MRI.

One quarter of the group to receive strawberry kiwi & lemonade flavored beverage with added sugar for 3 weeks. MRIs will be performed before starting and then after 3 weeks of daily beverage consumption wherein participants will be presented with visual stimuli of two beverage logos, one representing a water solution and another representing the assigned beverage. Each 1-second presentation signals impending delivery of 3 mL of the associated beverage via a plastic mouthpiece during MRI.

One quarter of the group to receive black cherry and orange flavored beverage no added sugar for 3 weeks. MRIs will be performed before starting and then after 3 weeks of daily beverage consumption wherein participants will be presented with visual stimuli of two beverage logos, one representing a water solution and another representing the assigned beverage. Each 1-second presentation signals impending delivery of 3 mL of the associated beverage via a plastic mouthpiece during MRI.

One quarter of the group to receive strawberry kiwi & lemonade flavored beverage no added sugar for 3 weeks. MRIs will be performed before starting and then after 3 weeks of daily beverage consumption wherein participants will be presented with visual stimuli of two beverage logos, one representing a water solution and another representing the assigned beverage. Each 1-second presentation signals impending delivery of 3 mL of the associated beverage via a plastic mouthpiece during MRI.

Change in Voxel-wise Blood Oxygen Level Dependent (BOLD) Including Outliers Using Functional Magnetic Resonance Imaging (fMRI) of Brain Activation Signals in Response to Beverage Taste and Logo

The fMRI paradigm assesses evoked blood oxygen level dependent (BOLD) response to receipt of study beverages (sweet and unsweet) and a water solution, and logo-elicited anticipation of both beverages and water solution. The visual stimuli are two beverage logos, a water logo, and a fixation cross. Each logo (1 second) signals impending delivery of 3 mL of the associated juice/water over 6 seconds, with the fixation cross otherwise presented. A jitter ranging from 5 to 13 seconds follows each trial. In total, the participants are shown 24 repeats of the events of interest over 4, 7-minute runs. Contrasts of interest are the post- > pre-intervention BOLD response to sweetened beverage logo > water logo. Parameter estimates for these contrasts are extracted and reported. A positive reported outcome reflects higher post- vs. pre-intervention (negative values reflect lower post- vs. pre-intervention) change in whole-brain BOLD response for sweetened beverage logo > water logo for each arm.

Baseline and Post-intervention Assessment. Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

Change in Voxel-wise Blood Oxygen Level-Dependent (BOLD) Brain Activation in Response to Beverage Taste and Logo by Body Mass Index (BMI)

The fMRI paradigm assesses evoked blood oxygen level dependent (BOLD) response to receipt of study beverages, (sweetened and unsweetened) and a water solution, and logo-elicited anticipation of both beverages and water solution. Whole-brain analyses are performed. Contrasts of interest for the within-subject models are post-intervention > pre-intervention BOLD response to beverage vs. water logo and contrasts of interest for the group model are sweetened beverage logo > water logo. To test the interaction of brain activation with BMI, BMI is entered as a covariate in the group model. Parameter estimates of significant BOLD response to these contrasts are extracted and reported. A positive reported outcome reflects higher post- vs. pre-intervention (negative values reflect lower post- vs. pre-intervention) change in BOLD response in the putamen for the sweetened beverage logo > water logo for each arm.

Baseline and Post-intervention Assessment. Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

Perceptual ratings of the assigned beverage using visual analog scales are assessed at the pre- and post-intervention behavioral visits. Visual analog scales (VAS) are presented on an iPad screen. The scale assesses response to taste after the participant consumes a small amount of the beverage. Perceived pleasantness of, and desire to consume the two beverages is measured using adapted labeled hedonic scales at pre-/post-intervention. Pleasantness is phrased 'How pleasant is this taste' and anchored by (-100) 'most unpleasant imaginable' to (100) 'most pleasant imaginable', and 'neutral' (0) in the middle. Desire follows a similar pattern using 'desire to consume' as the phrasing. Pleasantness and desire of the assigned beverage is also evaluated at the 9 intervention assessments. Higher scores represent higher pleasantness and desire.

Pre-intervention Behavioral Assessment; Post-intervention Behavioral Assessment; Post-intervention Assessment completed approximately 5 weeks after the Pre-intervention Assessment

Stop-signal reaction time to assigned beverage logo are assessed at the pre- and post-intervention visits. The behavioral response inhibition task (stop-signal task) examines motor disinhibition in response to beverage logos. This allows for the assessment of bias toward the logos and is sensitive to detect changes due to the intervention. The task is performed on an iPad app where participants complete the task twice, once at the pre-intervention and once at the post-intervention behavioral visit. The task contains 6 runs, where 3 runs present the logo of the assigned beverage and the other 3 present the logo of the same-flavor unassigned beverage. Within each run of this task, 64 (20 "go") trials are presented, and participants are instructed to make a speeded response to a "go" stimulus except for trials when a "stop" signal occurs (an X presented over the logo), in which case participants are instructed to withhold their response.

Pre-intervention Behavioral Assessment; Post-intervention Behavioral Assessment; Post-intervention Assessment completed approximately 5 weeks after the Pre-intervention Assessment

Percent Change in Voxel-wise Blood Oxygen Level Dependent (BOLD) Including Outliers Using Functional Magnetic Resonance Imaging (fMRI) of Brain Activation Signals in During Rest

The investigators use resting state fMRI (rsfMRI) data to assess intrinsic functional connectivity and network analyses. Functional connectivity is commonly quantified by measuring the synchronization of low-frequency BOLD fluctuations across pairs of brain regions of interest (ROIs) via correlation coefficients (see statistical analyses). rsfMRI data is acquired in one run of 7 minutes; participants are asked to remain still with their eyes open, and to fixate on the fixation cross.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

Modulation of Blood Oxygen Level Dependent (BOLD) Using Functional Magnetic Resonance Imaging (fMRI) of Brain Activation Signals in Response to Beverage Taste and Logo by TaqIA Single Nucleotide Polymorphism Status

Saliva from participants is used to extract DNA using standard salting-out and solvent precipitation methods, to yield an average of 45 µg of DNA. The TaqIA (rs1800497) assays are done using a fluorogenic 5_nuclease (Taqman, ABI) method on an ABI Prism 7000 Sequence Detection System via the allelic discrimination mode. Reactions containing 20ng of DNA are performed in 10 µl reactions with TaqMan Universal Polymerase Chain Reaction Master Mix using standard cycling conditions. Independent investigators score allele sizes; inconsistencies are reviewed and rerun when necessary. For every assay, each 96-well plate includes non-template and DNA standards of known genotype. All genotyping is performed at the UNC-CH Advanced Analytics Core

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

The Food Frequency Questionnaire (FFQ) is a self-reported checklist of 76 foods and beverages with a frequency response section. Subjects report generally how often each item is consumed over a two-week period of time. The six possible responses are 1= never in the last two weeks, 2= 1-3 times in the last 2 weeks, 3= 4-6 times in the last 2 weeks, 4= 7-9 times in the last two weeks, 5= 10-13 times in the last 2 weeks, 6= daily or more in the last two weeks. Response information is used to estimate daily caloric intake (number of kcal) and macronutrient content (percent calories from carbohydrate/fat/protein). Food pattern is assessed as an aggregate of these measures. Changes in food pattern will be assessed as a difference from baseline to post-intervention assessment.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

Change in Beverage Intake Pattern From Baseline to Post-Intervention Assessment by Beverage Intake Questionnaire

To better capture variation in regular beverage intake patterns, the Beverage Intake Questionnaire is administered which queries directly about intake of all types of beverages. Similar to the Food Frequency Questionnaire, subjects report generally how often each item is consumed over a two-week period of time. The possible responses are 1= never in the last two weeks, 2= 1-3 times in the last 2 weeks, 3= 4-6 times in the last 2 weeks, 4= 7-9 times in the last two weeks, 5= 10-13 times in the last 2 weeks, 6= daily or more in the last two weeks. Responses information is used to estimate daily caloric intake from beverages (number of kcal) and macronutrient content (number of calories from carbohydrate/fat/protein). Changes in beverage intake are assessed as a difference from baseline to post-intervention assessment.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

Change in Physical Activity From Baseline to Post-Intervention Assessment by the Short-Form International Physical Activity Questionnaire

The International Physical Activity Questionnaire (IPAQ), which has shown high test-retest reliability, assesses the types of intensity of physical activity and sitting time that people do as part of their daily lives and estimates total physical activity in metabolic equivalent of task (MET-min/week) and time spent sitting. Changes in physical activity are assessed as a difference from pre- to post-intervention assessment.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

The Dutch Eating Behavior Questionnaire is a 33-item self-report measure designed to assess the type of eating behavior and is organized into 3 subscales (emotional eating, externally-induced eating, and restrained eating). Subjects rate the frequency of their eating behaviors using a 5-point scale, where 1=never, 2=seldom, 3=sometimes, 4=often, and 5=very often. The Restrained Eating subscale consisted of 10 items and the scores range from 10 (worse outcome) to 50 (better outcome). The change is calculated as the difference between scores at Baseline and Post-Intervention Assessment.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

Change in Food Craving as Assessed by the Food Craving Inventory (FCI) Score Changes of Food Pattern From Baseline by Food Frequency Questionnaire During the Intervention

The Food Craving Inventory is a 28-item instrument measuring the frequency over the past month of general cravings and cravings for specific types of foods, namely: high fats, sweets, carbohydrates/starches, and fast-food fats. Subjects rate how often they have experienced a craving for each food on a 5-point frequency scale, where 1=never, 2=rarely (once or twice), 3=sometimes, 4= often, 5= always/almost every day. Food craving score is calculated as a total sum, and the change score is calculated from the difference between baseline to post-intervention assessment.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

The Power of Food scale assesses reported appetitive drive, food reward responsivity, sensitivity to food cues in the environment, and the frequency of food-related thoughts. The 21-item scale prompts subjects to rate how much they agree with statements about hedonic hunger on a 5-point scale, where 1=do not agree at all, 2=agree a little, 3=agree somewhat, 4=agree, and 5=strongly agree. The change in total PFS score will be calculated from the difference between baseline to post-intervention assessment.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

The Yale Food Addiction Scale (YFAS) is designed to identify participants who exhibit signs of possible food addiction to specific foods. The 9-item questionnaire is based on substance dependence criteria in the DSM-IV-TR, as well as on scales that are used to assess behavioral addictions. Subjects rate how often they have experienced a possible food addictive behavior on a 5-point frequency scale, where 0=never, 1=once a month, 2=2-4 times per month, 3= 2-3 times per week, 4= 4+ times per week. The change in total score is calculated from the difference between baseline to post-intervention assessment.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

The Barratt Impulsiveness Scale is one of the most commonly used self-report measures of impulsivity. This instrument comprises 15 items that assess three independent sub-dimensions of impulsivity: (a) Attention; (b) Non-planning; (c) Motor. Collectively, the three sub-dimensions represent a total impulsivity score. Items are statements about behavior and participants rate each item are scored from 1 (Rarely/Never) to 4 (Almost Always/Always). The change in total score is calculated from the difference between baseline to post-intervention assessment.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

Change in General Sensitivity to Reward and Sensitivity to Punishment as Assessed by the Sensitivity to Punishment and Sensitivity to Reward Questionnaire

The Sensitivity to Punishment/Sensitivity to Reward Questionnaire (SPSRQ) is a self-reported instrument that includes 48 yes/no questions divided into two subscales: Sensitivity to Reward (SR) and Sensitivity to Punishment (SP). Items statements about behavior, and participants will rate each item are scored from 1 (Definitely True) to 5 (Definitely False). The change in total score is calculated from the difference between baseline to post-intervention assessment.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

The BIS/BAS scales are designed to assess individual differences in the sensitivity of two systems: A behavioral avoidance (or inhibition) system (BIS) and a behavioral approach system (BAS). The questionnaire includes 24 items. Items are statements about behavior and participants rate each item are scored from 1 (very true for me) to 4 (very false for me). The change in total score is calculated from the difference between baseline to post-intervention assessment.

Baseline Assessment; Post-Intervention Assessment, Post-Intervention Assessment completed approximately 5 weeks after the Baseline Assessment

Inclusion Criteria: Potential participants will be eligible for the study if they have BMI scores between the 18 and 34 at baseline. Exclusion Criteria: Individuals with probable current Axis I psychopathology or any fMRI contra-indicators (e.g., metal implants, braces) will be excluded. Those with a probable Axis I diagnosis will be provided with treatment referral information and encouraged to seek treatment, current regular use (3 or more times a week) of psychoactive drugs (e.g., cocaine, marijuana, nicotine), regular smoking, serious medical problems (e.g., cancer, diabetes), dietary practices that do not allow intake of intervention beverages.

Peirce JW. PsychoPy--Psychophysics software in Python. J Neurosci Methods. 2007 May 15;162(1-2):8-13. doi: 10.1016/j.jneumeth.2006.11.017. Epub 2007 Jan 23.