Effects of severe obesity and sleeve gastrectomy on cortical thickness in adolescents.

OBJECTIVE: Neurocognitive differences in pediatric obesity may be underpinned by cortical structural alterations. Differences in cortical thickness associated with severe obesity were examined, and preliminary evidence was sought for changes following vertical sleeve gastrectomy (VSG). METHODS: A total of 18 adolescents with severe obesity (OB) and 17 without obesity (nOB), aged 14 to 21, underwent T1-weighted structural magnetic resonance imaging. A subset was scanned twice 5 months apart to compare cortical thickness following VSG (n = 6) with two control groups: wait-listed (n = 9) and nOB (n = 12). RESULTS: At baseline, OB had a thinner cortex than nOB in motor and superior parietal cortices. At follow-up, VSG adolescents lost weight, the wait-listed group gained weight, and nOB did not change. Group × Time interactions indicated that VSG had cortical thinning in orbitofrontal, primary sensorimotor, superior, and middle temporal cortices and thickening in lingual, fusiform, and lateral occipital cortices. Wait-listed and nOB groups largely did not change. CONCLUSIONS: Severe obesity is associated with a thinner cortex in motor and attentional function-associated regions. VSG resulted in cortical thinning in reward valuation, sensory, and perceptual regions and thickening in visual regions. Surgery-related changes in regions distinct from those associated with obesity suggest compensation, rather than normalization. These results provide preliminary evidence supporting structural neural alterations following sleeve gastrectomy.

Altered neural correlates of episodic memory in adolescents with severe obesity.

Negative effects of obesity on memory and associated medial temporal circuitry have been noted in animal models, but the status in humans, particularly children, is not well established. Our study is the first to examine neural correlates of successful memory encoding of visual scenes and their associated context in adolescents with severe obesity (age 14-18 years, 43% male). Despite similar subsequent memory as adolescents without obesity (BMI for age and sex <95th percentile), those with severe obesity (BMI for age and sex 120% above the 95th percentile) showed reduced hippocampal, parahippocampal, frontal, and parietal engagement during encoding of remembered visual scenes and greater lateral temporal engagement during encoding of their associated context. Standardized testing revealed a trend level group difference in memory performance, with a larger magnitude of obesity-related difference in recollection-related memory that was mediated by individual differences in lateral temporal activation during contextual encoding. The observed widespread functional alterations are concerning in light of the importance of mnemonic processing for academic achievement and feeding behavior and underscore the need for prevention and intervention initiatives for pediatric obesity.

Cognitive Performance as Predictor and Outcome of Adolescent Bariatric Surgery: A Nonrandomized Pilot Study.

Objectives: Evidence in adults suggests that improvements in cognitive performance may follow weight loss resulting from bariatric surgery, and baseline cognitive performance may be associated with weight loss following surgery. This has not been evaluated in adolescents. Method: Participants were 38 adolescents of age 14-21 years composed of three groups: (1) 12 adolescents with severe obesity who received vertical sleeve gastrectomy during the study (VSG); (2) 14 adolescents with severe obesity who were wait-listed for VSG (WL); and (3) 12 healthy weight controls (HC). Participants completed testing of visual memory, verbal memory, and executive functioning at baseline (T1), which occurred presurgery for the VSG group, and approximately 4 months after baseline (T2). Body mass index (BMI) was assessed at T1, T2, and additionally at 6 months following VSG for the adolescents who received surgery. Results: Although there was evidence of greater improvement for the VSG as compared with WL and HC groups in visual and verbal memory, group differences did not reach significance and effect sizes were small (η2 < 0.01). There was a significant positive association between indices of baseline executive functioning and excess BMI loss at 6 months postsurgery. Conclusions: This small pilot study showed no significant differences by group in cognitive performance post-VSG. There was a significant association of baseline cognitive performance with weight loss outcomes. Given the very preliminary nature of these results in a small sample, future research should examine these relationships in a larger sample and evaluate mechanisms of these associations (e.g., insulin resistance, sleep, physical activity).

Effect of Adolescent Bariatric Surgery on the Brain and Cognition: A Pilot Study.

OBJECTIVE: Neurocognitive deficits in pediatric obesity relate to poor developmental outcomes. We sought preliminary evidence for changes in brain and cognitive functioning relevant to obesogenic behavior following vertical sleeve gastrectomy (VSG) in adolescents relative to wait-listed (WL) and healthy controls (HC). METHODS: Thirty-six adolescents underwent fMRI twice 4 months apart, during executive, reward, and episodic memory encoding, in addition to behavioral testing for reward-related decision making. RESULTS: VSG adolescents lost weight, while WL gained weight and HC did not change between time points. Gains in executive and reward-related performance were larger in VSG than control groups. Group × Time interaction (P < 0.05 corrected) in left prefrontal cortex during N-back showed greater presurgical activation and postsurgical reduction comparable to HC levels but increased in WL between time points. Similarly, left striatal parametric response to reward value reduced after surgery to HC levels; WL did not change. Memory-related medial temporal activation did not change in any group. CONCLUSIONS: Results provide pilot evidence for functional brain changes induced by VSG in adolescents with severe obesity. Weight loss and gain were paralleled by reduced and increased prefrontal activation, respectively, suggesting neural plasticity related to metabolic change.

The Influence of Televised Food Commercials on Children's Food Choices: Evidence from Ventromedial Prefrontal Cortex Activations.

OBJECTIVE: To investigate how food commercials influence children's food choices. STUDY DESIGN: Twenty-three children ages 8-14 years provided taste and health ratings for 60 food items. Subsequently, these children were scanned with the use of functional magnetic resonance imaging while making food choices (ie, "eat" or "not eat") after watching food and nonfood television commercials. RESULTS: Our results show that watching food commercials changes the way children consider the importance of taste when making food choices. Children did not use health values for their food choices, indicating children's decisions were largely driven by hedonic, immediate rewards (ie, "tastiness"); however, children placed significantly more importance on taste after watching food commercials compared with nonfood commercials. This change was accompanied by faster decision times during food commercial trials. The ventromedial prefrontal cortex, a reward valuation brain region, showed increased activity during food choices after watching food commercials compared with after watching nonfood commercials. CONCLUSION: Overall, our results suggest watching food commercials before making food choices may bias children's decisions based solely on taste, and that food marketing may systematically alter the psychological and neurobiologic mechanisms of children's food decisions.

Healthy eating decisions require efficient dietary self-control in children: A mouse-tracking food decision study.

Learning how to make healthy eating decisions, (i.e., resisting unhealthy foods and consuming healthy foods), enhances physical development and reduces health risks in children. Although healthy eating decisions are known to be challenging for children, the mechanisms of children's food choice processes are not fully understood. The present study recorded mouse movement trajectories while eighteen children aged 8-13 years were choosing between eating and rejecting foods. Children were inclined to choose to eat rather than to reject foods, and preferred unhealthy foods over healthy foods, implying that rejecting unhealthy foods could be a demanding choice. When children rejected unhealthy foods, mouse trajectories were characterized by large curvature toward an eating choice in the beginning, late decision shifting time toward a rejecting choice, and slowed response times. These results suggested that children exercised greater cognitive efforts with longer decision times to resist unhealthy foods, providing evidence that children require dietary self-control to make healthy eating-decisions by resisting the temptation of unhealthy foods. Developmentally, older children attempted to exercise greater cognitive efforts for consuming healthy foods than younger children, suggesting that development of dietary self-control contributes to healthy eating-decisions. The study also documents that healthy weight children with higher BMIs were more likely to choose to reject healthy foods. Overall, findings have important implications for how children make healthy eating choices and the role of dietary self-control in eating decisions.

The child brain computes and utilizes internalized maternal choices.

As children grow, they gradually learn how to make decisions independently. However, decisions like choosing healthy but less-tasty foods can be challenging for children whose self-regulation and executive cognitive functions are still maturing. We propose a computational decision-making process in which children estimate their mother's choices for them as well as their individual food preferences. By employing functional magnetic resonance imaging during real food choices, we find that the ventromedial prefrontal cortex (vmPFC) encodes children's own preferences and the left dorsolateral prefrontal cortex (dlPFC) encodes the projected mom's choices for them at the time of children's choice. Also, the left dlPFC region shows an inhibitory functional connectivity with the vmPFC at the time of children's own choice. Our study suggests that in part, children utilize their perceived caregiver's choices when making choices for themselves, which may serve as an external regulator of decision-making, leading to optimal healthy decisions.

Apples or candy? Internal and external influences on children's food choices.

The goal of this concise narrative review is to examine the current literature regarding endogenous and exogenous influences on youth food choices. Specifically, we discuss internal factors such as interoception (self-awareness) of pain and hunger, and neural mechanisms (neurofunctional aspects) of food motivation. We also explore external factors such as early life feeding experiences (including parenting), social influences (peers), and food marketing (advertising). We conclude with a discussion of the overlap of these realms and future directions for the field of pediatric food decision science.

Can neural activation in dorsolateral prefrontal cortex predict responsiveness to information? An application to egg production systems and campaign advertising.

Consumers prefer to pay low prices and increase animal welfare; however consumers are typically forced to make tradeoffs between price and animal welfare. Campaign advertising (i.e., advertising used during the 2008 vote on Proposition 2 in California) may affect how consumers make tradeoffs between price and animal welfare. Neuroimaging data was used to determine the effects of brain activation in dorsolateral prefrontal cortex (dlPFC) on choices making a tradeoff between price and animal welfare and responsiveness to campaign advertising. Results indicated that activation in the dlPFC was greater when making choices that forced a tradeoff between price and animal welfare, compared to choices that varied only by price or animal welfare. Furthermore, greater activation differences in right dlPFC between choices that forced a tradeoff and choices that did not, indicated greater responsiveness to campaign advertising.

Neurofunctional correlates of ethical, food-related decision-making.

For consumers today, the perceived ethicality of a food's production method can be as important a purchasing consideration as its price. Still, few studies have examined how, neurofunctionally, consumers are making ethical, food-related decisions. We examined how consumers' ethical concern about a food's production method may relate to how, neurofunctionally, they make decisions whether to purchase that food. Forty-six participants completed a measure of the extent to which they took ethical concern into consideration when making food-related decisions. They then underwent a series of functional magnetic resonance imaging (fMRI) scans while performing a food-related decision-making (FRDM) task. During this task, they made 56 decisions whether to purchase a food based on either its price (i.e., high or low, the "price condition") or production method (i.e., with or without the use of cages, the "production method condition"), but not both. For 23 randomly selected participants, we performed an exploratory, whole-brain correlation between ethical concern and differential neurofunctional activity in the price and production method conditions. Ethical concern correlated negatively and significantly with differential neurofunctional activity in the left dorsolateral prefrontal cortex (dlPFC). For the remaining 23 participants, we performed a confirmatory, region-of-interest (ROI) correlation between the same variables, using an 8-mm3 volume situated in the left dlPFC. Again, the variables correlated negatively and significantly. This suggests, when making ethical, food-related decisions, the more consumers take ethical concern into consideration, the less they may rely on neurofunctional activity in the left dlPFC, possibly because making these decisions is more routine for them, and therefore a more perfunctory process requiring fewer cognitive resources.

Robust relation between temporal discounting rates and body mass.

When given the choice between $100 today and $110 in 1 week, certain people are more likely to choose the immediate, yet smaller reward. The present study examined the relations between temporal discounting rate and body mass while accounting for important demographic variables, depressive symptoms, and behavioral inhibition and approach. After having their heights and weights measured, 100 healthy adults completed the Monetary Choice Questionnaire, the Beck Depression Inventory-II, and the Behavioral Inhibition Scale/Behavioral Approach Scale. Overweight and obese participants exhibited higher temporal discounting rates than underweight and healthy weight participants. Temporal discounting rates decreased as the magnitude of the delayed reward increased, even when other variables known to impact temporal discounting rate (i.e., age, education level, and annual household income) were used as covariates. A higher body mass was strongly related to choosing a more immediate monetary reward. Additional research is needed to determine whether consideration-of-future-consequences interventions, or perhaps cognitive control interventions, could be effective in obesity intervention or prevention programs.

Brain responses to food logos in obese and healthy weight children.

OBJECTIVE: To evaluate brain activation in response to common food and nonfood logos in healthy weight and obese children. STUDY DESIGN: Ten healthy weight children (mean body mass index in the 50th percentile) and 10 obese children (mean body mass index in the 97.9th percentile) completed self-report measures of self-control. They then underwent functional magnetic resonance imaging while viewing food and nonfood logos. RESULTS: Compared with the healthy weight children, obese children showed significantly less brain activation to food logos in the bilateral middle/inferior prefrontal cortex, an area involved in cognitive control. CONCLUSION: When shown food logos, obese children showed significantly less brain activation than the healthy weight children in regions associated with cognitive control. This provides initial neuroimaging evidence that obese children may be more vulnerable to the effects of food advertising.