in the past forty - five years , the incidence of obesity in the pediatric population in the united states has more than tripled , with approximately one in three children aged 219 classified as overweight ( body mass index ( bmi ) 8594% for age and sex ) or obese ( bmi 95% for age and sex ) . while it is clear that obesity correlates with negative health outcomes such as hypertension and type ii diabetes , mounting evidence now links obesity to poorer adult cognitive functioning [ 24 ] . specifically , studies demonstrate an association between adult obesity and decreased cortical gray matter volume with poorer performance on cognitive assessments [ 2 , 3 , 58 ] . one theory is that decreased cognition results from the hypertensive effects , often comorbidity with obesity . elias and colleagues determined that hypertension and obesity together have a cumulative negative relationship with cognition ; however they also predict poorer cognition independently . the interplay between obesity and brain function relates to executive function ( ef ) , which refers to self - regulatory cognitive processes that are associated with monitoring and controlling both thought and goal - directed behaviors [ 4 , 11 ] . there are several domains of ef , including ( 1 ) inhibitory control ( suppression of actions that are inappropriate in a given context and that interfere with a goal - driven behavior ) , ( 2 ) attention ( the ability to maintain a consistent behavioral response during continuous and repetitive activity ) and the closely related concept of mental flexibility ( disengagement of an irrelevant task set and subsequent engagement of a relevant task set despite interference and/or priming ) , ( 3 ) reward sensitivity ( the relative dominance of the behavioral activation system driving motivated behavior associated with risk - taking behavior ) , and ( 4 ) working memory ( active maintenance and flexible updating of goal / task relevant information with limited capacity ) . because the vast majority of studies investigating the relationship between obesity and varying domains of executive function are cross - sectional rather than longitudinal , there is a question of directionality in the relationship [ 4 , 12 ] . predisposition to obesity could include a dysregulation of specific limbic neural circuits connected with the orbitofrontal cortex [ 9 , 12 ] , given that these limbic circuits and the orbitofrontal cortex are associated with the inhibitory dimension of ef . in prior studies , the orbitofrontal cortex volume is positively associated with high quality food choices and performance on measures of executive function . rothemund and colleagues compared activity levels of the dorsal striatum , associated with reward anticipation and habit learning , and the ofc in obese versus lean adults with functional magnetic resonance imaging ( fmri ) . this comparative hyperactivation of the ofc in obese individuals could suggest that this cortical area is working harder to suppress chronically hyperactive appetite - stimulating areas . alternatively , obesity could induce development of neural dysfunction . in a longitudinal study , sabia and bmi measurements were attained from subjects during early adulthood ( mean age = 25 ) , early midlife ( mean age = 44 ) , and late midlife ( mean age = 61 ) . results revealed that being obese at 2 - 3 of these time points was associated with lower scores of executive function , even after adjusting for age , sex , and education difference . poorer executive function was also associated specifically with a large increase in bmi between early and late midlife . in a separate longitudinal study , gustafson determined that risk of atrophy of the temporal lobe increased 1316% per 1.0  kg / m increase in bmi . however , the study did not find significant evidence of atrophy in the frontal , occipital , or parietal lobes . if obesity does have a detrimental effect on the brain , it would stand to reason that it is important to prevent the development of obesity during a critical period of brain development , particularly during the development of executive function which has been closely correlated with academic success , social function , and emotional control [ 1921 ] . for example , working memory and inhibition are associated with achievements in english , mathematics , and science for 11- and 12-year - old children . several studies have shown that children aged 35 undergo significant and rapid development of executive function which continues to mature into adolescence [ 2226 ] . the prefrontal cortex so closely associated with executive function may be the last region of the brain to mature , and each dimension of ef ( e.g. , inhibition , shifting , and working memory ) may have its own developmental trajectory and timeline [ 20 , 25 , 26 ] . therefore , executive function is quite vulnerable to a stressor such as obesity during childhood . there is an obvious need for novel prevention and intervention strategies to curb the childhood obesity epidemic . enhancing our understanding of neural mechanisms associated with pediatric obesity could direct these future strategies . as evidenced above , there is a relationship between bmi and executive function in adults , but there still remains a question of causality . in children and adolescents , the relationship between these two variables is less clearly established . therefore to guide future pediatric obesity prevention efforts , this systematic literature review will seek to answer the question ,  what is the relationship between executive function and obesity in children and adolescents ?  to better understand the potential mechanisms that might link ef and obesity , we also included an assessment of the neurostructural published studies and obesity . lastly , we collected data regarding how frequently cognitive function was evaluated , given that it is considered a possible mediator of executive function . we conducted a systematic literature review , with eligibility criteria and search strategy created a priori   and based on the cochrane handbook of systematic reviews . a broad search was conducted using the keywords : executive function , children , and obesity , to determine the central executive function ( ef ) domains evaluated in current studies . inhibitory control , attention / mental flexibility , reward sensitivity , and working memory were the four recurrent domains determined . as a result of this preliminary search , the final keywords utilized for the investigation were executive function , inhibitory control , attention , mental flexibility , reward sensitivity , working memory , cognitive function , prefrontal cortex , orbitofrontal cortex , bmi , obesity , adolescence , pre - school , and healthy children . the reviewer assessed the abstract for inclusion criteria and then examined each full - text report for quality assessment and data extraction . inclusion criteria included english language ages 218 all races , ethnicities , and genders , healthy participants , excluding obesity and randomized controlled trials ( rcts ) , meta - analysis , longitudinal studies , cross - sectional studies , prospective and retrospective review studies and those published since the year 2000 . studies excluded measured ef performance in children who had additional diagnoses in addition to being overweight ( e.g. , adhd , type ii diabetes , and sleep apnea ) , instituted an intervention which altered ef performance ( e.g. , aerobic exercise ) , or measured fitness rather than obesity . studies were organized according to variables evaluated : executive function ( ef ) orbitofrontal ( ofc ) and prefrontal ( pfc ) cortices , or cognitive function . for studies included pertaining to ef , information extracted during the literature review included bmi or bmi percentile of subject groups , age of pediatric population studied , method of measurement of ef , and comparative differences in ef task performance . for studies included pertaining to ofc or pfc imaging , information extracted during the literature review included weight classification of subjects , age of pediatric population studied , method of ofc and pfc imaging , and comparative differences in ofc and pfc structure and function . for studies pertaining to cognitive functioning , information extracted included whether this variable was measured as a mediator of ef or independent of ef , method of cognitive function assessment , and results . we reviewed 1,065 unique abstracts : 31 from pubmed , 87 from google scholar , 16 from science direct , and 931 from psycinfo . of those abstracts , 28 met inclusion criteria and were reviewed . from the articles reviewed , additional 3 articles were added from article references ( n = 31 ) . twenty - three studies pertained to executive function ( 2 also studied the prefrontal and orbitofrontal cortices ; 6 also studied cognitive function ) , five studied the relationship between obesity and prefrontal and orbitofrontal cortices , and three evaluated cognitive function and obesity . of the 31 abstracts which met inclusion criteria , 23 examined executive function ( ef ) . table 1 summarizes the results , examining each of the ef domains measured , specifying the age of participants , indicating the method of ef domain assessment , and relating the association of each ef domain with obesity . table 2 illustrates the relative distribution of the total number of studies conducted in childhood versus adolescent pediatric subjects , specific to ef domains . the 4  ef domains examined were inhibitory control , reward sensitivity , attention , and working memory ( table 1 ) . inhibitory control was most often examined ( 76.9% ) in the childhood studies ( table 2 ) . a range of tasks measured this ef domain and included delay of gratification task , self - control task , children 's behavior questionnaire , classroom engagement , social behavior questionnaire , go - no go task , behavioral rating inventory of executive functioning ( self - report ) , and incompatibility task of attention assessment battery . despite the great variability in assessment methods , the studies together demonstrate an association between higher childhood bmis for age and poorer performance on inhibitory control tasks [ 2936 ] . additionally , some studies demonstrated the predictive value of inhibitory control at a young age : poorer performance at a young age ( 27 years ) predicted a higher bmi at a later age ( 5.515 years ) ( refer to table 1 ) . conversely , a better inhibitory performance at age 6 predicted a healthier bmi at age 10 - 11 .   the remaining 3 alternative ef domains ( attention , reward sensitivity , and working memory ) each had few representative studies and therefore corresponded to only 38.4% of the total number of studies examining the relationship between ef and obesity in the pediatric population . obese females were shown to have poorer ability to focus attention compared to healthy females , but this relationship was not evidenced in males . reward sensitivity was associated with impulsivity and proven to significantly predict bmi indirectly through propensity to overeat , assessed by parent - reported child 's eating behavior questionnaire ( p < 0.001 ) . huh et al . elucidated five latent classes of obesity risk in 4th grade children based on their behavior :   ( 1 ) high sedentary behavior , high fat / high sugar ( hf / hs ) intake , and weight conscious ; ( 2 ) high sedentary behavior , hf / hs intake , and not weight conscious ; ( 3 ) dieting without exercise , weight conscious ; ( 4 ) active , healthy eating ; ( 5 ) low healthy , snack food , inactive , and not weight conscious . they noted a significant association between classification and child weight status ( p < 0.001 ) . specifically , riggs et al . determined that youth who were classified as class 1 , 2 , or 3 , demonstrated significantly poorer working memory than children in the two healthier classes ( p < 0.001 ) . there were 4 main ef domains evaluated : inhibitory control , attention / mental flexibility , reward sensitivity , and working memory . a range of tasks measured inhibitory control and included go - no go task , incompatibility task of attention assessment battery , stop signal task , iowa gambling task , stroop task , five - digit test , and computerized cognitive test battery . obese individuals demonstrated less inhibitory control than healthy weight adolescents , and poor performance on inhibitory control tasks was associated with smaller orbitofrontal cortex volume in obese teenagers ( refer to table 1 ) . one study which aimed to evaluate inhibitory control suggested that the variability of responses to their tasks indicated lapses in attentional ability rather than inhibitory control . the second most examined ef domain in adolescents was both mental flexibility and attention , which were evaluated by 27.3% of the adolescence studies ( table 2 ) . included studies used the following tasks : trail - making test , wisconsin card - sorting test , computerized cognitive test battery , five - digit test switching , color - word interference test stroop , and d2 attention endurance test ( refer to table 1 ) . for every one of these tasks , obese adolescents performed worse than healthy weight participants ( table 1 ) . within obese participants , bmi was inversely related to performance on the color - word interference test stroop ( table 1 ) . working memory and reward sensitivity had only one representative study each ( 9.0% ) ( table 2 ) . similar to attention / mental flexibility , working memory performance of obese adolescents was significantly worse than that of the healthy weight controls , even after controlling for iq ( 110.7  13.3 versus 99.4  13.8 ;  p < 0.001 ) . nine of the 31 articles ( 29.0% ) included in this paper included cognitive function as well as ef . a third of these studies examined cognitive function as a mediator of executive function and therefore controlled for the subject 's intelligence quotient or academic performance when determining the association between ef and obesity . all of these studies noted an inverse relationship between excess weight and performance on ef tasks even after controlling for general cognitive function . the remaining two - thirds of articles examined the association between general cognitive function and obesity . one study examined this in children using the planning subtest of the cognitive assessment system , which pertains to aspects of ef including strategy generation and application , self - regulation , intentionality , and utilization of knowledge . performance was significantly inversely related to both waist girth ( p < 0.05 ) and body fat ( p < 0.01 ) of children 711 year olds . brain imaging indicates specific areas of the brain where different domains of ef function , specifically the dorsolateral prefrontal cortex ( dlpfc ) and the orbitofrontal cortex ( ofc ) [ 4 , 54 , 55 ] . in our systematic literature review , we found 7 studies which examined the relationship between these areas of interest in the brain and obesity in adolescents ( refer to table 3 ) . all 7 of the included studies evaluated the ofc , while only 3 assessed the dlpfc . the literature research yielded no data available for the pediatric population under the age of 9 years old . three studies examined the reactivity of the dlpfc and ofc in response to food images using functional magnetic resonance imaging ( fmri ) ( table 3 ) . obese subjects demonstrated significantly ( p < 0.001 ) greater activation of the pfc ( before meal ) and significantly ( p < 0.001 ) less reduction of activation of the pfc ( aftermeal ) compared to healthy weight controls . davids et al . also found that obese subjects had hyperactivity in the dlpfc compared to healthy weight controls in response to food cues ( left dlpfc , t = 3.23 , p < 0.001 ; right dlpfc , t = 2.65 , p < 0.006 ) , but did not explicitly control for pre- and after meal states . the ofc of obese subjects was also highly activated in obese subjects after meal compared to healthy weight controls ( p < 0.001 ) . more directly evaluated the relationship between ef and obesity by using fmri to evaluate the ofc , while female participants performed a go - no go task , a classic test of inhibition . this behavioral task presents stimuli in a continuous stream , and subjects perform a binary decision with each stimulus . one stimulus requires a motor response ( go ) , while the other requires the withholding of a response ( no go ) . body mass index was negatively correlated with ofc activation during performance of the task ( p = 0.05 ) . also combined imaging analyses with performance of a go - no go task and used magnetic resonance imaging to significantly negatively correlate subject performance with individual ofc volume ( 32.3  3.68 versus 33.3  3.99 ; p = 0.005 ) , thereby linking higher bmi with poorer performance on inhibitory control tasks and smaller ofc grey matter volumes . this indicates that neurostructural deficits associated with obesity and exhibited in behavioral cognitive tasks are apparent by the age of adolescence . burger and stice correlated the dietary restraint score of subjects to their activation of the ofc and dlpfc in response to milkshake anticipation , milkshake receipt , and food images . elevated activity of right ofc ( r = 0.57 ) and bilateral dlpfc ( right , r = 0.49 ; left , r = 0.55 ) in subjects in response to milkshake receipt was positively correlated with restraint scores . this relationship suggests hypersensitivity to reward during ingestion of food , which could potentiate risk for obesity . there was no correlation of frontal cortical area activity in neither response to milkshake anticipation nor in response to food images . as we strive for progress in the development of interventions to curb the pediatric obesity epidemic , we review what we know in order to direct us towards what we need to know . many studies have revealed the interplay between executive function ( ef ) and obesity in the adult population ; however , few studies demonstrate the extent to which this relationship exists in children and adolescents . we examined 31 studies which met inclusion criteria , and 23 of these evaluated at least one of the 4 common ef domains in our population of interest . in both childhood and adolescence , inhibitory control is associated with bmi and with less control associated with higher bmis . poor performance on inhibitory control tasks at age 2 was correlated with higher bmi at age 5.5 even after controlling for age 2 bmi . poor performance at ages 3 and 5 correlated with higher bmi up to at least the age of 12 and the most rapid weight gain 312 years ; however , this study did not control for baseline bmi . poor performance at age 7 significantly predicted bmi at each subsequent time point of ages 7 ( p < 0.001 ) , 9 ( p < 0.001 ) , 11 ( p < 0.001 ) , 13 ( p < 0.001 ) , and 15 ( p < 0.001 ) , but this study only examined hispanic female children . better performance at age 6 significantly correlated with a healthier weight at ages 9 - 10 , even after controlling for baseline bmi , sports participation , child cognitive skills , and preexisting family characteristics ( p = 0.030 ) . the orbitofrontal cortex correlates with inhibitory behavior as measured by functional magnetic resonance imaging ( fmri ) and magnetic resonance imaging ( mri ) . the studies identified through this systematic literature review revealed that both the function and the anatomy of the ofc were altered as evidenced by fmri and mri data ( see table 3 ) . however , it is important to note that this relationship was only investigated in youth aged 9 and older . thus , it isnot clear when the structure and the function were initially altered or if this could be reversed . while obese adolescents showed a decreased level of activation of ofc before meal versus healthy weight controls , they showed elevated ofc activity after meal , functioning inversely to the patterns seen in the lean controls . this could suggest the development of resistance to signaling in the obese adolescent . before meal the obese adolescent does not demonstrate an inhibitory control signal as strongly as a healthy weight subject , but after meal the obese adolescent shows an elevated inhibitory signal compared to the healthy weight subject , showing a compensatory effect in which the brain ramps up its signaling in attempt to produce a correlated higher bmi with a greater number of errors in an inhibitory control behavioral task . maayan et al . contributes to this finding by revealing that there is a negative correlation between bmi , overall performance on an inhibitory control behavioral task , and ofc gray matter volume . this indicates that there is a difference in neuroanatomy of obese individuals that is detectable behaviorally by the early age of 15 years . this difference in orbitofrontal volumes is especially important during the adolescent years , when the patterning of activity in the ofc of adolescents resembles that of children , and the nucleus accumbens ( reward center ) patterning of activity resembles that of adults , which serves to predispose adolescents to risk - taking behavior with little self - regulation . in addition to inhibitory control alterations , this paper found differences in the ef domains of attention / mental flexibility , reward sensitivity , and working memory , associated with obesity in both child and adolescent populations . unfortunately , each of these domains and age groups had few representative studies . in addition , the studies that evaluated multiple domains disagreed about the validity of the differences evidenced in each . for example , verdejo- garca et al . studied adolescents aged 1316 and found significant differences in obese versus healthy weight subjects within the ef domains of inhibition and mental flexibility . however , the study did not find significant differences in the ef domains of working memory , planning , and reasoning . in contrast , cserjsi et al . found significant differences in working memory as well as attention , but not for intelligence or verbal fluency . the reason for contrary findings among studies may be due to variability of testing method , as evidenced in table 1 . despite the advantage that the studies included in this paper examined different age ranges , this was confounded by the variability among ef assessment method , even when evaluating the same ef domain . future research should aim to use a more uniform assessment method , to allow for better comparison of findings and the formation of a more accurate account of the relationship that exists between obesity and executive function in youth . the national institutes of health has recently developed an executive functioning toolkit to create clearer consistency of methodology and assessment . this systematic review reveals a consistent inverse association between obesity and executive function in children and adolescents . this could be accomplished by longitudinal assessments that apply uniform measurement approaches to assess the executive function of participants . baseline measurements of children 's bmi and performance on ef tasks can serve to confirm the existence of a negative correlation between these two variables , while later time points can examine how the ef changes overtime in accordance with changing bmi . given that cognitive function may be a mediator of executive function , future studies should consider controlling for the intelligence quotient or baseline academic success of participants when evaluating ef . if it is determined that executive dysfunction could predispose a child to obesity , this would inform early intervention strategies . additional studies would need to establish the extent of decline exhibited as children and adolescents develop and the possibility of reversing the dysfunction . it is important to note that physical activity has been associated with improving ef in children and therefore should remain an integral part of any obesity intervention strategy . conversely , if it is determined that lower ef abilities predispose a child to obesity , prevention and intervention strategies should focus on the early improvement of the child 's executive function in addition to the teaching of healthy behaviors . riggs et al . emphasized changing child impulse control , decision making , and social competence in an intervention strategy . the study found that children demonstrated significant changes in positive attitude towards both self - regulation and appetitive behavior . pauli - pott et al . studied children aged 7.515 years and found that performance on inhibitory control tasks was positively associated with the ability to lose weight during a 1-year intervention program , but this association pertained more to adolescents than younger children . taken together , these studies evidence the idea that perhaps a successful intervention program would focus on the improvement of executive function , with particular emphasis on the inhibitory control domain , in addition to healthy behaviors such as eating well and exercise . perhaps it is not sufficient to focus solely on how children eat and move , but it is necessary to build on how they think . this type of publication bias could lead to an incomplete understanding of the current state of knowledge about the association between ef and childhood / adolescent obesity . future research examining the link and directionality between ef and childhood obesity should be longitudinal rather than cross - sectional and use a uniform method of ef measurement to direct future intervention strategies .
the objective of this paper is to examine the relationship between the development of executive function ( ef ) and obesity in children and adolescents . 
 we reviewed 1,065 unique abstracts : 31 from pubmed , 87 from google scholar , 16 from science direct , and 931 from psycinfo . 
 of those abstracts , 28 met inclusion criteria and were reviewed . from the articles reviewed , an additional 3 articles were added from article references ( n = 31 ) . 
 twenty - three studies pertained to ef ( 2 also studied the prefrontal and orbitofrontal cortices ( ofcs ) ; 6 also studied cognitive function ) , five studied the relationship between obesity and prefrontal and orbitofrontal cortices , and three evaluated cognitive function and obesity . 
 inhibitory control was most often studied in both childhood ( 76.9% ) and adolescent ( 72.7% ) studies , and obese children performed significantly worse ( p < 0.05 ) than healthy weight controls on various tasks measuring this ef domain . 
 although 27.3% of adolescent studies measured mental flexibility , no childhood studies examined this ef domain . 
 adolescents with higher bmi had a strong association with neurostructural deficits evident in the ofc . 
 future research should be longitudinal and use a uniform method of ef measurement to better establish causality between ef and obesity and consequently direct future intervention strategies .