Executive functioning and behavioral impulsivity of young women who binge eat

Authors

  • Nichole R. Kelly MS,

    Corresponding author
    1. Department of Psychology, Virginia Commonwealth University, Richmond, Virginia
    • Department of Psychology, Virginia Commonwealth University, Richmond, VA
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  • Cynthia M. Bulik PhD,

    1. Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
    2. Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
    Search for more papers by this author
  • Suzanne E. Mazzeo PhD

    1. Department of Psychology, Virginia Commonwealth University, Richmond, Virginia
    2. Department of Pediatrics, Virginia Commonwealth University, Richmond, Virginia
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Abstract

Objective:

To examine the link between binge eating, executive functioning, and behavioral impulsivity.

Method:

Fifty women who reported engaging in weekly binge eating in the absence of regular compensatory behaviors and 66 women with no history of binge eating completed several self-report questionnaires and a brief neuropsychological battery, including the Wisconsin Card Sorting Task and Conner's Continuous Performance Task.

Results:

Hierarchical regression analyses revealed that groups did not differ in executive functioning after controlling for depression, anxiety, body mass, general intelligence, and psychotropic medication use. Correlation analyses suggest that individuals who endorse more frequent binge eating might have greater difficulties thinking flexibly or shifting attention. Individuals who binge eats are also more likely to behave impulsively, but only for emotional reasons.

Discussion:

Although this study is unable to determine whether these cognitive and behavioral factors precede or follow binge-eating episodes, outcomes have implications for treatment and prevention. © 2013 by Wiley Periodicals, Inc. (Int J Eat Disord 2013)

Introduction

A deeper understanding of the neuropsychological functioning of individuals with eating disorders (EDs) is important as it provides direction for the psychological and pharmacological treatment of these disorders.1 In addition, the identification of neuropsychological impairments associated with EDs has the potential to provide an objective means of evaluating symptom severity and prognosis.2 Despite the clear advantages of neuropsychological research in EDs, most of this work has focused on individuals with anorexia nervosa (AN) and bulimia nervosa (BN),2 and little research has investigated individuals who engage in binge eating in the absence of regular compensatory behaviors.

Binge Eating

Binge eating, or the consumption of an amount of food that is larger than most people would eat during a similar period of time and under similar circumstances accompanied by a sense of loss of control,3 is prevalent and found among a wide range of racially/ethnically diverse individuals.4–6 This eating behavior is also associated with numerous psychosocial comorbidities, including depression, low self-esteem, and body dissatisfaction,5–10 and it has been implicated in the onset of threshold EDs.11, 12 In addition, women with subthreshold levels of binge eating report social impairment and emotional distress at levels comparable to those of women with threshold binge eating disorder (BED9). Further, although many adults who binge eat are obese,7, 10 the negative psychological correlates of binge eating do not appear to be attributable to obesity.13–16 Thus, binge eating represents a significant public health concern.17 Nonetheless, research has only recently started to investigate the neuropsychological and behavioral correlates of this behavior. Preliminary research suggests binge eating may be related to both executive dysfunction and behavioral impulsivity.

Executive Functioning and Binge Eating

Executive functioning “consists of those capacities that enable a person to engage successfully in independent, purposive, self-serving behavior”(p. 35).18 In turn, executive dysfunction includes decrements in planning, difficulties demonstrating inhibition, heightened impulsivity, cognitive rigidity, and problems with shifting attention.18 Thus, impairments in executive functioning can significantly impede one's ability to carry out goal-directed behaviors, and to inhibit impulsive behavior, such as binge eating.

To examine the association between binge eating and executive functioning, Svaldi et al.19 assessed the neuropsychological functioning of 17 women with BED and 18 healthy controls. Women with BED demonstrated less cognitive flexibility and greater impairments in decision-making skills compared to those in the control group. A similar association between binge eating and executive dysfunction was identified by Duchesne et al.20 In their investigation, 30 obese participants with BED and 38 obese participants without BED were matched with respect to their estimated intelligence, age, and education. Participants in both groups completed a number of neuropsychological tests assessing a range of executive functions, including the Wisconsin Card Sorting Task (WCST).21 Relative to the control group, participants with BED had significantly more perseverative errors and greater difficulties maintaining set, suggesting greater cognitive rigidity and difficulties shifting attention. Planning and problem-solving abilities were also lower in the binge eating group.20

In contrast, outcomes from two recent studies did not provide evidence for a link between executive dysfunction and binge eating.22, 23 Davis et al.22 used several neuropsychological measures to examine the decision-making abilities of three groups of women: (1) obese with BED, (2) obese without BED, and (3) normal weight. Results indicated that obese women with and without BED had poorer decision-making skills than the normal weight group, but were not significantly different from one another. However, these statistical differences disappeared when the authors controlled for education level; normal weight individuals had significantly more education. The authors attributed this confound to the inverse association between obesity and socioeconomic status (SES),24 although SES was not evaluated. Similarly, Galioto et al.23 examined the executive function of morbidly obese individuals with current or previous BED (n = 41) and those without BED (n = 90) and did not find any significant group differences. Interestingly, clinical levels of cognitive impairment (i.e., scores 1.5 standard deviations [SD] below mean) were evident in both groups.

Binge Eating and Behavioral Impulsivity

Although neuropsychological studies have yielded mixed outcomes regarding executive functions, such as cognitive impulsivity, investigations examining structural and functional brain abnormalities among individuals engaging in binge eating are more consistent. For example, Schafer et al.25 found greater gray matter volume in the medial orbitofrontal cortex of individuals with BED relative to a normal sample. The orbitofrontal cortex has been implicated in a number of cognitive and behavioral processes commonly engaged before, during, and after eating, including decision-making, inhibition, hunger, and satiety.26, 27 Although it is unclear whether localized abnormalities in the brain represent risk factors for or artifacts of binge eating, Schafer et al. propose that they might be linked to processes identified via functional neuroimaging. Specifically, the orbitofrontal cortex is more reactive when exposed to food, which has been attributed to alterations in reward processing associated with the anticipation of eating something pleasurable.28–32

Similarly, some individuals with frontotemporal dementia exhibit binge eating behavior despite reporting satiety, and also manifest heightened preferences for sweet foods.33, 34 Relative to non-overeating individuals with dementia and healthy controls, individuals in Woolley et al.'s34 study also showed significantly more atrophy in the right ventral insula and right rostral orbitofrontal cortex, regions of the brain associated with responding to food cravings and emotional awareness; the more disinhibition, the greater the atrophy. Taken together, preliminary investigations of brain abnormalities support the idea that, when exposed to desirable foods, some individuals are more likely to binge eat, perhaps in part due to a heightened sense of reward associated with the intake of such foods and/or difficulties using cognitive skills that might inhibit that behavior (behavioral impulsivity) or consider other options (problem-solving).

In further support of this notion, binge eating has also been linked to self-reported difficulties with general behavioral inhibition.35–37 For example, Anestis et al.35 found that people who endorsed higher levels of behavioral impulsivity were more likely to binge eat. Similarly, undergraduate women who reported greater tendencies to act impulsively in the face of distress were also more likely to binge eat.36 Disinhibited eating behavior, or overeating, has been significantly correlated with brief behavioral descriptors indicative of frontal lobe damage (e.g., repeats same mistakes), the part of the brain associated with executive dysfunction.37, 38

Until recently, behavioral impulsivity has frequently been conceptualized as a unidimensional construct. In their review of 222 studies, Fischer et al.39 found that, relative to other domains of behavioral impulsivity (i.e., lack of planning, lack of perseverance, and sensation seeking), negative urgency, or “the tendency to engage in impulsive behaviors under conditions of negative affect…despite the potentially harmful longer-term consequences” (p.561),40 demonstrated the strongest relationship with binge eating. As a result, these authors recommended the use of a multidimensional assessment of impulsivity.

Summary and Aims

Considered together, both cognitive and behavioral systems influence binge eating. Additional investigations of these systems in the context of binge eating are needed to elucidate factors contributing to the onset and/or maintenance of this disordered eating behavior. Moreover, cognitive and behavioral difficulties, such as problems making decisions, considering alternative solutions, and inhibiting impulsive behavior, might hinder efforts to reduce binge-eating behavior. Indeed, neuropsychological deficits are linked to treatment outcomes among those with EDs; the greater the number of cognitive deficits, the worse the long-term prognosis.41 Similarly, impulsivity is one of the most powerful predictors of treatment drop out among individuals with EDs.42 It is therefore critical to gain a better understanding of the neuropsychological and behavioral dysfunctions associated with binge eating as they might prove to be useful intervention targets.

The purpose of this study was to assess the executive functioning of young women engaging in weekly binge eating in the absence of regular compensatory behavior and compare their outcomes to a control sample of young women without binge eating behavior. Variables previously associated with executive functioning (i.e., depression, state anxiety, BMI, and estimated intelligence) served as covariates.43–46 It was hypothesized that young women who engaged in binge eating would demonstrate poorer executive functioning (i.e., a more impulsive cognitive style, greater difficulties with shifting and/or maintaining set, greater cognitive rigidity) compared with those who did not binge eat. A secondary aim of this study was to explore between-group differences in behavioral impulsivity. Considering the link between BMI and poorer psychosocial functioning across multiple domains,47 including emotional impulsivity,48 individual differences in participants' BMI were controlled in these analyses. Increased depressive symptomatology has also been linked to greater behavioral impulsivity,49–51 and it was therefore included as a covariate in analyses of the secondary aim. It was hypothesized that individuals in the binge-eating group would report higher behavioral impulsivity (particularly negative urgency)39 relative to their non-bingeing peers.

Method

Procedure

This study was a between-groups design comprised of two parts. Part I included a series of self-report questionnaires completed in a large computer laboratory with an online database. Questionnaires were randomized to avoid response habituation. Height and weight were collected by research staff in a separate room. Part II entailed the completion of a brief neuropsychological battery (in which the order of assessments was also randomized). Prior to participating in the current study, participants provided consent in person, procedures for which were conducted in accordance with the Institutional Review Board. Participants were recruited from undergraduate psychology classes and received course credit for their involvement.

Part I: Measures

Demographic Questionnaire

Participants were asked to provide information regarding their age, year in school, race/ethnicity, psychotropic medication use, previous brain injuries, and presence of medical conditions that could greatly influence their eating (e.g., Prader-Willi Syndrome).

Body Mass Index (BMI)

Height and weight were ascertained in-person, using a digital scale and stadiometer, respectively, in a private area, and BMI was calculated.

Eating Disorder Examination-Self-report Questionnaire

Binge eating behavior was assessed with the Eating Disorder Examination-Self-report Questionnaire (EDE-Q),52 a 41-item instrument adapted from a structured clinical interview (i.e., EDE). Good 2-week test–retest reliability for this measure was ascertained in an undergraduate sample of women (.81).53 In other studies, EDE and EDE-Q subscales were significantly correlated (r = .60–.77), suggestive of adequate convergent validity.54, 55 To ensure disparate binge and non-binge eating groups, an additional item was added to this measure to assess for the presence of lifetime binge eating behaviors.

Center for Epidemiological Studies Depression Scale

The Center for Epidemiological Studies Depression Scale (CES-D) is a 20-item self-report measure of depressive symptomatology56 that yields internally consistent scores (Cronbach's alpha = 0.85). The measure has been found to discriminate between depressed and non-depressed individuals and exhibit convergent validity with other measures of depression.56 Depressive symptoms for the previous week are rated on a four-point scale from 0 (Rarely, None of the Time, or Less than One Day) to 3 (Most or All of the Time, or 5-7 Days). Positive items are reverse scored with higher scores indicating more depressive symptomatology. Cronbach's alpha in this study was .92.

UPPS Impulsive Behavior Scale

The UPPS Impulsive Behavior Scale (UPPS) Scale is a 45-item questionnaire which assesses four domains of impulsivity: lack of planning, lack of perseverance, negative urgency, and sensation seeking.57 Each item is rated on a scale from 1 (Not true of me) to 5 (Very true of me). Subscale scores range from one to four; higher scores indicate greater impulsivity. Subscale scores manifest discriminant validity from one another,58 and the UPPS effectively discriminated between a healthy control group and individuals with significant psychopathology.40 UPPS items have also demonstrated good estimated internal consistency.35, 59, 60 In this study, Cronbach's alphas for the subscales ranged from .83 to .91.

Part II: Measures

State-Trait Anxiety Inventory for Adults

The State-Trait Anxiety Inventory for Adults (STAI) is a self-report measure of state and trait anxiety.61 The state subscale (SAI), administered in this study immediately before starting the neuropsychological battery, consists of 20 statements with response options ranging from 1 (not at all or almost never) to 4 (very much so or almost always); higher scores indicate greater anxiety. The STAI yields internally consistent scores in diverse samples (Cronbach's alphas > .90) and has demonstrated concurrent, convergent, divergent, and construct validity.61, 62 Cronbach's alpha in this study was .94.

Conner's Continuous Performance Task

The Conner's Continuous Performance Task (CPT-II) is a 14-min, computerized measure of sustained attention, behavioral disinhibition, and cognitive impulsivity.63 Instructions for this measure are presented on the computer screen. Participants are first administered a brief set of practice items, after which the test begins. For each item, participants are asked to strike a key when the letter “X” is presented. The measure has good internal consistency (Cronbach's alpha = .66 to .95)64 and is able to discriminate effectively between normal controls and individuals with ADHD (Conners & MHS Staff). The Errors of Commission T-Score was used to assess behavioral disinhibition or cognitive impulsivity; higher scores are indicative of greater cognitive impulsivity and behavioral disinhibition.

Wisconsin Card Sorting Test

The Wisconsin Card Sorting Test (WCST) is a computerized assessment of planning and the ability to utilize environmental feedback to shift cognitive sets.21, 65 Participants are asked to place the top card from a single deck on to the top of one of four stimulus cards. The computer then informs the participant as to whether or not his or her card placement was correct based on a pre-established set of patterns. Participants are then asked to use this information to obtain as many correct cards as possible. Administration time varies between 15 and 30 min. Factor-analytic studies and structural equation modeling provide evidence for the construct validity of the WCST.66–68 Performance outcomes extracted for analyses included T-score values for participants' Total number of Errors, as well as their Perseverative Responses; higher T-scores are indicative of better performance. Together, these outcomes indicate individuals' ability to think abstractly, shift and maintain cognitive set, and demonstrate cognitive flexibility.21, 65

Wide Range Achievement Test -4th Edition

The Wide Range Achievement Test 4th Edition (WRAT-4) is a measure of academic achievement in the domains of reading, spelling, and arithmetic.69 Studies suggest that executive functioning is correlated with general cognitive functioning.46 The Reading subtest of the WRAT-4 was administered as an estimate of general cognitive functioning as this measure correlates with IQ (r = .69–.70).69 Items from the Reading subscale are internally consistent (α = .88–.93) among a sample of 17–24 year olds; coefficients for split-half reliabilities were similar.69 WRAT-4 subtests also correlate significantly with other tests of achievement and cognitive abilities providing evidence of concurrent validity.69

Participants

Inclusion/Exclusion Criteria

Women who reported (in Part I) that they engaged in weekly subjective (SBE) or objective (OBE) binge episodes in the absence of regular (i.e., ≥3 per week) compensatory behaviors in the last 28 days70, 71 were contacted and asked to participate in Part II. OBEs refer to the consumption of an objectively large amount of food, while SBEs refer to “normal” caloric consumption; both are accompanied by a sense of loss of control, which is considered by many72–75 to be the core pathological component of binge eating as it is most strongly associated with negative psychiatric outcomes. Thus, this study recruited participants engaging in SBEs and/or OBEs. Simultaneously, women who reported no binge eating in the previous 28 days, as well as no history of binge eating (in Part I), were randomly selected to participate in Part II. Participants were excluded from Part II if they reported significant or recent brain injuries (i.e., ≥30 min of loss of consciousness, any memory loss or hospitalization, or ≥2 concussions within last year), or the presence of medical conditions that could greatly influence eating behaviors. If participants had a BMI below 18.5 or were not between the ages of 18 and 25, they were also excluded from the study.

Sample Characteristics

A total of 631 women (Mage = 19.2 ± 1.5) completed Part I of this study; 38 participants failed to provide consent for Part II of this study. Others were excluded from Part II for the following: 109 women endorsed binge eating less than weekly, 35 women had a BMI < 18.5, 110 women reported engaging in regular compensatory behaviors (90% of whom were exercising excessively), seven women reported an underlying condition that may significantly influence their eating habits, and 14 women indicated a history of significant or recent brain injury. Several women were excluded for more than one of these reasons.

A total of 116 women completed Part II of this study; 66 denied engaging in current or previous binge eating (no binge group) and 50 endorsed regular binge eating behavior (binge group; see Table 1 for demographic information). Within the binge-eating group, nine women reported engaging in OBEs exclusively, 14 reported SBEs exclusively, and 27 reported both (of note, executive functioning outcomes did not differ between these groups, results for which are available from first author upon request). Women in this group endorsed an average of 9.2 binges (SD = 6.63; range = 4–40) in the previous 28 days. In both groups, four women reported vomiting or misusing laxatives or diuretics one to four times in the last 28 days, and approximately half reported exercising excessively between one and 11 times. Twelve participants endorsed current psychotropic medication use. Chi-square analyses indicated that significantly more participants in the binge eating group reported current psychotropic medication use than those in the non-binge group, χ2(1, N = 116) = 5.55, p < .02. Groups also differed significantly in regard to race/ethnicity, χ2(4, N = 116) = 14.05, p < .007; a greater percentage of women in the binge eating group identified as White.

Table 1. Participant demographic information
 Binge GroupNo Binge Group
(n = 50)(n = 66)
  1. BMI, body mass index; CES-D, Center for Epidemiological Studies Depression Scale; SAI, State Anxiety Inventory; WRAT-4, Wide Range Achievement Test-4th Edition.

AgeM = 19.32SD = 1.65M = 19.03SD = 1.27
BMIM = 24.46SD = 5.10M = 23.41SD = 5.18
Depression (CES-D)M = 23.74SD = 11.99M = 13.32SD = 8.90
State anxiety (SAI)M = 38.68SD = 11.56M = 31.82SD = 9.77
Estimated intelligence (WRAT-4)M = 101.12SD = 9.42M = 99.35SD = 9.75
Year in school
 Freshman56.0%n = 2857.6%n = 38
 Sophomore16.0%n = 821.1%n = 14
 Junior18.0%n = 916.7%n = 11
 Senior10.0%n = 54.5%n = 3
Race/ethnicity
 White/Caucasian56.0%n = 2825.8%n = 17
 Black/African American24.0%n = 1243.9%n = 29
 Asian/Asian American8.0%n = 415.2%n = 10
 Hispanic/Latina2.0%n = 19.1%n = 6
 Other10.0%n = 56.1%n = 4
Current psychotropic medication use
 Yes18.0%n = 94.5%n = 3
 No82.0%n = 4195.5%n = 63

Several 2 × 2 (binge group × psychotropic medication use group[0 = no use; 1 = current use]) and 2 × 5 (binge group × race/ethnicity group) between-groups analyses of variance (ANOVA) were conducted to determine whether executive functioning outcomes differed significantly between binge eating groups based on race/ethnicity or psychotropic medication use, respectively. Interaction terms in ANOVAs examining the influence of race/ethnicity and binge eating group on executive functioning outcomes were not significant, WCST Total Errors, F(4, 113) = 1.42, p = .233; WCST Perseverative Responses, F(4, 113) = 0.90, p = .464; CPT-II Errors of Commission, F(4, 113) = 1.11, p = .358, suggesting that between-groups differences in executive functioning were not significantly influenced by race/ethnicity. With respect to psychotropic medication use, two ANOVA interaction terms were non-significant, WCST Total Errors, F(1, 113) = 1.13, p = .291; WCST Perseverative Responses, F(1, 113) = 1.80, p = .183, and one was, CPT-II Errors of Commission, F(1, 113) = 8.50, p < .004. As a result, psychotropic medication use was added to the primary aims analyses as a covariate.

Statistical Procedures

Preliminary Analyses

IBM SPSS Statistics 19.0 (Chicago, IL) was used for data entry and analyses. Data that were not collected online were entered into SPSS and verified twice by undergraduate research assistants. Descriptive statistics for Part II participants (N = 116) indicated that missing data were minimal. Four participants completed two of three neuropsychological tests due to computer malfunction. As such, these data were assumed to be missing completely at random (MCAR), or not related to other measured variables. Little's MCAR analyses conducted separately for each group resulted in non-significant chi-square tests (binge group χ2 = 62.71, df = 58; p = .313; non-binge group χ2 = 20.67, df = 88; p > .100), confirming that the missing neuropsychological data were not related to any demographic, predictor, or criterion variable. When missing data are both minimal76 and MCAR, any method of handling missing data is considered appropriate.77, 78 Thus, pairwise deletion was used in this study.

As suggested, assumptions of parametric data were evaluated within groups.79 Several variables were skewed and/or kurtotic, although univariate outliers were in range. To produce a distribution more robust to the effects of outliers, BMI scores were Winsorized.80–82 For the remaining nonnormal variables, Winsorized scores could not be computed (e.g., 25% of participants endorsed the lowest possible total score) and square root, log and inverse transformations were conducted sequentially until the normality assumption was adequately met. Unless otherwise noted, all statistical tests were interpreted at the 5% significance level.

Primary Aim Analyses

This study's primary aim was analyzed via hierarchical regression analyses (HRA). Separate HRAs were conducted for each criterion variable or indicator of executive functioning and each HRA had two blocks/steps. The predictor variables entered in to the first block of each regression model were depression, state anxiety, BMI, psychotropic medication use (dummy coded 0 = no use, 1 = current use), and estimated intelligence (Model 1). Then, participants' binge eating status was dummy coded (0 = no binge eating; 1 = binge eating) and entered in to the second block of each regression model (Model 2).

Secondary Aim Analyses

HRAs were also used to examine secondary hypotheses (i.e., after controlling for BMI and depression, individuals who binge eating would report higher behavioral impulsivity, especially negative urgency, compared with controls). One HRA was completed for each criterion variable. To control statistically for variations in the outcome variables due to BMI and depression, participants' body mass and CES-D scores were entered in to the first block (Model 1). Group assignment was added to the second block (Model 2).

Results

Primary Aim Results

HRAs suggest that the binge-eating group did not differ significantly from controls with respect to cognitive impulsivity or rigidity, or the ability to shift or maintain set, after accounting for differences in depression, state anxiety, BMI, psychotropic medication use, and intelligence (see Table 2). Moreover, both groups' adjusted mean scores (back transformed, as appropriate) were within one standard deviation of the mean T-score (i.e., M = 50, SD = 10) for each outcome, indicating “normal” executive functioning (CPT-II Errors of Commission, Mbinge = 55.99 ± 11.74, Mnon-binge = 53.65 ± 11.53; WCST Total Errors, Mbinge = 48.90 ± 12.69, Mnon-binge = 54.72 ± 12.41; WCST Perseverate Responses, Mbinge = 52.82 ± 14.92, Mnon-binge = 58.15 ± 14.59). Contrary to previous research, most covariates did not have a significant effect on any indicators of executive functioning. The only significant effects were found for general intelligence on WCST Total Errors and BMI on WCST Perseverative Responses (see Table 1 for covariates' M and SD). Interestingly, despite the lack of significant between-group differences in indicators of executive functioning, total number of binge episodes (log transformed to meet the normality assumption), was significantly, albeit moderately, correlated with Perseverative Responses T-scores (r = −.33); those engaging in more binge episodes demonstrated more difficulties thinking flexibly or shifting cognitive set. The total number of binge episodes was not significantly correlated with any other indicator of executive functioning (CPT-II Errors of Commission, r = .20; WCST Total Errors, r = .26).

Table 2. Results of hierarchical regression analyses examining between group differences in indicators of executive functioning
OutcomePredictorModel 1Model 2
BSEBβR2FΔBSEBβR2FΔf2
  • BMI, body mass index; CES-D, Center for Epidemiological Studies Depression Scale; SAI, State Anxiety Inventory; WRAT-4, Wide Range Achievement Test-4th Edition.

  • Note:

  • *

    p < .05.

CPT-II Commission
 BMI−0.260.31−0.08.040.82−0.330.32−0.10.040.740.01
CES-D0.220.870.03  −0.020.920.00   
SAI7.869.550.10  7.069.610.09   
WRAT-4−0.090.12−0.08  −0.090.11−0.08   
Psychotropic medication group3.453.400.10  3.053.440.09   
Binge eating group     2.062.390.10   
WCST Total Errors
 BMI−0.020.01−0.15.061.36−0.020.01−0.16.060.060.00
CES-D0.010.030.02  0.000.030.01   
SAI−0.010.320.00  −0.010.33−0.01   
WRAT-4−0.010.00−0.19*  −0.010.00−0.20   
Psychotropic medication group0.010.120.01  0.000.120.00   
Binge eating group     0.020.080.03   
WCST preservative responses
 BMI0.670.400.16*.051.050.850.410.20.072.950.03
CES-D−0.411.13−0.04  0.211.170.02   
SAI9.6812.300.09  11.7212.240.11   
WRAT-40.180.140.13  0.200.140.14   
Psychotropic medication group−1.944.38−0.04  −0.944.38−0.02   
Binge eating group     −5.243.05−0.19   

Secondary Aim Results

HRAs suggest that, after controlling for variations in BMI and depression, individuals in the binge-eating group reported significantly greater sensation seeking behavior (UPPS Sensation Seeking; Mbinge = 2.86 ± 0.60, Mnon-binge = 2.73 ± 0.60) and negative urgency (UPPS Negative Urgency; Mbinge = 2.98 ± 0.62, Mnon-binge = 2.28 ± 0.61) than those in the non-binge-eating group (see Table 3). As hypothesized, the link between binge eating and negative urgency produced the greatest effect size relative to any other variable in these analyses (see Table 3; by convention, f2 effect sizes of 0.02, 0.15, and 0.35 are considered small, moderate, and large, respectively).83 The binge eating groups did not differ significantly with respect to lack of premeditation (UPPS Premeditation; Mbinge = 2.02 ± 0.05, Mnon-binge = 1.85 ± 0.05) or perseverance (UPPS Perseverance; Mbinge = 2.04 ± 0.54, Mnon-binge = 1.73 ± 0.54).

Table 3. Differences in behavioral impulsivity between binge-eating and non-binge eating group
OutcomePredictorModel 1Model 2
BSEBβR2BSEBβR2f2
UPPS premeditationBMI0.010.010.040.000.170.000.010.000.043.840.03
CES-D0.010.030.03  −0.020.03−0.06   
Group     0.190.100.21   
UPPS perseveranceBMI0.000.00−0.080.2720.92**0.000.00−0.090.270.400.00
CES-D0.050.010.52  0.040.010.50   
Group     0.020.020.06   
UPPS negative urgencyBMI0.030.020.140.3226.00**0.020.020.070.4014.80**0.13
CES-D0.260.040.53  0.190.040.39   
Group     0.460.120.33   
UPPS sensation seekingBMI0.030.020.150.084.87**0.020.020.090.147.57**0.07
CES-D−0.100.04−0.25  −0.150.04−0.37   

Discussion

This study is one of few to investigate the neuropsychology of binge eating.19, 20, 22, 23 Although some research suggests that impairments in executive functioning play a role in binge eating,19, 20 outcomes are mixed22, 23 and are only generalizable to clinical samples meeting BED diagnostic criteria. Yet, many individuals experience subclinical forms of BED,4, 6 and both subthreshold and threshold binge eating are associated with significant impairments in psychological functioning.9 Thus, utilizing a sample with subthreshold symptoms enhances the generalizability of outcomes. In addition, previous research19, 20, 22, 23 investigating executive functioning among individuals who binge eats has not controlled for the influence of comorbid psychopathology or BMI. Controlling for these variables in this study provides a clearer picture of the association between executive functioning and binge eating.

Executive Functioning Outcomes

Results from this study suggest that, binge eating in the absence of compensatory behaviors is not associated with impairments in executive functioning. The mean scores of both the binge-eating and control groups were within the normal range. These findings are inconsistent with some research19, 20 and consistent with other investigations of executive functioning of clinical samples with BED.22, 23 A number of factors, most notably significant variations in sample characteristics, render it difficult to compare the results of this study to that of previous investigations and might also account for discrepant findings across studies.

Specifically, previous studies19, 20, 22, 23 only included obese individuals in their evaluation of binge eating and executive functioning. Considering the inverse association between obesity and executive functioning,43, 45 individuals in these studies may have had poorer executive functioning outcomes than those engaging in binge eating in the current study, whose average BMI was below 25.22 Moreover, some studies retained individuals with concurrent mood disorders19, 20 without controlling for the impact of depression/anxiety on participants' neuropsychological outcomes. As depressive symptoms are typically higher among those who binge eat,5, 8 the variance in outcomes associated with depression or other comorbid disorders might account for other studies' significant outcomes. Although the depression and anxiety covariates were unrelated to executive functioning outcomes in this study, previous samples typically included women seeking mental health treatment. Treatment-seeking individuals may have exhibited greater psychopathology than those in this study.84–87

Moreover, this study evaluated a young, college-enrolled sample. Previous studies evaluated older adults with fewer than 12 years of education.19, 20, 22, 23 Executive functions develop steadily across adolescence and peak in young adulthood88 and are correlated with general intellectual functioning.46 These relations might explain why outcomes differed in this study. Further, although the measures used in this study yield normed T-scores, other studies used raw scores.19, 20 Consequently, comparisons regarding mean scores were not possible, nor would they necessarily be meaningful considering the samples' variations in age and education.

Another interesting age-related consideration is the potential influence of binge eating on brain abnormalities associated with binge eating.25 If these abnormalities are the consequences of regularly engaging in binge eating, it might not be until mid-to-late adulthood that such structural and functional changes translate to significant differences in one's neuropsychological functioning. In any case, it is important to note that, despite finding significant between-group differences in outcomes, both groups' mean scores in Svaldi et al.'s19 study were in the normal range. It is thus unclear whether these group differences have practical implications. Further, although this study's sample was not extremely large, it is unlikely that the absence of significant differences in neuropsychological functioning is attributable to Type II error. Between-group differences in executive functioning were identified in two previous studies19, 20 with sample sizes of 78 and 35, respectively.

It is also possible that differences in executive functions might only be evident in situations in which these functions are taxed, such as when experiencing negative affect or when confronted with food- or body-related stimuli. Indeed, individuals with BED demonstrate attentional biases for high-calorie food and negative weight- and shaped-related stimuli.89, 90 Similarly, several studies evaluating structural and functional brain processes associated with binge eating were conducted in the context of eating or in the presence of food.32, 33 In further support of this idea, participants in the binge-eating group in this study only reported higher behavioral impulsivity when experiencing negative affect or, conversely, to promote pleasurable feelings.

In general, executive functioning is a notoriously complex neuropsychological construct,91, 92, 88 and there is disagreement regarding the structure, definition, and assessment of these higher order cognitive functions. Thus, findings from this study might simply highlight a lack of significant group differences in executive functioning as captured by the WCST65 and the CPT-II.63 However, as reviewed here, outcomes from neuroimaging and neuropsychological studies, self-report data, and research with individuals with brain injury support the notion that some individuals who binge eat also manifest difficulties with cognitive and behavioral facets of executive functions. In one example,34 neuroimaging identified a link between atrophy in the right rostral orbito frontal cortex and binge eating. In the same study, executive functioning did not differ between those engaging in binge eating and a normal, healthy sample. Thus, findings from Woolley et al. and this study support the notion that neuroimaging, neuropsychological, and behavioral assessments lack convergence regarding their assessment and identification of cognitive and/or functional disabilities and should be considered different albeit complimentary sources of data.93 Indeed, this study's self-report data suggest that significant depressive symptoms and behavioral impulsivity difficulties exist in the absence of neuropsychological impairments. In fact, among participants in the binge-eating group, the mean depression score was equivalent to the clinical cutoff.94, 95 Thus, the average undergraduate woman engaging in regular binge eating in the absence of regular compensatory behaviors is also at risk for clinical levels of depression.

Behavioral Impulsivity Outcomes

Consistent with previous research,36, 39 a strong association was found between binge eating and negative urgency. Findings from both self-report and neuroimaging studies suggest that individuals who engage in regular binge eating also demonstrate heightened sensitivity to reward and punishment,25, 32, 96, 97 which is hypothesized to translate to greater reactivity to distressing emotions. Individuals who experience difficult emotions and negative urgency more intensely might be more prone to binge eating as a means of coping with their feelings despite the potential physical (e.g., stomach discomfort, weight gain) and emotional (e.g., guilt, shame) consequences. In these instances, binge eating might serve as an emotional avoidance strategy.98

In addition to negative urgency, participants in the binge-eating group also reported greater sensation seeking, or the desire to engage in activities that are exciting and potentially dangerous. Contrary to our hypotheses, groups did not differ with respect to their lack of premeditation or perseverance after controlling for the influence of BMI and depression. Lack of premeditation refers to difficulties considering the consequences of one's behavior before acting. Lack of perseverance includes difficulties avoiding distracting stimuli to stay focused on tasks. These subscales differ from negative urgency and sensation seeking in that they do not refer to behavioral tendencies associated with emotional states. For example, individuals who find potentially dangerous activities enjoyable might be more inclined to engage in other impulsive behaviors, such as binge eating, to enhance their mood. Thus, findings suggest that individuals who binge eats are not necessarily incapable of considering the consequences of their behavior, but might be more vulnerable to the tendency to engage in impulsive behaviors to both alleviate uncomfortable feelings and promote pleasurable ones.

Clinical Implications

Outcomes support the notion that individuals engaging in regular binge eating behavior also have a difficult time managing distressing emotions, and might engage in impulsive behaviors in an attempt to mitigate intense affect. Thus, interventions focused on reducing binge eating behavior should help individuals enhance their ability to tolerate and manage difficult affective states. It might also be beneficial to assist these individuals with identifying more adaptive sensation seeking activities to replace maladaptive behaviors, such as binge eating. Current findings also reinforce the importance of addressing negative urgency in the treatment of binge eating, such as implementing “if-then” interventions to help individuals establish a new link between any emotional cue and an action plan (e.g., “If situation X arises, then I will do Y”) that differs from binge eating.97 As this link is strengthened, this new, more adaptive action plan becomes easier to access and subsequently implement in the face of distress. It is also important for clinicians and researchers to be aware of the association between negative urgency and treatment dropout among patients with EDs.42 Finally, in consideration of the binge eating group's average CES-D score, it is important that clinicians treating binge eating also assess and address clinically significant levels of depression.

Outcomes from this study could also inform programs focused on disordered eating prevention. This study included young adults who are already binge eating and engaging in impulsive behavior when distressed. Thus, binge eating prevention efforts may benefit from a focus on helping younger children better regulate their emotions and impulsive behaviors. Such interventions would likely have significant public health utility as they may also prevent the onset of other disorders characterized by pathological features similar to binge eating (e.g., BN, substance abuse). Similarly, in their ED outreach efforts, colleges and universities tend to focus on AN and BN. Considering the pervasiveness of binge eating among this undergraduate sample, and the potential presence of significant comorbid depression, staff should also educate students about available treatments for binge eating and related symptomatology.

Limitations, Strengths, and Future Studies

Although this study addresses a significant gap in the binge eating literature, several limitations must be noted. First, most data were self-report, which can be limited by response biases. Second, covariates in this study were largely unassociated with executive functioning outcomes. These unexpected findings may be the result of a number of measurement- and sample-related factors (e.g., limited range in BMI and intellectual functioning, use of a single depression score versus diagnostic or severity group or frequency of depressive episodes; use of a non-clinical versus clinical sample). Indeed, a review of the association between depression and cognitive functioning indicates that significant heterogeneity in the means by which these constructs are assessed contributes to difficulties drawing conclusions regarding the nature of their association.99 It is recommended that future research examining the cognitive functioning of those engaging in regular binge eating continues to investigate the influence of various forms of psychopathology to clarify the relations among these variables.

A third concern is that a sample comprised exclusively of undergraduate women limits the generalizability of the results. However, because the prevalence of binge eating is high among undergraduate women,6 this is a particularly appropriate population to investigate. Moreover, the sample was racially/ethnically diverse. Nonetheless, future research should replicate these findings with other samples, including those with a broader range of age and educational attainment, men, and clinical samples. Comparing the neuropsychological presentation of those in the current study to those engaging in regular compensatory behavior (i.e., those who meet criteria for BN) could also assist with clarifying the possible link between executive functioning and binge eating behavior. A final limitation is the cross-sectional design of this study, which does not provide information about the temporal associations among variables. Longitudinal designs beginning in early childhood would greatly assist with clarifying these relations. Experimental designs could also be used to evaluate individual's cognitive and behavioral reactions to the introduction of negative affect or palatable foods.

It is also important to acknowledge the limitations associated with the assessment of executive functioning. This study paints a limited picture of the executive functions of those engaging in regular binge eating as it included only two indicators of cognitive impulsivity, rigidity, and shifting and maintaining set. Moreover, it included a relatively high functioning and educated sample, which contributed to a limited range of general intellectual and executive functioning. To address these limitations and promote comparisons of executive function outcomes across studies, it is recommended that researchers calculate T-scores if available, rather than controlling for age and education. Other psychological and physiological variables associated with impaired cognitive functioning, such as psychotropic medication use, depression, and BMI, should also be statistically controlled. Finally, although it can be costly and burdensome to administer comprehensive neuropsychological batteries to research participants, such a process might be appropriate. On the basis of extensive evaluations, researchers in Norway100 have identified a cognitive profile associated with AN and, based on this profile, recommended a standardized battery of neuropsychological tests. Their aim is to promote consistent examination of the cognitive functioning of individuals with AN to facilitate cross-study comparisons. A similar process is recommended to better understand the cognitive processes that contribute to the onset and maintenance of binge eating behavior. Similarly, additional research is needed to clarify if there is a degree of binge eating severity at which point executive dysfunction becomes evident, and how this extreme level of disordered eating behavior and associated neuropsychological difficulties might influence treatment.

In sum, individuals engaging in regular binge eating did not differ from their non-binge eating peers in regards to their executive functioning. Although correlation analyses suggest that, among the binge eating group, individuals endorsing more frequent binge eating might have greater difficulties thinking flexibly or shifting attention, additional research is needed to clarify the link between binge eating severity and neuropsychological dysfunction; indeed, other indicators of executive functioning did not correlate significantly with total binge episodes. Consistent with secondary hypotheses, individuals in the binge-eating group reported that they are more likely to engage in impulsive behavior (but only when distressed or seeking to enhance pleasurable feelings). Findings can inform the modification and subsequent improvement of current intervention and prevention programs for binge eating behavior, while also providing direction for the future examination of its neuropsychological contributors.

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