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.
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.