Proactive inhibition: An element of inhibitory control in eating disorders

Neurobiology and Cognition in Girls at High-Risk of Eating Disorders: Exploring Imaging-Derived Trait Markers

BACKGROUND

Eating disorders (EDs) are serious psychiatric disorders characterized by impairments in neurocognition and altered brain structure. To date the majority of studies have investigated these in acutely ill or recovered individuals. Studying children at familial high risk (FHR) for psychiatric disorders allows investigating vulnerability traits or trait markers that may be present before disorder onset. Our study is the first one to examine executive function and brain structure in girls at FHR for ED (Anorexia Nervosa, Bulimia Nervosa, and Binge Eating Disorder) compared to controls (girls not at familial high risk - HC).

METHODS

Forty-six (46) FHR girls (median age: 10.5 years, range: 9) and 50 HC girls (median age: 12 years, range: 8) completed a battery of neuropsychological tests assessing cognitive flexibility, inhibitory control, and working memory. Structural magnetic resonance imaging assessed grey matter volume (GMV) and cortical thickness (CT).

RESULTS

Girls at FHR for ED performed a higher number of errors in a cognitive flexibility task compared to HC (β = 0.15, p < 0.05). They also had increased GMV in posterior regions such as the right supramarginal gyrus, middle occipital gyrus, and lingual/fusiform gyrus compared to HC (p < 0.05 cluster-level FWE-corrected), as well as increased CT in the left transverse pole (p < 0.001) and right posterior cingulate cortex (p < 0.05).

CONCLUSIONS

Girls at FHR show characteristic neurocognitive performance similar to that seen in individuals with ED, as well as differences in brain structure compared to HC. Our findings, together with previous evidence, highlight impairment in cognitive flexibility as a possible trait marker of ED. Further longitudinal studies are needed to confirm differences in GMV and CT identified in this study.

Exploring the relationship between proactive inhibition and restrictive eating behaviours in severe and enduring anorexia nervosa (SE-AN)

BACKGROUND

There is a need for improved understanding of why 20-30% of individuals with anorexia nervosa (AN) develop a severe and enduring form of illness (SE-AN). Previously, we reported differences in proactive inhibition (a pre-emptive slowing of responses) in individuals with AN compared to healthy controls (after controlling for intolerance of uncertainty). The present study is a preliminary exploration of proactive inhibition in which we compared women with SE-AN with healthy comparison (HC) women and explored its association with restrictive/avoidant eating behaviours.

METHODS

Thirty-four women with SE-AN (defined by >3 years of illness and a previous unsuccessful course of eating disorder treatment) and 30 HCs completed (a) a cued reaction time task, to assess proactive inhibition, and (b) questionnaires assessing restrictive/avoidant eating behaviours and intolerance of uncertainty.

RESULTS

Both SE-AN and HC participants showed slower reaction times under conditions of uncertainty, indicating proactive inhibition in both groups. There was a main effect of group, with SE-AN participants showing significantly slower reaction times compared to HC. There was no interaction between group and condition, suggesting that individuals with SE-AN did not differ in proactive inhibition compared to HCs. However, post-hoc analysis between-group tests for each trial type revealed that group differences were only present under conditions of uncertainty. Proactive inhibition was not significantly associated with self-reported restrictive/avoidant eating behaviours, including when taking intolerance of uncertainty into consideration.

CONCLUSIONS

It is unlikely that proactive inhibition contributes to avoidant and restrictive eating behaviours seen in SE-AN. Our findings suggest that the SE-AN group are relatively more cautious when responding under conditions of uncertainty. Longitudinal studies and between-group comparisons of individuals across different stages of illness will be required to elucidate the way in which proactive inhibition is specifically implicated in SE-AN, rather than in AN more generally.

Performing well but not appreciating it - A trait feature of anorexia nervosa

Background

Despite advances in the etiology of anorexia nervosa (AN), a large subgroup of individuals does not profit optimally from treatment. Perfectionism has been found to be a risk factor predicting the onset, severity, and duration of AN episodes. To date, perfectionism has been studied predominantly by the use of self-report questionnaires, a useful approach that may, however, be impacted by demand characteristics, or other distortions of introspective or metacognitive access.

Methods

Here we circumvent these problems via a behavioral paradigm in which participants perform a modified Go/NoGo task, whilst self-evaluating their performance. We compared a group of 33 adolescent females during their first episode of AN (age = 16.0) with 29 female controls (age = 16.2), and 23 adolescent girls recovered from AN (age = 18.3) with 23 female controls (age = 18.5). The controls were closely matched by intelligence quotient and age to the two clinical groups.

Results

First-episode AN and control participants performed equally well on the task (reaction time and errors of commission), whereas the recovered group displayed significantly faster reaction times but incurred the same error rate. Despite performing at least as good as and predominantly better than control groups, both clinical groups evaluated their performances more negatively than controls.

Conclusion

We offer a novel behavioral method for measuring perfectionism independent of self-report, and we provide tentative evidence that this behavioral manifestation of perfectionism is evident during first-episode AN and persists even after recovery.

Electrophysiological Correlates of Different Proactive Controls during Response Competition and Inhibition Tasks

The present study aims to investigate the behavioral outcomes and the antecedent brain dynamics during the preparation of tasks in which the discrimination is either about the choice (choice response task; CRT) or the action (Go/No-go), and in a task not requiring discrimination (simple response task; SRT). Using event-related potentials (ERPs), the mean amplitude over prefrontal, central, and parietal-occipital sites was analyzed in 20 young healthy participants in a time frame before stimulus presentation to assess cognitive, motor, and visual readiness, respectively. Behaviorally, participants were faster and more accurate in the SRT than in the CRT and the Go/No-go. At the electrophysiological level, the proactive cognitive and motor ERP components were larger in the CRT and the Go/No-go than the SRT, but the largest amplitude emerged in the Go/No-go. Further, the amplitude over parieto-occipital leads was enhanced in the SRT. The strongest intensity of the frontal negative expectancy wave over prefrontal leads in the Go/No-go task could be attributed to the largest uncertainty about the target presentation and subsequent motor response selection and execution. The enhanced sensory readiness in the SRT can be related to either an increased visual readiness associated with task requirements or a reduced overlap with proactive processing on the scalp.

Patients with Methamphetamine Use Disorder Show Highly Utilized Proactive Inhibitory Control and Intact Reactive Inhibitory Control with Long-Term Abstinence

Methamphetamine use disorder (MUD) is a chronic brain disorder that involves frequent failures of inhibitory control and relapses into methamphetamine intake. However, it remains unclear whether the impairment of inhibitory control in MUD is proactive, reactive or both. To address this issue, the current study used the conditional stop-signal task to assess proactive and reactive inhibitory control in 35 MUD patients with long-term abstinence and 35 matched healthy controls. The results showed that MUD patients with long-term abstinence had greater preparation costs than healthy controls, but did not differ in performance, implying a less efficient utilization of proactive inhibitory control. In contrast, MUD patients exhibited intact reactive inhibitory control; reactive but not proactive inhibitory control was associated with high sensation seeking in MUD patients with long-term abstinence. These findings suggest that proactive and reactive inhibitory control may be two different important endophenotypes of addiction in MUD patients with long-term abstinence. The current study provides new insight into the uses of proactive and reactive inhibitory control to effectively evaluate and precisely treat MUD patients with long-term abstinence.

Attenuated neuronal and autonomic responses during error processing in anorexia nervosa

INTRODUCTION

Anorexia nervosa (AN) is a severe psychiatric illness with alarming mortality rates. Nevertheless, despite former and recent research results, the etiology of AN is still poorly understood. Of particular interest is that, despite exaggerated response control and increased perfectionism scores, patients with AN seem not to perform better that those unaffected in tasks that require inhibitory control. One reason might be aberrant processing of errors. The objective of our study was thus to obtain further insight into the pathopsychology of AN. We were particularly interested in neuronal and autonomic responses during error processing and their association with behavior.

METHODS

We analyzed 16 acute patients suffering from restrictive type AN and 21 healthy controls using functional magnetic resonance imaging (fMRI) with simultaneous physiological recordings during a Go/Nogo response inhibition task. Data were corrected for noise due to cardiac and respiratory influence.

RESULTS

Patients and controls had similarly successful response inhibition in Nogo trials. However, in failed Nogo trials, controls had significantly greater skin conductance responses (SCR) than in correct Nogo trials. Patients did not exhibit elevated SCR to errors. Furthermore, we found significantly increased neuronal responses, especially in the amygdala and hippocampus, in controls compared to patients during error trials. We also found significant positive correlations in controls but not in patients between Nogo performance and activation in the salience network core regions after errors.

CONCLUSION

Acute restrictive type AN patients seem to lack neuronal and autonomic responses to errors that might impede a flexible behavior adaption.

Area-specific Modulation of Functional Cortical Activity During Block-based and Trial-based Proactive Inhibition

Animals can suppress their behavioral response in advance according to changes in environmental context (proactive inhibition: delaying the start of response), a process in which several cortical areas may participate. However, it remains unclear how this process is adaptively regulated according to contextual changes on different timescales. To address the issue, we used an improved stop-signal task paradigm to behaviorally and electrophysiologically characterize the temporal aspect of proactive inhibition in head-fixed rats. In the task, they must respond to a go cue as quickly as possible (go trial), but did not have to respond if a stop cue followed the go cue (stop trial). The task alternated between a block of only go trials (G-block) and a block of go-and-stop trials (GS-block). We observed block-based and trial-based proactive inhibition (emerging in GS-block and after stop trial, respectively) by behaviorally evaluating the delay in reaction time in correct go trials depending on contextual changes on different timescales. We electrophysiologically analyzed task-related neuronal activity in the primary and secondary motor, posterior parietal, and orbitofrontal cortices (M1, M2, PPC, and OFC, respectively). Under block-based proactive inhibition, spike activity of cue-preferring OFC neurons was attenuated continuously, while M1 and M2 activity was enhanced during motor preparation. Subsequently, M1 activity was attenuated during motor decision/execution. Under trial-based proactive inhibition, the OFC activity was continuously enhanced, and PPC and M1 activity was also enhanced shortly during motor decision/execution. These results suggest that different cortical mechanisms underlie the two types of proactive inhibition in rodents.

Proactive and reactive inhibitory control in eating disorders

Altered inhibitory control has been implicated in the development and maintenance of eating disorders (ED), however it is unclear how different types of inhibitory control are affected across the EDs. We explored whether individuals with bulimia nervosa (BN), binge eating disorder (BED) and anorexia nervosa (AN) differed from healthy individuals (HC) on two types of motor inhibitory control: proactive inhibition (related to the preparation/initiation of a response) and reactive inhibition (withholding a response in reaction to a signal). Ninety-four women (28 AN, 27 BN, 11 BED, 28 HC) completed two neuropsychological tasks (a cued reaction time task and a stop signal task), and questionnaires assessing clinical variables, mood, anxiety, and inhibitory control. Self-reported inhibitory control was poorer in women with BN compared to the HC and AN groups, but greater in women with AN compared to all other groups. However, no group differences in reactive inhibition were observed. Proactive inhibition was augmented in women with AN compared to HC, and this was related to self-reported intolerance of uncertainty. The findings suggest that proactive inhibition may be a relevant target for behavioural interventions for AN, and call for further research into the relationship between intolerance of uncertainty and proactive inhibition.

Behind binge eating: A review of food-specific adaptations of neurocognitive and neuroimaging tasks

Recurrent binge eating, or overeating accompanied by a sense of loss of control, is a major public health concern. Identifying similarities and differences among individuals with binge eating and those with other psychiatric symptoms and characterizing the deficits that uniquely predispose individuals to eating problems are essential to improving treatment. Research suggests that altered reward and control-related processes may contribute to dysregulated eating and other impulsive behaviors in binge-eating populations, but the best methods for reliably assessing the contributions of these processes to binge eating are unclear. In this review, we summarize standard neurocognitive and neuroimaging tasks that assess reward and control-related processes, describe adaptations of these tasks used to study eating and food-specific responsivity and deficits, and consider the advantages and limitations of these tasks. Future studies integrating both general and food-specific tasks with neuroimaging will improve understanding of the neurocognitive processes and neural circuits that contribute to binge eating and could inform novel interventions that more directly target or prevent this transdiagnostic behavior.