Characteristics of psychomotor performance and time cognition in moderately obese patients

Reduced Temporal Sensitivity in Obesity: Evidence From a Simultaneity Judgement Task

Preliminary evidence showed a reduced temporal sensitivity (i.e., larger temporal binding window) to audiovisual asynchrony in obesity. Our aim was to extend this investigation to visuotactile stimuli, comparing individuals of healthy weight and with obesity in a simultaneity judgment task. We verified that individuals with obesity had a larger temporal binding window than healthy-weight individuals, meaning that they tend to integrate visuotactile stimuli over an extended range of stimulus onset asynchronies. We point out that our finding gives evidence in support of a more pervasive impairment of the temporal discrimination of co-occurrent stimuli, which might affect multisensory integration in obesity. We discuss our results referring to the possible role of atypical oscillatory neural activity and structural anomalies in affecting the perception of simultaneity between multisensory stimuli in obesity. Finally, we highlight the urgency of a deeper understanding of multisensory integration in obesity at least for two reasons. First, multisensory bodily illusions might be used to manipulate body dissatisfaction in obesity. Second, multisensory integration anomalies in obesity might lead to a dissimilar perception of food, encouraging overeating behaviours.

Deficits in executive function and suppression of default mode network in obesity

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Using a case-control design, obese individuals exhibited worse performance across a number of neurocognitive tests compared to healthy BMI controls, particularly in tasks measuring executive function.

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In a functional MRI N-Back task measuring working memory performance, obese individuals exhibited greater BOLD activity in task-negative brain regions, suggesting deficits in suppression of the default mode network (DMN).

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Obese individuals exhibited differences in cortical morphometry in frontal, temporal, and parietal regions linked to executive function.

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Integrative analyses implicated aspects of behavioral performance, inefficient DMN suppression, and cortical morphometry.

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Results suggest that obesity is associated with a diverse range of functional, structural and behavioural deficits in executive functioning; longitudinal studies are needed to clarify causal versus consequential influences.

Background

Although nutritional and metabolic factors are well established in obesity, neurocognitive determinants are less understood. Using data from the Human Connectome Project, this study concurrently investigated neurocognitive performance, neural activation during a working memory task, and cortical brain morphometry in relation to obesity in a group of young adults, 22–35 years old.

Methods

Using a case-control design, obese individuals (n = 243, body mass index [BMI] ≥ 30 kg/m²) were compared to a control group of lean BMI individuals (n = 469, BMI = 18–24.9 kg/m²). Performance tests comprised a battery of behavioral neurocognitive assessments. Neural activity was measured as blood-oxygenation-level-dependent (BOLD) activity during an N-Back task using functional magnetic resonance imaging (fMRI). Cortical morphometry included indices of volume, thickness, and surface area.

Results

Relative to the control group, the obese group exhibited significantly worse performance in terms of the National Institutes of Health Toolkit (NIH) 9-Hole Peg Board, Penn Working Memory Test, Delay Discounting, Penn Progressive Matrices, NIH Picture Vocabulary Test, Dimensional Change Card Sort Test and the in-scanner N-Back working memory test (FDR-corrected ps<0.05; ds = 0.231–0.405). The obese group also exhibited significantly greater BOLD activation in N-Back task-negative regions, including the ventromedial prefrontal cortex, posterior cingulate, and right precentral gyrus (FDR-corrected ps<0.05). Supplemental functional connectivity analyses provided evidence that the implicated regions were part of the default mode network. Significant differences in morphometry were present in the medial orbitofrontal cortex, rostral anterior cingulate cortex, inferior and superior parietal gyri, and temporal pole (FDR-corrected p<0.001). A data-driven integrative model classified 73.8% of participants correctly.

Conclusions and Relevance

This multimodal investigation suggests diverse aspects of neurocognition are associated with obesity, particularly implicating deficits in executive function and ineffective suppression of the default mode network.

Assessment of executive functioning in binge-eating disorder independent of weight status

OBJECTIVE

Executive functioning (EF) problems may serve as vulnerability or maintenance factors for Binge-Eating Disorder (BED). However, it is unclear if EF problems observed in BED are related to overweight status or BED status. The current study extends this literature by examining EF in overweight and normal-weight BED compared to weight-matched controls.

METHOD

Participants were normal-weight women with BED (n = 23), overweight BED (n = 32), overweight healthy controls (n = 48), and normal-weight healthy controls (n = 29). The EF battery utilized tests from the National Institutes of Health (NIH) Toolbox and Delis-Kaplan Executive Function System (D-KEFS).

RESULTS

After controlling for years of education and minority status, overweight individuals performed more poorly than normal-weight individuals on a task of cognitive flexibility requiring generativity (p < .01), and speed on psychomotor performance tasks (p = .01). Normal-weight and overweight BED performed worse on working memory tasks compared to controls (p = .04). Unexpectedly, normal-weight BED individuals out-performed all other groups on an inhibitory control task (p < .01). No significant differences were found between the four groups on tasks of planning.

DISCUSSION

Regardless of weight status, BED is associated with working memory problems. Replication of the finding that normal-weight BED is associated with enhanced inhibitory control is needed.

Association between adiposity and cognitive function in young men: Hormonal mechanisms

OBJECTIVE

To determine the association between adiposity, hormones, and cognition in young men with abdominal obesity.

METHODS

In this cross-sectional observational study, 53 nondiabetic men with abdominal obesity (mean body mass index, 37.3 kg/m(2) ; age, 22-45 years) and normal intelligence underwent detailed measures of body composition, hormonal profiles, and cognition. Age- and education-adjusted performance in five cognitive domains was examined.

RESULTS

Total fat percentage was negatively associated with visuospatial skills (P = 0.002) and visual memory (P = 0.012). Insulin resistance (homeostatic model assessment of insulin resistance) was also negatively associated with these domains (P = 0.05 and trend, P = 0.06, respectively). Total testosterone levels were negatively associated with executive function and verbal learning and memory (P = 0.04 for each), but free testosterone was not. Sex hormone-binding globulin (SHBG) was also inversely associated with performance in these domains (P = 0.015 and trend, P = 0.09, respectively). In a stepwise regression model including percentage fat, homeostatic model assessment of insulin resistance, SHBG, and free testosterone, SHBG was the only variable selected for executive function (P = 0.05) and showed a trend for verbal learning and memory (P = 0.09).

CONCLUSIONS

Adiposity and insulin resistance were associated with worse function in visual domains. An unexpected negative association is reported between SHBG and cognitive measures, which seemed to be independent of free testosterone levels.

Peers and Obesity during Childhood and Adolescence: A Review of the Empirical Research on Peers, Eating, and Physical Activity

Obesity during childhood and adolescence is a growing problem in the United States, Canada, and around the world that leads to significant physical, psychological, and social impairment. In recent years, empirical research on factors that contribute to the development and maintenance of obesity has begun to consider peer experiences, such as peer rejection, peer victimization, and friendship. Peer experiences have been theoretically and empirically related to the “Big Two” contributors to the obesity epidemic, eating and physical activity, but there has not been a comprehensive review of the extant empirical literature. In this article, we review and synthesize the emerging theoretical and empirical literatures on peer experiences in relation to: (a) eating (food consumption and food selection); and (b) physical activity, during childhood and adolescence. A number of limitations and issues in the theoretical and empirical literatures are also discussed, along with future research directions. In conclusion, we argue that the involvement of children and adolescents’ peer networks in prevention and intervention efforts may be critical for promoting and maintaining positive behavioral health trajectories.

Metabolic and endocrine correlates of cognitive function in healthy young women

OBJECTIVE

Obesity has been associated with cognitive decline in longitudinal studies of older individuals. We hypothesized that the cognitive sequelae of obesity may be detectable in the reproductive years. In addition, we explored the hypothesis that these associations may be mediated by the hormonal milieu.

DESIGN AND METHODS

Of 49 young healthy lean and overweight women aged 20-45, we investigated the association between performance on a battery of cognitive tests, body composition parameters [body mass index, total fat, abdominal (visceral, subcutaneous, and total) adipose tissue, and muscle], and hormone levels (insulin, adiponectin, leptin, insulin-like growth factor 1 (IGF-1), estrogen, testosterone, and vitamin D).

RESULTS

We found a significant negative association between both visceral adiposity and muscle, and performance in the domain of verbal learning and memory, after controlling for age and education. Other body composition parameters showed similar trends (0.05 < P < 0.10). Additionally, the degree of insulin resistance was negatively associated with executive function domain. None of the associations between the other hormones examined (adipokines, IGF-1, gonadal hormones, and vitamin D) and cognitive function were significant.

CONCLUSION

These preliminary findings suggest a possible association between obesity and cognitive function in healthy young women of reproductive age. More research is warranted into the potential modulatory effect of insulin resistance on this association.

Neurobehavioural correlates of body mass index and eating behaviours in adults: a systematic review

The worldwide increase in obesity has spurred numerous efforts to understand the regulation of eating behaviours and underlying brain mechanisms. These mechanisms can affordably be studied via neurobehavioural measures. Here, we systematically review these efforts, evaluating neurocognitive tests and personality questionnaires based on: (a) consistent relationship with obesity and eating behaviour, and (b) reliability. We also considered the measures' potential to shed light on the brain mechanisms underlying these individual differences. Sixty-six neurocognitive tasks were examined. Less than 11%, mainly measures of executive functions and food motivation, yielded both replicated and reliable effects. Several different personality questionnaires were consistently related to BMI. However, further analysis found that many of these questionnaires relate closely to Conscientiousness, Extraversion and Neuroticism within the Five-Factor Model of personality. Both neurocognitive tests and personality questionnaires suggest that the critical neural systems related to individual differences in obesity are lateral prefrontal structures underpinning self-control and striatal regions implicated in food motivation. This review can guide selection of the highest yield neurobehavioural measures for future studies.