Rachel Galioto

Body mass index and brain structure in healthy children and adolescents

Obesity is associated with cognitive dysfunction in children and adolescents, although the mechanisms underlying these deficits remain unclear. This study examined the associations between body mass index (BMI) and regional gray matter volume and white matter integrity in 120 healthy children and adolescents (6–18 years of age) who underwent magnetic resonance and diffusion tensor imaging. Bonferroni-corrected partial correlation analyses controlling for demographic and clinical characteristics revealed significant inverse associations between demographically standardized BMI values and gray matter volume of frontal (r = −0.31) and limbic (r = −0.35) brain regions. No such pattern emerged for fractional anisotropy of white matter tracts. Subsequent hierarchical regression analyses indicated that the relationship between standardized BMI and structural gray and white matter brain indices did not vary with age. These findings suggest that obesity in children and adolescents is associated with decreased volume of frontal and limbic cerebral gray matter regions. Further research is much needed to better elucidate possible brain-based mechanisms for cognitive dysfunction associated with obesity.

Cognitive function in morbidly obese individuals with and without binge eating disorder

OBJECTIVE Obesity is associated with poorer cognitive function and impulsivity, which may contribute to binge eating disorder (BED). The objective of this study was to compare cognitive function in morbidly obese individuals with and without BED. METHOD A total of 131 morbidly obese individuals (41 with past or present BED, 90 with no BED history) completed a computerized battery of cognitive tests including executive, memory, language, and attention. RESULTS Both groups of participants evidenced high rates of cognitive impairment; however, no significant differences emerged between persons with and without BED on cognitive testing. Comparison of persons without BED, current BED, and past BED also yielded no differences. DISCUSSION In the present sample, morbidly obese individuals with and without BED were clinically indistinguishable on tests of cognitive function. Our findings suggest that obesity, rather than binge eating, may be more directly related to cognition. Future studies should further examine this relationship because it might provide greater insight into the neural mechanisms for this BED.

Cognitive function is linked to adherence to bariatric postoperative guidelines

BACKGROUND Impairment in cognitive function is found in a significant subset of individuals undergoing bariatric surgery, and recent work shows this impairment is associated with smaller postoperative weight loss. Reduced cognitive function could contribute to poorer adherence to postoperative guidelines, although this has not been previously examined. The present study examined the relationship between cognitive function and adherence to bariatric postoperative guidelines. We expected that higher cognitive function would be associated with better adherence to postoperative guidelines. METHODS Thirty-seven bariatric surgery patients completed cognitive testing and a self-report measure of adherence to postoperative bariatric guidelines during their 4- to 6-week postoperative appointment. RESULTS Strong correlations were observed between adherence to postoperative guidelines and cognitive indices of attention, executive function, and memory. CONCLUSIONS Results show that cognitive performance is strongly associated with adherence to postoperative guidelines shortly after bariatric surgery. Further work is needed to clarify whether this relationship is present at later postoperative stages and the degree to which this relationship mediates postoperative weight loss outcomes.

THE EFFECTS OF EXPOSURE TO SLENDER AND MUSCULAR IMAGES ON MALE BODY DISSATISFACTION

This research examined the effects of appearance-based comparisons to muscular and slender idealized male bodies and the contribution of internalization and social comparison to change in body dissatisfaction. Participants were 111 male undergraduates who completed measures of body dissatisfaction, internalization, and social comparison and viewed images of either muscular or slender men in advertisements or product-only advertisements. Results indicated that exposure to both muscular and slender images was associated with an increase in body dissatisfaction, with no significant differences in the change in body dissatisfaction between the two image conditions. Internalization and trait social comparison were each associated with an increase in body dissatisfaction; however, upward social comparison was only a significant predictor of a change in body dissatisfaction for the males who viewed muscular images. These results highlight the impact of slender models on young mens body dissatisfaction and support the examination of media literacy interventions with this population.

Adherence and Weight Loss Outcomes in Bariatric Surgery: Does Cognitive Function Play a Role?

Although bariatric surgery is the most effective intervention for severe obesity, a significant minority of participants fail to achieve or maintain optimal weight loss at extended follow-up. Accumulating evidence suggests that adherence to prescribed postoperative recommendations, including attendance at follow-up appointments and dietary and physical activity, is related to improved weight loss outcomes. However, adherence to these guidelines presents a significant challenge for many patients, potentially due in part to deficits in cognitive function. In this paper, we briefly examine current literature of adherence on postoperative weight loss outcomes, and review emerging evidence that the cognitive dysfunction present in a subset of obese individuals is related to weight loss outcomes following bariatric procedures. We then extend these findings, positing a role for cognitive function in moderating the relationship between adherence and postoperative outcomes.

Neurocognitive Effects of Obesity and Bariatric Surgery.

This review paper will discuss the recent literature examining the relationship between obesity and neurocognitive outcomes, with a particular focus on cognitive changes after bariatric surgery. Obesity is now recognized as an independent risk factor for adverse neurocognitive outcomes, and severely obese persons appear to be at even greater risk. Bariatric surgery is associated with rapid improvements in cognitive function that persist for at least several years, although the mechanisms underlying these improvements are incompletely understood. Assessment of cognitive impairment in bariatric surgery patients is challenging, and improved methods are needed, as poorer performance on neuropsychological tests of memory and executive function leads to poorer clinical weight outcomes. In addition to its clinical importance, further study in this area will provide key insight into obesity-related cognitive dysfunction and clarify the possibility of an obesity paradox for neurological outcomes.

Uncontrolled eating is associated with reduced executive functioning

Accumulating evidence indicates obesity is associated with reduced cognitive functioning, particularly attention and executive function, as well as maladaptive eating behaviour such as uncontrolled eating. The current study examined relationships between eating patterns and attention/executive function test performance in lean and obese individuals. Sixty‐two (32 lean, 30 obese) healthy young adults (21.13 ± 2.31 years; 56.5% female) completed the abbreviated Three‐Factor Eating Questionnaire (TFEQ‐R18) to assess eating patterns, including uncontrolled eating, cognitive restraint, and emotional eating. The Go/No‐Go (GNG), Running Memory Continuous Performance Test (RCMPT) and Standard Continuous Performance Test from the Automated Neuropsychological Assessment Metrics‐4 were administered as measures of executive functioning and attention. An independent samples t‐test revealed greater report of uncontrolled eating in obese compared with lean participants (t[60] = −2.174, P < 0.05; d = −0.55) but no differences in cognitive restraint or emotional eating. Multivariate analysis of variance revealed cognitive differences between lean and obese groups (F[6, 54] = 3.86, P < 0.005; λ = 0.70; ηp2 = 0.30), which were driven by GNG reaction time (F[1, 59] = 8.36, P < 0.01, d = 0.74). Pearson bivariate correlations revealed a positive correlation between uncontrolled eating and reaction time on GNG (r = 0.343, P < 0.05) and RMCPT (r = 0.267, P < 0.05) in all participants. Relative to lean participants, obese individuals reported higher levels of uncontrolled eating and exhibited slower performance on a task of inhibitory control. In the full sample, greater self‐reported dyscontrol in eating behaviour was related to slower inhibitory control and working memory. Results support a link between executive function and control of eating behaviour. Obese individuals may be more vulnerable to difficulties in these domains relative to those who are lean.

The Effects of Breakfast and Breakfast Composition on Cognition in Adults

Extensive literature has addressed the acute cognitive effects of breaking a fast. Recent reviews in this line of work have synthesized available research on the cognitive consequences of fasting compared with nutrient intake and the cognitive effects of macronutrient consumption. These largely have been inconclusive, possibly in part because of selection criteria limiting the scope of studies covered. The purpose of the current review is to integrate the results of the literature examining the cognitive effects of breakfast and breakfast composition in adults with the use of a flexible definition of breakfast, specifically, any caloric intake after a fasting period of ≥8 h. This review includes 38 studies that examine the acute cognitive impact of breakfast and 16 studies that examine the effects of breakfast composition. Results suggest that healthy adults show a small but robust advantage for memory (particularly delayed recall) from consuming breakfast. Largely equivocal results emerge for attention and motor and executive function; there were no effects from breakfast on language. Regarding breakfast composition, a smaller number of studies and widely disparate methodology addressing this question preclude definitive conclusions about the effects of cognition. A subset of this literature examines these questions in the context of glucoregulation; the findings emphasize the importance of considering differences in glucoregulation in research designs, even among healthy cohorts. The limitations of this literature include methodologic differences, such as the use of different tests to measure cognitive constructs, as well as the effects of timing in test administration.

Cognitive reserve preserves cognitive function in obese individuals

ABSTRACT Obesity is an established risk factor for cognitive impairment. Theories of cognitive reserve suggest that premorbid factors, such as intellectual ability, may attenuate the expression of cognitive impairment due to age or disease. The current study examined whether cognitive reserve, defined as estimated premorbid intellectual ability, moderates the relationship between obesity and cognitive function in obese adults. Participants without major medical or psychological conditions completed a computerized battery of neuropsychological tests. Hierarchical regression models found a significant interaction between BMI and cognitive reserve for attention/executive function and memory, suggesting that cognitive reserve attenuates the expression of obesity-related cognitive impairment.

Physical activity and cognitive function in bariatric surgery candidates

Cognitive impairment is common in severe obesity. Lack of physical activity is a likely contributor to impairment in this population, as many obese persons are inactive and physical activity has been positively and independently associated with cognitive function in healthy and medically-ill samples. This study investigated whether physical activity, measured by self-report of aerobic physical activity in 85 bariatric surgery candidates, was associated with cognitive function. A subset of 31 participants also completed objective activity monitoring. Steps/d and high-cadence min/week, representative of ambulatory moderate to vigorous physical activity (MVPA), were calculated. Approximately one quarter of participants self-reported at least 30 min/d of aerobic MVPA, at least 5 d/week. Median steps/d was 7949 (IQR = 4572) and median MVPA min/week was 105 (IQR = 123). Cognitive deficits were found in 32% of participants (29% memory, 10% executive function, 13% language, 10% attention). Controlling for demographic and medical factors, self-reported aerobic physical activity was weakly correlated with lower attention (r = –0.21, p = 0.04) and executive function (r = –0.27, p < 0.01) and both self-reported aerobic physical activity and objectively-determined MVPA min/week were negatively correlated with memory (r = –0.20, p = 0.04; r = –0.46; p = 0.02, respectively). No other correlations between physical activity measures and cognitive function were significant. Contrary to expectations, greater levels of physical activity were not associated with better cognitive functioning. Such findings encourage future studies to clarify the association among cognitive function and physical activity in obese persons.