Impairment of cognitive performance associated with dieting and high levels of dietary restraint

The Contribution of Psychological Symptoms to Cognitive Difficulties in Youth With Postural Orthostatic Tachycardia Syndrome and Chronic Pain

INTRODUCTION

Subjectively experienced cognitive difficulties are common in youth with postural orthostatic tachycardia syndrome. The pathophysiological and psychological contributions of these cognitive impairments remain unclear.

METHOD

Participants were 96 adolescents and young adults diagnosed with postural orthostatic tachycardia syndrome and admitted to an intensive pain treatment program. Participants completed cognitive assessment and measures of postural orthostatic tachycardia syndrome symptoms, pain intensity, pain catastrophizing, anxiety, depression, and functional disability.

RESULTS

Self-reported autonomic symptom intensity, but not severity of heart rate change, was associated with cognitive performance. Symptoms of depression were associated with decreases in most measures of cognitive functioning. Pain intensity, pain catastrophizing, and depression but not cognitive scores and physiological measures, were significant predictors of disability.

CONCLUSION

Depression appears to be a significant contributor to the cognitive difficulties in youth with postural orthostatic tachycardia syndrome. These findings highlight the importance of assessing and treating affective symptoms in this population along with medical and lifestyle approaches to treating postural orthostatic tachycardia syndrome symptoms.

Temporary Self-Deprivation Can Impair Cognitive Control: Evidence From the Ramadan Fast

During Ramadan, people of Muslim faith fast by not eating or drinking between sunrise and sunset. This is likely to have physiological and psychological consequences for fasters, and societal and economic impacts on the wider population. We investigate whether, during this voluntary and temporally limited fast, reminders of food can impair the fasters' reaction time and accuracy on a non-food-related test of cognitive control. Using a repeated measures design in a sample of Ramadan fasters (N = 190), we find that when food is made salient, fasters are slower and less accurate during Ramadan compared with after Ramadan. Control participants perform similarly across time. Furthermore, during Ramadan performances vary by how recently people had their last meal. Potential mechanisms are suggested, grounded in research on resource scarcity, commitment, and thought suppression, as well as the psychology of rituals and self-regulation, and implications for people who fast for religious or health reasons are discussed.

Drive for thinness in adolescents predicts greater adult BMI in the Growth and Health Study cohort over 20 years

OBJECTIVE

In youth, a preoccupation with weight and the desire to be thinner, or drive for thinness, might persist into adulthood and predict reward-based compulsive eating and greater weight status.

METHODS

A total of 623 women were enrolled from a prospective cohort study starting at 10 years old and assessed up to 20 years later. Drive for thinness was measured five times during adolescence. In adulthood (mean age = 39.5), drive for thinness, reward-based eating drive, and BMI were measured.

RESULTS

Structural equation modeling found cumulative adolescent drive for thinness predicted higher scores for both adult drive for thinness and reward-based eating drive. Youth drive for thinness was not directly associated with adult BMI but rather indirectly through adult drive for thinness. Reward-based eating drive was not associated with adult BMI.

CONCLUSIONS

Drive for thinness during the critical developmental years may exert long-term effects on adulthood eating behaviors tied to greater weight gain, potentially reflecting an important early target of intervention.

A meta-analysis of the relationship between eating restraint, impaired cognitive control and cognitive bias to food in non-clinical samples

AIM

Food restriction is argued to be a precursor for unhealthy preoccupation with food, possibly leading to the development of an eating disorder. We updated previous meta-analyses that examined the relationship between eating restraint and deficits in either general or food-related attentional and inhibitory control. We hypothesized that inconsistencies in the literature around eating restraint, impaired cognitive control, impulsivity and cognitive biases for food could be attributed to the scale used to measure eating restraint.

METHOD

A (preregistered) subgroup meta-analysis examined whether patterns of impaired cognitive control and cognitive bias for food in predominantly healthy (non-clinical) samples differed as a function of the scale used to measure eating restraint. A series of exploratory meta-analyses were carried out for specific attentional bias tasks. In total 57 datasets were included.

RESULTS

The subgroup analysis did not provide evidence that the relationship between eating restraint and impaired or biased cognitions differed significantly as a function of restraint scale. Heterogeneity across studies was high. When examining specific attentional bias tasks there was no evidence that increased eating restraint was associated with increased attentional bias or distraction by food cues, regardless of which scale was used to measure eating restraint.

CONCLUSIONS

There is little experimental evidence for the common narrative that increased eating restraint is related to impaired cognitive control generally or increased cognitive bias for food, in non-clinical samples.

Meal skipping and cognition along a spectrum of restrictive eating

OBJECTIVE

Inadequate nutrition adversely impacts brain development and cognitive functioning (Pollitt et al., 1983). Studies examining the acute impact of eating regular meals on cognition have reported inconsistent findings, necessitating the exploration of individual differences in samples contributing to equivocal results. The present study examines the impact of skipping lunch on cognitive ability in college-aged students by including eating restraint as a moderator.

METHODS

Participants were 99 college-aged students (M = 19.7 years, SD = 1.5) randomized to a blinded 'lunch' or 'lunch-omission' condition, and assessed on memory, attention, processing speed, set shifting, and eating disorder symptomology.

RESULTS

Regressing long and short-term memory on the lunch manipulation, eating restraint scores, and their interaction revealed significant interactions: those who had lunch had superior memory performance, but only for those reporting lower levels of eating restraint. Regressing set shifting speed on the manipulation, those who had lunch had slower set shifting speed than those who skipped, but only for those reporting lower levels of eating restraint.

CONCLUSIONS

Results suggest that skipping lunch may have immediate consequences on cognition, however, cognitive enhancing effects may be diminished in the presence of even low levels of eating restraint. Findings highlight the significance of purported subclinical levels of eating restraint and may inform health education strategies.

Western diet, obesity and bariatric surgery sequentially modulated anxiety, eating patterns and brain responses to sucrose in adult Yucatan minipigs

Palatable sweet/fatty foods overconsumption is a major risk factor for obesity and eating disorders, also having an impact on neuro-behavioural hedonic and cognitive components comparable to what is described for substance abuse. We hypothesized that Yucatan minipigs would show hedonic, cognitive, and affective neuro-behavioral shifts when subjected to western diet (WD) exposure without weight gain, after the onset of obesity, and finally after weight loss induced by caloric restriction with (RYGB) or without (Sham) gastric bypass. Eating behavior, cognitive and affective abilities were assessed with a spatial discrimination task (holeboard test) and two-choice feed tests. Brain responses to oral sucrose were mapped using 18F-FDG positron emission tomography. WD exposure impaired working memory and led to an “addiction-type” neuronal pattern involving hippocampal and cortical brain areas. Obesity induced anxiety-like behavior, loss of motivation, and snacking-type eating behavior. Weight loss interventions normalized the motivational and affective states but not eating behavior patterns. Brain glucose metabolism increased in gustatory (insula) and executive control (aPFC) areas after weight loss, but RYGB showed higher responses in inhibition-related areas (dorsal striatum). These results showed that diet quality, weight loss, and the type of weight loss intervention differently impacted brain responses to sucrose in the Yucatan minipig model.

Mechanisms and Effects of Dietary Restriction on CNS and Affective Disorders

Neuropsychiatric disorders, including depression contribute significantly to global disability and possess high social and health burden. Management is dominated by pharmacotherapy and psychotherapy; nevertheless, such treatments prevent or treat less than half of the patients, suggesting that alternative approaches are required. Emerging data suggest that diet may be an adjustable risk factor for psychiatric disorders. Caloric restriction (CR) possesses protective effects in almost all organs including the brain. However, the precise molecular pathways of these effects remain uncertain. In this review, we will discuss the putative neurobiological mechanisms of CR on the brain. The article will address also the molecular basis of the antidepressant effects of CR, primarily including ghrelin signaling, CREB neurotropic effects and ketone bodies production. Then we will highlight the probable effect of CR on the neuroinflammation, which emerges as a key pathogenetic factor for the majority of neuropsychiatric disorders. Finally, we discuss the so called caloric restriction mimetics, compounds that reproduce properties of CR. Further research will be required to verify the safety and efficacy of CR before a general approval can be proposed to introduce it and its mimetics in clinical practice for the treatment of neuropsychiatric disorders.

Sex differences in dietary intake in British Army recruits undergoing phase one training

Background

British Army Phase One training exposes men and women to challenging distances of 13.5 km·d^− 1 vs. 11.8 km·d^− 1 and energy expenditures of ~ 4000 kcal·d^− 1 and ~ 3000 kcal·d^− 1, respectively. As such, it is essential that adequate nutrition is provided to support training demands. However, to date, there is a paucity of data on habitual dietary intake of British Army recruits. The aims of this study were to: (i) compare habitual dietary intake in British Army recruits undergoing Phase One training to Military Dietary Reference Values (MDRVs), and (ii) establish if there was a relative sex difference in dietary intake between men and women.

Method

Researcher led weighed food records and food diaries were used to assess dietary intake in twenty-eight women (age 21.4 ± 3.0 yrs., height: 163.7 ± 5.0 cm, body mass 65.0 ± 6.7 kg), and seventeen men (age 20.4 ± 2.3 yrs., height: 178.0 ± 7.9 cm, body mass 74.6 ± 8.1 kg) at the Army Training Centre, Pirbright for 8-days in week ten of training. Macro and micronutrient content were estimated using dietary analysis software (Nutritics, Dublin) and assessed via an independent sample t-test to establish if there was a sex difference in daily energy, macro or micronutrient intakes.

Results

Estimated daily energy intake was less than the MDRV for both men and women, with men consuming a greater amount of energy compared with women (2846 ± 573 vs. 2207 ± 585 kcal·day^− 1, p < 0.001). Both sexes under consumed carbohydrate (CHO) when data was expressed relative to body mass with men consuming a greater amount than women (4.8 ± 1.3 vs. 3.8 ± 1.4 g·kg^− 1·day^− 1, p = 0.025, ES = 0.74). Both sexes also failed to meet MDRVs for protein intake with men consuming more than women (1.5 ± 0.3 vs. 1.3 ± 0.3 g·kg^− 1·day^− 1, p > 0.030, ES = 0.67). There were no differences in dietary fat intake between men and women (1.5 ± 0.2 vs. 1.5 ± 0.5 g·kg^− 1·day^− 1, p = 0.483, ES = 0.00).

Conclusions

Daily EI in men and women in Phase One training does not meet MDRVs. Interventions to increase macronutrient intakes should be considered along with research investigating the potential benefits for increasing different macronutrient intakes on training adaptations.

The relationship between dietary restraint and deficits in reasoning about causes of obesity

Objective: Increased levels of dietary restraint are associated with deficits on many cognitive tasks. Less is known about how individual differences in restraint influences complex cognition such as reasoning which is the focus of this research.Design: Two experimental studies are reported. In study 1, participants (n = 158) completed a causal conditional reasoning task with statements about weight-related and general causal relationships. Study 2 replicated and extended study 1. Participants (n = 108) completed a causal conditional reasoning task focusing on behavioural causes of weight change or general statements.Main outcome measure: Causal conditional reasoning task performance.Results: In study 1, levels of dietary restraint were negatively associated with reasoning abilities for weight-related statements only. Study 2 replicated the negative association between dietary restraint and reasoning finding the effect in both weight-related, and general, causal judgements.Conclusion: The novel findings show that individual differences in dietary restraint have a wider relationship with cognition than previously demonstrated. Results tentatively support theoretical explanations of a reduction in cognitive capacity, rather than differences in belief, explaining reasoning deficits. These findings open an interesting avenue for research and might have implications for effective decision making about personal health behaviours, such as food choice.

Does Depleting Self-Control Result in Poorer Vigilance Performance?

OBJECTIVE

To investigate whether depleting self-control prior to vigilance results in a steeper vigilance decrement.

BACKGROUND

The resource-control theory of vigilance asserts that an inherent bias toward self-generated mind-wandering draws attentional resources away from the primary task. This study seeks to test whether depleting self-control, the potential mechanism of self-generated mind-wandering, results in poorer vigilance performance.

METHOD

This study featured a between-subjects design where participants either completed a typing task that depleted self-control resources or a standard typing task that did not require self-control before performing a vigilance task. In the self-control depletion condition, participants typed a passage while omitting any "e" and "space" keys. In the standard typing task, participants typed the same passage without skipping any keys. Following both typing tasks, participants in both conditions completed an identical 12-min vigilance task.

RESULTS

Results demonstrated decreased accuracy and increased reaction times over time for both groups. Depleting self-control did not result in significant differences in accuracy, reaction time, nor a steeper vigilance decrement.

CONCLUSION

These results provide evidence against resource-control theory and self-control as an explanation for vigilance, and provide further support for cognitive resource theory as the predominant explanation for vigilance impairments.

APPLICATION

It is still unclear exactly what constitutes a "resource." A better understanding of the nature of these resources can help researchers and practitioners identify how they can be replenished, which could enhance human performance in situations requiring vigilance such as baggage screening.

Estimation of energy balance and training volume during Army Initial Entry Training

BACKGROUND

Adequate dietary intake is important for promoting adaptation and prevention of musculoskeletal injury in response to large volumes of physical training such as Army Initial Entry Training (IET). The purpose of this study was to evaluate training volume and dietary intake and estimate energy balance in Army IET soldiers.

METHODS

Dietary intake was assessed by collecting diet logs for three meals on each of three, non-consecutive days during the first week of IET. Training volume was measured across 13 weeks of training using Actigraph wGT3X accelerometers. Training intensity was classified using Sasaki vector magnitude three cut points. Energy expenditure estimates were calculated during weeks two and three of training using the modified Harris-Benedict equation and by estimation of active energy expenditure using metabolic equivalents for each classification of physical activity. All data is presented as mean ± standard deviation.

RESULTS

A total of 111 male soldiers (ht. = ± 173 ± 5.8 cm, age = 19 ± 2 years, mass = 71.6. ± 12.4 kg) completed diet logs and were monitored with Actigraphs. IET soldiers performed on average 273 ± 62 min low, 107 ± 42 min moderate, 26 ± 22 min vigorous, and 10 ± 21 min of very vigorous intensity physical activity daily across 13 weeks. The estimated total daily energy expenditure was on average 3238 ± 457 kcals/d during weeks two and three of IET. Compared to week one caloric intake, there was a caloric deficit of 595 ± 896 kcals/d on average during weeks two and three of IET. Regression analysis showed that body weight was a significant predictor for negative energy balance (adj. R2 = 0.54, p < 0.001), whereby a 1 kg increase in body mass was associated with a 53 kcal energy deficit.

CONCLUSIONS

Based on week one dietary assessment, IET soldiers did not consume adequate calories and nutrients to meet training needs during red phase (weeks one through three). This may directly affect soldier performance and injury frequency. IET soldiers undergo rigorous training, and these data may help direct future guidelines for adequate nourishment to optimize soldier health and performance.

Effects of almond consumption on the post-lunch dip and long-term cognitive function in energy-restricted overweight and obese adults

The post-lunch dip in cognition is a well-established phenomenon of decreased alertness, memory and vigilance after lunch consumption. Lunch composition reportedly influences the post-lunch dip. Moreover, dieting is associated with cognitive function impairments. The negative effects of dieting have been reversed with nut-supplemented diets. The aims of this study were to (1) evaluate the acute effect of an almond-enriched high-fat lunch or high-carbohydrate lunch on the post-lunch decline in cognitive function, and (2) evaluate the effects of chronic almond consumption as part of an energy-restricted diet on the memory and attention domains of cognitive function. In total, eighty-six overweight and obese adults were randomised to consume either an almond-enriched diet (AED) or a nut-free control diet (NFD) over a 12-week weight loss intervention. Participants were also randomised to receive either an almond-enriched high-fat lunch (A-HFL) (>55 % energy from fat, almonds contributing 70-75 % energy) or a high-carbohydrate lunch (HCL) (>85 % energy from carbohydrates) at the beginning and end of the weight loss intervention. Memory and attention performance indices decreased after lunch consumption (P<0·001). The A-HFL group ameliorated the decline in memory scores by 57·7 % compared with the HCL group (P=0·004). Both lunch groups had similar declines in attention. Moreover, memory and attention performance indices increased after the 12-week intervention period (P<0·05) with no difference between the AED and NFD groups. In conclusion, almond consumption at a midday meal can reduce the post-lunch dip in memory. However, long-term almond consumption may not further improve cognitive function outcomes in a weight loss intervention.

A Mechanistic Basis for the Beneficial Effects of Caloric Restriction On Longevity and Disease: Consequences for the Interpretation of Rodent Toxicity Studies

Caloric restriction in rodents has been repeatedly shown to increase life span while reducing the severity and retarding the onset of both spontaneous and chemically induced neoplasms. These effects of caloric restriction are associated with a spectrum of biochemical and physiological changes that characterize the organism's adaptation to reduced caloric intake and provide the mechanistic basis for caloric restriction's effect on longevity. Here, we review evidence suggesting that the primary adaptation appears to be a rhythmic hypercorticism in the absence of elevated adrenocorticotropin (ACTH) levels. This characteristic hypercorticism evokes a spectrum of responses, including reduced body temperature and increased metabolic efficiency, decreased mitogenic response coupled with increased rates of apoptosis, reduced inflammatory response, reduced oxidative damage to proteins and DNA, reduced reproductive capacity, and altered drug-metabolizing enzyme expression. The net effect of these changes is to (1) decrease growth and metabolism in peripheral tissues to spare energy for central functions, and (2) increase the organism's capacity to withstand stress and chemical toxicity. Thus, caloric restriction research has uncovered an evolutionary mechanism that provides rodents with an adaptive advantage in conditions of fluctuating food supply. During periods of abundance, body growth and fecundity are favored over endurance and longevity. Conversely, during periods of famine, reproductive performance and growth are sacrificed to ensure survival of individuals to breed in better times. This phenomena can be observed in rodent populations that are used in toxicity testing. Improvements over the last 30 years in animal husbandry and nutrition, coupled with selective breeding for growth and fecundity, have resulted in several strains now exhibiting larger animals with reduced survival and increased incidence of background lesions. The mechanistic data from caloric restriction studies suggest that these large animals will also be more susceptible to chemically induced toxicity. This creates a problem in comparing tests performed on animals of different weights and comparing data generated today with the historical database. The rational use of caloric restriction to control body weight to within preset guidelines is a possible way of alleviating this problem.

Body mass loss correlates with cognitive performance in primates under acute caloric restriction conditions

Brain functions are known to consume high levels of energy, thus, the integrity of cognitive performance can be drastically impacted by acute caloric restriction. In this study, we tested the impact of a 40% caloric restriction on the cognitive abilities of the grey mouse lemur (Microcebus murinus). Twenty-three male mouse lemurs were divided into two groups: 13 control animals (CTL) that were fed with 105kJ/day and 10calorie restricted (CR) animals that received 40% less food (63kJ/day) than the CTL animals. The animals were fed according to their group for 19days. Before treatment, we assessed baseline associative learning capacities, resting metabolic rates and locomotor performance of both animal groups. After treatment, we tested the same functions as well as long-term memory. Our results showed that CR animals had lower learning performance following caloric restriction. The effects of caloric restriction on memory recall varied and depended on the metabolism of the individual animal. Body mass loss was linked to memory test performance in the CR group, and lower performance was observed in individuals losing the most weight. While CR was observed to negatively impact learning, locomotor capacities were preserved in CR animals, and there were higher resting metabolic rates in the CR group. Our data reinforce the strong link between energy allocation and brain function, and suggest that in the context of food shortage, learning capacities could be a limiting parameter in the adaptation to a changing environment.

Test-retest reliability and effects of repeated testing and satiety on performance of an Emotional Test Battery

The P1vital® Oxford Emotional Test Battery (ETB) comprises five computerized tasks designed to assess cognition and emotional processing in human participants. It has been used in between-subjects experimental designs; however, it is unclear whether the battery can be used in crossover designs. This is of particular importance given the increasing use of ETB tasks for repeated assessment of depressed patients in clinical trials and clinical practice. In addition, although satiety state has been reported to affect performance on some cognitive and emotional tasks, it is not known whether it can influence performance on the ETB. Two studies explored these issues. In Experiment 1, 30 healthy women were tested on the ETB on 4 separate occasions (each a week apart) in a within-subjects design. In Experiment 2, another 30 healthy women were randomized to either a satiated or a hungry condition, where they were given an ad libitum lunch of cheese sandwiches, before (satiated) or after (hungry) they were asked to complete the ETB. Experiment 1 demonstrated good test–retest reliability for the ETB. One of the tasks was free from practice effects, whilst performance on the other four tasks stabilized after the first two sessions. In Experiment 2, eating to satiety only affected performance on a single ETB task. These results suggest that the ETB can be used in crossover designs after two initial training sessions. Further, as a robust satiety manipulation had only a limited effect on a single ETB task, it is unlikely that appetitive state will confound ETB performance.

Social cognition in children at familial high-risk of developing an eating disorder

Objective: Diagnosis of an eating disorder (ED) has been associated with differences in social cognition. To date research investigating social cognition and ED has mainly employed patient and recovered samples. It is therefore unclear whether differences in social cognition are present prior to onset of ED, potentially contributing to development, or whether differences observed are a consequence of the disorder. We aimed to further explore whether individuals at high-risk for ED present social cognition characteristics previously found in ED groups.

Methods: Our sample was drawn from a population-based cohort, the Avon Longitudinal Study of Parents and Children (ALSPAC). Data on maternal ED behaviors over the lifetime were collected through in-depth clinical interviews (n = 1128) conducted using the Structured Clinical Interview for DSM disorders (SCID), and were used to categorize mothers according to ED behaviors over the lifetime: Restricting and Excessive Exercising (n = 58), Purging (n = 70), Binge-eating (n = 72), Binging and Purging (n = 66), no ED (n = 862). High-risk status of children was determined using these maternal lifetime behavioral phenotypes. Children at high-risk (maternal ED exposure) were compared to children at low-risk (born to mothers with no ED) on three measures of social cognition: the Social Communication Disorders Checklist (SCDC) (n = 922), the faces subtest of the Diagnostic Analysis of Non-Verbal Accuracy (DANVA) (n = 722), and the Emotional Triangles Task (n = 750).

Results: Children at high-risk for ED showed poorer performance on measures of social cognition compared to children at low-risk. Maternal lifetime binge-eating, and maternal lifetime binging and purging were associated with poorer social communication in children (OR: 2.4, 95% CI: 1.0, 5.7, p = 0.05; and OR: 2.7, 95% CI: 1.1, 6.5, p = 0.03 respectively). Maternal binging and purging was also found to be associated with differential facial emotion processing and poorer recognition of fear from social motion cues (B: −0.7, 95% CI: −1.1, −0.2, p = 0.004).

Discussion: Children at high-risk for ED showed slight differences in some areas of social cognition when compared to children at low-risk. Characteristic patterns in social cognition are present in children at high-risk for ED, particularly among children whose mothers have binge-eating and purging behaviors over the lifetime. Our findings support the hypothesis that these differences may be part of an intermediate phenotype for ED: perhaps contributing to development, or perhaps indexing a shared liability with psychiatric disorders characterized by abnormal social cognition.

Integrating fundamental concepts of obesity and eating disorders: implications for the obesity epidemic

Physiological mechanisms promote weight gain after famine. Because eating disorders, obesity, and dieting limit food intake, they are famine-like experiences. The development of the concept of meeting an ideal weight was the beginning of increasing obesity. Weight stigma, the perception of being fat, lack of understanding of normal growth and development, and increased concern about obesity on the part of health providers, parents, and caregivers have reinforced each other to promote dieting. Because weight suppression and disinhibition provoke long-term weight increase, dieting is a major factor producing the obesity epidemic. The integrated eating disorder-obesity theory included in this article emphasizes that, contrary to dieters, lifetime weight maintainers depend on physiological processes to control weight and experience minimal weight change.

Design and pilot results of a mobile phone weight-loss application for women starting a meal replacement programme

We developed and tested a mobile phone application (app) to support individuals embarking on a partial meal replacement programme (MRP). Overweight or obese women were randomly allocated to one of two study groups. The intervention group received an MRP Support app. The control group received a static app based on the information available with the MRP. A total of 58 adult women (Support n = 28; Control n = 30) participated in the 8-week trial. Their BMI was 26-43 kg/m² Usage data suggested that the intervention group were more engaged with using the app throughout the study period. Mixed modelling revealed that the difference in weight loss between the intervention and control groups (estimated mean, EM = 3.2% and 2.2% respectively) was not significant (P = 0.08). Objective data suggested that users of the Support app were more engaged than those using the control app. A total of 1098 prompts (54%) asking people in the intervention group to enter their meals were completed prior to the evening prompt. Women in the intervention group reported a greater increase in positive affect (i.e. mood) than those in the control group (EM = 0.48 and -0.01, respectively) (P = 0.012). At Week 8, those in the control group reported a greater decrease in the effort they were willing to put into staying on the diet than those who received the Support app (EM = -2.8 and -1.4, respectively) (P = 0.024). The Support app could be a useful adjunct to existing MRPs for psychological outcomes.

Continuous glucose monitoring and cognitive performance in type 2 diabetes

BACKGROUND

Type 2 diabetes is associated with reductions in cognitive function that are associated with glycated hemoglobin (HbA1c) levels, but there is no information on whether cognition is related to postmeal glucose spikes. We explored the relationship of cognition to glucose levels measured by a continuous glucose monitoring system (CGMS) both before and after a weight loss diet.

SUBJECTS AND METHODS

Forty-four white subjects with type 2 diabetes (59.0 ± 6.2 years old; body mass index, 32.8 ± 4.2 kg/m(2); HbA1c, 6.9 ± 1.0%) completed an 8-week energy-restricted (approximately 6-7 MJ, 30% deficit) diet. Cognitive functioning (short-term memory, working memory, speed of processing [inspection time], psychomotor speed, and executive function) was assessed during four practice sessions, baseline, and Week 8. Parallel glucose levels were attained using the CGMS in 27 subjects. Outcomes were assessed by fasting blood glucose (FBG), postprandial peak glucose (G(max)), time spent >12 mmol/L (T > 12), and 24-h area under the glucose curve (AUC(24)).

RESULTS

Despite a fall in FBG of 0.65 mmol/L after 8 weeks, digits backward results correlated with FBG at both Week 0 and Week 8 (r = -0.43, P < 0.01 and r = -0.32, P < 0.01, respectively). Digits forward results correlated with FBG (r = -0.39, P < 0.01), G(max) (r = -0.46, P < 0.05), and AUC(24) (r = -0.50, P < 0.01) at Week 0 and FBG (r = -0.59, P < 0.001), G(max) (r = 0.37, P = 0.01), AUC(24) (r = -0.41, P < 0.01), and percentage weight loss (r = 0.31, P < 0.01) at Week 8. Cognitive function was not altered by weight loss, gender, baseline lipid levels, or premorbid intelligence levels (National Adult Reading Test).

CONCLUSIONS

FBG, G(max,) and AUC(24) were related to cognitive function and an energy-restricted diet for 8 weeks did not alter this relationship.

Are dieting-related cognitive impairments a function of iron status?

The aim of the present study was to investigate whether the impairments in cognitive function observed in unsupported dieting are related to compromised Fe status. During a non-clinical intervention, overweight participants (age: 18-45 years, BMI: 25-30 kg/m²) either participated in a commercially available weight-loss regimen (n 14), dieted without support (n 17) or acted as a non-dieting control group (n 14) for a period of 8 weeks. Measurements of cognitive function and blood chemistry were taken at a pre-diet baseline, after 1 week and 8 weeks of dieting. After 1 week, unsupported dieters displayed impaired verbal memory, executive function and slower reaction speeds than the other two groups, this difference disappearing by the end of the study. There were no significant group-related changes in blood chemistry over the course of the study, although there were group-related changes in a number of self-reported food-related cognitions. In conclusion, impaired cognition among unsupported dieters is not due to compromised Fe status and is most likely to result from psychological variables.

Performance on the Iowa Gambling Task is related to magnitude of weight loss and salivary cortisol in a diet-induced weight loss intervention in overweight women

The overall objective of this study was to examine the relationship between executive function, specifically decision-making, and weight loss. We used the Iowa Gambling Task (IGT) to characterize decision-making and compared performance on this task to weight loss in obese women (n=29) participating in a 12-week controlled, calorie-reduced intervention. We hypothesized that a greater amount of weight loss over the course of the intervention would be associated with better performance on the IGT, assessed at the end of the intervention. The intervention led to significant weight loss of 5.8±3.1 kg (p<0.05) and fat loss of 5.1±3.0 kg (p<0.05). Body weight and fat mass losses over the 12-week intervention varied widely, ranging from -12.5 kg to 0.0 kg for body weight and -10.4 kg to +0.8 kg for fat mass. A greater amount of body weight loss was correlated (r=0.425; p<0.01) with a higher total score on the IGT. Similarly, the reduction in body fat mass was also correlated with the IGT score (r=0.408; p<0.05). We examined other physiological (salivary cortisol), metabolic (resting energy expenditure), and behavioral (food intake; dietary restraint) factors that might be related to differences in the magnitude of weight loss. Of these variables, ad libitum consumption of energy, fat and protein during a buffet meal was inversely related to weight loss (r=-0.428; p<0.05; r=-0.375; p<0.05 and r=-0.472; p=0.01, respectively). The present study is the first to report an association between diet-induced weight loss and performance on the IGT, and this association was specific to the loss of body fat. Our results suggest that differences in weight loss may be linked to executive function that involves decision-making about events that have emotionally or socially salient ramifications. These findings underscore the need to further investigate higher cognitive and neuroendocrine pathways that may influence or be altered by the process of dieting and weight loss.

Working memory performance and preoccupying thoughts in female dieters: Evidence for a selective central executive impairment

OBJECTIVE

The study aimed to extend previous research into the impaired cognitive performance of spontaneous dieters by employing the Double Span Memory Task to investigate the relationship between weight-loss dieting and performance simultaneously on the three subsystems of working memory.

METHOD

A sample of 33 dieting and 33 non-dieting women were presented with increasingly longer sequences of common objects, displayed successively in different, randomly chosen locations of a 4 x 4 grid. Participants were then asked to name the objects (phonological loop), point to the locations (visuospatial sketch pad), or both (central executive). Participants also completed self-report measures of preoccupying cognitions, dietary restraint, depressed affect, and verbal intelligence.

RESULTS

Current dieters performed more poorly than non-dieters on combined recall, but not on the single recall of objects or locations. They also scored more highly on self-rated preoccupying cognitions.

CONCLUSION

Dieting to lose weight selectively impairs central executive functioning, rather than the storage capacity of the two slave systems. This dieting-related central executive deficit is at best partly attributable to the preoccupying thoughts about food, weight, and body shape accompanying dieting.

Clinical management of behavioral characteristics of Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a complex neurodevelopmental disorder caused by an abnormality on the long arm of chromosome 15 (q11-q13) that results in a host of phenotypic characteristics, dominated primarily by hyperphagia and insatiable appetite. Characteristic behavioral disturbances in PWS include excessive interest in food, skin picking, difficulty with a change in routine, temper tantrums, obsessive and compulsive behaviors, and mood fluctuations. Individuals with PWS typically have intellectual disabilities (borderline to mild/moderate mental retardation) and exhibit a higher overall behavior disturbance compared to individuals with similar intellectual disability. Due to its multisystem disorder, family members, caregivers, physicians, dieticians, and speech-language pathologists all play an important role in the management and treatment of symptoms in an individual with PWS. This article reviews current research on behavior and cognition in PWS and discusses management guidelines for this disorder.

Longitudinal examination of obesity and cognitive function: results from the Baltimore longitudinal study of aging

BACKGROUND

Obesity indices (i.e. BMI, waist-to-hip ratio) show differential relationships to other health outcomes, though their association to neurocognitive outcome is unclear.

METHODS

We examined whether central obesity would be more closely associated with cognitive function in 1,703 participants from the Baltimore Longitudinal Study of Aging.

RESULTS

Longitudinal mixed-effects regression models showed multiple obesity indices were associated with poorer performance in a variety of cognitive domains, including global screening measures, memory, and verbal fluency tasks. Obesity was associated with better performance on tests of attention and visuospatial ability. An obesity index by age interaction emerged in multiple domains, including memory and attention/executive function.

CONCLUSION

Obesity indices showed similar associations to cognitive function, and further work is needed to clarify the physiological mechanisms that link obesity to poor neurocognitive outcome.

Development and validation of a Food Preoccupation Questionnaire

OBJECTIVE

Existing Food Preoccupation Questionnaires do not take account of food-related thoughts that have a positive emotional valence. We report on the development and validation of a questionnaire that provides independent assessments of thought frequency and emotional valence (positive, negative or neutral).

METHOD

In Study 1 questionnaire items were validated against a three-day diary measure with 40 males and females. In Study 2 the questionnaire was administered to 130 males and females alongside a range of other measures.

RESULTS

The questionnaire showed good construct validity, internal reliability, and test-retest reliability. Dieters and females scored higher on frequency and negativity subscales. There was also a significant interaction between sex and diet status on thought frequency, with females showing a stronger relationship between the two.

DISCUSSION

The questionnaire should be useful for exploring the cognitive impact of dieting and relationships between food preoccupation, food processing biases and overeating.

Long-term effects of provided low and high glycemic load low energy diets on mood and cognition

Energy-restricted low glycemic load diets are being used increasingly for weight loss. However, the long-term effects of such regimens on mood and cognitive performance are not known. We assessed the effects of low glycemic load (LG) and high glycemic load (HG) energy-restricted diets on mood and cognitive performance during 6 months of a randomized controlled trial when all food was provided. Subjects were 42 healthy overweight adults (age 35+/-5 years; BMI 27.8+/-1.6 kg/m(2)) with a mean weight loss of 8.7+/-5.0% that did not differ significantly by diet randomization. Mood was assessed by using the Profile of Mood States (POMS) questionnaire. Cognitive performance was assessed by using computerized tests of simple reaction time, vigilance, learning, short-term memory and attention, and language-based logical reasoning. Worsening mood outcome over time was observed in the HG diet group compared to the LG for the depression subscale of POMS (p=0.009 after including hunger as a covariate). There was no significant change over time in any cognitive performance values. These findings suggest a negative effect of an HG weight loss diet on sub-clinical depression but, in contrast to a previous suggestion, provide no support for differential effects of LG versus HD diets on cognitive performance.

Neuropsychologische Befunde bei Anorexia und Bulimia nervosa im Kindes- und Jugendalter

Zusammenfassung: Anorexia und Bulimia nervosa sind häufige psychiatrische Erkrankungen des Kindes- und Jugendalters, die insbesondere Mädchen betreffen. Im Akutzustand der Starvation treten bei Essstörungen eine Vielzahl von hormonellen, neuropsychologischen und hirnmorphologischen Veränderungen auf, von denen einige nur teilweise reversibel sind. Komorbide psychiatrische Erkrankungen verkomplizieren das Krankheitsbild und erschweren adäquate therapeutische Interventionen. Der folgende Artikel setzt sich ausführlich mit den neuropsychologischen Defiziten bei Essstörungen, möglichen Einflussfaktoren auf die kognitive Leistungsfähigkeit und daraus resultierenden Implikationen für den klinischen Alltag auseinander.

Neuropsychological study of underweight and "weight-recovered" anorexia nervosa compared with bulimia nervosa and normal controls

OBJECTIVE

To compare executive, memory and visuospatial functioning of DSM-IV anorexia nervosa (AN), bulimia nervosa (BN), and normal controls (NC).

METHOD

A comparison of women involving: (i) 16 AN with body mass indices (BMI) < or = 17.5 kg/m(2); (ii) 12 AN with BMI > 18.5 kg/m(2) for at least 3 months; (iii) 13 BN; and (iv) 16 NC participants was performed with groups of similar age and intelligence. Groups were assessed with EDE-12, MADRS, HAMA, Cognitive Drug Research (CDR) battery, and Bechara tasks.

RESULTS

Significant impairments in CDR Power of Attention were present in underweight AN and BN participants. CDR Morse Tapping was significantly impaired in all clinical groups. The BN and weight-recovered AN groups were significantly impaired on CDR immediate word recall. The BN group alone was significantly impaired on CDR delayed word recall.

CONCLUSION

Attentional impairment is similar in AN and BN. Impaired motor tasks in AN persist after "weight-recovery" and are similar to impairments in BN. BN may be discriminated from AN on word recall.

Examination of cognitive function during six months of calorie restriction: results of a randomized controlled trial

BACKGROUND

Calorie restriction increases longevity in many organisms, and calorie restriction or its mimetic might increase longevity in humans. It is unclear if calorie restriction/dieting contributes to cognitive impairment. During this randomized controlled trial, the effect of 6 months of calorie restriction on cognitive functioning was tested.

METHODS

Participants (n = 48) were randomized to one of four groups: (1) control (weight maintenance), (2) calorie restriction (CR; 25% restriction), (3) CR plus structured exercise (CR + EX, 12.5% restriction plus 12.5% increased energy expenditure via exercise), or (4) low-calorie diet (LCD; 890 kcal/d diet until 15% weight loss, followed by weight maintenance). Cognitive tests (verbal memory, visual memory, attention/concentration) were conducted at baseline and months 3 and 6. Mixed linear models tested if cognitive function changed significantly from baseline to months 3 and 6, and if this change differed by group. Correlation analysis was used to determine if average daily energy deficit (quantified from change in body energy stores) was associated with change in cognitive test performance for the three dieting groups combined.

RESULTS

No consistent pattern of verbal memory, visual retention/memory, or attention/concentration deficits emerged during the trial. Daily energy deficit was not significantly associated with change in cognitive test performance.

CONCLUSIONS

This randomized controlled trial suggests that calorie restriction/dieting was not associated with a consistent pattern of cognitive impairment. These conclusions must be interpreted in the context of study limitations, namely small sample size and limited statistical power. Previous reports of cognitive impairment might reflect sampling biases or information processing biases.

Body mass index and neuropsychological function in healthy children and adolescents

Elevated body mass index (BMI) is associated with adverse neurocognitive outcome in adults, including reduced neuropsychological test performance. It is unknown whether this relationship also exists in children and adolescents. A total of 478 children and adolescents (age 6-19) without significant medical or psychiatric history provided demographic information and completed a computerized cognitive test battery. Participants were categorized using clinical criteria into underweight, normal weight, at risk for overweight and overweight groups based on age and gender. Partial correlation and MANCOVA analyses adjusting for age and intellectual function found no relationship between BMI and cognitive test performance in the full sample. However, analyses performed separately by gender showed that underweight females exhibited poorer memory performance than other female BMI groups. These findings suggest that elevated BMI is not associated with cognitive function in healthy children and adolescents, though underweight might be a risk factor for reduced memory performance in females. Further work is needed to clarify the inconsistent findings between adults and minors.

Impairment of cognitive performance in dietary restrained women when imagining eating is not affected by anticipated consumption

Dietary restraint is associated with impairments on tasks requiring concurrent processing of food-related information and performance of a secondary cognitive task. The aim of the present study was to investigate whether manipulating information about post-task consumption of food enhances the cognitive impairments observed in restrained eaters when they are required to think about food at the same time as performing a simple reaction time task. On separate trials within the same session, restrained (n=29) and unrestrained eaters (n=29) were asked to imagine eating a slice of chocolate cake and drinking glass of water while performing a simple reaction time task. Half the participants were told that they would not be able to consume the cues following the task, while the other half were told that they would be required to eat the cake and drink the water. The reaction time performance of restrained eaters was slowed when imagining eating the cake, relative to imagining drinking the water in both the consumption and no consumption conditions. No effects of cue exposure on reaction time were found for unrestrained eaters. The results suggest that dietary restrained eaters are more reactive to food cues but that this effect is not modulated by information about post-task consumption of the food.

Emotional, external, restrained eating and overweight in Dutch adolescents

The purpose of this study was to determine how emotional, external and restrained eating behavior and other health-related lifestyle factors were associated with being overweight in adolescents. Moreover, demographic and ethnic differences in eating behavior have been examined. The respondents were 10,087 Dutch adolescents aged 11-16 years (M= 13.0, SD= 0.8). Self-reported eating behavior was measured with the DEBQ. Health-related lifestyle was determined by physical activity, breakfasting, fruit consumption and snacking. High restrained, and low external eating were positively associated with being overweight, whereas no significant association between emotional eating and being overweight was found for girls, and a negative association for boys. Adolescents who ate breakfast on a daily basis were less likely to be overweight than those who ate breakfast irregularly or never. Being overweight was positively associated with fruit consumption for girls and negatively with physical activity for boys.

Construct validation of the Restraint Scale in normal-weight and overweight females

The Restraint Scale (RS) is a widely used measure to assess restrained eating. The purpose of this study was to examine the construct validity of the RS in a sample of normal-weight (n=349) and overweight (n=409) females using confirmatory factor analyses of the RS in relation to other measures for dieting, overeating and body dissatisfaction. Following Laessle et al. [(1989a). A comparison of the validity of three scales for the assessment of dietary restraint. Journal of Abnormal Psychology, 98, 504-507], we assumed a three-factor structure: (1) overeating and disinhibitory eating, (2) dieting and restriction of food intake, and (3) body dissatisfaction and drive for thinness. Analyses revealed that the RS loaded significantly on all three factors for both samples, confirming its multifactorial structure. However, the RS appears to capture these constructs differently in overweight and normal-weight females such that the RS may overestimate restraint in overweight individuals. This may explain the greater effectiveness of the RS in predicting counter-regulation in normal-weight than in overweight samples of dieters.

Cognitive dietary restraint and cortisol: importance of pervasive concerns with appearance

The purpose of this study was to elucidate the nature of the relationship between dietary restraint and physiological stress, by investigating which eating and body-related constructs are related to salivary cortisol and to perceived stress. Female undergraduates (N = 170) completed self-report measures on dietary restraint, appearance beliefs, body satisfaction variables, perceived stress, and eating self-efficacy. Participants also provided two saliva samples. The first sample was collected after awakening, and the second was collected 6-8 h later. A factor analysis was performed in order to reduce redundancy in the set of measures surrounding eating and body attitudes, which yielded three factors. The findings indicated that women with stronger beliefs about the importance of their appearance, as well as negative emotions and cognitions surrounding their body image, had higher levels of cortisol in the afternoon. These appearance and body-related constructs were also associated with higher levels of perceived stress. However, perceived stress was not associated with salivary cortisol. There were no significant relationships between any of the eating or psychological variables and morning cortisol levels. These results suggest that dysfunctional cognitions surrounding appearance and body image significantly contribute to the relationship between dietary restraint and elevations in cortisol excretion. Implications for interventions and women's health are discussed.

Relationship between dieting to lose weight and the functioning of the central executive

The study investigated the impact of weight-loss dieting on the four identified functions of the central executive of working memory: dual-task performance, random generation, task switching and activation of long-term memory. Participants were 32 female current dieters and 32 female non-dieters who completed four well-established cognitive tasks designed to tap each specific function. Participants also completed tasks designed to load on the phonological loop and visuo-spatial sketch pad working memory systems, as well as self-report measures of depressed affect and preoccupying cognitions. Dieters performed more poorly than non-dieters on all central executive measures except random generation. These dieting-related differences were most evident on moderately complex trials, and were partially mediated by preoccupying thoughts about food, weight and body shape, but not by BMI or depressed affect. It was concluded that weight-loss dieting has a relatively global impact on central executive functioning and thus has wide-ranging cognitive consequences.

Everyday dietary behaviour and the relationship between attention and meal size

Previously, it has been demonstrated that overeating can occur when an individual engages in a cognitive task during a meal. One possibility, therefore, is that task performance can provide a measure of attention to dietary control. To explore this idea we measured performance on an otherwise irrelevant task during a meal. In two experiments, we compared intake and performance across five groups of females; dieters, and four groups of non-dieters, each with contrasting high and low scores on the restraint scale of the Dutch Eating Behaviour Questionnaire and the disinhibition scale of the Three-Factor Eating Questionnaire. Our analysis suggests that a correspondence can exist between task performance and intake (Experiment 1) and this might be influenced by the extent to which foods are regarded as forbidden (Experiment 2). However, aspects of our data are difficult to reconcile with the idea that task performance reflects a simple measure of attention to dietary control. Instead, one possibility is that individuals differ in the way that they choose to allocate attention during a meal. In relation to this idea, we discuss the possibility that some individuals choose to avoid food-related cognition by engaging strategically with other aspects of their cognitive environment.

Weight loss strategies, stress, and cognitive function: supervised versus unsupervised dieting

The early stages of dieting to lose weight have been associated with neuro-psychological impairments. Previous work has not elucidated whether these impairments are a function solely of unsupported or supported dieting. Raised cortico-steroid levels have been implicated as a possible causal mechanism. Healthy, overweight, pre-menopausal women were randomised to one of three conditions in which they dieted either as part of a commercially available weight loss group, dieted without any group support or acted as non-dieting controls for 8 weeks. Testing occurred at baseline and at 1, 4 and 8 weeks post baseline. During each session, participants completed measures of simple reaction time, motor speed, vigilance, immediate verbal recall, visuo-spatial processing and (at Week 1 only) executive function. Cortisol levels were gathered at the beginning and 30 min into each test session, via saliva samples. Also, food intake was self-recorded prior to each session and fasting body weight and percentage body fat were measured at each session. Participants in the unsupported diet condition displayed poorer vigilance performance (p = 0.001) and impaired executive planning function (p = 0.013) (along with a marginally significant trend for poorer visual recall (p = 0.089)) after 1 week of dieting. No such impairments were observed in the other two groups. In addition, the unsupported dieters experienced a significant rise in salivary cortisol levels after 1 week of dieting (p < 0.001). Both dieting groups lost roughly the same amount of body mass (p = 0.011) over the course of the 8 weeks of dieting, although only the unsupported dieters experienced a significant drop in percentage body fat over the course of dieting (p = 0.016). The precise causal nature of the relationship between stress, cortisol, unsupported dieting and cognitive function is, however, uncertain and should be the focus of further research.

Dietary restraint and cognitive performance in children

Adults who attempt to restrict their dietary intake also tend to perform worse on a range of cognitive tasks. However, the extent to which this finding generalises to children has remained unclear. Following studies involving adults, we asked 44 girls (mean age = 10.1 years) to complete a simple reaction-time task and the Tower of London task. This group was selected from a local community school in the East Midlands (UK). Dietary restraint was measured using a version of the Dutch Eating Behaviour Questionnaire that had been adapted for use by children. Our results indicate that children with high restraint scores have longer reaction times and they also tend to perform worse on the TOL task. Other aspects of our data also suggest the dietary restraint may be correlated negatively with a measure of academic ability. We discuss reasons why restraint and performance might be related causally and we conclude that this issue warrants further scrutiny.