Disinhibited Eating and Executive Functioning in Children and Adolescents: A Systematic Review and Meta-Analysis.

A growing body of research suggests disinhibited eating and weaker executive function (EF) are two risk factors for pediatric obesity. Emerging brain imaging and behavioral findings support the notion that EF skills impact eating regulation. However, a major gap in the current literature is a synthesis of the association between various EF skills and disinhibited eating patterns across child development. To address this gap, a systematic review and meta-analysis was conducted to examine the effect of EF skills on disinhibited eating behaviors among youth ages 3-18 years old. PubMed and PsychINFO databases were utilized and data from 15 studies with a total sample of 4909 youth were included. A random effects meta-analysis revealed a small negative effect of overall EF skills on disinhibited eating behavior, r = -0.14, p < 0.01. Analysis of individual EF skills found working memory had an overall medium negative effect on disinhibited eating behavior, r = -0.25, p < 0.05. Taken together, findings from this meta-analysis support an inverse relationship between EF abilities and disinhibited eating patterns in children and adolescents, such that poorer EF abilities are associated with higher levels of disinhibited eating. Given the effect on eating behavior, future research is needed to assess whether EF difficulties may be a barrier to effective weight management in youth. Specifically, research is needed to examine whether EF skills may be a key target to consider for effective obesity prevention and treatment in children and adolescents.

Cerebrovascular Perfusion among Older Adults with and Without Cardiovascular Disease.

BACKGROUND AND PURPOSE: Cardiovascular disease (CVD) encompasses a range of disorders that affect health and functioning in older adults. While cognitive declines have been linked to both cardiovascular and cerebral blood perfusion, protective neurovascular mechanisms raise the question whether cerebrovascular perfusion differs as a function of cardiovascular health status. The present study examined whether cerebrovascular perfusion significantly differs between healthy older adults with and without diagnosed CVD. The study also examined whether previously documented sex differences in cerebral perfusion would be replicated. METHODS: Twenty CVD patients without significant heart failure and 39 healthy controls were recruited to undergo a comprehensive assessment, including an interview, echocardiogram, and magnetic resonance imaging). Arterial spin labeling was used to quantify cerebral blood perfusion. RESULTS: Both groups exhibited mean left ventricular ejection fractions that fell within normal limits. In line with previous research, women exhibited significantly higher cerebral perfusion than men. There were no significant group differences in whole brain cerebrovascular perfusion, regional perfusion, or white matter perfusion by patient status after accounting for sex and age. CONCLUSIONS: These findings suggest that the effects of mild CVD on cerebrovascular perfusion are minimal. Future studies are needed to investigate the mechanisms involved in maintaining cerebrovascular perfusion in the context of altered peripheral perfusion and to determine whether this finding extends to more acute or severe CVD.

Cerebrovascular perfusion among older adults is moderated by strength training and gender.

Cerebral perfusion is important in older adults as it is linked to cognitive declines. Physical activity can improve blood flow in the body but little is known about the relationship between physical activity and cerebral perfusion in older adults. In particular, no study has investigated the relation between strength training and cerebral perfusion. We examined whether different types of physical activity (assessed with the Rapid Assessment of Physical Activity questionnaire) were associated with MRI cerebrovascular perfusion in 59 older adults. There was a significant interaction between gender and strength training, such that women who engaged in strength training (weight lifting or calisthenics) at least once per week exhibited significantly greater cerebrovascular perfusion than women who did not. This interaction remained significant after controlling for other physical activity, demographics, and health variables. These findings suggest that regular strength training can be beneficial for cerebrovascular health in women.

Obesity is associated with reduced white matter integrity in otherwise healthy adults.

Existing work demonstrates that obesity is independently associated with cognitive dysfunction and macrostructural brain changes; however, little is known about the association between obesity and white matter (WM) integrity. We explore this relationship in a large cohort of otherwise healthy subjects. The present study classified 103 adult participants from the Brain Resource International Database between 21 and 86 years of age without history of neurological, medical, or psychiatric illness according to BMI (normal weight, overweight, obese) and subjected them to diffusion tensor imaging (DTI). Resulting fractional anisotropy (FA) indexes for the corpus callosum and fornix were examined in relation to BMI and age in a multiple regression framework. Results indicated that increasing BMI was independently associated with lower FA in the genu, splenium, and fornix, and a BMI × age interaction emerged for FA in the splenium and body of the corpus callosum. When categorized, obese persons demonstrated lower FA than normal and overweight persons for all WM indexes, but no FA differences emerged between overweight and normal persons. Results indicate both a direct association between obesity and reduced WM tract integrity and an interaction between obesity and aging processes on certain WM tracts in otherwise healthy adults. While such findings suggest a possible role for adiposity in WM dysfunction and associated cognitive deficits, prospective studies are needed to clarify the nature of these relationships and elucidate underlying mechanisms.

Sustained attention is associated with left ventricular ejection fraction in older adults with heart disease.

Poor cardiac pumping efficiency has shown to lead to cognitive impairments in patients with cardiovascular disease (CVD). The current study examined the relationship between left ventricular ejection fraction and sustained attention and inhibitory processes measured by the Adaptive Rate Continuous Performance Task and the Go/No-go test. Participants were 67 older outpatients (age 68.5 +/- 7.4) with a range of CVD. Associations between cognition and ejection fraction were examined via linear regression analysis. Results were consistent with the hypothesis that lower ejection fraction is significantly associated with decrements in sustained attention and vigilance. Overall, the results provide support for the hypothesis that a change in cardiac pumping leads to decrements in some aspects of attention; however, inhibitory processes are relatively spared. (JINS, 2009, 15, 137-141.).

A fMRI Study of Verbal Working Memory, Cardiac Output, and Ejection Fraction in Elderly Patients with Cardiovascular Disease.

Cardiovascular disease (CVD) is associated with cognitive deficits even in the absence of stroke. We examined the relationship between cardiac performance, as measured by cardiac output (CO) and ejection fraction (EF), and brain activity during a verbal working memory (VWM) task in elderly CVD patients who tend to be at increased risk for vascular cognitive impairments. Seventeen patients were recruited from a cohort participating in an ongoing prospective study examining the effects of CVD on cognitive function in the elderly. Participants were diagnosed with CVD (age 68±8) and completed a 2-back VWM task in a 1.5T fMRI paradigm. CO and EF were calculated from echocardiogram measures. Task-related activation was averaged in a priori regions of interest. The relationship between CO, EF, and 2-back-related activity was modeled using partial correlations (two-tailed p<.05) controlling for age and 2-back accuracy. All participants were globally cognitively intact as indicated by Mini-Mental Status Exam and Dementia Rating Scale scores. Mean accuracy on the 2-back was 78±9% while reaction time averaged 1,027±192 ms. Mean CO and EF values showed a large range (CO: 3.55 to 6.31; EF: 0.36 to 0.76) but average values were within the normal range. After controlling for age and 2-back accuracy, lower EF was related to decrease in left insula activity (r=0.61, p=0.03). There were trends for EF to be related to accuracy (r=0.47, p=0.09) and reaction time (r=-0.48, p=0.09). CO was also related to insula activity (r=0.60, p=0.04) and activity in the supplementary motor area activity (r=0.66, p=0.01). Cardiac performance was related to decreased efficiency in task related brain areas and tended to be related to performance on a VWM task in elderly patients with CVD. Results have implications for a line of investigation indicating that cardiac and systemic vascular indices could be used as proxy measures to examine mechanisms of cerebrovascular dysfunction in the elderly.

Imaging phonological similarity effects on verbal working memory.

Studies of verbal working memory (VWM) report that performance declines as the phonemic similarity of stimuli increases. To determine how phonological similarity affects brain function during VWM, "standard" and "similarity" versions of the 2-Back task were presented to 34 healthy participants during functional magnetic resonance imaging (FMRI). Letter consonants presented during similarity blocks rhymed, while consonants did not rhyme during standard blocks. Empirical ROIs were identified from significant 2-Back-related activity observed during either condition. A priori ROIs were selected from functional neuroimaging literature on phonological processing. Although VWM-related activity was not modulated by similarity in any of four regions recruited (dorsolateral prefrontal, posterior parietal, anterior insular, and supplementary motor cortices), four of five regions of deactivation exhibited significantly greater deactivation during the similarity compared to the standard condition (posterior cingulate, paracentral lobule, posterior insula, and parahippocampal gyrus). In a priori phonological processing-related ROIs, similarity did not affect observed increases in activity (supplementary motor area, Broca's area, and cerebellum), while two of the three regions exhibiting decreased activity (near Wernicke's area and Heschel's Gyrus) also exhibited more deactivation during similarity. Accuracy was lower during the similarity 2-Back, positively related to activity within recruited VWM-related ROIs, and inversely related to activity in regions of VWM-related deactivation. Based on known functions of these ROIs, we conclude that language, audition, and self-reflection processes may disengage during phonological interference, while activity levels are maintained in regions recruited during VWM processing. Similarity effects likely include suspension of attention to unrelated and distracting processes to improve concentration.

Clock drawing and frontal lobe behavioral effects of memantine in Alzheimer's disease: a rater-blinded study.

Caregivers of Alzheimer's disease patients treated with memantine have reported improved frontal lobe behaviors. The present study examined these possible improvements in executive functioning using rater-blinded scoring of a clock-drawing test. Fifty-one Alzheimer's disease patients were treated with open-label memantine for 10 weeks. Clock drawing and Mini-Mental State Examination data were collected before and after treatment. Clock drawing improved significantly with treatment, whereas Mini-Mental State Examination data did not. Twenty-seven patients judged as improved in frontal lobe behaviors by caregivers demonstrated a statistically significant improvement in clock drawing to command, whereas 24 patients judged to be unchanged or worse with memantine in their frontal lobe behaviors had no change in their clock drawing and had worsening on their Mini-Mental State Examination. The current findings suggest that memantine improves frontal lobe behavior in some Alzheimer's disease patients and that clock drawing to command may be sensitive to these improvements.