Kristina L. McFadden

Differences in the neuronal response to food in obesity-resistant as compared to obesity-prone individuals.

Despite living in an obesogenic environment, some individuals maintain a thin phenotype compared to the majority who are at risk for weight gain and obesity. Understanding how these different phenotypes regulate energy intake is critical. The objective of this study was to examine the differences in neuronal response to visual food cues in adults recruited as either obesity-resistant (OR) or obesity-prone (OP) based on self-identification, BMI, and personal/family weight history. 25 OR and 28 OP individuals were studied after 4 days of eucaloric energy intake. Functional magnetic resonance imaging (fMRI) was performed in the fasted and acute fed states (30 min after a test meal) while subjects viewed images of foods of high hedonic value and neutral non-food objects. Measures of appetite using visual analog scales were performed before and every 30 min after the test meal for 3 h. In the fasted state, food as compared to nonfood images elicited significant response in the insula, somatosensory cortex, parietal cortex, and visual cortex in both OR and OP. The acute fed state resulted in significant attenuation of these and other brain areas in the OR but not OP individuals. Furthermore, OP as compared to OR individuals showed greater activation of medial and anterior prefrontal cortex (PFC) in response to the test meal. Adjusting for fat mass did not impact these results. Attenuation of insula/PFC response to food images in the fed state was associated with greater reductions in hunger. These findings suggest that individuals prone to weight gain and obesity have altered neuronal responses to food cues in brain regions known to be important in energy intake regulation. These altered responses may represent an important mechanism contributing to excess energy intake and risk for obesity.

Attitudes Toward Complementary and Alternative Medicine Influence Its Use

OBJECTIVE The aim of this study was to explore how attitudes toward complementary and alternative medicine (CAM) and conventional medicine influence CAM use in a healthy population, and how health locus of control and exercise further affect CAM use. DESIGN A cross-sectional survey design was used. PARTICIPANTS The sample consisted of 65 healthy graduate students. MAIN OUTCOME MEASURES Since previous studies have focused on the attitudes of medical providers toward CAM, there are currently no standard, widely used measures of attitudes toward CAM from the perspective of the healthcare recipient. Thus, a new measure, the Complementary, Alternative, and Conventional Medicine Attitudes Scale (CACMAS) was created to address how attitudes of healthcare recipients affect CAM use. The Multidimensional Health Locus of Control Scale (MHLC) was used to investigate effects of health locus of control on CAM use, and participants reported which of 17 listed CAM treatments they had used in the past, were currently using, or would likely use in the future. Participants also reported days of exercise in the past month to explore if those engaging in healthy behaviors might report more CAM use. RESULTS Having a philosophical congruence with CAM and agreement with holistic balance was associated with increased CAM use. Dissatisfaction with conventional medicine was also related to increased CAM use, but to a lesser extent. Those attributing health to personal behaviors (an internal health locus of control) reported more CAM use, as did those engaging in more resistance training in the previous month.

Effects of exercise on resting-state default mode and salience network activity in overweight/obese adults.

Despite the common use of exercise as a weight-loss strategy, little is known about its neuronal effects, and how these may be related to cognitive changes that impact food intake. The current study assessed the effects of a 6-month exercise intervention on intrinsic activity in the default mode network (DMN), a functionally connected network of brain regions including posterior cingulate cortex, cuneus/precuneus, medial prefrontal cortex, medial temporal lobe, and inferior parietal cortices, and salience network, which includes the anterior cingulate cortex and insula. Resting-state functional MRI data were acquired in 12 overweight/obese individuals. The intervention was associated with a reduction in DMN activity in the precuneus (P=0.003, family-wise error-corrected), which was associated with greater fat mass loss (P=0.013) as well as reduced perceived hunger (Three Factor Eating Questionnaire, P=0.024) and hunger ratings in response to a meal (P=0.013). No changes were observed in the salience network in response to the exercise intervention. The association between DMN change and both fat mass loss and reduction of hunger ratings suggests that DMN function may be involved in the regulation of food intake behaviors. Given previous reports of DMN overactivity in overweight/obese individuals, the present findings may indicate an exercise-related ‘normalization’ of network function.

Abnormalities in gamma-band responses to language stimuli in first-degree relatives of children with autism spectrum disorder: an MEG study

BackgroundSynchronous neural oscillatory activity in the gamma range (30–80 Hz) has been shown to be abnormal in individuals with autism spectrum disorders (ASD) and their first-degree relatives in response to simple auditory stimuli. Gamma-band abnormalities in ASD probands have been seen in response to language stimuli, but this has not been investigated in first-degree relatives. This is of particular interest given that language impairments are a core symptom of ASD and may be part of the broad autism phenotype (BAP) seen in relatives.MethodsMagnetoencephalography recordings during a continuous word recognition task were obtained for 23 parents of a child with ASD (pASD) and 28 adult control participants. Total and evoked gamma-band activity, as well as inter-trial phase-locking factor (PLF), were measured in response to the task. Beta-band activity was also measured, due to its suggested role in language processing. Participants completed a series of language measures to assess the relationship between brain activity and language function, and lateralization of task-related activity was assessed.ResultsThe pASD group showed increased evoked gamma and beta activity, while controls had decreased evoked activity. Additionally, while both groups showed a reduction in total gamma power (commonly seen in language tasks), this reduction was more prominent in the control group. The pASD group demonstrated significantly worse performance on a measure of phonology compared to controls. Significant but distinct relationships were found between gamma/beta activity and language measures within the two groups. In addition, while the overall task generally elicited left lateralized responses, pASD showed greater left lateralization than controls in some regions of interest.ConclusionsAbnormalities in oscillatory responses to language were seen in pASD that are consistent with previous findings in ASD probands. Gamma-band responses to language stimuli have not previously been assessed in first-degree relatives of ASD probands and these findings are supportive of gamma-band activity as a heritable, neurophysiological biomarker of ASD. The possible relationship seen between language function and neural activity in the current study should be investigated further to assess if oscillatory response abnormalities may contribute to behavioural manifestations of the BAP.

Acupressure as a Non-Pharmacological Intervention for Traumatic Brain Injury (TBI)

Acupressure is a complementary and alternative medicine (CAM) treatment using fingertips to stimulate acupoints on the skin. Although suggested to improve cognitive function, acupressure has not been previously investigated with a controlled design in traumatic brain injury (TBI) survivors, who could particularly benefit from a non-pharmacological intervention for cognitive impairment. A randomized, placebo-controlled, single-blind design assessed the effects of acupressure (eight treatments over 4 weeks) on cognitive impairment and state of being following TBI, including assessment of event-related potentials (ERPs) during Stroop and auditory oddball tasks. It was hypothesized that active acupressure treatments would confer greater cognitive improvement than placebo treatments, perhaps because of enhanced relaxation response induction and resulting stress reduction. Significant treatment effects were found comparing pre- to post-treatment change between groups. During the Stroop task, the active-treatment group showed greater reduction in both P300 latency (p = 0.010, partial η² = 0.26) and amplitude (p = 0.011, partial η² = 0.26), as well as a reduced Stroop effect on accuracy (p = 0.008, partial η² = 0.21) than did the placebo group. Additionally, the active-treatment group improved more than did the placebo group on the digit span test (p = 0.043, Cohens d = 0.68). Together, these results suggest an enhancement in working memory function associated with active treatments. Because acupressure emphasizes self-care and can be taught to novice individuals, it warrants further study as an adjunct treatment for TBI.

The role of alpha-7 nicotinic receptors in food intake behaviors.

Nicotine alters appetite and energy expenditure, leading to changes in body weight. While the exact mechanisms underlying these effects are not fully established, both central and peripheral involvement of the alpha-7 nicotinic acetylcholine receptor (α7nAChR) has been suggested. Centrally, the α7nAChR modulates activity of hypothalamic neurons involved in food intake regulation, including proopiomelanocortin and neuropeptide Y. α7nAChRs also modulate glutamatergic and dopaminergic systems controlling reward processes that affect food intake. Additionally, α7nAChRs are important peripheral mediators of chronic inflammation, a key contributor to health problems in obesity. This review focuses on nicotinic cholinergic effects on eating behaviors, specifically those involving the α7nAChR, with the hypothesis that α7nAChR agonism leads to appetite suppression. Recent studies are highlighted that identify links between α7nAChR expression and obesity, insulin resistance, and diabetes and describe early findings showing an α7nAChR agonist to be associated with reduced weight gain in a mouse model of diabetes. Given these effects, the α7nAChR may be a useful therapeutic target for strategies to treat and manage obesity.

Cardiovascular benefits of acupressure (Jin Shin) following stroke

OBJECTIVES Acupressure, a complementary and alternative medicine (CAM) treatment, uses fingertips, rather than needles, to stimulate acupoints on the skin and has been implicated as a successful treatment for a variety of medical disorders. However, acupressures underlying mechanisms remain unclear. One theory is that acupoint stimulation modulates autonomic nervous system activity. Previous studies have suggested that acupressure may positively affect heart rate and blood pressure. The current study investigated the effects of a type of acupressure, Jin Shin, on cardiovascular function in stroke survivors, a population that could especially benefit from a treatment promoting cardiovascular health. The study tested the hypothesis that active acupressure treatments would reduce heart rate and blood pressure (i.e., induce a greater relaxation response) above and beyond that seen during placebo acupressure treatments. METHODS A randomised, placebo-controlled, single-blind crossover design was utilised, in which 16 participants received 8 weeks of either active or placebo acupressure followed by washout and crossover into the opposite treatment condition. Heart rate and blood pressure measurements were taken throughout treatments. RESULTS Active acupressure treatments were associated with a significantly greater (p=.043, eta(2)=.30) and faster (p=.002, eta(2)=.76) reduction in heart rate compared to that seen during placebo treatments. No treatment effect on blood pressure was found. CONCLUSIONS Active acupressure reduced heart rate significantly more than did placebo acupressure during treatments. Although no treatment effect on blood pressure was found, this could be due to 67% of participants taking antihypertensive medications during the study.

Test-retest reliability of the 40 Hz EEG auditory steady-state response.

Auditory evoked steady-state responses are increasingly being used as a marker of brain function and dysfunction in various neuropsychiatric disorders, but research investigating the test-retest reliability of this response is lacking. The purpose of this study was to assess the consistency of the auditory steady-state response (ASSR) across sessions. Furthermore, the current study aimed to investigate how the reliability of the ASSR is impacted by stimulus parameters and analysis method employed. The consistency of this response across two sessions spaced approximately 1 week apart was measured in nineteen healthy adults using electroencephalography (EEG). The ASSR was entrained by both 40 Hz amplitude-modulated white noise and click train stimuli. Correlations between sessions were assessed with two separate analytical techniques: a) channel-level analysis across the whole-head array and b) signal-space projection from auditory dipoles. Overall, the ASSR was significantly correlated between sessions 1 and 2 (p<0.05, multiple comparison corrected), suggesting adequate test-retest reliability of this response. The current study also suggests that measures of inter-trial phase coherence may be more reliable between sessions than measures of evoked power. Results were similar between the two analysis methods, but reliability varied depending on the presented stimulus, with click train stimuli producing more consistent responses than white noise stimuli.

Efficacy of acupressure for non-pharmacological stress reduction in college students

OBJECTIVES Identifying a non-pharmacological intervention to reduce the stress response could be particularly beneficial to college students, a group prone to considerable stress. Acupressure has shown some efficacy in reducing stress in adults following stroke or traumatic brain injury (TBI), but multiple treatments were required. Results from single treatments in healthy populations have been mixed. DESIGN The current study used a randomised, placebo-controlled, single-blind design to investigate the use of a single acupressure treatment for stress reduction in healthy college students (n=109) during a stressor. INTERVENTIONS Participants were randomly assigned to one of three single, 40-min interventions: active acupressure, placebo acupressure, or a relaxation CD control. A math task stressor administered before and after the intervention assessed intervention effects on stressor responsivity. MAIN OUTCOME MEASURES Stress responses were measured by physiological (heart rate (HR), heart rate variability (HRV), skin conductance response (SCR)) and subjective measures (State Anxiety Inventory, nine-item Psychological Stress Measure) of anxiety and stress. RESULTS All interventions were associated with the following changes during the post-intervention stressor compared to the pre-intervention stressor: reduced HR (p<0.001), increased HRV (p<0.024), reduced SCR (p<0.001), reduced subjective stress scores (p<0.001), and increased correct answers (p<0.001). Although all groups demonstrated stress reduction, there were no significant group differences after a single treatment. CONCLUSIONS All interventions significantly reduced the stress response, although not differently. The lack of active acupressure-associated treatment effects appears to be due to insufficient dosing.

Propensity to Obesity Impacts the Neuronal Response to Energy Imbalance

The mechanisms responsible for the propensity to gain weight or remain normal weight are poorly understood. The objective of this study was to study the neuronal response to visual food cues during short-term energy imbalance in healthy adults recruited as obesity-resistant (OR) or obesity-prone (OP) based on self-identification, body mass index, and personal/family weight history. Twenty-five OR and 28 OP subjects were studied in underfed (UF) and overfed (OF) as compared to eucaloric (EU) conditions in a randomized crossover design. Each study phase included a 3-day run-in diet, 1 day of controlled feeding (basal energy needs for EU, 40% above/below basal energy needs for OF/UF), and a test day. On the test day, fMRI was performed in the acute fed stated (30 min after a test meal) while subjects viewed images of foods of high hedonic value and neutral non-food objects. Measures of appetite and hormones were also performed before and every 30 min after the test meal. UF was associated with significantly increased activation of insula, somatosensory cortex, inferior and medial prefrontal cortex (PFC), parahippocampus, precuneus, cingulate, and visual cortex in OR. However, UF had no impact in OP. As a result, UF was associated with significantly greater activation, specifically in the insula, inferior PFC, and somatosensory cortex in OR as compared to OP. While OF was overall associated with reduced activation of inferior visual cortex, no group interaction was observed with OF. In summary, these findings suggest that individuals resistant to weight gain and obesity are more sensitive to short-term energy imbalance, particularly with UF, than those prone to weight gain. The inability to sense or adapt to changes in energy balance may represent an important mechanism contributing to excess energy intake and risk for obesity.