Hippocampal-dependent appetitive control is impaired by experimental exposure to a Western-style diet

Animals fed a Western-style diet (WS-diet) demonstrate rapid impairments in hippocampal function and poorer appetitive control. We examined if this also occurs in humans. One-hundred and ten healthy lean adults were randomised to either a 1-week WS-diet intervention or a habitual-diet control group. Measures of hippocampal dependent learning and memory (HDLM) and of appetitive control were obtained pre- and post-intervention. HDLM was retested at 3-weeks follow-up. Relative to controls, HDLM performance declined in the WS-diet group (d=0.43), but was not different at follow-up. Appetitive control also declined in the WS-diet group (d=0.47) and this was strongly correlated with HDLM decline (d=1.01). These findings demonstrate that a WS-diet can rapidly impair appetitive control in humans - an effect that could promote overeating in consumers of a WS-diet. The study also suggests a functional role for the hippocampus in appetitive control and provides new evidence for the adverse neurocognitive effects of a WS-diet

A high-fat high-sugar diet predicts poorer hippocampal-related memory and a reduced ability to suppress wanting under satiety

Animal data indicate that greater intake of fats and sugars prevalent in a Western diet impairs hippocampal memory and tests of behavioral inhibition known to be related to hippocampal function (e.g., feature negative discrimination tasks). It has been argued that such high fat high sugar diets (HFS) impair the hippocampus, which then becomes less sensitive to modulation by physiological state. Thus retrieval of motivationally salient memories (e.g., when seeing or smelling food) occurs irrespective of state. Here we examine whether evidence of similar effects can be observed in humans using a correlational design. Healthy human participants (N = 94), who varied in their habitual consumption of a HFS diet, completed the verbal paired associate (VPA) test, a known hippocampal-dependent process, as well as liking and wanting ratings of palatable snack foods, assessed both hungry and sated. Greater intake of a HFS diet was significantly associated with a slower VPA learning rate, as predicted. Importantly, for those who regularly consumed a HFS diet, while reductions in liking and wanting occurred between hungry and sated states, the reduction in wanting was far smaller relative to liking. The latter effect was strongly related to VPA learning rate, suggestive of hippocampal mediation. In agreement with the animal literature, human subjects with a greater intake of a HFS diet show deficits in hippocampal-dependent learning and memory, and their desire to consume palatable food is less affected by physiological state – a process we suggest that is also hippocampal related

The Role of Disgust in Male Sexual Decision-Making

Sexual arousal is known to increase risky behaviors, such as having unprotected sex. This may in part relate to the emotion of disgust, which normally serves a disease avoidant function, and is suppressed by sexual arousal. In this report we examine disgust's role in sexual decision-making. Male participants received two study packets that were to be completed at home across two different time-points. Participants were asked to complete one packet in a sexually aroused state and the other in a non-aroused state. Participants were asked to rate: (1) arousal, (2) disgust, (3) willingness for sex, and (4) disease risk toward a range of female targets, which varied in level of potential disease risk (sex-worker vs. non sex-worker) and attractiveness. A measure of trait disgust was also included along with other related scales. Sexual arousal was associated with reduced disgust and reduced judgments of disease risk for all targets—these latter two variables being correlated—and with enhanced willingness to have sex with all of the depicted persons. Willingness to have sex when aroused (in contrast to non-aroused) was predicted by disease risk judgments and trait disgust, suggesting both direct (state) and indirect (trait) effects of disgust on sexual decision-making

Chemosensory abilities in consumers of a western-style diet

People vary in their habitual diet and also in their chemosensory abilities. In this study we examined whether consumption of a Western-style diet, rich in saturated fat and added sugar, is associated with either poorer or different patterns of chemosensory perception, relative to people who consume a healthier diet. Participants were selected based on a food frequency questionnaire, which established whether they were likely to consume a diet either higher or lower in saturated fat and added sugar. Eighty-seven participants were tested for olfactory ability (threshold, discrimination, identification), gustatory ability (PROP sensitivity, taste intensity, quality and hedonics), and flavour processing (using dairy fat-sugar-odour mixtures). A Western-style diet was associated with poorer odour identification ability, greater PROP sensitivity, poorer fat discrimination, different patterns of sweetness taste enhancement, and hedonic differences in taste and flavour perception. No differences were evident for odour discrimination or threshold, in perception of taste intensity/quality (excluding PROP) or the ability of fats to affect flavour perception. The significant relationships were of small to moderate effect size, and would be expected to work against consuming a healthier diet. The discussion focuses on whether these diet-related differences precede adoption of a Western-style diet and/or are a consequence of it

Improved self-control : the benefits of a regular program of academic study

Academic examination stress impairs regulatory behavior by consuming self-control strength (Oaten & Cheng, 2005). In this study, we tested whether a study intervention program, a form of repeated practice of self-control, could improve regulatory strength and dampen the debilitating effects of exam stress. We assessed 2 cohorts at baseline and again at the commencement of exams. Without any intervention, we replicated our previous findings of deteriorations in regulatory behaviors at exam time. Students receiving the study program, however, showed significant improvement in self-regulatory capacity as shown by an enhanced performance on a visual tracking task following a thought-suppression task. During examinations, these participants also reported significant decreases in smoking, alcohol, and caffeine consumption and an increase in healthy eating, emotional control, maintenance of household chores, attendance to commitments, monitoring of spending, and an improvement in study habits. Hence, the study program not only overcame deficits caused by exam stress but actually led to improvements in self-control even during exam time.16 page(s

Improvements in self-control from financial monitoring

We tested whether the repeated practice of self-control could improve regulatory strength over time. Regulatory performance was assessed at baseline, then at monthly intervals for a period of four months using a visual tracking task. Perceived stress, emotional distress and self-efficacy were assessed by questionnaire. Participants entered a four-month self-control exercise drill designed to increase regulatory strength: a financial monitoring program. Participants showed significant improvement in self-regulatory capacity as measured by an enhanced performance on the visual tracking task following a thought-suppression task. Perceived stress, emotional distress and self-efficacy remained stable. A control group not participating in any self-control exercise showed no signs of improvement over the same time span.15 page(s

The effect of appropriate and inappropriate stimulus color on odor discrimination

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Academic examination stress impairs self-control

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Longitudinal improvements in self-control from financial monitoring

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Longitudinal gains in self-regulation from regular physical exercise

Objectives: The purpose of the present study was to test whether the repeated practice of self-regulation could improve regulatory strength over time. Method: Regulatory performance was assessed at baseline, then at monthly intervals for a period of 4 months using a visual tracking task. Perceived stress, emotional distress, self-efficacy and general regulatory behaviour were assessed by questionnaire. Following a 2-month control phase, participants entered a 2-month self-regulation programme designed to increase regulatory strength: a programme of regular physical exercise. Results: Relative to the control phase, participants who exercised showed significant improvement in self-regulatory capacity as measured by an enhanced performance on the visual tracking task following a thought-suppression task. During the regulatory exercise phase, participants also reported significant decreases in perceived stress, emotional distress, smoking, alcohol and caffeine consumption, and an increase in healthy eating, emotional control, maintenance of household chores, attendance to commitments, monitoring of spending and an improvement in study habits. The control phase showed no systematic changes in performance on the visual tracking task across sessions. Reports of perceived stress, emotional distress and regulatory behaviours were also stable across sessions. Conclusions: The uptake and maintenance of an exercise programme over a 2-month period produced significant improvements in a wide range of regulatory behaviours. Nearly every major personal and social problem has some degree of regulatory failure. The idea that the capacity for self-regulation can be improved is therefore of vast practical importance.17 page(s