Ramona Guerrieri

The interaction between impulsivity and a varied food environment: its influence on food intake and overweight.

Objective:The current study tests the influence of two factors, the obesogenic environment and impulsivity, on food intake in primary school children. Our current food environment offers a large variety of cheap and easily available sweet and fatty foods. This obesogenic environment is believed to be a cause of the recent obesity epidemic. Impulsive people are generally less successful at inhibiting prepotent responses and they are reward sensitive. We investigate whether the interaction between an obesogenic environment and an impulsive person leads to overeating.Design:A quasi-experimental 2 (reward sensitive versus not reward sensitive) by 2 (successful response inhibitors versus unsuccessful response inhibitors) by 2 (monotonous versus varied food environment) between-subjects design with caloric intake during a taste test as the main dependent variable. The link between impulsivity and overweight was also examined.Subjects:78 healthy primary school children (age: 8–10 years).Measurements:We measured two aspects of impulsivity: reward sensitivity and deficient response inhibition. Subsequently, one aspect of the obesogenic environment was manipulated; half of the participants received monotonous food during a bogus taste test whereas the other half tasted food that was varied in colour, form, taste and texture.Results:As expected, reward sensitivity interacted with variety. In the monotony group there was no difference in food intake between the less and more reward-sensitive children (183 kcal±23 s.d. versus 180 kcal±21 s.d.). However, in the variety group the more reward-sensitive children ingested significantly more calories than the less reward-sensitive children (237 kcal±30 s.d. versus 141 kcal±19 s.d.). Reward sensitivity was not linked to overweight. Deficient response inhibition did not interact with variety, but it was linked to overweight.Conclusion:It is suggested that reward sensitivity could be a causal mechanism for overeating in an obesogenic environment whereas prepotent response inhibition may be a maintaining factor of the problem of overeating.

The interactive effect of hunger and impulsivity on food intake and purchase in a virtual supermarket

Objective:It has been shown repeatedly that impulsivity, obesity and food intake are related; obese people are more impulsive than lean people and impulsive people eat more than less impulsive people. The relation between impulsivity and food intake might be state dependent; hunger motivates food seeking behaviour and food consumption, especially of high caloric food. Difficulties to overrule automatic behavioural tendencies might make impulsive people more susceptible to the effects of hunger on food selection. Therefore, they are expected to increase their intake more than low impulsive people when feeling hungry.Study 1:Fifty-seven female participants were randomly assigned to a hunger or sated condition. Response inhibition (a measure of impulsivity) and food intake were measured. Results show that impulsive participants ate significantly more, but only when feeling hungry.Study 2:Ninety-four undergraduate students participated. Hunger, response inhibition and the purchase of food in a virtual supermarket were measured. The same interaction was found: impulsive participants bought most calories, especially from snack food, but only when feeling hungry.Conclusion:Hunger and impulsivity interact in their influence on consumption. These data suggest that reducing hunger during calorie restricting diets is important for successful weight loss, particularly for the impulsive dieters.

High-restrained eaters only overeat when they are also impulsive

Recent work shows that the inability to inhibit basic motor responses (like pressing a button) is related to overeating, weight gain and overweight. In the present study it was tested whether this inability to inhibit motor responses--or impulsivity--can differentiate between successful and unsuccessful restrained eaters. A typical preload and food exposure paradigm was used and it was hypothesized that only the high-restrained eaters that are simultaneously inefficient inhibitors of prepotent motor responses would overeat when confronted with tempting foods. In line with the hypothesis, the data show that overeating follows from an interaction between restraint and impulsivity; high-restrained eaters only overate when they were also impulsive. It is concluded that being restrained per se is not a determinant of overeating. Being a restrained eater only bears the risk of overeating in case of coexisting impulsivity.

Heavy drinking is associated with deficient response inhibition in women but not in men

Poor response inhibition has been associated with a wide range of problem behaviours, including addictive behaviours, and could represent a general vulnerability factor. Standard tests of response inhibition have used neutral stimuli. Here we tested whether a deficit in response inhibition in heavy drinkers would be stronger for stimuli related to their problem (alcohol) or not. Response inhibition was assessed with a stop signal task, using four classes of pictures: alcohol-related, soft drinks, erotic (control appetitive categories) and neutral pictures. Participants were 32 heavy and 32 light drinkers. An equal amount of men and women were tested in both drinking groups, in view of recent studies reporting that response disinhibition may be most pronounced in heavy drinking women. Main results were first that no domain-specific differences in response inhibition were found in both groups. Second, heavy drinking females showed stronger response inhibition deficits than other groups. Results are discussed in light of a possible gender difference in response inhibition as a risk factor for addictive behaviours.

ACUTE STRESS ENHANCES MEMORY FOR EMOTIONAL WORDS, BUT IMPAIRS MEMORY FOR NEUTRAL WORDS

This article examined effects of acute stress on memory for neutral and emotional words. Participants (n = 40) were exposed to either a psychosocial stressor or a control task, followed by a memory test. The stress hormone cortisol was measured in saliva before and after stress induction and after the memory test. Acute stress had a differential effect on memory such that recall of neutral words was impaired, whereas that of emotional words was enhanced. These effects on memory performance were not mediated by cortisol. The authors conclude that it makes little sense to speculate about memory effects and elevated levels of cortisol because such effects might depend on the valence of the material that is learned.

Specificity of the failure to inhibit responses in overweight children

UNLABELLED Poor response inhibition has been associated with obesity, excessive food intake, and other consumptive behaviours, including alcohol use. However, the correlation between obesity and addictive behaviours like alcoholism is low: people who are obese appear to have a specific problem in restraining food intake. This would imply that obese people have more difficulties in inhibiting responses towards food, compared to other rewarding stimuli. In the present study 89 children (ages 7-9) were tested with the stop signal task, in which responses towards food pictures or toy pictures had to be inhibited. Results showed that children were less effective in inhibiting responses towards food and percentage overweight predicted a lower ability to inhibit responses in general. When dichotomizing the sample in overweight and lean children, it appeared that overweight children were specifically less effective in inhibition towards food cues, compared to lean children. IN CONCLUSION The results confirm weight related inhibitory problems and might explain the increased overeating to food cues in overweight children, as reported in the literature.

Disinhibition is easier learned than inhibition. The effects of (dis)inhibition training on food intake

Impulsivity seems to be a strong candidate when it comes to psychological factors leading to overeating and eventually to obesity (Guerrieri, Nederkoorn, & Jansen, 2008). The question is whether reversing the logic and strengthening an individuals inhibitory skills will be equally potent against overeating. In the current study the stop signal task was adjusted so that one group of female students (n=21) gradually got more trials in which they could practise inhibition (inhibition), whereas another group (n=20) gradually got more trials in which they had to react quickly, without having time to think or inhibit (impulsivity). A third group (n=20) did a neutral reading task (control). The participants in the impulsivity group had a significantly higher caloric intake during a subsequent taste test, whereas the inhibition group did not differ from the control group. Hence, the data support that impulsivity is a direct cause of overeating. However, the concept of inhibition training needs to be investigated further. Issues like the specificity of inhibition training (general vs. food specific) need to be addressed and used to optimise the training so that its effectiveness can be tested within clinical settings.

The effects of priming restrained versus disinhibited behaviour on alcohol-seeking in social drinkers

BACKGROUND Deficient response inhibition (disinhibition) may play a causal role in alcohol abuse, with impaired inhibition occurring prior to, and acting as a risk factor for, subsequent alcohol problems. We experimentally primed either disinhibited or restrained behaviour while participants completed a Stop-Signal task, before examining the effects on alcohol-seeking behaviour. METHODS Fifty three social drinkers completed a Stop-Signal task following instructions that either emphasised rapid responding at the expense of successful inhibition (Disinhibition group) or vice versa (Restrained group). Subsequent ad lib alcohol-seeking was measured with a bogus taste test. RESULTS As predicted, participants in the Disinhibition group consumed more beer during the taste test compared to participants in the Restrained group. Furthermore, within the Restrained group only, correlations indicated that those participants who responded more cautiously during the Stop-Signal task subsequently consumed less beer. CONCLUSIONS An experimental manipulation of response set during a response inhibition task, emphasising either restrained or disinhibited responding, has a causal influence on alcohol-seeking behaviour in social drinkers.

Reward-sensitive women overeat in a varied food environment, but only when hungry

In the current study we tried to elucidate the relationship between a personality trait, reward sensitivity, and an environmental variable; food variety. Based on scarce previous research we predicted that reward sensitivity would interact with variety in the food environment so that especially high reward sensitive individuals would be vulnerable to overeating in a varied food environment. It turned out that especially the high reward individuals did indeed overeat in a varied food environment. However, this was only the case for the highly reward sensitive individuals who experienced feelings of hunger. In other words, reward sensitivity does not affect food intake in varied food environments as long as feelings of hunger are not present. Future research should concentrate on identifying other factors that interact with the person and the environment to discourage reward-related overeating.

Inducing impulsivity versus inhibition affects food intake in a sample of healthy women

Previous research has related impulsivity to increased food intake and obesity. However, the precise nature of this relationship is not clear. One possibility is that impulsivity causes overeating and hence contributes to overweight. To test this possibility, we induced impulsivity versus inhibition to see whether this would affect subsequent food intake. Participants performed the stop signal task with either an inhibition instruction or an impulsive instruction, and were then asked to do a taste test. We expected that inducing impulsivity, by training people to act impulsively during the task, would lead to more food intake during a subsequent bogus taste test compared to inducing inhibition. Restraint and current dieting were also measured. Restraint status had no effect, but dieting status turned out to be an important moderating factor: the non-dieters acted as expected and ate more after the impulsivity induction than after the inhibition induction. However, current dieters did the opposite and ate more after the inhibition induction. Possible explanations are discussed. At least for non-dieters, we can conclude that heightened impulsivity versus inhibition leads to higher food intake.