Impact of Olfactory Priming on Food Intake in an Alzheimer's Disease Unit.

Alzheimer's disease (AD) is often associated with feeding difficulties and changes in eating behavior with may lead to malnutrition. In French nursing homes, AD patients may live in special care units that better meet dementia residents' needs. However, meals are often delivered to AD patients by using meal trays coming from central kitchens. This led to the disappearance of cues that could help residents to foresee mealtime, such as the smell of food odors. The aim of the present study was to assess the impact of odorizing the dining room of AD Units with a meat odor before lunch on subsequent food intake and eating behavior. Thirty-two residents (>75 years old) from three AD Units were included in the study. They participated in two control lunches and two primed lunches, for which a meat odor was diffused in the dining room 15 minutes before the arrival of the meal tray (olfactory priming). Results of the first replication showed a significant effect of olfactory priming, with a 25% increase in meat and vegetable consumption compared to the control condition. Behavioral measurements also showed a significant increase of resident's interest toward the meal in the primed lunch. However, this effect was no longer observed when the priming session was replicated two weeks later with the same priming odor and the same menu. Although further research is needed to understand why this priming effect cannot be replicated, our experiment is one of the very first to investigate the effect of food odor priming on subsequent food intake in AD patients in a real-life setting.

Orofacial reactivity to the sight and smell of food stimuli. Evidence for anticipatory liking related to food reward cues in overweight children.

Whether food liking may be a risk factor of overconsumption and overweight/obesity remains a controversial issue. So far, most studies used subjective reports to assess consummatory behavior, approaches that might overlook subtle or implicit hedonic changes to sensory properties of foods. Therefore, we used a cue-exposure approach by recording different measures of hedonic processes (orofacial reactivity, self-rated pleasantness, food preference) in 6-11 years old overweight (n=20) and normal-weight (n=20) children. Children were exposed to the smell and sight of high and low-energy density food stimuli and to non-food stimuli during pre- and post-prandial states. Their facial and verbal responses were videotaped and parent's reports of children's eating styles and appetitive traits were collected using the Children's Eating Behavior Questionnaire (CEBQ). Results showed that orofacial reactivity, as an objective measure of anticipatory liking, was more discriminative than self reports, with overweight children displaying more lip sucking than normal-weight children when exposed to high energy food pictures and to food odorants. Orofacial reactivity to food cues was also associated with BMI and children's eating styles (food responsiveness, emotional overeating, and desire to drink). Finally, overweight children classified more frequently non-food odorants as members of the food category during the pre-prandial state than during the post-prandial state, suggesting a possible influence of affective/motivational bias on odor categorization. Our findings suggest that orofacial responsiveness may be relevant to assess the sensitivity to energy-dense food reward cues in overweight children and for signaling, as an index of anticipatory liking, a potential risk for the development of overweight/obesity.