Sniffing out Parkinson's disease : Psychophysical and neurophysiological studies of impaired olfactory information processing in Parkinson's disease

Wolters, E.C.H. [Promotor]Stam, C.J. [Promotor]Berendse, H.W. [Copromotor

Impact of ambient odors on food intake, saliva production and appetite ratings

The aim of this study was to investigate the effect of ambient odor exposure on appetite, salivation and food intake. 32 normal-weight young women (age: 21.4\ua0\ub1\ua05.3\ua0year; BMI: 21.7\ua0\ub1\ua01.9\ua0kg/m2) attended five test sessions in a non-satiated state. Each participant was exposed to ambient odors (chocolate, beef, melon and cucumber), in a detectable but mild concentration, and to a control condition (no-odor exposure). During each condition, at different time points, participants rated appetite for 15 food products, and saliva was collected. After approximately 30\ua0min, ad libitum intake was measured providing a food (chocolate rice, high-energy dense product) that was congruent with one of the odors they were exposed to. A significant odor effect on food intake (p\ua0=\ua00.034) and salivation (p\ua0=\ua00.017) was found. Exposure to odors signaling high-energy dense products increased food intake (243.97\ua0\ub1\ua022.84\ua0g) compared to control condition (206.94\ua0\ub1\ua024.93\ua0g; p\ua0=\ua00.03). Consistently, salivation was increased significantly during chocolate and beef exposure (mean: 0.494\ua0\ub1\ua00.050\ua0g) compared to control condition (0.417\ua0\ub1\ua00.05\ua0g; p\ua0=\ua00.006). Even though odor exposure did not induce specific appetite for congruent products (p\ua0=\ua00.634), appetite scores were significantly higher during odor exposure (p\ua0<\ua00.0001) compared to the no-odor control condition and increased significantly over time (p\ua0=\ua00.010). Exposure to food odors seems to drive behavioral and physiological responses involved in eating behavior, specifically for odors and foods that are high in energy density. This could have implications for steering food intake and ultimately influencing the nutritional status of people

Dynamics of autonomic nervous system responses and facial expressions to odors

Why we like or dislike certain products may be better captured by physiological and behavioral measures of the autonomic nervous system (ANS) than by conscious or classical sensory tests. Responses to pleasant and unpleasant food odors presented in varying concentrations were assessed continuously using facial expressions and responses of the ANS. Results of 26 young and healthy female participants showed that the unpleasant fish odor triggered higher heart rates and skin conductance responses, lower skin temperature, fewer neutral facial expressions and more disgusted and angry expressions (p <0.05). Neutral facial expressions differentiated between odors within 100 ms, after the start of the odor presentation followed by expressions of disgust (180 ms), anger (500 ms), surprised (580 ms), sadness (820 ms), scared (1020 ms), and happy (1780 ms) (all p-values <0.05). Heart rate differentiated between odors after 400 ms, whereas skin conductance responses differentiated between odors after 3920 ms. At shorter intervals (between 520 and 1000 ms and between 2690 and 3880 ms) skin temperature for fish was higher than that for orange, but became considerable lower after 5440 ms. This temporal unfolding of emotions in reactions to odors, as seen in facial expressions and physiological measurements supports sequential appraisal theories