2015 Volume 19 Issue 1 Pages 24-32
Purpose: Elderly patients who suffer from dysphagia and dementia tend to eat only small portions of dysphagia diet, including blenderized food, while they eat larger portions if the visual appearance of such food is closer to that of normal food. In this study, we examined the effect of the visual perception of food on swallowing function and cerebral blood flow.
Methods: Thirty-one healthy adults (19 males and 12 females) took part in the study. The subjects were shown images of both normal food and blenderized normal food on an i-Pad. First, we used nearinfrared topography (NIRS) to examine changes in oxygenated hemoglobin concentrations (Oxy-Hb) in the prefrontal cortex. Next, we conducted the repetitive saliva swallowing test (RSST) and measured salivary amylase activity. We also examined the reliability of our study with 22 subjects, 12 males and 10 females, of the 31 participants.
Results: Oxy-Hb levels were significantly higher with normal food than with blenderized food (p＜0.05), though the reliability was low. RSST values were significantly higher with normal food than with blenderized food (p＜0.01), with high reliability (ICC＝0.62). There were no significant differences in salivary amylase activity values, with low reproducibility.
Discussion: In cases where higher Oxy-Hb values were shown with normal food than with blenderized food, their appetite might be stimulated and the projection pathway from the amygdala to the prefrontal cortex might be activated. The low reliability in this test may have been due to habituation through learning as well as the effect of processing of information, other than visual information, in the frontal lobe. The RSST showed higher values with normal diet than with blenderized food, suggesting that the appearance of normal food increased saliva secretion and enhanced swallowing reflex.
