Swallowing and cough reflexes in patients with dementia

Sasaki’s group has extensively studied the association between aspiration pneumonia and cough/swallowing reflexes, and has demonstrated that these important reflexes are well maintained throughout the whole life, but decrease profoundly during the night and to a less extent during the day time in patients with vascular accidents such as basal ganglia infarction. In Japan, patients with dementia are increasing in number, therefore it seems to be very important to know the condition of their cough/swallowing reflexes. However, few reports dealing with cough/swallowing reflexes in patients with dementia could be found. Thus, we investigated the cough/swallowing reflexes in patients with dementia in the daytime. Subjects included 30 patients with dementia (age = 81.9 ± 1.5, 10 men, 20 women, vascular type 10, Alzheimer type 20) and 55 age-matched healthy nondementia volunteers (age = 79.8 ± 1.1, 23 men, 32 women). Nobody had taken either ACE inhibitors or levodopa. The swallowing reflex was induced by a bolus injection of tap water (0.5, 1.0, 2.0, 4.0 mL) into the pharynx through a nasal catheter. This reflex was evaluated by the volume injected that elicited a response within 4 s following the injection. The cough reflex was evaluated according to the method by Fujimura et al. using inhaled capsaicin (0.49–250 mmol/L). These two reflexes were examined on the same day (Tables 1, 2). In the swallowing reflex, the percentage of individuals who responded to 0.5 mL, 1.0 mL, 2.0 mL and 4.0 mL of water was 68%, 28%, 0% and 4%, respectively, in the dementia group (n = 25), and 84%, 12%, 2% and 2%, respectively, in the control group (n = 51). In the cough reflex, the dementia group (n = 28) also showed a slightly lower response rate than the control group (n = 54), but there was no statistically significant difference in these reflexes between dementia and control groups, and between vascular and Alzheimer types. In the present study, both swallowing and cough reflexes were demonstrated to be well maintained in patients with dementia in the daytime. Wada et al. reported that the swallowing reflex was significantly poorer in severe Alzheimer disease (AD) patients compared with that in a mild to moderate AD group, and that neuroleptics had a bad effect on the reflex. In our study, no individuals had a history of aspiration pneumonia within a year, and only one vascular dementia patient had a symptom of dysphagia. Neuroleptics were given to less than 10% of the individuals examined in the both groups. Most patients suffered from moderate to mild dementia, because very severe dementia patients Table 1 Swallowing reflex in the two groups