Sensitivity of the cough reflex in young and elderly subjects.
OBJECTIVE
To compare the sensitivity of the cough reflex--which is said to be normal in elderly people--in elderly and young subjects.


METHODS
20 elderly (14 female) subjects, mean (SEM) age 83 (1) years and 20 young (nine female) subjects, mean (SEM) age 27 (1) years, who were all non-smokers. None of the subjects was taking antitussive drugs and none suffered from clinically evident lung, cardiac or neurological disease. Five elderly subjects were unable to perform adequate spirometry and were excluded from analysis.


METHODS
Each subject inhaled 10 ml of nebulized distilled water and isotonic saline (as placebo) for 30 s, 10 min apart in a randomized double-blind crossover fashion. The cough frequency induced with each treatment was recorded on a click counter.


RESULTS
Cough frequency on inhaling distilled water was significantly lower in the elderly group than in the younger group, with a difference of 9.53 (95% confidence intervals: 3.63, 15.4; P < 0.001). None of the subjects coughed when inhaling placebo solution, resulting in significant differences in cough frequencies between distilled water and placebo of 5.87 (2.82, 8.92; P < 0.05) for the elderly group and 15.4 (11.0, 19.8; P < 0.0005) for the younger group.


CONCLUSIONS
The sensitivity of the cough reflex appears to be significantly reduced in elderly subjects. This may increase the risk of aspiration and bronchopulmonary infection in old age, even in the absence of respiratory disease.
Newnham
D M
DM
Department of Medicine for the Elderly, Woodend Hospital, Aberdeen, UK.
Hamilton
S J
SJ
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003371:Cough / Q000503:physiopathology*; D004311:Double-Blind Method; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D011015:Pneumonia, Aspiration / Q000209:etiology / Q000503:physiopathology; D012021:Reflex, Abnormal / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology