Background Huntington's disease (HD) is a neurodegenerative condition resulting in motor, cognitive and behavioural dysfunction. Physiotherapists are involved in the management of respiratory problems during the later stages of the disease1 yet little is known about the respiratory system during the progression through the stages of the disease.

Aim The aim of this study was to measure respiratory function in people with HD at different stages of the disease in order to identify if and when changes in respiratory function occurred.

Method Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and peak cough flow (PCF) were measured in people with HD; 6 pre-manifest, 8 mid-stage and 10 late stage (total n=24). Measurements were taken following American Thoracic Society Guidelines. Comparisons were made against predicted values based on ECCS (European Community for Coal and Steel). Kruskall Wallace analysis was undertaken to test for differences between the stages of the disease.

Results All patients completed the study. Significant differences were found between the 3 stages of HD for all outcomes ((χ2=17.5, 17.3, 14.5; df 2); p≤0.001). Mean predicted values for FVC and FEV1 were greater than 100% at the presymptomatic stage, were between 73.3% and 74% at the middle stage and between 20% and 21% at the late stage.

Conclusions Respiratory function is reduced in people with HD in the middle and later stages of the disease. These findings have implications for adequate gaseous exchange; hence exercise tolerance and airway clearance. Further research needs to be undertaken to increase the power of these findings; to investigate underlying mechanisms for the deficits (eg, neuromuscular coordination, cognitive/motivational) and to investigate management strategies for slowing respiratory function decline.