The effect of non-invasive positive pressure ventilation (NIPPV) on cognitive function in amyotrophic lateral sclerosis (ALS): a prospective study

Objectives-Neuropsychological investigations have shown a degree of cogniti ve dysfunction in a proportion of nondemented patients with ALS. Respirator y muscle weakness in ALS can lead to nocturnal hypoventilation, resulting i n sleep disturbance and daytime somnolence. Sleep deprivation of this type may cause impairments in cognitive function, but this has not been formally evaluated in ALS. Methods-Cognitive functioning was evaluated in nine patients with ALS with sleep disturbance caused by nocturnal hypoventilation (NIPPV group), and in a comparison group of 10 similar patients without ventilation problems (co ntrol group). The NIPPV group then started non-invasive positive pressure v entilation (NIPPV) at night. After about 6 weeks, change in cognitive funct ion was evaluated. Results-Statistically significant improvement in scores on two of the seven cognitive tests was demonstrated in the NIPPV group postventilation, and a trend towards significant improvement was found for two further tests. Sco res in the control group did not improve significantly for these four tests , although an improvement was found on one other test. Conclusions-Nocturnal hypoventilation and sleep disturbance may cause cogni tive dysfunction in ALS. These deficits may be partially improved by NIPPV over a 6 week period. This has important implications for investigations of both cognitive dysfunction in non-demented patients with ALS, and the effe ct of ventilation on quality of life.