Hyperventilation and attention: effects of hypocapnia on performance in a Stroop task

This study aimed to investigate the effect of hypocapnia on attentional per formance. Hyperventilation, producing hypocapnia, is associated with physio logical changes in the brain and with subjective symptoms of dizziness, con centration problems and derealization. In this study (N = 42), we examined cognitive performance on a Stroop-like task, following either 3 min of hypo capnic or normocapnic overbreathing. Both overbreathing trials were run on separate days, each preceded by a baseline trial with the same task during normal breathing. More and other symptoms were reported after hypocapnia co mpared to normocapnia. Also. more errors were made and progressively slower reaction times (RT's) were observed during recovery from hypocapnia. These performance deficits were only found in participants characterized by apne as. The number of symptoms did not correlate with RT's or errors. The patte rn of data suggested that hypoxia, as a result of apneas during recovery fr om hypocapnia, caused the cognitive performance deficit. (C) 2000 Elsevier Science B.V. All rights reserved.