Electrophysiological assessment of the effects of obstructive sleep apnea on cognition

Abstract

We used electrophysiological measures to investigate the effects of obstructive sleep apnea on attention, learning, and memory. Thirty subjects (OSA group, n = 15, control group n = 15) participated in n-back tests, accompanied by P300 recordings, to investigate working memory and attention. The mirror-drawing test was used to study procedural memory, and the trail-making test (TMT) was used to evaluate divided attention and executive function. No significant group difference in reaction time was found in the 0-back and 1-back tests. In the 2-back test, reaction times of patients were longer than those of the control group. No P300 wave was obtained in the OSA group in any (0-, 1-, or 2-back) n-back test. In contrast, in the control group, significant P300 waves were recorded except for the 2-back test. The mirror-drawing scores were unaffected by sleep apnea. There was no difference between groups in the TMT-A test on any of the trials. Although no group difference was found in the first or second trials of the TMT-B test, OSA patients were less successful in learning on the third trial. According to our study results, OSA affects attention and executive function adversely however, we could not detect a significant effect on working or procedural memory.

Figure 1. Statistically significant P300 waves were recorded only under the 0-back condition.

Grand average for subjects in control and OSA groups. Top row: control, bottom row: OSA. Results are shown for the Pz electrode. Black: responses to standard (non-target) stimuli, red: responses to deviant (target) stimuli. Shaded regions indicate the confidence interval of the responses (mean ±2 SEM).