General low alertness in people with obstructive sleep apnea.

STUDY OBJECTIVES: In patients with obstructive sleep apnea (OSA), a previous study using a Go/No-Go task reported an average attention deficit. However, the temporal dynamics of such a deficit is unknown. Here, we investigated whether attention deficits in different subdomains increased as test progressed. We also investigated the effect of target frequency and speed of stimulus presentation on performance.

METHODS: twenty-seven non-treated people with OSA and 27 age- and sex-matched controls underwent a 15-minute Go/No-Go task, divided into 6 blocks. Each block was subdivided into three different interstimulus intervals (1, 2, and 4s). Three blocks had a low and three had a high target probability (20% and 80%, respectively). Measured were reaction time (alertness), variability of reaction time (sustained attention), commission errors (response inhibition), and omission errors (focused attention).

RESULTS: Alertness was lower in the group with OSA compared to controls, as evidenced by a significantly higher average reaction time. This effect was seen from the start of the task, continued until the end, but did not increase in test progression. The temporal pattern of intrinsic alertness deficits in patients with OSA was found to be independent of target frequency or interstimulus interval.

CONCLUSIONS: The primary attention problem in OSA is on the alertness subdomain irrespective of the number of required responses or speed of stimulus presentation. The present results support the notion that OSA is distinct from other neurological and psychiatric conditions, such as depression or chronic pain. The results also posit significant concerns regarding daily life activities (e.g., driving).