High arousal threshold is associated with impaired sustained attention in patients with obstructive sleep apnea

Impaired sustained attention is common in patients with obstructive sleep apnea (OSA), but the influencing factors are unclear. OSA patients with high Arousal threshold (ArTH) often experience severer hypoxia, possibly worsening sustained attention.

To determine the association between ArTH and sustained attention in OSA.

OSA was defined as apnea-hypopnea index (AHI) ≥5 events/hour in polysomnography. ArTH was scored using three criteria (1 point each): 1) AHI<30 events/hour, 2) minimum peripheral oxygen saturation >82.5%, and 3) hypopnea proportion >58.3%. High and low ArTH was defined as 0-1 and ≥2 points respectively. Sustained attention was evaluated by Psychomotor Vigilance Task (PVT). Impaired sustained attention manifested as higher lapse probability, slower mean 1/reaction time (RT), slower slowest 10% 1/RT, and slower fastest 10% 1/RT.

We included 97 OSA patients, with 59 high and 38 low ArTH patients. High ArTH group exhibited higher lapse probability (15.08±3.12 vs. 4.72±1.61%, p=0.004), lower slowest 10% 1/RT (1.76±0.09 vs. 2.06±0.07 s^-1, p=0.009), mean 1/RT (2.77±0.09 vs. 3.05±0.05 s^-1, p=0.008), fastest 10% 1/RT (3.64±0.10 vs. 3.86±0.06 s^-1, p=0.068) with adjustment of age, gender, and overweight. These results remained similar after additionally adjusting education levels and percentages of non-rapid eye movement sleep stage 3. Linear trends were observed between lower ArTH scores and higher lapse probability (p-for-trend=0.015), lower slowest 10% 1/RT (p-for-trend=0.009), mean 1/RT (p-for-trend=0.010) and fastest 10% 1/RT (p-for-trend=0.092).

High ArTH may be associated with impaired sustained attention in OSA patients. Assessing ArTH may help identify OSA patients at high risk for attention impairment.