Continuous positive airway pressure improves gait cognitive control in severe obstructive sleep apnoea

Obstructive sleep apnoea syndrome (OSAS) has structural and functional cerebral consequences, which involve cognitive and gait limitations. Severe OSAS is associated with higher stride time variability (STV), a clinical biomarker of cognitive gait control. The impact of continuous positive airway pressure treatment (CPAP) on STV in severe OSAS has never been assessed. Prospective, controlled study evaluating the effect of 8 weeks of CPAP treatment in 12 severe OSAS patients (age=57.2±8.9 years, BMI=27.4±3.1 kg.m-2, AHI=46.3±11.7) compared to 10 matched control subjects. Spatiotemporal gait parameters are recorded at spontaneous speed and STV calculated. The cognitive control of gait and posture is assessed using a dual task paradigm (gait or posture and cognitive task (Stroop test) performed simultaneously). Performance at Stroop test is evaluated by calculating the correct response rate. Before CPAP, OSAS patients show a greater STV compared to controls (3.1±1.1% vs 2.1±0.5%, p=0.02), a higher centre of pressure area (131.2±79.8mm² vs 66.9±21.9mm², p=0.02) and a lower correct response rate in dual task condition while walking (p<0.001) or standing (p<0.001). After CPAP, STV (post-CPAP STV: 2.4±0.5%, p=0.005 vs pre-CPAP) and cognitive performance in dual task are improved in OSAS group and do not differ anymore from controls. Severe OSAS patients present an altered gait control, which may be improved by CPAP treatment. Our results suggest their cognitive origin.