P002 CPAP therapy compliance and changes in cognitive function in patients with obstructive sleep apnoea

AIMS: Obstructive sleep apnoea (OSA) has been implicated in the pathophysiology of Alzheimer’s disease (AD). Intermittent hypoxia and arousals may contribute to mechanisms leading to accumulation of amyloid beta plaques and intraneuronal neurofibrillary tangles seen in AD. Treatment with Continuous Positive Airway Pressure (CPAP) improves symptoms and cardiovascular sequalae of OSA, and may also mitigate the progression of AD. We investigated, in patients with moderate to severe OSA, whether CPAP compliance altered cognitive test scores. METHODS: Cognitive testing with the Addenbrooke’s Cognitive Examination-Revised Version (ACE-R) was performed before commencing CPAP and repeated after 3 to 5 years. Student’s independent t-test was used to compare changes in ACE-R between compliant and non-complaint groups based on usage greater than 4 hours/day. RESULTS: 30 subjects, mean age 67 years (SD=6.4), had baseline ACE-R of 90 (SD=4.75). At follow up, treatment compliant subjects demonstrated improvement in cognitive test scores in the memory and visuospatial cognitive domains with a mean improvement in memory of 1.5 points p=0.01 95% CI [0.33, 2.67], and mean improvement in visuospatial cognition of 0.95 points p=0.01 95% CI [0.23, 1.7]. Scores for CPAP non-compliant subjects showed no significant difference over time. CONCLUSION: Sustained use of CPAP over time results in a statistically significant improvement in ACE-R test scores, in the subdomains of memory and visuospatial cognition. However, the clinical significance of these findings is unclear and requires further research, as the scores remained in the normative range.