To explore the relationship between oxygen saturation (SpO2) and cognitive function in older adults from longevity areas in China.
A total of 2 285 participants aged ≥65 years according to the 2012 Chinese Longitudinal Healthy Longevity Survey were included in this study. Among them, 1 739 participants aged 65-99 years were randomly selected, and 546 participants aged ≥100 years were totally involved. A standardized questionaire was used to collect the information of demographic characteristics, life styles, disease history, etc. Cognitive function was evaluated using the Mini Mental State Examination Scale. Arterial oxygen saturation and heart rate were measured by pulse oximetry. Differences in cognitive function between the low SpO2 group (<0.94) and normal SpO2 group (≥0.94) were analyzed, and logistic regression models were used to analyze the relationship between SpO2 and cognitive function.
The total score of cognitive function was 22.6±9.7 for the 1 922 participants in the normal SpO2 group, and 18.8 ± 11.0 for the 363 participants in the low SpO2 group (t=6.11, P<0.001). The proportion of cognitive impairment in the low SpO2 group was 36.6% (n=133), and 22.9% (n=441) in the normal SpO2 group (χ(2)=30.44, P<0.001). RESULTS from stepwise logistic regression analysis showed that the risk of cognitive impairment increased with each year of increased age (OR 1.07; (95% CI: 1.05-1.09), P<0.001). Low SpO2, vision disorders, impaired activities of daily living, dyslipidemia, unmarried status, and lack of exercise were also associated with increased risk of cognitive impairment (OR 1.64; (95% CI: 1.11-2.43), OR 1.73; (95% CI: 1.27-2.35), OR 3.54; (95% CI: 2.62-4.79), OR 1.38; (95% CI: 1.02-1.86), OR 2.05; (95% CI: 1.34-3.13), OR 1.83; (95% CI: 1.13-2.97), respectively, P<0.05). Stratified analysis by age group showed that the association between SpO2 and cognitive impairment was most significant in participants aged ≥90 years (OR 1.58; (95% CI: 1.09-2.28), P=0.016).
Low oxygen saturation was associated with higher risk of cognitive impairment in our population of elderly adults.