Sleep Breathing Disorders and Cognitive Function in the Elderly: An 8-Year Follow-up Study. The Proof-Synapse Cohort

Study Objectives: Sleep breathing disorder (SBD) may be an important factor in age-related cognitive decline. In a cohort of healthy elderly subjects, we performed an 8-y longitudinal study to assess whether changes in cognitive function occur in untreated elderly patients with SBD and without dementia and the factors implicated in these changes. Design: A population-based longitudinal study. Setting: Clinical research settings. Participants: A total of 559 participants of the PROOF study aged 67 y at the study entry and free from neurological disorders were examined. Interventions: N/A. Measurements and Results: Abnormal breathing events were defined by an apnea-hypopnea index (AHI) > 15. The raw cognitive data and averaged Z-scores for the attentional, executive, and memory functions were collected at the baseline and follow-up. At baseline, AHI > 15 was found in 54% of subjects with 18% having an AHI > 30. At follow-up, the presence of abnormal breathing events was associated with a slight but significant decline in the attentional domain (P = 0.01), which was more evident in the subjects with an AHI > 30 (P = 0.004). No significant changes over time were observed in the executive and memory functions. Several indices of chronic hypoxemia, defined either as a cumulative peripheral oxygen saturation (SpO(2)) < 90% or a minimal SpO(2), accounted for portions of the variance in the decline in attention. All observed effects were small, accounting for 4-7% of variance in multivariate models. Conclusions: In healthy elderly subjects, various components of sleep breathing disorder at baseline were associated with small changes in selected cognitive functions specific to the attention domain after controlling for multiple comorbidities, such as sleepiness, hypertension, diabetes, anxiety, and depression.