Sleep breathing disorders and cognitive decline in healthy elderly followed for eight years: The PROOF cohort

Abstract

Sleep breathing disorders (SBD) are the most common sleep disorders frequently under-diagnosed in elderly populations. However, it is it well known that this disorder may contribute to the age-related cognitive decline. In a cohort of healthy elderly subjects, we performed an 8-year longitudinal study to assess whether changes in cognitive function occur in untreated SBD elderly and the nocturnal factors implicated in these changes. A total of 559 participants of the community-based PROOF study aged 67 years at the study entry and free from neurological disorders were examined. SBD was defined by an apnea-hypopnea index (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 8 years later. Estimates of the longitudinal changes were computed for each of the three cognitive abilities by subtracting the averaged scores of last from the first evaluation (delta score, Δ). At baseline, an AHI > 15 was found in 54% of subjects with 18% having a severe form (AHI > 30). At follow-up, the presence of SBD was associated with a slight but significant decline in the attentional domain (P = .01), which was more evident in the subjects with an AHI > 30 (P = .004). The decline of memory score was related to sleep fragmentation (p < .001) without contribution of indices of nocturnal hypoxemia. In healthy elderly subjects, the presence of SBD was associated with a significant decline in attentional and memory function. While the severity of the sleep disorder reflected by the AHI and the severity of sleep fragmentation accounted for the degree of the attentional and memory decline, chronic intermittent hypoxemia had small effect. Interestingly, in some subjects of this population the treatment by positive airway pressure it would be to prevent the long-term cognitive decline (Crowford-Achour & al. 2015). These data stressed the need to make cognitive rehabilitation in elderly and treat the SBD disorder to prevent the long-term cognitive decline. The presence of abnormal respiratory events longitudinally induces a decline in the age-related decline. These pathologies are underdiagnosed in the elderly. These data were essential when it discusses the effect of cognitive rehabilitation in elderly population for which the treatment of SBD coulb be potentiated it.