Aims

To investigate the effect of OSA on the cognitive evolution of patients with AD.

Methods

In this prospective, single-center study (NCT02814045), patients with mild-moderate AD with and without untreated OSA were evaluated at the baseline and after 12, 24 and 36 months of follow-up. OSA was defined as an apnea-hypopnea index (AHI) >15/h. The primary outcome was measured by the cognitive scores on the Alzheimer’s Disease Assessment Scale-Cognitive subscale (ADAS-cog) and Mini-Mental State Examination (MMSE).

Results

The cohort included 146 patients with 125 validated PSGs, from which 40 patients were diagnosed as non-OSA (32%) and 85 as OSA (68%). The median [IQR] age of the eligible individuals was 75.0 [72.0;80.0] years and the majority was composed of women (57.25%). In addition, the mean (SD) MMSE score at the baseline was 23.53 (2.23).

In the ADAS-cog score, the mean (SD) change at the 12 months of follow-up was 2.97 (5.73) and 0.29 (5.65) for the non-OSA and OSA group, respectively. The estimated mean (95%) difference between the groups was -2.76 (0.12 to 0.16) (p=0.033). No cognitive changes were observed at several cognitive domains evaluated. There was a cognitive decline along the 3 years of follow-up according to the MMSE score (p<0.001) (Figure 1), but no differences between the groups were observed.

Conclusions

OSA was not associated with a worse cognitive evolution after 36 months of follow-up. Further studies will be necessary to improve the understanding of the OSA impact on the cognitive evolution of AD patients.