Comorbid insomnia and sleep apnea (COMISA) is associated with worse verbal episodic memory in older women.

Study objectives: To investigate whether comorbid insomnia and sleep apnea (COMISA) is associated with poor verbal memory in older adults, and whether this relationship is moderated by sex.

Methods: 110 older adults aged (65-83), all diagnosed with OSA, completed overnight polysomnography and cognitive testing. COMISA was defined as OSA plus an Insomnia Severity Index score ≥ 11. Verbal memory was assessed via the delayed recall component of the ADCS-PACC. Moderation analysis examined the interaction between COMISA and sex on verbal memory performance, adjusting for age, body mass index, APOE4 status, and education. Post hoc sleep architecture differences between men and women with COMISA and women with COMISA compared to OSA only were analyzed using MANCOVA.

Results: COMISA was associated with significantly worse verbal memory performance, with this effect driven by women (b=-2.82, SE=0.94, t=-3.01, p=0.003) and absent in men (b=0.62, SE=0.97, t=0.63, p=0.528). Post hoc analyses revealed that women with COMISA showed reduced REM sleep and increased SWS compared to men with COMISA.

Conclusions: COMISA is linked to sex-specific cognitive vulnerability, with older women showing worse verbal memory than men. Post hoc analyses revealed differences in sleep architecture by sex within COMISA, warranting further investigation into stage-specific sleep contributions to cognitive risk. These findings highlight the importance of sex-informed approaches to assessing and managing cognitive risk in aging populations.

Clinical trial registration: Registry: ClinicalTrials.gov; Name: Is Obstructive Sleep Apnea Important in the Development of Alzheimer's Disease?; Identifier: NCT05094271; URL: https://clinicaltrials.gov/study/NCT05094271.