Older women with comorbid insomnia and sleep apnea show worse memory performance

New research among older adults with sleep apnea reveals that verbal memory performance is significantly worse in women - but not in men - who also have insomnia.

Results show that older adults with comorbid insomnia and sleep apnea - often referred to as COMISA - demonstrated worse memory performance than those with sleep apnea alone. This interaction remained significant even after adjusting for age, body mass index, sleep apnea severity, and education. However, when analyzed by sex, COMISA was significantly associated with worse verbal memory outcomes in women, but not in men.

"We expected that having both insomnia and sleep apnea would worsen memory for everyone, but only older women showed this vulnerability. That was striking, especially because women typically outperform men on verbal memory tasks," said lead author Breanna Holloway, who has a doctorate in clinical psychology and behavioral medicine and is a postdoctoral researcher at UC San Diego School of Medicine. "The fact that COMISA seemed to offset that advantage hints at a hidden sleep-related pathway to cognitive decline in women. Prior studies have shown increased incidence of Alzheimer's disease in women with untreated sleep apnea."

The study is published in the Dec. 1 issue of the Journal of Clinical Sleep Medicine, the official publication of the American Academy of Sleep Medicine.

The study involved 110 older adults between the ages of 65 and 83 who were diagnosed with obstructive sleep apnea. They completed an overnight sleep study and cognitive testing, and insomnia and verbal memory were assessed using validated tools. COMISA was present in 37% of participants.

According to the authors, sex differences in sleep architecture may explain the cognitive vulnerability observed in women with COMISA. Post hoc analyses revealed that women with COMISA had reduced rapid eye movement sleep and more slow wave sleep compared with men, underscoring the importance of considering sex-specific patterns when evaluating COMISA.

These results point to an overlooked risk in women with both insomnia and sleep apnea. Because women are more likely to have insomnia and often go undiagnosed for sleep apnea, recognizing and treating COMISA early could help protect memory and reduce dementia risk."

Breanna Holloway, lead author

The researchers noted that the findings support sex-specific screening and treatment strategies.

Dr. Atul Malhotra, the Peter C. Farrell Presidential Endowed Chair in Pulmonary Medicine at University of California San Diego School of Medicine and pulmonologist at UC San Diego Health, was the principal investigator for this study.