Pathophysiology of Obstructive Sleep Apnea in Aging Women

Abstract

The following review is designed to explore the pathophysiology of sleep apnea in aging women. The review initially introduces four endotypes (i.e., a more collapsible airway, upper airway muscle responsiveness, arousal threshold, and loop gain) that may have a role in the initiation of obstructive sleep apnea. Thereafter, sex differences in the prevalence of sleep apnea are considered along with differences in the prevalence that exist between younger and older women. Following this discussion, we consider how each endotype might contribute to the increase in prevalence of sleep apnea in aging women. Lastly, we address how modifications in one form of respiratory plasticity, long-term facilitation, that might serve to mitigate apneic events in younger women may be modified in aging women with obstructive sleep apnea. Overall, the published literature indicates that the prevalence of sleep apnea is increased in aging women. This increase is linked primarily to a more collapsible airway and possibly to reduced responsiveness of upper airway muscle activity. In contrast, modifications in loop gain or the arousal threshold do not appear to have a role in the increased prevalence of sleep apnea in aging women. Moreover, we suggest that mitigation of long-term facilitation could contribute to the increased prevalence of sleep apnea in aging women.

Keywords: Arousal threshold; Loop gain; Obstructive sleep apnea; Post-menopause.

Fig. 1

Schematic diagram showing the sequence of events leading to the development of a central and/or obstructive apnea, and subsequent events that re-establish patency of the upper airway. Various points along the pathway (see points A–D) are highlighted. At each of these points, the mechanisms that contribute to sleep apnea (i.e., controller gain, arousal threshold, upper airway anatomy/collapsibility, and upper airway muscle responsiveness) are highlighted. In addition, the potential impact that aging in women (see boxes with blue outline and white fill) might have on the various mechanisms and ultimately the prevalence/severity of sleep apnea are highlighted. For example, aging in women could lead to upper airway anatomical modifications leading to increased collapsibility of the upper airway. Please note that the asterisk within the blue box indicates that there is published data which supports a link between age in women and the pathophysiological mechanism that impacts the prevalence and severity of sleep apnea. On the other hand, double dagger indicates that there is little evidence or no published evidence to indicate that these mechanisms are responsible for the increased prevalence of apnea in aging women