Association between nocturnal hypoxic burden and subjective memory functioning in patients with obstructive sleep apnea

Subjective memory complaints are frequently reported by patients with obstructive sleep apnea (OSA), yet their relationship with apnea-hypopnea index (AHI) remains unclear. In this study, we investigated the association between nocturnal oxygen desaturation time (T90) and subjective memory functioning in patients with OSA.

This prospective cross-sectional study included 102 patients diagnosed with OSA. Participants were classified into desaturated (T90 ≥ 20%) and non-desaturated (T90 < 20%) groups. Subjective memory functioning was assessed using the Memory Functioning Questionnaire (MFQ). MFQ total and subscale scores were examined according to T90-based groups and AHI-defined OSA severity, with Holm correction applied for multiple MFQ comparisons. Multivariable linear regression analysis was performed to examine the association between continuous T90 and MFQ total score after adjustment for relevant potential confounders.

The desaturated group showed lower MFQ total scores and lower scores in selected MFQ subscales; however, these between-group differences were not statistically significant after Holm correction for multiple comparisons. MFQ scores did not differ significantly across AHI-defined OSA severity groups. In multivariable analysis, T90 was not independently associated with MFQ total score, whereas higher education level was associated with higher MFQ total scores.

Patients with greater nocturnal oxygen desaturation showed a pattern of poorer subjective memory functioning; however, these differences were not statistically significant after correction for multiple comparisons. These findings suggest that the relationship between nocturnal hypoxemia and subjective memory complaints in OSA is likely multifactorial and should be interpreted in the context of relevant demographic and clinical factors.