Sex-Specific Differences in Nutritional Status and Olfaction in Association with Cognitive Impairment Amongst Older Adults with Long COVID Syndrome

<b>Background/Objectives</b>: Long COVID has emerged as a significant public health concern, characterized by persistent symptoms following SARS-CoV-2 infection. Cognitive impairment is a common sequela, particularly among older adults (OAs). Although olfactory dysfunction and malnutrition have been previously associated with cognitive decline, it remains elusive to what extent sex-specific variations in these and additional factors will be pivotal to guiding targeted interventions in a sex-specific manner. To fill this gap in knowledge, we undertook a study with the purpose of investigating the contribution of sex-specific risk factors to the development of cognitive impairment (CI) in a cohort of OAs hospitalized with long COVID. <b>Methods</b>: We undertook a cross-sectional study among OAs hospitalized at a geriatric care unit. Olfactory function was assessed using the Sniffin' Stick Test. Cognitive impairment was evaluated by the Mini-Mental State Examination, and nutritional status was assessed with the Mini Nutritional Assessment (MNA). Statistical analyses included linear regression. <b>Results</b>: A total of 45 patients with long COVID were included, of whom 51% were female. The prevalence of CI was lower in men compared to women. In the single variable analysis, nutritional factors were associated with CI only in women; importantly, the loss of olfactory function was associated with CI in the whole group and to CI in women after multivariate analysis. <b>Conclusions</b>: Olfactory dysfunction is a potential biomarker for cognitive impairment in OAs with long COVID in a sex-specific manner. In our study nutritional status and probable obesity could be additional factors associated with CI; nevertheless, this was not confirmed in our multivariate analysis; therefore, this hypothesis would need to be tested in larger studies.