Subjective distress mediates the association between olfactory dysfunction duration and depression in post COVID 19 patients

Abstract

Olfactory dysfunction (OD) has been reported in individuals who recovered from COVID-19. Those with OD after COVID-19 (COVID-19 group) exhibited more severe psychiatric symptoms than those with OD from other etiologies (non-COVID-19 group). This study investigates differences in psychological symptoms and related clinical factors between these groups. Fifty-two participants (COVID-19 group: 26; non-COVID-19 group: 26) were recruited. Both objective and subjective olfactory function were assessed, and symptoms of depression, anxiety, and perceived stress were measured using self-reported scales. There were no significant differences in objective and subjective olfactory function or psychological symptoms between the groups, except for age and the short version of the Questionnaire of Olfactory Disorders-negative statements (sQOD-NS). The sQOD-NS score was negatively correlated with OD duration only in the COVID-19 group. In both groups, the sQOD-NS was significantly correlated with Patient Health Questionnaire-9 (PHQ-9) scores. Mediation analysis showed that OD duration indirectly affected PHQ-9 scores via the sQOD-NS in the entire sample, particularly in the COVID-19 group. These findings suggest that subjective distress from OD may mediate the relationship between OD duration and depressive symptoms in COVID-19 patients, highlighting the need for targeted psychiatric interventions after recovery from COVID-19.

Keywords: Anxiety disorders; COVID-19; Depressive disorder; Olfaction disorders; Psychological distress.

Fig. 1

Association between sQOD-NS scores and clinical and psychological variables in participants with olfactory dysfunction (OD). Scatter plots showing the relationship between (A) sQOD-NS and OD duration, (B) sQOD-NS and PHQ-9 total scores, and (C) sQOD-NS and GAD-7 total scores.

Fig. 2

Standardized regression coefficients for the sQOD-NS-mediated association between the duration of olfactory dysfunction and PHQ-9 total score. (A) Entire sample (n = 38), (B) COVID-19 group (n = 20), (C) Non-COVID-19 group (n = 18). Note: *p <.05, **p <.01, ***p <.001, ^† p =.054. All presented effects are unstandardized; Path a is the effect of OD duration on the mediators; Path b is the effect of mediators on the PHQ-9; Path c’ is the direct effect of OD duration on PHQ-9; Path c is the total effect of OD duration on PHQ-9.

Fig. 3

Standardized regression coefficients for the sQOD-NS-mediated association between the duration of olfactory dysfunction and GAD-7 total score in the entire sample (n = 38). Note: *p <.05, **p <.01. All presented effects are unstandardized; Path a is the effect of OD duration on mediators; Path b is the effect of mediators on GAD-7; Path c’ is the direct effect of OD duration on GAD-7; and Path c is the total effect of OD duration on GAD-7.

Fig. 4

Standardized regression coefficients for the sQOD-NS-mediated association between the duration of olfactory dysfunction and mood symptom in the subjects with objective OD (n = 26). (A) A mediation model for PHQ-9, (B) A mediation model for GAD-7. Note: *p <.05, **p <.01. All presented effects are unstandardized; Path a is the effect of OD duration on mediators; Path b is the effect of mediators on mood symptoms; Path c’ is the direct effect of OD duration on mood symptoms; and Path c is the total effect of OD duration on mood symptoms.