Olfactory Dysfunction Predicts the Development of Depression in Older US Adults

Abstract

Neuroanatomic connections link the olfactory and limbic systems potentially explaining an association between olfactory dysfunction and depression. Some previous studies have demonstrated that olfactory dysfunction is associated with increased depressive symptoms. However, these studies were cross-sectional and unable to establish which develops first. We used longitudinal data to determine if impaired odor identification increased subsequent depressive symptoms or vice versa. We assessed olfaction and depression in the National Social Life, Health, and Aging Project, a nationally-representative, 15-year longitudinal study of older U.S. adults. Olfaction was measured using a validated odor identification test (Sniffin’ Sticks). Depressive symptoms were measured using a modified version of the validated Center for Epidemiological Studies Depression Scale. Multivariable logistic regression models examined the temporal relationships between developing olfactory dysfunction and depression while accounting for demographics, disease comorbidities, alcohol use, smoking, and cognition. Older adults with olfactory dysfunction had concurrent frequent depressive symptoms (OR = 1.20, 95% CI = 1.00 - 1.43). Among healthy adults at baseline, those who had olfactory dysfunction were more likely to develop frequent depressive symptoms 5 or 10 years later (OR = 2.22, 95% CI = 1.13 - 4.37). Conversely, those with frequent depressive symptoms at baseline were not more likely to develop olfactory dysfunction 5 or 10 years later. We show for the first time that olfactory dysfunction predicts subsequent development of depression in older U.S. adults. These data support screening for depression in older adults with chemosensory impairment and set the stage for disentangling the relationship between olfaction and depression.

Olfactory dysfunction in cystic fibrosis: Impact of CFTR modulator therapy

“…Olfaction is a key sense, and impairments in olfaction have substantial adverse impacts on QOL and cognitive health [7] . Olfactory dysfunction can weaken sense of taste and adversely impact eating preference, which may affect nutritional status [26] .…”

The effect of multimorbidity on changes in health-related quality of life following hip and knee arthroplasty

“…Multimorbidity in all but three studies was measured by a count of the number of chronic conditions. In the three studies, multimorbidity was measured with the Comorbidity Index (CMI) (Curyto et al, 1999), and the Charlson Comorbidity Index (CCI) (Eliyan et al, 2020;Sutin et al, 2013), respectively, which account for both the number of conditions and severity of the conditions. Depressive symptoms were measured by self-reported symptoms using the Centre for Epidemiologic Studies Depression (CES-D) scale in fifteen studies; the NSHAP Depressive Symptoms Measure (NDSM) in one study (Eliyan et al, 2020), the Geriatric Depression Scale in two studies (Feng et al, 2013;Oslin et al, 2002); the EURO-D symptom scale in one study (Marroig et al, 2019); and the 12 items adapted from Primary Care Evaluation of Mental Disorders (PRIME-MD) mood disorders section in one study (Roberts et al, 1997) (Table 4.1).…”

“…All reviewed longitudinal studies but three provided information on change of depressive symptoms, with three (Chou, 2008Roberts et al, 1997) also reporting on the incidence of depressive symptoms. Three studies (Eliyan et al, 2020Vink et al, 2009) focused on multimorbidity and the incidence of depression only (Table 4.2).…”

“…The results showed that participants who did not report depressive symptoms at baseline and follow-up (the "never depressed") had a lower multimorbidity score at baseline, compared to those who remained depressed, became depressed, and those who had remitted depression from baseline to follow-up. Another study in the US (Eliyan et al, 2020) examined the relationship between olfactory function and development of depression. The results showed that multimorbidity at baseline predicted onset of depressive symptoms among participants with normal olfactory function (OR = 1.51, 95% CI = 1.08-2.11).…”

Symptoms of Depression Change With Olfactory Functions

“…Interestingly, overall healthy older adults were more likely to develop depressive symptoms 5 or 10 years after losing their sense of smell [15]. On the other hand, depressed patients express impaired olfactory functions, mainly for odor identi cation [16][17][18][19][20] but also at the level of odor thresholds [9;21-23] and, even though there is limited evidence, for odor discrimination [3;16].…”