# Olfactory identification, cognition, depressive symptoms, and 5-year mortality in patients with subjective cognitive decline, mild cognitive impairment, and Alzheimer’s disease

## TL;DR

This study explores how olfactory impairment relates to mortality in patients with cognitive decline and Alzheimer's disease.

## Contribution

It is the first to examine the relationship between olfactory function and 5-year mortality in these patient groups.

## Key findings

- Olfactory performance did not significantly predict mortality in patients with cognitive impairment.
- Cognitive attention and depressive symptoms were significant predictors of mortality.
- Demographic factors like age and gender also influenced mortality outcomes.

## Abstract

An association between odor and cognitive impairment has been shown in many studies. The objective of the present hospital-based, single-center retrospective study was to assess the impact of odor impairment on the mortality of patients with Alzheimer’s disease (AD), subjective cognitive decline (SCD), and mild cognitive impairment (MCI).

Odor function was measured by Sniffin Sticks (Burghart Messtechnik, Holm, Germany) and the assessment of self-reported olfactory functioning and olfaction-related quality of life (ASOF) test. Cognitive performance was assessed by an extensive neuropsychological test battery, symptoms of depression were diagnosed with the Geriatric Depressive Scale (GDS). The influence of demographic factors such as gender, age, and education were examined.

Although the univariate analyses and pairwise post hoc comparison showed significant differences for some of the olfactory performance tests/subtests, the multivariate models showed no association between olfactory test performance and mortality among patients with cognitive impairment. “Attention,” a domain of the Neuropsychological Test Battery Vienna (NTBV), as well as depressive symptoms, gender, and age, showed a significant influence on the mortality of the patient group.

Lower olfactory performance showed no impact on mortality. However, decreased cognitive function of “Attention” can be considered as an influential predictor for mortality.