Markers of olfactory dysfunction and progression to dementia: A 12-year population-based study

Area of Science:

• Neuroscience
• Gerontology
• Epidemiology

Background:

• Olfactory dysfunction (OD) is increasingly recognized as a potential early marker for neurodegenerative diseases.
• Identifying reliable predictors of dementia risk is crucial for timely intervention in aging populations.

Purpose of the Study:

• To evaluate olfactory dysfunction (OD) markers for estimating dementia risk in older adults.
• To investigate the combined effect of OD and APOE genotype on dementia hazard.

Main Methods:

• A population-based study (SNAC-K, n=2473, mean age 70) assessed OD using the Sniffin sticks odor identification task.
• Objective and subjective OD, and OD combined with APOE status, were analyzed.
• Dementia hazard over 12 years was estimated using Cox regression.

Main Results:

• OD was associated with a 2.01-fold increased hazard of dementia.
• Severe OD (anosmia) showed the strongest association (2.92-fold increased hazard).
• APOE ε4 carriers with anosmia had the highest dementia hazard (up to 19.84-fold for ε4/ε4).

Conclusions:

• Olfactory dysfunction is a significant predictor of dementia risk in older adults.
• Severe olfactory impairment, especially when combined with genetic predisposition (APOE ε4), substantially elevates dementia risk.