Differences in Odor Identification in Early-Onset and Late-Onset Depression

Area of Science:

• Neuroscience
• Gerontology
• Psychiatry

Background:

• Odor identification (OI) dysfunction is a potential early predictor of dementia in late-life depression (LLD).
• Distinct patterns of OI dysfunction may exist between early-onset depression (EOD) and late-onset depression (LOD).

Purpose of the Study:

• To compare odor identification (OI) abilities between EOD and LOD patients.
• To investigate the relationship between OI and cognitive function in EOD and LOD patients.

Main Methods:

• Recruited 179 LLD patients and 189 normal controls (NCs).
• Utilized clinical assessments, olfactory testing, and comprehensive neuropsychological evaluations.
• Employed correlation and mediation analyses to examine OI and cognition links.

Main Results:

• LOD patients demonstrated significantly lower OI scores and a higher prevalence of OI dysfunction compared to EOD patients and NCs.
• OI scores correlated with global cognition, memory, language, and visuospatial abilities in EOD patients, but not in LOD patients.
• Auditory Verbal Learning Test recall and Boston Naming Test scores partially mediated the OI score differences between EOD and LOD groups.

Conclusions:

• Late-onset depression patients exhibit more severe odor identification deficits than early-onset depression patients.
• Memory and language impairments mediate the observed differences in odor identification between EOD and LOD patients.