Odor identification dysfunction in late-life depression with suicidal ideation

Background

Suicide is more prevalent among older adults compared to younger individuals. Late-life depression (LLD) poses the highest risk for suicide. However, early recognition of suicidal ideation is challenging. Dysfunction in odor identification (OI), a characteristic of LLD, may hold potential for early identification of suicidal ideation. This study aims to compare OI between LLD patients with suicidal ideation (LLD-S) and LLD patients without suicidal ideation (LLD-NS), and examine its relationship with cognitive function.

Methods

A total of 262 LLD-NS patients, 63 LLD-S patients, and 316 healthy normal older adults (HOAs) underwent OI testing, standardized clinical interviews, and comprehensive neuropsychological assessments.

Results

(1) LLD-S patients exhibited lower OI scores and poorer cognitive performance (including global cognition, information processing speed, memory, language, executive function, and visuospatial ability) compared to LLD-NS patients and HOAs. (2) There were interactive effects between suicidal ideation and OI dysfunction, leading to lower scores in information processing speed and visuospatial ability. (3) OI dysfunction mediated the differences in cognition between the LLD-NS and LLD-S groups.

Limitations

The present study was a cross-sectional design.

Conclusions

LLD-S patients had worse odor identification than LLD-NS patients and HOAs, suggesting that OI testing could be a valuable approach for identifying suicidal ideation in LLD and screening for suicide risk. The presence of both OI impairment and suicidal ideation was associated with poorer cognitive performance in LLD.