Olfactory dysfunction is associated with gait impairment in older adults: evidence for a shared amygdala substrate.

Olfactory dysfunction and gait impairment are common in older adults and may reflect shared neural vulnerability. While prior studies have reported associations between olfactory and motor performance, evidence integrating quantitative gait assessment and brain structural measures in community-dwelling older populations remains limited. We conducted a community-based cross-sectional study including 1105 participants from the Taizhou Imaging Study. Olfactory identification was assessed using the 12-item Sniffin' Sticks Screening Test. Gait performance was evaluated using the Timed Up and Go (TUG) test, the Tinetti test, and high-dimensional gait parameters from a wearable system. Sparse sliced inverse regression was used to derive data-driven gait patterns. Structural MRI quantified regional brain volume proportions, and associations were analyzed using generalized linear and beta regression models. Poorer olfactory identification was significantly associated with impaired gait performance. Specifically, TUG duration and sluggish-imbalanced gait pattern scores, reflecting reduced gait efficiency and symmetry, were negatively associated with olfactory identification (β =  - 0.049, P = 0.003; β =  - 0.064, P = 0.040). Amygdala volume proportion was significantly associated with both olfactory identification and gait. Adjustment for amygdala volume attenuated the associations between olfactory identification and TUG duration and sluggish-imbalanced gait pattern scores by 6.4% and 10.2%, respectively. Olfactory dysfunction is associated with multidimensional gait impairment in community-dwelling older adults. Partial attenuation of this association by amygdala volume suggests a shared neural substrate underlying sensory and motor decline. These findings provide evidence for early monitoring and risk stratification of age-related functional decline and neurodegenerative conditions.