Olfactory stimuli and enhanced postural stability in older adults.

Ameliorating postural instability is an important component of geriatric health care. The effect of olfactory stimuli (lavender and black pepper oils) on postural control in 17 older adults (78+/-6 years old) who had no apparent neurological deficits was studied. Measurements of center of pressure (CoP) trajectories were done with subjects standing quietly on a force plate. Control measurements were compared with olfactory interventions: brief exposure to sham (distilled water), lavender oil, and black pepper oil; experiments were repeated with eyes open and eyes closed. From the CoP data, the root mean square (RMS) displacement and velocity in mediolateral (ML) and antero-posterior (AP) directions, and the total trajectory length were computed. This study found that with eyes closed, olfactory stimulation with either lavender or black pepper oil significantly decreased both ML and AP RMS velocities and trajectory lengths compared with baseline. In contrast, little effect was observed under the eyes-open condition. Decreases in RMS displacements were small and mostly insignificant. The study suggests that olfactory stimulation may improve posture stability in older adults through decreasing the velocities of postural adjustments during normal sway.