Effect of olfactory stimulation on static and dynamic balance in healthy subjects: Brief report

Background: The previous studies showed that the odor can improve balance in the elderly. The purpose of the current study was to determine the effect of olfactory stimulus and its gender specific effect on the balance of young healthy people. Methods: This is a pretest-posttest semi experimental study comprised 40 healthy volunteers (age range 18-73 years) from February 2016 through May 2017. The static balance test with one-leg standing time (OLST) and dynamic balance test using Biodex balance system to measure overall stability index (OSI), anterior/posterior stability index (APSI), medial/lateral stability index (MLSI) and overall limit of stability index (OLOSI) randomly were performed before and after application of lavender scant as the olfactory stimuli. A two-way repeated measurement ANOVA was used to assess the effect of olfactory stimulus conditions and gender on dynamic balance indexes (OSI, APSI, MLSI, and OLOSI). Since the distribution of the OLST was not normal, the generalized estimating equations (GEE) method was used. Significance level of P<0.05 was adopted for all comparisons. Means are reported±SD unless otherwise stated. SPSS software, version 21 (IBM SPSS, Armonk, NY, USA) was used to carry out all statistical analyses. Results: The results showed that in comparison of the two different conditions (no odor/with odor), there was no significant difference in any of static and dynamic balance indexes (P>0.05). There were significant differences in relation to the interaction of the gender and odor in OSI (P=0.026), APSI (P=0.019). For gender, there were statistically significant differences in OSI (P=0.002, F (1,38)=11.649), APSI (P=0.001, F(1,38)=12.057), and MLSI (P=0.007, F(1,38)=8.228) for females. Conclusion: Although there was no effect of odor on balance control of young healthy people, we found that the odor has gender specific effect. This is probably due to the more sensitivity of females to the odor.