Low to moderate genetic influences on the rapid smell test SCENTinelTM

SCENTinel - a rapid, inexpensive smell test that measures odor detection, intensity, identification, and pleasantness - was developed for population-wide screening of smell function. SCENTinel was previously found to screen for multiple types of smell disorders. However, the effect of genetic variability on SCENTinel test performance is unknown, which could affect the tests validity. This study assessed performance of SCENTinel in a large group of individuals with a normal sense of smell to determine the test-retest reliability and the heritability of SCENTinel test performance. One thousand participants (36 [IQR 26-52] years old, 72% female, 80% white) completed a SCENTinel test at the 2021 and 2022 Twins Days Festivals in Twinsburg, OH, and 118 of those completed a SCENTinel test on each of the festivals two days. Participants comprised 55% percent monozygotic twins, 13% dizygotic twins, 0.4% triplets, and 36% singletons. We found that 97% of participants passed the SCENTinel test. Test-retest reliability ranged from 0.57 to 0.71 for SCENTinel subtests. Broad-sense heritability, based on 246 monozygotic and 62 dizygotic twin dyads, was low for odor intensity (r=0.03) and moderate for odor pleasantness (r=0.4). Together, this study suggests that SCENTinel is a reliable smell test with only moderate heritability effects, which further supports its utility for population-wide screening for smell function.