Low to moderate genetic influences on the rapid smell test SCENTinel^™

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 test's 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 festival's 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.