Olfactory perception in children

Abstract

The ability to smell is important for protection from danger and quality of life, even in children. Although smell loss is rare in children, it can be indicative of some childhood disorders and may be useful for understanding some disorders. This paper reviews the methods and results of behavioral testing olfaction in children, with an emphasis on odor identification, the most common method of assessing the sense of smell in both children and adults. The Pediatric Smell Wheel^® is described as a relatively new and powerful tool for testing olfaction in children as young as 4 years of age. An example of its use in testing children with a childhood disorders (autism spectrum disorder, ASD) is provided in addition to a review of the literature on smell function in ASD. It is possible to reliably test sense of smell in children as young as 4 years old and many studies have shown that performance improves with age and can be impacted by childhood disorders. Sex differences in children are briefly discussed. Finally, the paper suggests other methods of testing olfaction in children, such as odor discrimination, that depend less on cognitive factors, which may enhance our understanding of the olfactory capabilities of young children.

Keywords: Autism; Development; Odor detection; Odor discrimination; Odor identification; Olfaction; Pediatric Smell Wheel®; Sex differences; Smell.

Fig. 1

Changes in scores on the University of Pennsylvania Smell Identification Test (UPSIT) across childhood and early adulthood years. From Doty (1986) with permission. Copyright^© 1986, Macmillan Publishing Company, a division of Macmillan, Inc.

Fig. 2

The Pediatric Smell Wheel^® (PSW). The PSW enjoys three advantages over most other published methods of testing children: (1) the odors were selected to be ones with which children are familiar; (2) both pictures and words are provided in the four-alternative forced choice task to reduce cognitive/linguistic load and potentially to improve performance; and (3) the test has a game-like quality that engages children. These qualities make the Smell Wheel a particularly attractive method of testing children's olfactory function and provide a testing format that appears to overcome attentional and other problems often associated with such testing. Photo courtesy of Sensonics International, Haddon Heights, NJ USA. Copyright^© 2012 Sensonics International.

Fig. 3

Mean percent correct (±SEM) scores on the Pediatric Smell Wheel^® as a function of age and gender. EA = experimenter-administered; SA = self-administered.

Fig. 4

Performance on the Pediatric Smell Wheel^® for typically developing children and those with Autism Spectrum Disorder. The data represent mean (±SEM) percent of items correctly identified. Performance for both groups was around 80% correct and did not differ between groups on any individual odors. Note: the popcorn smell was weak in the version of the test that we used and was thus excluded from the analysis.