Rapid Assessment of Olfactory Sensitivity Using the “Sniffin’ Sticks”

Enhanced sensitivity to odors due to chemosignals associated with anxiety

Chemocommunication is important in human nonverbal communication. Behavioral effects of anxiety chemosignals on recipients are established but it is unknown whether odor sensitivity can be modulated by such stimuli. We tested recipients' sensitivity to phenylethyl alcohol (PEA) and n-butanol after exposure to anxiety chemosignals, neutral chemosignals and blank condition. As fourth condition, a horror movie was shown, to compare the effects of visual stimuli and chemosignals on odor sensitivity. Odor sensitivity for PEA was significantly increased by anxiety chemosignals compared to blank condition. No change in odor sensitivity was evident for n-butanol. We also investigated the composition of the applied chemosensory stimuli using untargeted one-dimensional gas chromatography-mass spectrometry (GC-MS) and -olfactometry (GC-O). Considering GC-MS data, several compounds were found with significantly higher normalized peak areas in anxiety sweat samples compared to the neutral samples. GC-O analysis indicated that the carboxylic acids dodecanoic acid and 3-hydroxy-3-methylhexanoic acid were potential main contributors to the odor of anxiety sweat samples, whereby tetradecanoic acid and patchouli alcohol were those of the odor of neutral sweat samples. This study provides evidence that anxiety chemosignals can improve odor sensitivity and constitutes a further step toward elucidating the composition of sweat samples used in chemical communication research.

Chemosensory function and food perception is affected in COPD, but unrelated to sarcopenia risk

BACKGROUND & AIMS

Patients with advanced COPD often have difficulty maintaining sufficient dietary intake. Chemosensory function influences food choice and intake but is often overlooked in dietary assessment and intervention strategies. This study aimed to assess differences in chemosensory function and hedonic evaluation of food between patients with COPD and age- and gender-matched healthy controls. Additionally, a possible association between increased risk of sarcopenia or frailty and chemosensory impairments was explored.

METHODS

We recruited 53 COPD patients (34 males, mean age 66.6 ± 7.6 years) and 53 controls (25 males, mean age 68.4 ± 5.7 years). Chemosensory function was assessed using a smell threshold, smell identification (Sniffin' Sticks, Burghart) and taste recognition test (Taste Strips, Burghart) and through self-report. Sensory properties (appearance, smell, taste, mouthfeel) of four standardized food products were evaluated on 9-point hedonic rating scales. Sarcopenia risk was assessed with the SARC-F.

RESULTS

The COPD group scored lower on both the smell (p = 0.026 for threshold, p = 0.001 for identification) and taste recognition tests (p < 0.001) and also reported more smell and taste impairments (p < 0.001) compared to controls. Hedonic evaluation of food items' appearance (p = 0.009) and smell (p = 0.033) was lower in COPD patients. Within the COPD group, risk of sarcopenia was not associated with chemosensory function.

CONCLUSION

This study demonstrates that COPD patients have poorer chemosensory function and experience more impairments compared to controls. COPD patients also tend to evaluate foods less positive than do their controls but within COPD patients, sarcopenia risk is not associated with chemosensory function.

Low odor awareness predicts reduced olfactory abilities in women with depressive symptoms, but not with anxiety symptoms

BACKGROUND

Olfactory disorders and affective symptoms are tightly related. However, the factors underlying this association are not yet understood. One candidate factor is "odor awareness": the degree of attention individuals pays to the odors. However, the association between odor awareness and olfactory abilities in individuals with affective symptoms has not been clarified yet.

METHOD

The present study examined whether odor awareness may moderate (a) the relation between olfactory dysfunctions and depressive and anxiety symptoms; (b) the relation between the perceptual ratings of the odors and depressive and anxiety symptoms in a sample of healthy women (n = 214). Self-report measures of depression and anxiety were collected, whereas the Sniffin' Stick test was employed to measure olfactory abilities.

RESULTS

Linear regression analysis revealed that individuals with higher depressive symptoms presented lower olfactory abilities and that odor awareness was a significant moderator of the association between depressive symptoms and olfactory abilities. Anxiety symptoms were not related to any of the olfactory abilities considered, and this relationship did not change according to odor awareness. The familiarity rating of the odor was significantly predicted by odor awareness. These results were confirmed by Bayesian statistics.

LIMITATIONS

The sample was composed only of women.

CONCLUSIONS

In a healthy population of women, only the presence of depressive symptoms is related to reduced olfactory performance. Odor awareness may be implicated in the development and maintenance of olfactory dysfunction; hence it could be used as a useful target for specific treatments in clinical settings.

A New Method for a Shorter and Valid Assessment of Olfactory Threshold in Repeated Measurement Designs Based on the Sniffin’ Sticks Test

Introduction

The Sniffin’ Sticks threshold test is widely used to assess olfactory threshold due to its high reliability and validity. Nevertheless, this test procedure is quite long with an average duration of 10 to 20 min. In study designs that require multiple olfactory threshold tests on short intervals, this could exhaust participants. To counteract this limitation, we developed the informed-four-reversal (INFOUR) short version of the Sniffin’ Sticks threshold test for repeated measurement designs and piloted it in a sample of normosmic participants.

Methods

Forty-two participants performed the original Sniffin’ Sticks version before being assigned either to the control group that repeated the original version or to the test group that conducted the INFOUR short version.

Results

The correlation between the original version at T1 and INFOUR at T2 was r = .75 and did not differ significantly from the retest reliability of the original version. Compared to the original version, the INFOUR took 42% less time to perform.

Conclusion

The INFOUR leads to a significant time saving, while maintaining good validity.

Implications

Therefore, this approach has the potential to be a useful tool for study protocols with repeated olfactory threshold measurements. In particular, when research protocols are time intensive or testing needs to the shortened, because the interventional effects are short or subtle.

Insulin Resistance Is Associated with Reduced Food Odor Sensitivity across a Wide Range of Body Weights

The worldwide obesity epidemic is a major health problem driven by the modern food environment. Recently, it has been shown that smell perception plays a key role in eating behavior and is altered in obesity. However, the underlying mechanisms of this phenomenon are not well understood yet. Since the olfactory system is closely linked to the endocrine system, we hypothesized that hormonal shifts in obesity might explain this relationship. In a within-subject, repeated-measures design, we investigated sensitivity to a food and a non-food odor in the hungry and sated state in 75 young healthy (26 normal weight, 25 overweight, and 24 obese) participants (37 women). To determine metabolic health status and hormonal reactivity in response to food intake, we assessed pre- and postprandial levels of insulin, leptin, glucose, and ghrelin. Odor sensitivity did not directly depend on body weight status/body mass index (BMI) or hunger state. However, we could establish a strong negative mediating effect of insulin resistance on the relationship between BMI/waist-hip ratio and olfactory sensitivity for the food odor. These findings indicate an impact of metabolic health status on sensitivity to food odors. Our results contribute to a better understanding of the mechanisms behind altered smell perception in obesity.