Due to the lack of active involvement in the driving situation and due to monotonous driving environments drivers with automation may be prone to become fatigued faster than manual drivers (e.g. ...Schömig et al., 2015). However, little is known about the progression of fatigue during automated driving and its effects on the ability to take back manual control after a take-over request. In this driving simulator study with Nö=ö60 drivers we used a three factorial 2ö×ö2ö×ö12 mixed design to analyze the progression (12ö×ö5ömin; within subjects) of driver fatigue in drivers with automation compared to manual drivers (between subjects). Driver fatigue was induced as either mainly sleep related or mainly task related fatigue (between subjects). Additionally, we investigated the drivers’ reactions to a take-over request in a critical driving scenario to gain insights into the ability of fatigued drivers to regain manual control and situation awareness after automated driving.
Drivers in the automated driving condition exhibited facial indicators of fatigue after 15 to 35ömin of driving. Manual drivers only showed similar indicators of fatigue if they suffered from a lack of sleep and then only after a longer period of driving (approx. 40ömin). Several drivers in the automated condition closed their eyes for extended periods of time. In the driving with automation condition mean automation deactivation times after a take-over request were slower for a certain percentage (about 30%) of the drivers with a lack of sleep (Mö=ö3.2; SDö=ö2.1ös) compared to the reaction times after a long drive (Mö=ö2.4; SDö=ö0.9ös). Drivers with automation also took longer than manual drivers to first glance at the speed display after a take-over request and were more likely to stay behind a braking lead vehicle instead of overtaking it.
Drivers are unable to stay alert during extended periods of automated driving without non-driving related tasks. Fatigued drivers could pose a serious hazard in complex take-over situations where situation awareness is required to prepare for threats. Driver fatigue monitoring or controllable distraction through non-driving tasks could be necessary to ensure alertness and availability during highly automated driving.
Olfactory dysfunction is a key symptom in patients with allergic rhinitis (AR). Despite the implications for quality of life, relatively few articles have tested olfactory function in their ...investigations. The current systematic review aimed to investigate the following 2 questions: (1) What does AR do to human olfaction? (2) How effective is the treatment of AR in restoring the sense of smell? A comprehensive literature search was performed, and human studies of any design were included. A total of 420 articles were identified, and 36 articles were considered relevant. Data indicate that the frequency of olfactory dysfunction increases with the duration of the disorder, and most studies report a frequency in the range of 20% to 40%. Although olfactory dysfunction does not appear to be very severe in patients with AR, its presence seems to increase with the severity of the disease. There is very limited evidence that antihistamines improve olfactory function. In addition, there is limited evidence that topical steroids improve the sense of smell, especially in patients with seasonal AR. This is also the case for specific immunotherapy. However, many questions remain unanswered because randomized controlled trials are infrequent and only a few studies rely on quantitative measurement of olfactory function.
Objective/Hypothesis
A common, lasting condition from traumatic brain injury is impairment to smell. In patients with olfactory impairment, recent meta‐analyses have demonstrated that olfactory ...training consistently improves higher‐order functions, such as odor identification. The focus of this work was to assess effects of olfactory training (OT) in posttraumatic olfactory loss patients through several metrics including psychophysical, olfactory bulb (OB) volume, and functional magnetic resonance imaging.
Study Design
Prospective cohort study.
Methods
Sniffin’ Sticks were used to classify two patient groups (anosmic N = 23 and hyposmic N = 14) and measure changes after OT. Additionally patients were asked the intensity, valence, and uncued identification of odors presented (coffee and peach) within the magnetic resonance imaging scanner before and after olfactory training. Olfactory training was performed twice daily with a four‐odor training set for 24 weeks, and sets were replaced halfway through the entire training session (~12 weeks).
Results
Patients had an increase in test scores (threshold and identification) and in‐scanner intensity ratings and identification. Anosmic patients showed improved olfactory thresholds to 2‐phenylethanol, increased intensity ratings, and activation in the right superior frontal gyrus (SFG) to odors after OT. Hyposmic patients were able to identify odors better after training. This behavior was mirrored with increased, ipsilateral activations in semantic processing areas such as Broca's area, left angular gyrus, and left SFG.
Conclusions
Taken together, along with neither patient group showing changes in OB volumes, OT improves olfactory performance in patients with posttraumatic olfactory loss and seems to be driven, at least in part, by top‐down processes (central) rather than bottom‐up (peripheral).
Levels of Evidence
2Laryngoscope, 129:1737–1743, 2019
Although the view that women's olfactory abilities outperform men's is taken for granted, some studies involving large samples suggested that male and female olfactory abilities are actually similar. ...To address this discrepancy, we conducted a meta-analysis of existing studies on olfaction, targeting possible sex differences. The analyzed sample comprised
= 8 848 (5 065 women and 3 783 men) for olfactory threshold (as measured with the Sniffin Sticks Test; SST),
= 8 067 (4 496 women and 3 571 men) for discrimination (SST),
= 13 670 (7 501 women and 6 169 men) for identification (SST), and a total sample of
= 7 154 (3 866 women and 3 288 men) for works using University of Pennsylvania Smell Identification Test (UPSIT). We conducted separate meta-analyses for each aspect of olfaction: identification, discrimination and threshold. The results of our meta-analysis indicate that women generally outperform men in olfactory abilities. What is more, they do so in every aspect of olfaction analyzed in the current study. However, the effect sizes were weak and ranged between
= 0.08 and
= 0.30. We discuss our findings in the context of factors that potentially shape sex differences in olfaction. Nevertheless, although our findings seem to confirm the "common knowledge" on female olfactory superiority, it needs to be emphasized that the effect sizes we observed were notably small.
Objective
Food odors serve as powerful stimuli signaling the food quality and energy density and direct food‐specific appetite and consumption. This study explored obesity‐related brain activation in ...response to odors related to high‐ or low‐energy‐dense foods.
Methods
Seventeen participants with obesity (BMI > 30 kg/m2; 4 males and 13 females) and twenty‐one with normal weight (BMI < 25 kg/m2; 9 males and 12 females) underwent a functional magnetic resonance imaging scan in which they received chocolate (high‐energy‐dense food) and cucumber (low‐energy‐dense food) odor stimuli. Participants’ olfactory and gustatory functions were assessed by the “Sniffin’ Sticks” and “Taste Strips” tests, respectively.
Results
Compared with normal‐weight controls, participants with obesity had lower odor sensitivity (phenylethyl alcohol) and decreased odor discrimination ability. However, participants with obesity demonstrated greater brain activation in response to chocolate compared with cucumber odors in the bilateral inferior frontal operculum and cerebellar vermis, right ventral anterior insula extending to putamen, right middle temporal gyrus, and right supramarginal areas.
Conclusions
The present study provides preliminary evidence that obesity is associated with heightened brain activation of the reward and flavor processing areas in response to chocolate versus cucumber odors, possibly because of the higher energy density and reinforcing value of chocolate compared with cucumber.
Abstract Background Animal studies show a strong link between the loss of olfactory function and depressive behavior. We analyzed, whether olfactory function is a marker for depression in humans. If ...so, reduced olfactory function can be expected in depression that improves to level of normality after successful antidepressive treatment. Methods Twenty-seven female in-patients with depression were compared to 28 healthy age-matched women at the beginning and at the end of antidepressive therapy or at two visits, respectively. Olfactory function was assessed comprehensively including threshold, discrimination and identification testing, chemosensory event related potentials and olfactory functional magnetic resonance imaging. Results At the beginning of psychotherapy the patients exhibited reduced olfactory discrimination, prolonged latencies of the event-related potential and reduced activation in secondary olfactory structures (thalamus, insula, and left middle orbitofrontal). After therapy, patients improved significantly in all of the parameters and consequently the differences between control group and patients vanished. Limitations and conclusion We conclude that olfaction is a marker for depression. However, the results are limited to a relatively selective sample of depressed women.
Age-related sensory impairment is a slow and gradual progress, which affects multiple modalities. Two contradictory hypotheses exist about the age-related decline of sensory thresholds. The common ...factor theory assumes one underlying factor-which accounts for the loss of several sensory modalities simultaneously-and the specific factor theory predicts that the sensory decline is uncorrelated between different modalities. In this study, we aimed to explore whether (i) there is a common factor of sensory thresholds in older people, (ii) older people assume that sensory decline in one modality also affects other modalities, (iii) there is a relation between sensory threshold and the subjective assessment of sensory function. This was accomplished by collecting both threshold measures and self-reported ratings for smell, hearing, taste, vision, and touch function in a group of 104 older people (mean age: 67.2 years; SD: 9.85; range: 50-100 years). Results indicated that there was no common factor of sensory thresholds, hence an impairment in one modality did not necessarily imply a shortfall in other modalities. In contrast, our results suggested one or two common factor(s) for the participants' ratings. Participants who reported a diminished function in one sense tended to generalize this rating to the other senses as well. The correspondence between subjective ratings and sensory thresholds was relatively good for vision and audition, although no correlations were observed for the other domains. These findings have implications for clinicians, suggesting that subjective measures should be combined with sensory threshold measurements when evaluating sensory dysfunction. Also, these data convey a positive message for older people and their physicians by showing that loss in one sensory modality does not necessarily generalize to losses across all sensory modalities.
Objective
We aimed to determine whether the pattern of olfactory impairment seen in psychophysical testing reflects underlying disease etiology.
Study Design
Retrospective cohort.
Methods
We ...performed a retrospective analysis of 1,226 patients from our tertiary referral center. Only hyposmic patients with the following conditions were included: postinfectious hyposmia, posttraumatic hyposmia, hyposmia secondary to sinonasal disease, and hyposmia secondary to Parkinson disease. Patients with anosmia were excluded.
Results
Using a repeated measures analysis of variance (within subject factor “test”: threshold T, discrimination D, identification I; between subject factor: “etiology”) with posthoc Bonferroni corrected t tests, we found significant interaction between the factors “test” and “etiology” (F6,2444 = 8.46, P < 0.001), indicating that different causes of hyposmia produce different patterns of olfactory loss with respect to the individual subtests T, D, and I . Specifically, patients with Parkinson disease performed relatively well in odor threshold testing, but poorly in odor identification and discrimination compared with the other etiology groups. Conversely, patients with sinonasal disease performed well in odor identification and discrimination but poorly in odor threshold. Patients with postinfectious and posttraumatic hyposmia performed relatively well in both thresholds and discrimination but poorly in identification. However, patients with posttraumatic hyposmia had globally reduced scores compared with the other groups.
Conclusion
This is the first study to comprehensively show that patterns of olfactory impairment reflect underlying disease etiology. We suggest that multicomponent olfactory testing should be performed, especially if there is diagnostic uncertainty. However, to clearly separate different patterns of olfactory loss to the various causes at an individual level, more work is needed.
Level of Evidence
4. Laryngoscope, 2016 127:291–295, 2017
Purpose
Although the prevalence of olfactory dysfunction in children is thought to be lower compared to adults, little is known about the actual frequency of etiologies of smell dysfunction in ...children. Aim of the study was (i) to describe the epidemiology of olfactory dysfunction in a pediatric population and (ii) to compare the distribution of etiologies to adults.
Material and methods
Data of patients consulting a smell and taste clinic between 2000 and 2017 were retrospectively analyzed. Frequency of major causes of olfactory dysfunction was examined with a focus on the pediatric population.
Results
A total of 7153 patients (164 children) were included in the analysis. Most children presented with congenital olfactory dysfunction (67%), or head-trauma (12%). In contrast, the cumulative frequency of olfactory loss associated with sinonasal disorders or acute infections of the upper airways was 6%. The frequency of etiologies of olfactory dysfunction changed with age: While the frequency of patients with congenital anosmia decreased, the frequency of causes related to infections of the upper respiratory tract and idiopathic causes increased.
Conclusion
About 2/3 of olfactory dysfunction in children are congenital while 1/3 is acquired. The frequency of etiologies causing olfactory dysfunction change significantly from children to an adult population.
Olfactory loss is associated with symptoms of depression. The present study, conducted on a large cohort of mostly dysosmic patients, aimed to investigate whether improvement in olfactory performance ...would correspond with a decrease in depression severity. In 171 participants (157 dysosmic), we assessed olfactory function and severity of depression before and after an average interval of 11 months, with many patients showing improvement in olfactory function. Separate analyses were conducted for (a) the whole group of patients and (b) the group of dysosmic patients using both classic and Bayesian approaches. For odor identification, Student t test demonstrated that the whole sample improved consistently, especially within the group of dysosmic patients. The dysosmic group also improved in odor threshold and overall olfactory function. Pearson correlation showed that an increase in olfactory function was associated with a decrease in depression severity, particularly in dysosmic patients. To conclude, the present results indicate that symptoms of depression change with olfactory function in general and odor identification in particular.
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