Influences of ethanol ingestion on olfactory function in humans

International consensus statement on allergy and rhinology: Olfaction

BACKGROUND

The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O).

METHODS

Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus.

RESULTS

The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies.

CONCLUSION

This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.

Does Improved Attention Induced by Caffeine Intake Affect Olfactory Function?

Objectives

Past several studies have proven that caffeine facilitates attentional enhancement by acting as an adenosine antagonist once it is absorbed by the body, resulting in improved psycho-behavioral function. Modern clinical olfactory function tests are usually assessed by psychophysical tests but due to a paucity of data, the influence of enhanced attention by caffeine on olfactory function still remains unclear. The objective of this study was to compare results of cognitive function (attention) and olfactory function before and after caffeine administration in order to analyze effects of caffeine on olfactory function in normosmic subjects.

Methods

This study enrolled 49 participants of Konkuk University Hospital with a mean age of 27.7 years who had patent olfactory clefts and no olfactory dysfunction from May 2015 to February 2016. Subjects were restrained from caffeine 10 hours before the test. On day 1, participant’s subjective olfactory function was evaluated before and after uptake of either caffeinated or decaffeinated coffee using visual analog scale (VAS) score, minimum cross-sectional area (MCA) measured by acoustic rhinometry, and the Korean version of Sniffin’ Stick II (KVSS II). Evaluation of participant’s attentional degree was measured by d2 test. On day 2, the same procedure was carried out with counterpart substance. The type of coffee initially administrated was randomly selected.

Results

After administration, caffeinated coffee resulted in significant attentional enhancement than decaffeinated coffee. Results of d2 test showed statistically significant differences in the parameters of total number of errors and omission errors. In both the caffeinated and decaffeinated groups, the patients showed slight increase in VAS score and nasal cavity area; however, the difference was not statistically significant. Also, caffeinated coffee intake compared to decaffeinated coffee intake showed no significant relevance to olfactory function.

Conclusion

Caffeine may significantly improve attentional congnitive function, while not have acute effects on olfactory function.

Technical Report—Applying Physics and Sensory Sciences to Spirits Nosing Vessel Design to Improve Evaluation Diagnostics and Drinking Enjoyment

Ethanol is the direct by-product of distillation. The vast majority of straight spirit beverages are bottled at 40%+ ABV (alcohol by volume). Aficionados, critics, spirits judges, and a significant percentage of drinkers choose to drink and evaluate spirits at bottled strength from traditional vessels. Olfactory perceptions are quickly compromised by abundant ethanol, numbing olfactory sensors and severely inhibiting aroma detection during evaluation. Traditional vessel redesigns have concentrated on minor styling changes, ignoring olfactory and physical sciences. Consumers’ continued search for value and quality and increased dependency on spirits competitions as a primary source of ratings emphasizes the need for a functional diagnostic vessel which displays and delivers aromas unobscured by ethanol olfactory numbing. The application of olfactory and physical science creates an engineered tasting vessel which eliminates severe ethanol olfactory numbing, optimizes aroma definition, and significantly improves diagnostics for those who evaluate, judge, rate, distill, and enjoy flavor nuances of spirits.

Olfactory and gustatory functions in patients with non-complicated type 1 diabetes mellitus

The aim of this study was to evaluate any possible relationship between diabetic state and olfactory and gustatory functions in patients with non-complicated diabetes mellitus type 1 (T1D), and also to present evidence of the association between olfactory and gustatory scores and HbA1c values and disease durations. The study included 39 patients with non-complicated T1D and 31 healthy controls. Clinical characteristics such as age, gender, duration of disease, education levels and biochemical analyses (fasting blood glucose, urea, creatinine, total cholesterol, low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein (HDL-C), triglyceride, HbA1c, C-peptide, postprandial blood glucose) were measured. Subjective olfactory and gustatory tests were performed for all participants. There were no significant differences in olfactory tests between the two groups (odor thresholds 8.63 ± 0.91 vs. 8.55 ± 0.57, p = 0.66; odor discrimination 12.97 ± 0.80 vs. 12.74 ± 0.79, p = 0.24; odor identification 13.81 ± 0.98 vs. 13.72 ± 0.89, p = 0.69; TDI score 35.34 ± 1.94 vs. 34.97 ± 1.4, p = 0.37). There were also no significant differences in gustatory tests between the two groups (bitter 3.45 ± 0.51 vs. 3.44 ± 0.50, p = 0.90; sweet 3.32 ± 0.48 vs. 3.38 ± 0.49, p = 0.60; salty 3.13 ± 0.72 vs. 3.10 ± 0.72, p = 0.88; total score of taste 13.16 ± 1.61 vs. 13.13 ± 1.22, p = 0.92). Comparison of gustatory and olfactory scores according to disease duration of type 1 diabetes mellitus patients revealed that there were no differences between groups (all p > 0.05). T1D without complications may not be associated with olfactory and gustatory dysfunction according to subjective testing. We also found that gustatory and olfactory functions may not be related with HbA1c values and disease duration in non-complicated T1D.

Disinhibition of olfaction: human olfactory performance improves following low levels of alcohol

We hypothesize that true human olfactory abilities are obscured by cortical inhibition. Alcohol reduces inhibition. We therefore tested the hypothesis that olfactory abilities will improve following alcohol consumption. We measured olfaction in 85 subjects, 45 in a between-subjects design, and 40 in a repeated-measures within-subjects design before and after consumption of alcoholic or non-alcoholic beverages. Subjects were also assessed using neurocognitive measures of inhibition. Following alcohol consumption, blood alcohol levels ranged from 0.005% to 0.11%. Across subjects, before any consumption of alcohol, we found that individuals who were less inhibited had lower (better) olfactory detection thresholds (r=0.68, p<0.005). Moreover, after alcohol consumption, subjects with low alcohol levels could make olfactory discriminations that subjects with 0% alcohol could not make (chance=33%, alcohol=51.3±22.7%, control=34.7±31.6%, t(43)=2.03, p<0.05). Within subjects, we found correlations between levels of alcohol and olfactory detection (r=0.63, p<0.005) and discrimination (r=-0.50, p<0.05), such that performance was improved at low levels of alcohol (significantly better than baseline for detection) and deteriorated at higher levels of alcohol. Finally, levels of alcohol-induced improved olfactory discrimination were correlated with levels of alcohol-induced cognitive disinhibition (r=0.48, p<0.05). Although we cannot rule out alternative non-inhibitory alcohol-induced routes of influence, we conclude that improved olfaction at low levels of alcohol supports the notion of an inhibitory mechanism obscuring true olfactory abilities.

Functional biomarkers for the acute effects of alcohol on the central nervous system in healthy volunteers

The central nervous system (CNS) effects of acute alcohol administration have been frequently assessed. Such studies often use a wide range of methods to study each of these effects. Unfortunately, the sensitivity of these tests has not completely been ascertained. A literature search was performed to recognize the most useful tests (or biomarkers) for identifying the acute CNS effects of alcohol in healthy volunteers. All tests were grouped in clusters and functional domains. Afterwards, the effect of alcohol administration on these tests was scored as improvement, impairment or as no effect. Furthermore, dose-response relationships were established. A total number of 218 studies, describing 342 different tests (or test variants) were evaluated. Alcohol affected a wide range of CNS domains. Divided attention, focused attention, visuo-motor control and scales of feeling high and of subjective drug effects were identified as the most sensitive functional biomarkers for the acute CNS effects of alcohol. The large number of CNS tests that are used to determine the effects of alcohol interferes with the identification of the most sensitive ones and of drug-response relationships. Our results may be helpful in selecting rational biomarkers for studies investigating the acute CNS effects of alcohol or for future alcohol- interaction studies.

Ethanol-regulated genes that contribute to ethanol sensitivity and rapid tolerance in Drosophila

BACKGROUND

Increased ethanol intake, a major predictor for the development of alcohol use disorders, is facilitated by the development of tolerance to both the aversive and pleasurable effects of the drug. The molecular mechanisms underlying ethanol tolerance development are complex and are not yet well understood.

METHODS

To identify genetic mechanisms that contribute to ethanol tolerance, we examined the time course of gene expression changes elicited by a single sedating dose of ethanol in Drosophila, and completed a behavioral survey of strains harboring mutations in ethanol-regulated genes.

RESULTS

Enrichment for genes in metabolism, nucleic acid binding, olfaction, regulation of signal transduction, and stress suggests that these biological processes are coordinately affected by ethanol exposure. We also detected a coordinate up-regulation of genes in the Toll and Imd innate immunity signal transduction pathways. A multi-study comparison revealed a small set of genes showing similar regulation, including increased expression of 3 genes for serine biosynthesis. A survey of Drosophila strains harboring mutations in ethanol-regulated genes for ethanol sensitivity and tolerance phenotypes revealed roles for serine biosynthesis, olfaction, transcriptional regulation, immunity, and metabolism. Flies harboring deletions of the genes encoding the olfactory co-receptor Or83b or the sirtuin Sir2 showed marked changes in the development of ethanol tolerance.

CONCLUSIONS

Our findings implicate novel roles for these genes in regulating ethanol behavioral responses.

Association between quality of cheap and unrecorded alcohol products and public health consequences in Poland

BACKGROUND

The research aimed to study the quality of cheap alcohol products in Poland. These included unrecorded alcohols (i.e., home-produced or illegally imported), estimated to constitute more than 25% of total consumption and fruit wines.

METHODS

A sample of alcohol products (n = 52) was collected from local markets and chemical analyses were conducted. The parameters studied were alcoholic strength, volatiles (methanol, acetaldehyde, and higher alcohols), ethyl carbamate, inorganic elements, and food additives including preservatives, colors, and sweeteners. The compositions of the beverages were then toxicologically evaluated using international standards.

RESULTS

With the exception of 1 fortified wine, the unrecorded alcohols were home-produced fruit-derived spirits (moonshine) and spirits imported from other countries. We did not detect any nonbeverage surrogate alcohol. The unrecorded spirits contained, on average, 45% vol of alcohol. However, some products with considerably higher alcoholic strengths were found (up to 85% vol) with no labeling of the content on the bottles. These products may cause more pronounced detrimental health effects (e.g., liver cirrhosis, injuries, some forms of malignant neoplasms, alcohol use disorders, and cardiovascular disease) than will commercial beverages, especially as the consumer may be unaware of the alcohol content consumed. Fruit wines containing between 9.5 and 12.2% vol alcohol showed problems in terms of their additive content and their labeling (e.g., sulfites, sorbic acid, saccharin, and artificial colors) and should be subjected to stricter control. Regarding the other components investigated, the suspected human carcinogens, acetaldehyde and ethyl carbamate, were found at levels relevant to public health concerns. While acetaldehyde is a typical constituent of fermented beverages, ethyl carbamate was found only in home-produced unrecorded alcohols derived from stone fruits with levels significantly above international guidelines.

CONCLUSIONS

The contamination of unrecorded alcohols with ethyl carbamate should be analyzed in a larger sample that also should include legal alcoholic beverages. Furthermore, the impacts of unrecorded alcohol on the health of people with lower socioeconomic status should be studied in detail. Overall, given the extent of the alcohol-attributable disease burden in Poland, the highest priority should be given to the problem of ethanol and its very high content in unrecorded alcohol products.

Drug-induced taste disorders

Numerous drugs have the potential to adversely influence a patient's sense of taste, either by decreasing function or producing perceptual distortions or phantom tastes. In some cases, such adverse effects are long lasting and cannot be quickly reversed by drug cessation. In a number of cases, taste-related adverse effects significantly alter the patient's quality of life, dietary choices, emotional state and compliance with medication regimens. In this review, we describe common drug-related taste disturbances and review the major classes of medications associated with them, including antihypertensives, antimicrobials and antidepressants. We point out that there is a dearth of scientific information related to this problem, limiting our understanding of the true nature, incidence and prevalence of drug-related chemosensory disturbances. The limited data available suggest that large differences exist among individuals in terms of their susceptibility to taste-related adverse effects, and that sex, age, body mass and genetic variations in taste sensitivity are likely involved. Aside from altering drug usage, management strategies for patients with taste-related adverse effects are sorely needed. Unfortunately, stopping a medication is not always an easy option, particularly when one is dealing with life-threatening conditions such as seizures, cancer, infection, diabetes mellitus and uncontrolled hypertension. Hopefully, the information contained in this review will sensitize physicians, researchers and drug manufacturers to this problem and will result in much more research on this pressing topic.

A Proposed Approach for Setting Occupational Exposure Limits for Sensory Irritants Based on Chemosensory Models

OBJECTIVES

Setting occupational exposure limits (OELs) for odorous or irritating chemicals is a global occupational health challenge. However, often there is inadequate knowledge about the toxicology of these chemicals to set an OEL and their irritation potencies are usually not recognized until they are manufactured or used in large quantities.

METHODS

In this paper, the importance of accounting for risk perception and communication; conditioned responses; and interindividual variability in tolerance, detection and susceptibility with respect to setting an OEL are discussed in relation to three chemosensory models. These parameters and models were then used to construct a flowchart-style methodology that can be used to set an OEL for a specific chemical.

RESULTS

The OEL identified for a chemical odorant or irritant will depend on the type of chemosensory effect that the chemical is likely to exhibit. For example, experience has shown that chemicals with a low odor threshold often require low OELs even though many are not toxic or do not cause irritation at those air concentrations.

CONCLUSION

In order to establish the appropriate OEL, organizations need to agree upon the percentage of the workforce that they are attempting to protect and the types of toxicological end points that are sufficiently important to protect against (e.g. transient eye irritation, enzyme induction or other reversible effects). This is particularly true for sensory irritants. The method described in this paper could also be extended to setting limits for ambient air contaminants where risk perception plays a dominant role in whether the public views the exposure as being reasonable or safe.

Olfactory toxicity: long-term effects of occupational exposures

OBJECTIVE

To present and discuss the results of research on olfactory function impairments related to chronic occupational exposure to industrial chemicals.

METHODS

This review is mainly focused on the results of epidemiological studies on olfactory function, evaluated using quantitative testing methods, in workers chronically exposed to airborne industrial chemicals. Papers published in peer-reviewed scientific journals were mainly considered.

RESULTS

The prevalence of olfactory impairments related to occupational exposure to chemicals is unknown: frequencies ranging 0.5-5% of all olfactory dysfunctions have been proposed, considering both exposure to chemicals and the use of pharmaceutical drugs, but the real relevance of this problem is possibly overlooked, especially considering that occupational exposure may account for a significant part of "idiopathic" smell disorders, i.e., the 10-25% of all olfactory problems within the general population. An adverse effect has been reported in workers chronically exposed to some metals as cadmium, chromium, manganese, arsenic, mercury, and organic lead, and to other chemicals as acrylates, styrene, and solvent mixtures. The results of relevant studies are discussed. A problem in the evaluation of data is that different methods have been applied in different studies, affecting the comparability of results.

CONCLUSIONS

To date, knowledge of the effect of chronic occupational exposure to industrial chemicals on olfactory function is largely incomplete, but supports the hypothesis that olfactory neuroepithelium is susceptible to environmental exposures to chemicals. Occupational-related olfactory impairment is usually sub-clinical, and can be only detected using adequate quantitative olfactory function testing procedures. Available data show the need for further good quality research in this field.

Effects of drugs on olfaction and taste

The fact that so many varied medications reportedly affect taste and smell is a testament to the complexity of the gustatory and olfactory systems. The reception, transduction, propagation, and perception of a chemical tastant or odorant requires the effective operation of numerous mechanisms--all of which may be susceptible in one way or another to a prescribed medication. Just as a diuretic may block the apical ion channels on a taste bud, or an antifungal can inhibit cytochrome p450-dependent enzymes at the level of the receptors, a chemotherapeutic agent can destroy mitosis in a replicating receptor cell and a steroid can lead to candidal overgrowth on the tongue surface. Medications not only have a perceivable taste themselves at times, but they can alter the mechanisms responsible for the ultimate perception of tastes and smells--either by direct or secondary means. It should be emphasized, as noted earlier in this article, that while many medications are to blame for the impairment or distortion of the gustatory or olfactory systems, it is not uncommon that the underlying medical problem for which they are prescribed is actually the culprit. Examples include epilepsy, migraines, hypothyroidism, schizophrenia, infections, and cancer. In fact, simple partial seizures emanating from regions of the brain such as the amygdala, hippocampus, parietal operculum, and rolandic operculum can lead to the chemosensory sensations that are most commonly considered unpleasant, such as "rotten apples," "cigarette," "peculiar," or "vomitus". While removing or changing an offending medication can reverse the effects on smell or taste perception, it is important to remember that lasting impairment may occur. This is vital for a physician to recognize prior to prescribing a medication. It is also necessary to report this to patients who may be devastated by chemosensory alterations after starting a new medication (eg, pastry chef, perfumist, wine specialist, plumber). Among the "risks" in a risks/benefits discussion with a patient regarding the use of a new medication, alterations in olfaction and taste appear to play an increasingly recognized role.