Just noticeable difference in olfaction: a discriminative tool between healthy elderly and patients with cognitive disorders associated with dementia

Computed Tomography Evaluation of the Paranasal Sinuses in Adults with Primary Ciliary Dyskinesia

Introduction  Primary ciliary dyskinesia is a rare inherited disease that results in a malfunction of mucociliary clearance and sinonasal complaints. Aplasia/hypoplasia of the frontal and sphenoid sinuses has been described as more frequent in this population. However, to date, no studies have provided a detailed description of computed tomography findings in adult patients with a diagnosis of this condition. Objective  To describe the computed tomography (CT) findings of adult patients with primary ciliary dyskinesia. Methods  Retrospective observational study of adult patients with primary ciliary dyskinesia who underwent CT. Results  Twenty-one adults were included in the study. Aplasia occurred in 38.1% of frontal sinuses and in 14.3% of sphenoid sinuses. Likewise, hypoplasia occurred in 47.6% of the frontal sinuses, in 54.8% of the sphenoid sinuses and in 40.5% of the maxillary sinuses. Furthermore, trabecular loss was identified in 61.9% ethmoidal sinuses. The mean Lund-Mackay score was 13.5. In addition, 9.5% of the patients had concha bullosa, 47.6% had marked bilateral inferior turbinate hypertrophy, 38.1% had marked middle turbinate hypertrophy, and 47.6% had marked septal deviation. Finally, we identified images suggestive of fungus ball, mucocele, osteoma, a possible antrochoanal polyp, and frontal bone erosions. Conclusion  The present study provides a detailed description of CT findings in patients with primary ciliary dyskinesia. We also describe abnormalities that must be identified for safer surgical planning and that suggest a diagnosis of primary ciliary dyskinesia if found in patients with a consistent clinical picture.

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.

Single-Neuron Comparison of the Olfactory Receptor Response to Deuterated and Nondeuterated Odorants

The mammalian olfactory receptors (ORs) constitute a large subfamily of the Class A G-protein coupled receptors (GPCRs). The molecular details of how these receptors convert odorant chemical information into neural signal are unknown, but are predicted by analogy to other GPCRs to involve stabilization of the activated form of the OR by the odorant. An alternative hypothesis maintains that the vibrational modes of an odorant's bonds constitute the main determinant for OR activation, and that odorants containing deuterium in place of hydrogen should activate different sets of OR family members. Experiments using heterologously expressed ORs have failed to show different responses for deuterated odorants, but experiments in the sensory neuron environment have been lacking. We tested the response to deuterated and nondeuterated versions of p-cymene, 1-octanol, 1-undecanol, and octanal in dissociated mouse olfactory receptor neurons (ORNs) by calcium imaging. In all, we tested 23 812 cells, including a subset expressing recombinant mouse olfactory receptor 2 ( Olfr2/OR-I7 ), and found that nearly all of the 1610 odorant-responding neurons were unable to distinguish the D- and H-odorants. These results support the conclusion that if mammals can perceive deuterated odorants differently, the difference arises from the receptor-independent steps of olfaction. Nevertheless, 0.81% of the responding ORNs responded differently to D- and H-odorants, and those in the octanal experiments responded selectively to H-octanal at concentrations from 3 to 100 μM. The few ORs responding differently to H and D may be hypersensitive to one of the several H/D physicochemical differences, such as the difference in H/D hydrophobicity.

Assessment of Social Transmission of Food Preferences Behaviors

Olfactory recognition deficits are suggested to be able to serve as clinical marker to differentiate Alzheimer's disease (AD) subjects from healthy aging groups. For example, olfactory dysfunction in AD can present as impairment in olfactory recognition, emerging during early stages of the disease and worsening while the disease progresses. The social transmission of food preferences (STFP) task is based on a rudimentary form of communication between rodents concerning distant foods dependent on the transmission of olfactory cues. Healthy wild-type mice would prefer to eat a novel, flavored food that was previously cued by a conspecific, and this food preference would be hampered in transgenic AD mice, such as the APP/PS1 model. Indeed, a strong preference for the cued food in C57Bl6/J mice of 3 months of age was found, and this was reduced in 3 months old transgenic APP/PS1 mice. In summary, STFP task could be a powerful measure to be integrated in present subclinical detection assays of AD.

Impaired olfactory function is related to the presence of neuropathy in adults with type 1 diabetes

INTRODUCTION

Olfactory dysfunction is suggested to be a clinical manifestation of central diabetic neuropathy. The aim of the study was to assess olfactory function in adult patients with type 1 diabetes.

MATERIALS AND METHODS

A total of 106 patients with type 1 diabetes and 30 healthy subjects were included in the study. We evaluated the metabolic control of diabetes and the presence of chronic complications. Olfactory function was assessed with Sniffin' Sticks.

RESULTS

We found a negative correlation between olfactory identification scores and body mass index ( Rs -0.2; p = 0.04) and triglycerides ( Rs = -0.2; p = 0.04). We showed lower olfactory identification scores in neuropathy group versus non-neuropathy group [8 (interquartile range, 7-9) vs 10 (interquartile range, 9-11) points; p = 0.005]. In multivariate linear regression, impaired olfaction was independently associated with neuropathy (beta, -0.3; p = 0.005). In multivariate logistic regression, diabetes duration (odds ratio, 1.06; 95% confidence interval, 1.00-1.11; p = 0.04) and olfactory identification score (odds ratio, 0.61; 95% confidence interval, 0.43-0.85; p = 0.003) were independently associated with neuropathy.

CONCLUSION

Olfactory dysfunction is observed in patients with type 1 diabetes and diabetic peripheral neuropathy.

Sensorineural Organs Dysfunction and Cognitive Decline: A Review Article

Vision, hearing, olfaction, and cognitive function are essential components of healthy and successful aging. Multiple studies demonstrate relationship between these conditions with cognitive function. The present article focuses on hearing loss, visual impairment, olfactory loss, and dual sensory impairments in relation to cognitive declination and neurodegenerative disorders. Sensorineural organ impairment is a predictive factor for mild cognitive impairment and neurodegenerative disorders in the elderly. We recommend early detection of sensorineural dysfunction by history, physical examination, and screening tests. Assisted device and early cognitive rehabilitation may be beneficial. Future research is warranted in order to explore advanced treatment options and method to slow progression for cognitive declination and sensorineural organ impairment.

Smell identification function as a severity and progression marker in Alzheimer's disease

BACKGROUND

Olfactory dysfunction, impaired smell identification in particular, is known as a diagnostic and a marker of conversion in Alzheimer's disease (AD). We aimed to evaluate the associations of olfactory identification impairments with cognition, illness severity, and progression in AD patients.

METHODS

Fifty-seven outpatients with late onset mild to moderate AD and 24 elderly non-demented controls (NDC) were assessed, at baseline and after three months, for Mini-Mental State Examination (MMSE), University of Pennsylvania Smell Identification Test (UPSIT), and Bristol Activities of Daily Living and Neuropsychiatry Inventory. AD participants were classified as Rapid Cognitive Decliners (RCD) defined on a priori with a loss of ≥2 points in MMSE within the previous six months.

RESULTS

AD participants had lower olfactory scores than NDC. RCD had lower olfaction scores compared with Non-Rapid Cognitive Decliners (NRCD). Although the baseline UPSIT scores were associated with baseline MMSE scores, it did not interact significantly with change in MMSE over the follow-up period. Using a median split for olfactory scores, the AD participants were classified as Rapid Olfactory Progressors (ROP) (UPSIT ≤ 15) and Slow Olfactory Progressors correlating significantly with RCD/NRCD groups. The ROP group with higher olfactory impairment indicated more symptomatic illness or severity, i.e. lower cognition, higher functional dependence, and presence of behavioral symptoms.

CONCLUSIONS

Our study supports association of smell identification function with cognition and its utility as an adjunct clinical measure to assess severity in AD. Further work, including larger longitudinal studies, is needed to explore its value in predicting AD progression.

The epidemiology of mild cognitive impairment (MCI) and Alzheimer's disease (AD) in community-living seniors: protocol of the MemoVie cohort study, Luxembourg

Background

Cognitive impairment and Alzheimer’s disease (AD) are increasingly considered a major public health problem. The MemoVie cohort study aims to investigate the living conditions or risk factors under which the normal cognitive capacities of the senior population in Luxembourg (≥ 65 year-old) evolve (1) to mild cognitive impairment (MCI) – transitory non-clinical stage – and (2) to AD. Identifying MCI and AD predictors undeniably constitutes a challenge in public health in that it would allow interventions which could protect or delay the occurrence of cognitive disorders in elderly people. In addition, the MemoVie study sets out to generate hitherto unavailable data, and a comprehensive view of the elderly population in the country.

Methods/design

The study has been designed with a view to highlighting the prevalence in Luxembourg of MCI and AD in the first step of the survey, conducted among participants selected from a random sample of the general population. A prospective cohort is consequently set up in the second step, and appropriate follow-up of the non-demented participants allows improving the knowledge of the preclinical stage of MCI. Case-control designs are used for cross-sectional or retrospective comparisons between outcomes and biological or clinical factors. To ensure maximal reliability of the information collected, we decided to opt for structured face to face interviews. Besides health status, medical and family history, demographic and socio-cultural information are explored, as well as education, habitat network, social behavior, leisure and physical activities. As multilingualism is expected to challenge the cognitive alterations associated with pathological ageing, it is additionally investigated. Data relative to motor function, including balance, walk, limits of stability, history of falls and accidents are further detailed. Finally, biological examinations, including ApoE genetic polymorphism are carried out. In addition to standard blood parameters, the lipid status of the participants is subsequently determined from the fatty acid profiles in their red blood cells. The study obtained the legal and ethical authorizations.

Discussion

By means of the multidisciplinary MemoVie study, new insights into the onset of cognitive impairment during aging should be put forward, much to the benefit of intervention strategies as a whole.

Management of Smell Dysfunction

Olfaction is an essential chemosensory system in the living world. Although less appreciated in humans, smell impairment significantly affects many aspects of quality of life. Smell disorders may be caused by an impaired nasal airway or by lesions in the olfactory system, leading to reduced or distorted smell perception. The most common causes of smell disorders are aging, upper respiratory tract infection, sinonasal disease, and head trauma. Recovery is rarely complete. Counseling is important in progressive or severe smell loss. In patients with distorted smell perception, antidepressant medication is sometimes necessary. Best response to treatment is achieved for nasal obstruction and sinonasal inflammatory disease. Treatment of olfactory impairment caused by sinonasal disease includes medication with topical and systemic steroids, or surgery for refractory cases. Although there are reports that surgical resection of olfactory neurons may lead to reinnervation and recovery of smell, adequate treatment of the smell loss remains an unmet need.