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Frontiers in Behavioral Neuroscience 2022There are a number of key features which make olfaction difficult to study; subjective processes of odor detection, discrimination and identification, and...
There are a number of key features which make olfaction difficult to study; subjective processes of odor detection, discrimination and identification, and individualistic odor hedonic perception and associated odor memories. In this systematic review we explore the role functional near-infrared spectroscopy (fNIRS) has played in understanding olfactory perception in humans. fNIRS is an optical neuroimaging technique able to measure changes in brain hemodynamics and oxygenation related to neural electrical activity. Adhering to PRISMA guidelines, results of this search found that generally the majority of studies involving healthy adult subjects observed increased activity in response to odors. Other population types were also observed, such as infants, individuals with autism, attention deficit hyperactivity disorder (ADHD), post-traumatic stress disorder (PTSD), mild cognitive impairment (MCI) and dysosmia. fNIRS coverage heavily favored the prefrontal cortex, temporal and parietal regions. This review finds that odor induced cortical activation is dependent on multiple factors, such as odorant type, gender and population type. This review also finds that there is room for improvement in areas such as participant diversity, use of wearable fNIRS systems, physiological monitoring and multi-distance channels.
PubMed: 36620865
DOI: 10.3389/fnbeh.2022.1040719 -
Journal of Asthma and Allergy 2022To summarize the current evidence regarding the prevalence of Allergic rhinitis (AR) and its symptoms, triggers, and impact on the quality of life of the Saudi... (Review)
Review
OBJECTIVE
To summarize the current evidence regarding the prevalence of Allergic rhinitis (AR) and its symptoms, triggers, and impact on the quality of life of the Saudi population.
METHODS
A Computerized Search in MEDLINE via PubMed, MEDLINE Core database, Scopus, and Web of Science was conducted using relevant keywords. A two-stage screening process, data extraction, and quality assessment were conducted by four independent reviewers. Comprehensive Meta-analysis was used for all statistical analyses (CMA; USA: version 3.3.070).
RESULTS
Sixteen articles (n= 31,990 patients) were included. The overall estimated prevalence of AR was 21.2%, 95% CI (12.8-33.1%). Males had a higher prevalence of AR than females (31.7% vs 27.1%), although the difference was not significant (OR=1.24, 95% CI: 0.78-1.953; p=0.356). Children and adolescents exhibited a lower prevalence of AR than adults (13.7% vs 31.1%). Urban AR prevalence was much greater than rural (38.4% vs 13.0%). Asthma, atopic dermatitis, and eczema are all associated with AR. The most common signs and symptoms of AR were headache 33.9%, watery discharge 28.6%, sneezing 24.6%, itchy nose, runny nose 22.2%, nasal obstruction or congestion 22.0%, loss of smell 21.9%, and wheezing 17.2%. The most prevalent triggers of AR were perfume 36.8%, dust 27.3%, air conditioning 23.4%, weather or temperature changes 17.8%, air pollution 14.5%, drugs or chemicals 13.8%, tobacco 10.8%, atopy 10.3%, and insects 10.2%.
CONCLUSION
The overall prevalence of AR in Saudi Arabia is 21.2%. The prevalence of AR was comparable in both males and females. However, it was higher in adults than in children and adolescents, and in urban areas than rural areas. Asthma, atopic dermatitis, and eczema co-occurrence with AR are common. AR has a negative impact on the quality of life of the patients in the form of interference with daily activities, sleep problems, difficulty of breath, and school absenteeism.
PubMed: 36582219
DOI: 10.2147/JAA.S391142 -
MedRxiv : the Preprint Server For... Jan 2023The omicron variant is thought to cause less olfactory dysfunction than previous variants of SARS-CoV-2, but the reported prevalence differs greatly between populations...
The omicron variant is thought to cause less olfactory dysfunction than previous variants of SARS-CoV-2, but the reported prevalence differs greatly between populations and studies. Our systematic review and meta-analysis provide information about regional differences in prevalence as well as an estimate of the global prevalence of olfactory dysfunction based on 62 studies reporting on 626,035 patients infected with the omicron variant. Our estimate of the omicron-induced prevalence of olfactory dysfunction in populations of European ancestry is 11.7%, while it is significantly lower in all other populations, ranging between 1.9% and 4.9%. When ethnic differences and population sizes are taken into account, the global prevalence of omicron-induced olfactory dysfunction in adults is estimated at 3.7%. Omicron’s effect on olfaction is twofold to tenfold lower than that of the alpha or delta variant, according to previous meta-analyses and our analysis of studies that directly compared prevalence of olfactory dysfunction between omicron and previous variants. The profile of prevalence differences between ethnicities mirrors the results of a recent genome-wide association study that implicated a gene locus encoding an odorant-metabolizing enzyme, UDP glycosyltransferase, to be linked to the extent of COVID-related loss of smell. Our analysis is consistent with the hypothesis that this enzyme contributes to the observed population differences.
PubMed: 36561176
DOI: 10.1101/2022.12.16.22283582 -
Biomedicines Nov 2022The prodromal phase of Parkinson's disease (PD) is characterised by many non-motor symptoms, and these have recently been posited to be predictive of later diagnosis.... (Review)
Review
The prodromal phase of Parkinson's disease (PD) is characterised by many non-motor symptoms, and these have recently been posited to be predictive of later diagnosis. Genetic rodent models can develop non-motor phenotypes, providing tools to identify mechanisms underlying the early development of PD. However, it is not yet clear how reproducible non-motor phenotypes are amongst genetic PD rodent models, whether phenotypes are age-dependent, and the translatability of these phenotypes has yet to be explored. A systematic literature search was conducted on studies using genetic PD rodent models to investigate non-motor phenotypes; cognition, anxiety/depressive-like behaviour, gastrointestinal (GI) function, olfaction, circadian rhythm, cardiovascular and urinary function. In total, 51 genetic models of PD across 150 studies were identified. We found outcomes of most phenotypes were inconclusive due to inadequate studies, assessment at different ages, or variation in experimental and environmental factors. GI dysfunction was the most reproducible phenotype across all genetic rodent models. The mouse model harbouring mutant A53T, and the wild-type hα-syn overexpression (OE) model recapitulated the majority of phenotypes, albeit did not reliably produce concurrent motor deficits and nigral cell loss. Furthermore, animal models displayed different phenotypic profiles, reflecting the distinct genetic risk factors and heterogeneity of disease mechanisms. Currently, the inconsistent phenotypes within rodent models pose a challenge in the translatability and usefulness for further biomechanistic investigations. This review highlights opportunities to improve phenotype reproducibility with an emphasis on phenotypic assay choice and robust experimental design.
PubMed: 36551782
DOI: 10.3390/biomedicines10123026 -
Integrative Cancer Therapies 2022Remote medical scent detection of cancer and infectious diseases with dogs and rats has been an increasing field of research these last 20 years. If validated, the... (Review)
Review
BACKGROUND
Remote medical scent detection of cancer and infectious diseases with dogs and rats has been an increasing field of research these last 20 years. If validated, the possibility of implementing such a technique in the clinic raises many hopes. This systematic review was performed to determine the evidence and performance of such methods and assess their potential relevance in the clinic.
METHODS
Pubmed and Web of Science databases were independently searched based on PRISMA standards between 01/01/2000 and 01/05/2021. We included studies aiming at detecting cancers and infectious diseases affecting humans with dogs or rats. We excluded studies using other animals, studies aiming to detect agricultural diseases, diseases affecting animals, and others such as diabetes and neurodegenerative diseases. Only original articles were included. Data about patients' selection, samples, animal characteristics, animal training, testing configurations, and performances were recorded.
RESULTS
A total of 62 studies were included. Sensitivity and specificity varied a lot among studies: While some publications report low sensitivities of 0.17 and specificities around 0.29, others achieve rates of 1 sensitivity and specificity. Only 6 studies were evaluated in a double-blind screening-like situation. In general, the risk of performance bias was high in most evaluated studies, and the quality of the evidence found was low.
CONCLUSIONS
Medical detection using animals' sense of smell lacks evidence and performances so far to be applied in the clinic. What odors the animals detect is not well understood. Further research should be conducted, focusing on patient selection, samples (choice of materials, standardization), and testing conditions. Interpolations of such results to free running detection (direct contact with humans) should be taken with extreme caution. Considering this synthesis, we discuss the challenges and highlight the excellent odor detection threshold exhibited by animals which represents a potential opportunity to develop an accessible and non-invasive method for disease detection.
Topics: Humans; Dogs; Animals; Rats; Odorants; Neoplasms; Smell; Communicable Diseases; Randomized Controlled Trials as Topic
PubMed: 36541180
DOI: 10.1177/15347354221140516 -
Chemical Senses Jan 2022Little attention has been paid to olfactory changes during pregnancy with contemporary studies limited in number and sample size. We examined whether pregnancy is... (Meta-Analysis)
Meta-Analysis
Little attention has been paid to olfactory changes during pregnancy with contemporary studies limited in number and sample size. We examined whether pregnancy is associated with differences in olfactory performance and if there were any specific gestational ages at which these differences occur through a comprehensive systematic review and meta-analysis of the current literature. An initial electronic database search identified 234 citations, which were screened at the abstract level. Twenty-three citations were germane for full-text review, and 13 met criteria for inclusion. Our review assessed 5 olfactory measures of interest: odor identification (n = 11 articles), threshold (n = 8), discrimination (n = 5), hedonics (n = 6), and intensity (n = 5). Nine of these 13 studies contained sufficient data for meta-analysis, and these studies included a total of 523 pregnant women and 365 non-pregnant controls. Despite previous subjective and objective reports of odor intolerances and odor hypersensitivity, we did not find any significant differences between pregnant and non-pregnant women in odor discrimination, thresholds, or hedonics. However, meta-analysis of 506 cases and 333 controls showed worse odor identification in pregnant women compared to controls in a random-effects model. Thus, we demonstrate worse performance at odor identification during pregnancy. In this review, we discuss the current evidence (and lack thereof) regarding olfaction in pregnancy as well as highlight current knowledge gaps in this field.
Topics: Pregnancy; Humans; Female; Smell; Odorants; Olfaction Disorders
PubMed: 36469055
DOI: 10.1093/chemse/bjac035 -
Physiological Reviews Jan 2023Taste and smell play a key role in our ability to perceive foods. Overconsumption of highly palatable energy-dense foods can lead to increased caloric intake and... (Review)
Review
Taste and smell play a key role in our ability to perceive foods. Overconsumption of highly palatable energy-dense foods can lead to increased caloric intake and obesity. Thus there is growing interest in the study of the biological mediators of fat taste and associated olfaction as potential targets for pharmacologic and nutritional interventions in the context of obesity and health. The number of studies examining mechanisms underlying fat taste and smell has grown rapidly in the last 5 years. Therefore, the purpose of this systematic review is to summarize emerging evidence examining the biological mechanisms of fat taste and smell. A literature search was conducted of studies published in English between 2014 and 2021 in adult humans and animal models. Database searches were conducted using PubMed, EMBASE, Scopus, and Web of Science for key terms including fat/lipid, taste, and olfaction. Initially, 4,062 articles were identified through database searches, and a total of 84 relevant articles met inclusion and exclusion criteria and are included in this review. Existing literature suggests that there are several proteins integral to fat chemosensation, including cluster of differentiation 36 (CD36) and G protein-coupled receptor 120 (GPR120). This systematic review will discuss these proteins and the signal transduction pathways involved in fat detection. We also review neural circuits, key brain regions, ingestive cues, postingestive signals, and genetic polymorphism that play a role in fat perception and consumption. Finally, we discuss the role of fat taste and smell in the context of eating behavior and obesity.
Topics: Animals; Humans; Feeding Behavior; Obesity; Smell; Taste; Taste Buds
PubMed: 36409650
DOI: 10.1152/physrev.00061.2021 -
The Cochrane Database of Systematic... Nov 2022Perception is the ability to understand information from our senses. It allows us to experience and meaningfully interact with our environment. A stroke may impair... (Review)
Review
BACKGROUND
Perception is the ability to understand information from our senses. It allows us to experience and meaningfully interact with our environment. A stroke may impair perception in up to 70% of stroke survivors, leading to distress, increased dependence on others, and poorer quality of life. Interventions to address perceptual disorders may include assessment and screening, rehabilitation, non-invasive brain stimulation, pharmacological and surgical approaches.
OBJECTIVES
To assess the effectiveness of interventions aimed at perceptual disorders after stroke compared to no intervention or control (placebo, standard care, attention control), on measures of performance in activities of daily living. SEARCH METHODS: We searched the trials registers of the Cochrane Stroke Group, CENTRAL, MEDLINE, Embase, and three other databases to August 2021. We also searched trials and research registers, reference lists of studies, handsearched journals, and contacted authors.
SELECTION CRITERIA
We included randomised controlled trials (RCTs) of adult stroke survivors with perceptual disorders. We defined perception as the specific mental functions of recognising and interpreting sensory stimuli and included hearing, taste, touch, smell, somatosensation, and vision. Our definition of perception excluded visual field deficits, neglect/inattention, and pain.
DATA COLLECTION AND ANALYSIS
One review author assessed titles, with two review authors independently screening abstracts and full-text articles for eligibility. One review author extracted, appraised, and entered data, which were checked by a second author. We assessed risk of bias (ROB) using the ROB-1 tool, and quality of evidence using GRADE. A stakeholder group, comprising stroke survivors, carers, and healthcare professionals, was involved in this review update.
MAIN RESULTS
We identified 18 eligible RCTs involving 541 participants. The trials addressed touch (three trials, 70 participants), somatosensory (seven trials, 196 participants) and visual perception disorders (seven trials, 225 participants), with one (50 participants) exploring mixed touch-somatosensory disorders. None addressed stroke-related hearing, taste, or smell perception disorders. All but one examined the effectiveness of rehabilitation interventions; the exception evaluated non-invasive brain stimulation. For our main comparison of active intervention versus no treatment or control, one trial reported our primary outcome of performance in activities of daily living (ADL): Somatosensory disorders: one trial (24 participants) compared an intervention with a control intervention and reported an ADL measure. Touch perception disorder: no trials measuring ADL compared an intervention with no treatment or with a control intervention. Visual perception disorders: no trials measuring ADL compared an intervention with no treatment or control. In addition, six trials reported ADL outcomes in a comparison of active intervention versus active intervention, relating to somatosensation (three trials), touch (one trial) and vision (two trials). AUTHORS' CONCLUSIONS: Following a detailed, systematic search, we identified limited RCT evidence of the effectiveness of interventions for perceptual disorders following stroke. There is insufficient evidence to support or refute the suggestion that perceptual interventions are effective. More high-quality trials of interventions for perceptual disorders in stroke are needed. They should recruit sufficient participant numbers, include a 'usual care' comparison, and measure longer-term functional outcomes, at time points beyond the initial intervention period. People with impaired perception following a stroke should continue to receive neurorehabilitation according to clinical guidelines.
Topics: Adult; Humans; Activities of Daily Living; Perceptual Disorders; Stroke; Stroke Rehabilitation; Vision Disorders; Randomized Controlled Trials as Topic
PubMed: 36326118
DOI: 10.1002/14651858.CD007039.pub3 -
Cureus Aug 2022The coronavirus can infect the upper respiratory tract, sinuses, and nose, and its severity manifests in its respiratory symptoms and neurological and psychological... (Review)
Review
The coronavirus can infect the upper respiratory tract, sinuses, and nose, and its severity manifests in its respiratory symptoms and neurological and psychological consequences. The majority of people who have COVID-19 present with moderate flu-like illness, and patients who are elderly with comorbid conditions, such as hypertension and diabetes, are more prone to experience severe illness and death. However, in the ongoing COVID-19 pandemic, neurological consequences have become a substantial source of morbidity and mortality. COVID-19 poses a global hazard to the nervous system because of its widespread dispersion and multiple pathogenic pathways. This review offers a critical assessment of the acute and long-term neurological effects of the COVID-19 virus. Some neurological problems include headache, dizziness, myalgia/fatigue, meningitis, ischemic/hemorrhagic stroke, and myelitis. Other people who have contracted COVID-19 also exhibit neurological features such as loss of taste and smell, reduced consciousness, and Guillain-Barré syndrome. This study seeks to help neurologists comprehend the wide range of neurologic aspects of COVID-19, as understanding neurological symptoms may help with the management and enhance the patient's outcomes.
PubMed: 36168382
DOI: 10.7759/cureus.28309 -
Current Opinion in Infectious Diseases Oct 2022Although acute COVID-19 has been milder in children and young people compared with adults, there is a concern that they may suffer persistent symptoms. There is a need... (Meta-Analysis)
Meta-Analysis
PURPOSE OF REVIEW
Although acute COVID-19 has been milder in children and young people compared with adults, there is a concern that they may suffer persistent symptoms. There is a need to define the clinical phenotype, determine those most at risk, the natural course of the condition and evaluate preventive and therapeutic strategies for both mental health and physical symptoms.
RECENT FINDINGS
More recent studies with control groups reported a lower prevalence of persistent symptoms in children and young people exposed to SARS-CoV-2. A systematic review and meta-analysis found that the frequency of the majority of reported persistent symptoms is similar in SARS-CoV-2 positive cases and controls. Children and young people infected with SARS-COV-2 had small but significant increases in persisting cognitive difficulties, headache and loss of smell. Factors associated with persisting, impairing symptoms include increased number of symptoms at the time of testing, female sex, older age, worse self-rated physical and mental health, and feelings of loneliness preinfection.
SUMMARY
This review highlights the importance of a control group in studies following SARS-CoV-2 infection, the need for case definitions and research to understand the outcomes of long COVID in children and young people.
Topics: COVID-19; Female; Humans; Mental Health; SARS-CoV-2; Post-Acute COVID-19 Syndrome
PubMed: 36098262
DOI: 10.1097/QCO.0000000000000854