-
Frontiers in Neural Circuits 2024Olfactory dysfunctions decrease daily quality of life (QOL) in part by reducing the pleasure of eating. Olfaction plays an essential role in flavor sensation and... (Review)
Review
Olfactory dysfunctions decrease daily quality of life (QOL) in part by reducing the pleasure of eating. Olfaction plays an essential role in flavor sensation and palatability. The decreased QOL due to olfactory dysfunction is speculated to result from abnormal neural activities in the olfactory and limbic areas of the brain, as well as peripheral odorant receptor dysfunctions. However, the specific underlying neurobiological mechanisms remain unclear. As the olfactory tubercle (OT) is one of the brain's regions with high expression of endogenous opioids, we hypothesize that the mechanism underlying the decrease in QOL due to olfactory dysfunction involves the reduction of neural activity in the OT and subsequent endogenous opioid release in specialized subregions. In this review, we provide an overview and recent updates on the OT, the endogenous opioid system, and the pleasure systems in the brain and then discuss our hypothesis. To facilitate the effective treatment of olfactory dysfunctions and decreased QOL, elucidation of the neurobiological mechanisms underlying the pleasure of eating through flavor sensation is crucial.
Topics: Humans; Quality of Life; Animals; Smell; Opioid Peptides; Olfactory Tubercle; Olfaction Disorders
PubMed: 38872907
DOI: 10.3389/fncir.2024.1408189 -
I-Perception 2024This conceptual paper examines the use of odours and scents in books to enhance storytelling and engage readers. While books often possess a distinctive smell linked to...
This conceptual paper examines the use of odours and scents in books to enhance storytelling and engage readers. While books often possess a distinctive smell linked to their material production, the intentional use of scents in books is rare. Our study focuses on scratch-and-sniff books, examining their narrative purposes and contributions to young children's literature. We conduct a narrative historical review, supplemented by a systematic search of databases, online catalogues and lists, to identify a collection of these scented books. Through this review, we explore the extent to which these books represent a unique category of children's picture books, investigating how their features align with theoretical understandings of quality characteristics in children's literature and the role of olfactory cues in storytelling. We address why most scented books target younger readers and discuss possible reasons for the absence of scented books for an adult readership. This intriguing asymmetry contrasts the use of scent in other media (such as film, theatre or virtual reality), often directed toward adults. In addition, this review sheds light on the innovative use of scents in books and their impact on reader immersion and narrative experience. Finally, we consider possible future uses of scent in the context of digital books (ebooks).
PubMed: 38868524
DOI: 10.1177/20416695241257566 -
PCN Reports : Psychiatry and Clinical... Mar 2024Olfactory reference disorder (ORD) is a mental illness in which individuals overestimate their sense of smell and worry about the negative impact of odors. Little is...
BACKGROUND
Olfactory reference disorder (ORD) is a mental illness in which individuals overestimate their sense of smell and worry about the negative impact of odors. Little is known about its successful treatment. A new cognitive behavioral model was developed based on cognitive behavioral therapy (CBT) for obsessive-compulsive disorder. Using this model, this study reports a successful treatment process of a 53-year-old female with ORD.
CASE PRESENTATION
The patient's initial diagnosis was schizophrenia, and improvements were observed, such as the disappearance of persecutory delusions, through medication therapy. During this treatment process, it became clear that the patient's preoccupation with her own offensive body odor was not a hallucination or delusion caused by schizophrenia but rather a symptom of ORD. Within a limited 4-week hospitalization period, high-intensity CBT was provided by a clinical psychologist and a psychiatrist. Multiple CBT techniques were employed, including case formulation to identify her beliefs, reviewing safety-seeking behaviors, attention shift training, behavioral experiments, public opinion polls, mindfulness meditation, and exposure and response prevention.
CONCLUSION
Following a seven-sessions intensive intervention over 3 weeks, her symptoms of ORD, anxiety, and depression reduced. High-frequency CBT practices could be beneficial in treatment of patients with severe ORD, addressing severe ORD cases, facilitating rapid improvement in both ORD symptoms and functioning.
PubMed: 38868464
DOI: 10.1002/pcn5.179 -
BMC Psychology Jun 2024This prospective study explored the impact of aligners on the oral health-related quality of life and anxiety of patients during the first month of orthodontic treatment...
BACKGROUND
This prospective study explored the impact of aligners on the oral health-related quality of life and anxiety of patients during the first month of orthodontic treatment and the first month of the retention phase.
METHODS
A total of 23 male and female patients (median age 25 y) treated with clear aligners were included. The OHRQoL questionnaire was used at certain time points during treatment (T1: placement of the first aligner; T2: after one day of use; T3: after seven days; T4: after one month; and T5: after one month in the retention phase). The State-Trait Anxiety Inventory (STAI) was also self-administered to assess state and trait anxiety (Y1 and Y2 subscales, respectively) at the T1, T4 and T5 time points. A population average generalized estimating equations logistic regression model was fit to assess the effect of time on the responses, and the Wald test was used to examine the overall effect of time.
RESULTS
Overall time was a significant predictor for most of the questions. However, time was marginally significant for the OHRQoL questions evaluating oral symptoms such as bad taste/smell, sores, and food accumulation. Tooth discolouration did not differ between time points. The general activity disturbance was significantly lower in the retention phase. Higher depression and anxiety scores were reported at the initial appointment and decreased thereafter.
CONCLUSIONS
CAT has a negative impact on quality of life and psychological status during the initial days of treatment. These impairments ameliorate at later treatment stages.
Topics: Humans; Quality of Life; Male; Female; Pilot Projects; Oral Health; Prospective Studies; Adult; Anxiety; Young Adult; Surveys and Questionnaires; Middle Aged
PubMed: 38867321
DOI: 10.1186/s40359-024-01834-2 -
PloS One 2024Learning an olfactory discrimination task leads to heterogeneous results in honeybees with some bees performing very well and others at low rates. Here we investigated...
Learning an olfactory discrimination task leads to heterogeneous results in honeybees with some bees performing very well and others at low rates. Here we investigated this behavioral heterogeneity and asked whether it was associated with particular gene expression patterns in the bee's brain. Bees were individually conditioned using a sequential conditioning protocol involving several phases of olfactory learning and retention tests. A cumulative score was used to differentiate the tested bees into high and low performers. The rate of CS+ odor learning was found to correlate most strongly with a cumulative performance score extracted from all learning and retention tests. Microarray analysis of gene expression in the mushroom body area of the brains of these bees identified a number of differentially expressed genes between high and low performers. These genes are associated with diverse biological functions, such as neurotransmission, memory formation, cargo trafficking and development.
Topics: Animals; Bees; Behavior, Animal; Learning; Mushroom Bodies; Brain; Smell; Odorants; Gene Expression Profiling; Conditioning, Classical
PubMed: 38865313
DOI: 10.1371/journal.pone.0304563 -
Journal of Enzyme Inhibition and... Dec 2024The spices and aromatic herbs were used not only in cooking to add flavour and smell to dishes but also for medicinal use. Nigella sativa, also called black cumin, is...
The spices and aromatic herbs were used not only in cooking to add flavour and smell to dishes but also for medicinal use. Nigella sativa, also called black cumin, is one of the species that contains an important bioactive component, thymoquinone (TQ), which has antioxidant, anti-inflammatory, antimicrobial, and antidiabetic effects. Curcuma longa, which also includes curcumin, has numerous anti-cancer properties. However, the bioavailability of curcumin is lower than that of its analogs. An analog of curcumin (EF-24), which has better bioavailability than curcumin, is capable of exerting a high anti-cancer effect. In our study, we determined the effects of PON1 enzyme activity on the proliferation and aggressiveness of glioblastoma cancer treated with TQ and EF-24 from lysates of the glioblastoma cell line U87MG. The results were determined as increased PON1 activity after treatment with TQ and EF-24 in the U87MG cell line ( < 0.0001).
Topics: Humans; Aryldialkylphosphatase; Glioblastoma; Benzoquinones; Curcumin; Cell Proliferation; Dose-Response Relationship, Drug; Molecular Structure; Structure-Activity Relationship; Drug Screening Assays, Antitumor; Antineoplastic Agents; Cell Line, Tumor; Tumor Cells, Cultured
PubMed: 38864175
DOI: 10.1080/14756366.2024.2339901 -
Laryngoscope Investigative... Jun 2024Olfactory training (OT) has emerged as a first-line therapeutic approach to the management of olfactory dysfunction. Conventional OT (COT) involves the systematic...
OBJECTIVES
Olfactory training (OT) has emerged as a first-line therapeutic approach to the management of olfactory dysfunction. Conventional OT (COT) involves the systematic home-based exposure to four distinct odors. Previous research has demonstrated that immersive OT (IOT) involving full-body exposure to dozens of distinct odors could also improve overall olfactory function. This study compared IOT and COT in terms of efficacy.
METHODS
A total of 60 patients were enrolled and assigned to three groups. The IOT group ( = 25) underwent immersive exposure to 64 odors once daily in a specialized theater. COT participants ( = 17) sniffed four typical odors in a set of four jars twice daily at home. A control group ( = 18) underwent passive observation. Olfactory function was assessed before and after training.
RESULTS
Significant improvements in composite threshold-discrimination-identification (TDI) scores were observed after training in both the IOT (mean difference = 2.5 ± 1.1. = .030) and COT (mean difference = 4.2 ± 1.3, = .002) groups. No changes were observed in the control group. A significantly higher proportion of patients in the COT group (41%) presented improvements of clinical importance (TDI ≥5.5) compared to the controls ( = .018). The improvements attained in the IOT group (20%) were less pronounced ( = .38).
CONCLUSION
While IOT did not exhibit the same efficacy as COT in restoring olfactory function, it still demonstrated promising outcomes. Future efforts to advance olfactory recovery should focus on cross-modal integration.
LEVEL OF EVIDENCE
Level 3.
PubMed: 38863999
DOI: 10.1002/lio2.1270 -
Scientific Reports Jun 2024Despite its high prevalence, the determinants of smelling impairment in COVID-19 remain not fully understood. In this work, we aimed to examine the association between...
Despite its high prevalence, the determinants of smelling impairment in COVID-19 remain not fully understood. In this work, we aimed to examine the association between olfactory bulb volume and the clinical trajectory of COVID-19-related smelling impairment in a large-scale magnetic resonance imaging (MRI) analysis. Data of non-vaccinated COVID-19 convalescents recruited within the framework of the prospective Hamburg City Health Study COVID Program between March and December 2020 were analyzed. At baseline, 233 participants underwent MRI and neuropsychological testing as well as a structured questionnaire for olfactory function. Between March and April 2022, olfactory function was assessed at follow-up including quantitative olfactometric testing with Sniffin' Sticks. This study included 233 individuals recovered from mainly mild to moderate SARS-CoV-2 infections. Longitudinal assessment demonstrated a declining prevalence of self-reported olfactory dysfunction from 67.1% at acute infection, 21.0% at baseline examination and 17.5% at follow-up. Participants with post-acute self-reported olfactory dysfunction had a significantly lower olfactory bulb volume at baseline than normally smelling individuals. Olfactory bulb volume at baseline predicted olfactometric scores at follow-up. Performance in neuropsychological testing was not significantly associated with the olfactory bulb volume. Our work demonstrates an association of long-term self-reported smelling dysfunction and olfactory bulb integrity in a sample of individuals recovered from mainly mild to moderate COVID-19. Collectively, our results highlight olfactory bulb volume as a surrogate marker that may inform diagnosis and guide rehabilitation strategies in COVID-19.
Topics: Humans; Olfactory Bulb; COVID-19; Male; Female; Middle Aged; Olfaction Disorders; Adult; Magnetic Resonance Imaging; SARS-CoV-2; Aged; Prospective Studies; Neuropsychological Tests; Smell
PubMed: 38862636
DOI: 10.1038/s41598-024-64367-z -
Learning & Memory (Cold Spring Harbor,... May 2024Associative learning enables the adaptive adjustment of behavioral decisions based on acquired, predicted outcomes. The valence of what is learned is influenced not only...
Associative learning enables the adaptive adjustment of behavioral decisions based on acquired, predicted outcomes. The valence of what is learned is influenced not only by the learned stimuli and their temporal relations, but also by prior experiences and internal states. In this study, we used the fruit fly to demonstrate that neuronal circuits involved in associative olfactory learning undergo restructuring during extended periods of low-caloric food intake. Specifically, we observed a decrease in the connections between specific dopaminergic neurons (DANs) and Kenyon cells at distinct compartments of the mushroom body. This structural synaptic plasticity was contingent upon the presence of allatostatin A receptors in specific DANs and could be mimicked optogenetically by expressing a light-activated adenylate cyclase in exactly these DANs. Importantly, we found that this rearrangement in synaptic connections influenced aversive, punishment-induced olfactory learning but did not impact appetitive, reward-based learning. Whether induced by prolonged low-caloric conditions or optogenetic manipulation of cAMP levels, this synaptic rearrangement resulted in a reduction of aversive associative learning. Consequently, the balance between positive and negative reinforcing signals shifted, diminishing the ability to learn to avoid odor cues signaling negative outcomes. These results exemplify how a neuronal circuit required for learning and memory undergoes structural plasticity dependent on prior experiences of the nutritional value of food.
Topics: Animals; Mushroom Bodies; Drosophila melanogaster; Neuronal Plasticity; Dopaminergic Neurons; Eating; Optogenetics; Association Learning; Smell; Olfactory Perception; Reward; Animals, Genetically Modified
PubMed: 38862177
DOI: 10.1101/lm.053997.124 -
Frontiers in Psychology 2024Olfactory dysfunction (OD) is frequent after SARS-CoV-2 infection. The aim of this study was to examine if long-term OD is common in post-COVID condition, and the...
INTRODUCTION
Olfactory dysfunction (OD) is frequent after SARS-CoV-2 infection. The aim of this study was to examine if long-term OD is common in post-COVID condition, and the relationship between olfaction, cognition, neuropsychiatric symptoms, and disease duration in these patients.
METHODS
This study included 121 participants with post-COVID condition and 51 healthy controls (HC). A comprehensive neuropsychological and neuropsychiatric assessment was conducted, encompassing various domains, including general cognition, processing speed, verbal fluency, attention, verbal memory, visual memory, visuoconstructive ability, visuospatial ability, abstraction, executive functions, anxious-depressive symptoms, general health perception, fatigue level, sleep quality, and olfaction. Statistical analyses were carried out to understand the relationship of OD with cognition, and its role as moderator variable.
RESULTS
In total, 25% of the post-covid patients had a reduced smell capacity, while only 9.3% of HC presented OD. Post-COVID patients had statistically significantly worse cognitive performance and clinical status than HC. Verbal fluency (AUC = 0.85, < 0.001), and attention (AUC = 0.82, < 0.001) were the variables that best discriminate between groups. OD seemed to be a moderator between fatigue and cognition, and between disease duration and attention (β = -0.04; = 0.014).
DISCUSSION
The study highlights marked cognitive and neuropsychiatric sequelae in individuals post-COVID relative to HC. Olfactory impairment exhibits correlations with both cognitive performance and general health. Olfaction emerges as a potential prognostic marker owing to its moderating influence on disease severity indicators.
PubMed: 38860043
DOI: 10.3389/fpsyg.2024.1407887