Insights into smell and taste sensitivity in normal weight and overweight-obese adolescents

Neurological soft signs and olfactory dysfunction in patients with borderline personality disorder

BACKGROUND

Borderline personality disorder (BPD) is a serious disorder with a lifetime prevalence of 2.7-5.9% and is thought to correlate with altered neuroplasticity. The aim of the present study is to investigate possible associations of BPD (-severity) and alterations in neurological soft signs (NSS) and olfactory function.

METHODS

For the monocentric observational study, 39 female subjects with a BPD diagnosis and 19 female healthy control subjects were recruited. The groups were matched by age. Olfactory functions were examined using Sniffin' Sticks. NSS were assessed by a standardized test with 50 items.

RESULTS

BPD subjects have higher NSS scores in group comparison. By contrast, there are no alterations in the total score of olfactory function, while the BPD subjects scored higher in smell identification. Within the BPD group, the total NSS score was discovered to have a negative correlation with olfactory function. BPD subjects taking antipsychotics show more NSS than those without. We found no significant influence of posttraumatic stress disorder on the NSS or olfactory function. The BPD-severity correlates with NSS.

LIMITATIONS

Due to the cross-sectional design, we did not have a follow up examination. The sample size was small, and all patients had psychiatric comorbidities. Additionally, we did not perform MRI to connect our findings with possible structural abnormalities.

CONCLUSIONS

Our study confirmed altered NSS in BPD patients, whereas no impairment in the olfactory function was found. Further research is required to establish NSS and smell tests as clinical screening tools in BPD patients and to uncover the disorder's impact on neuroplasticity.

Olfactory function in diabetes mellitus

Diabetes mellitus (DM) is an increasingly common disease in both children and adults. In addition to neuronal and/or vascular disorders, it can cause chemosensory abnormalities including olfactory deterioration. The purpose of this article is to summarize current knowledge on olfactory function in DM, highlighting the impact of co-morbidities, especially obesity, thyroid dysfunction, chronic kidney disease and COVID-19 on olfactory outcomes. Research to date mostly shows that olfactory impairment is more common in people with diabetes than in the general population. In addition, the presence of concomitant diseases is a factor increasing olfactory impairment. Such a correlation was shown for type 1 diabetes, type 2 diabetes and gestational diabetes. At the same time, not only chronic diseases, but also DM in acute conditions such as COVID-19 leads to a higher prevalence of olfactory disorders during infection. Analyzing the existing literature, it is important to be aware of the limitations of published studies. These include the small number of patients studied, the lack of uniformity in the methods used to assess the sense of smell, frequently relying on rated olfactory function only, and the simultaneous analysis of patients with different types of diabetes, often without a clear indication of diabetes type. In addition, the number of available publications is small. Certainly, further research in this area is needed. From a practical point of view decreased olfactory performance may be an indicator for central neuropathy and an indication for assessing the patient's nutritional status, examining cognitive function, especially in older patients and performing additional diagnostic tests, such as checking thyroid function, because all those changes were correlated with smell deterioration.

Editorial for the Special Issue "Effects of COVID-19 on Lifestyle Behaviors in Children with Obesity"

During the last four decades, the prevalence of obesity has increased dramatically worldwide; concomitantly, a progressive rise in the prevalence of obesity, diabetes, and other nutrition-related chronic diseases has also been observed in childhood [...].

Investigating the Relationships between Taste Preferences and Beverage Intake in Preadolescents

Sugar-sweetened beverages are known promotors of adverse health outcomes. This study aimed to find a relation between taste perception, preferences for beverages, anthropometric parameters, and frequency of beverage consumption. Taste perception of sweetness was tested using an adopted sensitivity test with sucrose and different concentrations of sugar-sweetened apple juice. Furthermore, bitter-compound 6-n-propylthiouracil (PROP) and salty perception were tested and accompanied by a questionnaire on beverage intake. We did not find a clear relationship between taste perception, anthropometrics, and beverage intake. Nevertheless, in males, the bitter intensity perception of PROP was positively correlated with the BMI percentiles (CDC, r = 0.306, p ≤ 0.043) and the waist circumference (r = 0.326, p = 0.031). Furthermore, the liking of sweet taste (p < 0.05) and sweet intensity rating (p < 0.05) of apple juice increased with intensity, and adolescents with overweight or obesity had a higher intake of free sugars from beverages (p < 0.001). The role of taste perception on anthropometric measures and beverage intake remains unclear and requires further investigation.

Chemosensory Ability and Sensitivity in Health and Disease: Epigenetic Regulation and COVID-19

Throughout the animal kingdom, our two chemical senses, olfaction and gustation, are defined by two primary factors: genomic architecture of the organisms and their living environment. During the past three years of the global COVID-19 pandemic, these two sensory modalities have drawn much attention at the basic science and clinical levels because of the strong association of olfactory and gustatory dysfunction with viral infection. Loss of our sense of smell alone, or together with a loss of taste, has emerged as a reliable indicator of COVID-19 infection. Previously, similar dysfunctions have been detected in a large cohort of patients with chronic conditions. The research focus remains on understanding the persistence of olfactory and gustatory disturbances in the post-infection phase, especially in cases with long-term effect of infection (long COVID). Also, both sensory modalities show consistent age-related decline in studies aimed to understand the pathology of neurodegenerative conditions. Some studies using classical model organisms show an impact on neural structure and behavior in offspring as an outcome of parental olfactory experience. The methylation status of specific odorant receptors, activated in parents, is passed on to the offspring. Furthermore, experimental evidence indicates an inverse correlation of gustatory and olfactory abilities with obesity. Such diverse lines of evidence emerging from basic and clinical research studies indicate a complex interplay of genetic factors, evolutionary forces, and epigenetic alterations. Environmental factors that regulate gustation and olfaction could induce epigenetic modulation. However, in turn, such modulation leads to variable effects depending on genetic makeup and physiological status. Therefore, a layered regulatory hierarchy remains active and is passed on to multiple generations. In the present review, we attempt to understand the experimental evidence that indicates variable regulatory mechanisms through multilayered and cross-reacting pathways. Our analytical approach will add to enhancement of prevailing therapeutic interventions and bring to the forefront the significance of chemosensory modalities for the evaluation and maintenance of long-term health.

The development of sniffing

Sniffing is a commonly displayed behavior in rodents, yet how this important behavior adjusts throughout development to meet the sensory demands of the animals has remained largely unexplored. In this issue of Chemical Senses, Boulanger-Bertolus et al. investigates the ontogeny of odor-evoked sniffing through a longitudinal study of rats engaged in several olfactory paradigms from infancy to adulthood. The results of this study yield a cohesive picture of sniffing behavior across three developmental stages, while also providing direct comparisons within subjects between these timepoints. As we discuss herein, these results advance the field in relation to existing literature on the development of odor-evoked sniffing behavior in several important ways.

The Number of Fungiform Papillae, Taste Sensitivity and Smell Functions of Children Aged 11–15

Differences in the ability to identify and perceive tastes and smells might influence food consumption and, ultimately, chronic nutrition-related conditions such as overweightness and obesity. This study aimed to investigate the associations between taste sensitivity and odour function, anthropometry, and quantity of fungiform papillae in children at age 11–15. Taste strips (4 base tastes), U-Sniff sticks (12 selected smells), and a filter paper strip impregnated with 6-n-propylthiouracil (PROP) were used. The photographic method was used to estimate the number of fungiform papillae (FP) on the tongue. The results showed that the quantity of FP was not related to anthropometry or gender. The taste test total scores were higher for girls, for whom the median score was 14 (12.0–15.0), than for boys, for whom the median score was 12 (9.0–13.0). Of the children, 13.9% had some difficulty in identifying odours. The Mann–Whitney U test showed that children who were most sensitive to bitter taste had more FP (p = 0.0001). The median score for this group (score = 4) was 34.0 (27.0–37.0). For those who had some problems with correctly assessing all bitter taste strips (score = 0–3), the median score was 24.0 (20.0–31.0). Higher numbers of FP were also observed in tasters, that is, people sensitive to PROP, than in nontasters. Only some measures of the taste function correlated with each other, but not very significantly. We concluded that there are multiple perceptual phases of taste, with no single measure able to entirely represent the sense of taste.

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.

Anxiety-related shifts in smell function in children and adolescents

Anxious adults show changes in smell function that are consistent with a durable shift in sensitivity toward particular odorants and away from others. Little is known regarding the development of these changes, including whether they exist in youth, are stable during the transition from childhood to adolescence, and whether odorant properties (e.g. trigeminal features, hedonic valence) affect anxiety-related differences in detection. To address this, we measured smell detection thresholds to phenyl ethyl alanine (PEA), a rose-like odorant with little trigeminal properties, and guaiacol (GUA), a smoke-like odorant with high trigeminal properties. These thresholds were measured at baseline and after an acute stress challenge, the Trier Social Stress Tests, in 131 healthy youth (in 4th, 7th, and 10th grades, age 9-16 years) that reported normal to elevated levels of anxiety. At baseline, high anxious youth exhibited heightened sensitivity to GUA coupled with reduced sensitivity to PEA, as well as a further exaggeration of this bias with acute stress. Importantly, sex, age, and hedonic valence moderated the relationship between trait anxiety and sensitivity to both odorants. Smell function and its aberrations are often overlooked in the literature on biomarkers of stress and anxiety. Taken together with the extant literature, these findings suggest that greater attention is warranted to characterize potential novel olfactory therapeutic targets-across the lifespan.

Odor-Taste-Texture Interactions as a Promising Strategy to Tackle Adolescent Overweight

The adolescence period is characterized by a considerable risk to weight gain due to the high consumption of food rich in sugar. A promising strategy to reduce sugar consumption may lie in exploiting the ability of our senses to interact to each other (cross-modal interactions). The aims were to investigate the cross-modal interactions and gustatory function in normal-weight and overweight adolescents. Fifty adolescents (25 overweight and 25 normal-weight) were involved. Subjects rated liking and attribute intensity in pudding samples obtained by adding vanilla aroma (0.1%; 0.3%), butter aroma (0.05%; 0.1%) or a thickener agent (1%; 1.5%) to a base formulation. The gustatory function was also measured through the “taste strips” methodology. Overweight adolescents were found to have a significantly (p < 0.001) worse ability to correctly identify all tastes. Cross-modal interactions occurred differently according to their body mass index, with a significant increase (p < 0.05) in sensory desirable characteristics (e.g., sweet and creaminess) due to aroma addition, especially in overweight subjects. Furthermore, butter aroma significantly increased hedonic responses only in overweight subjects. Tricking our senses in the way of perceiving sensory attributes could be a promising strategy to develop innovative food formulations with a reduced sugar amount, which will lead to a potential decrease in caloric intake and help to tackle the obesity epidemic.

The Influence of Common Noncommunicable Diseases on Chemosensory Perception and Clinical Implications in Children and Adolescents

An increased incidence of noninfectious chronic diseases, such as obesity, diabetes, and allergies, has been noted in the last century, especially in the last 2 to 3 generations. Evidence suggested that the interrelation among these chronic conditions in pediatric age (e.g., children and adolescents aged 4-16 y) is complex and still unknown, reinforcing the interest of pediatricians in these diseases. Of interest is the need to better understand the link between these pathologies and sensory perception, since the chemical senses of taste and smell, together with chemesthesis, are reported to have a role in food choices and may provide a novel target for intervention in the treatment of these pathologies. This review aims to explore the current evidence on the link between these chronic conditions and chemosensory perception (i.e., taste and smell). In addition, the putative role that chemosensory perception may have on food choices and eating behavior of children and adolescents affected by these diseases are highlighted. Furthermore, the review addresses the unexplored issues that need to be investigated in this area. The literature data search suggested that no clear relation between taste and smell perception and the aforementioned diseases in young population yet exists. However, some possible trends have been highlighted in the adult population, in whom the duration of disease might have affected the relation. There is a need for further, high-quality, hypothesis-led research, with robust measures of taste and smell functions as the primary outcomes, to strengthen or deny this evidence.

Taste dysfunction in children - a clinical perspective and review of assessment methods

Taste dysfunction has been associated with aging and is therefore thought to be less common in children. However, children can face medical conditions influencing their taste function. Measuring and understanding taste dysfunction in children may foster the development of treatments/interventions mitigating the detrimental effects of taste dysfunction on children's appetite and quality of life. But measuring loss of taste function requires adequate tools. This review was conducted to (1) provide an overview of etiologies (i.e., disease and iatrogenic) associated with taste dysfunction in a pediatric population; (2) to investigate which tools (psychophysical tests and questionnaires) are available to assess taste function in children; and (3) to identify what tools can be and are actually used in clinical practice. It is concluded that only a minority of available tools to assess taste function in children are readily suitable for a pediatric clinical setting. Considering the profound impact of taste dysfunction in the pediatric setting, developing and implementing a standard taste test that is sensitive, simple, and practical to use with children is pertinent.