The relationship of autistic traits to taste and olfactory processing in anorexia nervosa

Inflammation and olfactory loss are associated with at least 139 medical conditions

Olfactory loss accompanies at least 139 neurological, somatic, and congenital/hereditary conditions. This observation leads to the question of whether these associations are correlations or whether they are ever causal. Temporal precedence and prospective predictive power suggest that olfactory loss is causally implicated in many medical conditions. The causal relationship between olfaction with memory dysfunction deserves particular attention because this sensory system has the only direct projection to memory centers. Mechanisms that may underlie the connections between medical conditions and olfactory loss include inflammation as well as neuroanatomical and environmental factors, and all 139 of the medical conditions listed here are also associated with inflammation. Olfactory enrichment shows efficacy for both prevention and treatment, potentially mediated by decreasing inflammation.

Bringing the autistic lifeworld to supportive technology design: an enactive approach

Supportive technologies for autistic individuals are promising in principle, yet their uptake remains limited. Critics argue that in current designs of supportive technologies, autism is mostly framed as a 'disorder' whose limitations can be pragmatically compensated for. To increase uptake, designers should get a better handle on how to incorporate the full richness of the autistic experience into the design process. This paper presents an integrative framework of the autistic lifeworld, called Autistic Lifeworld Design (hereafter: ALD). ALD evolved in a transdisciplinary research setting, substantiated by 11 design case studies with autistic young adults as well as theoretical inquiries into enactivism, design and autism. It consists of four dimensions of experience - sensory, habitual, social, and affective -, each providing specific pointers on how to better understand how autistic people experience the world and how supportive technologies may complement that experience. By adopting an enactive approach, ALD enables a reframing of supportive technology as helping to sustain different levels of homoeostasis. It offers a novel lens that allows designers to put the lived experiences of autistic individuals at the centre of the design process, with special attention to the role of bodily structures and processing in shaping these experiences.

Olfactory loss is a predisposing factor for depression, while olfactory enrichment is an effective treatment for depression

The loss of olfactory stimulation correlates well with at least 68 widely differing neurological disorders, including depression, and we raise the possibility that this relationship may be causal. That is, it seems possible that olfactory loss makes the brain vulnerable to expressing the symptoms of these neurological disorders, while daily olfactory enrichment may decrease the risk of expressing these symptoms. This situation resembles the cognitive reserve that is thought to protect people with Alzheimer’s neuropathology from expressing the functional deficit in memory through the cumulative effect of intellectual stimulation. These relationships also resemble the functional response of animal models of human neurological disorders to environmental enrichment, wherein the animals continue to have the induced neuropathology, but do not express the symptoms as they do in a standard environment with restricted sensorimotor stimulation.

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.

Olfactory capacity in anorexia nervosa: correlations with set-shifting ability

PURPOSE

The purpose of this study is to examine olfactory capacity in adults with anorexia nervosa (AN), in terms of odor identification and odor threshold and search for possible correlations between odor identification and cognitive flexibility in this population.

METHODS

Thirty-nine patients diagnosed with AN and 60 healthy participants, participated. Odor identification was assessed using the University Pennsylvania Smell Identification Test and a two alternative forced choice, ascending method with n-butanol was used to assess odor threshold. Cognitive flexibility was determined using the Intra/Extra-Dimensional Set-Shift test (IED), a subtest of the Cambridge Neuropsychological Test Automated Battery (CANTAB).

RESULTS

Patients with AN presented a poorer performance in odor identification compared with controls (p = 0.001). No differences were found in odor threshold, between the two groups. Patients with AN exhibited poor cognitive flexibility compared with controls (p = 0.003). A significant correlation between odor identification and cognitive flexibility was documented in AN (p = 0.01), but not in controls.

CONCLUSION

Our findings suggest that olfactory capacity is altered in AN: Qualitative characteristics of olfaction were affected in patients with AN (lower odor identification), while there was no difference in quantitative characteristics (odor threshold) compared with controls. Furthermore, odor identification in AN was correlated to cognitive flexibility.

LEVEL OF EVIDENCE

Level III: case-control analytic study.

Sweet, Salty, and Umami Taste Sensitivity and the Hedonic Perception of Taste Sensations in Adolescent Females with Anorexia Nervosa

OBJECTIVE

The aim of this study was to perform analysis of sensitivity to sweet, salty, and umami tastes based on three measurement methods and of the hedonic perception of taste sensations in adolescent females with anorexia nervosa (AN). The aim of the research was to confirm the results of other authors in terms of the perception of sweet and salty taste in patients with AN, and then develop knowledge about the perception of umami taste, which is still insufficiently studied.

METHOD

A total of 110 females with an age ranging from 13 to 19 years, including 50 newly diagnosed patients with a restrictive subtype of AN and 60 healthy controls participated in gustatory research involving analyses of taste perception (recognition thresholds, ability to identify the taste correctly, taste intensity, and hedonic response) applying the sip and spit method.

RESULTS

Females with AN showed reduced sensitivity to salty taste and increased sensitivity to umami taste and, more often than healthy controls, wrongly classified the taste of solutions with a low sucrose concentration. Patients with AN assessed the sodium chloride and monosodium glutamate tastes less negatively than did control participants, and they did not show differences in their hedonic assessment of sucrose.

CONCLUSIONS

The taste sensitivity alterations in females with AN demonstrated in this paper do not entail decreased hedonic assessment of taste experiences. Based on our results, we cannot consider the observed variation in taste sensitivity in patients with AN to be a factor that increases their negative attitude toward food consumption.

Atypical Sensory Processing Is Associated With Lower Body Mass Index and Increased Eating Disturbance in Individuals With Anorexia Nervosa

BACKGROUND

Elevated autism spectrum disorder (ASD) traits are associated with anorexia nervosa (AN). Conversely, eating disturbances, which are core characteristics of AN, are common in ASD. Among individuals with ASD, atypical sensory processing is associated with eating disturbance. Because AN and ASD appear to overlap, it would be crucial to understand whether sensory processing atypicality exist also in AN. Further, it would be essential to find if atypical sensory processing is associated with eating disturbances in individuals with AN, since treatment modifications may be needed. We therefore aimed to examine whether atypical sensory processing is associated with AN and its core characteristics.

METHODS

Participants of the current study included 42 individuals with AN and 40 healthy controls (HCs). All participants were adult women. Sensory processing, other ASD traits, and eating disorder symptoms were assessed with self-report questionnaires.

RESULTS

Individuals with AN reported lower registration, decreased sensation seeking, increased sensory sensitivity, and increased sensation avoiding compared to HCs. When analyzing groups with restrictive AN (AN-R) and binge-purge type AN (AN-BP) separately, only individuals with AN-R exhibited decreased sensation seeking, and only those with AN-BP exhibited lower registration. After controlling for body mass index as a covariate, group differences remained significant only in sensory sensitivity between individuals with AN and HCs. Increased atypical sensory processing predicted lower body mass index and increased disordered eating.

CONCLUSION

Results suggest that sensory processing appears to differ between AN and HC women, and AN subtypes may exhibit distinct sensory processing atypicality. Sensory sensitivity may be stable traits whereas other aspects of atypical sensory processing may be related to acute AN. Atypical sensory processing may contribute to the severity of AN, and thus it is crucial to recognize sensory processing differences when treating individuals with AN.

Subjective Taste and Smell Changes in Conjunction with Anxiety and Depression Are Associated with Symptoms in Patients with Functional Constipation and Irritable Bowel Syndrome

BACKGROUND

Patients with functional constipation (FC) and irritable bowel syndrome (IBS) often report psychological abnormalities and decreased eating enjoyment. Several patients also complain of changes in the sense of smell and taste, but these are often disregarded clinically.

AIMS

Therefore, there is a need to determine whether taste/smell disturbances and psychological abnormalities are present in patients with FC or IBS and whether these are related to the severity of lower gastrointestinal symptoms.

METHODS

A total of 337 subjects were recruited, including FC (n = 115), IBS (n = 126), and healthy controls (n = 96). All participants completed questionnaires evaluating taste and smell (taste and smell survey (TSS)), Lower Gastrointestinal Symptoms Rating Scale (LGSRS), Hamilton anxiety scale (HAMA), and Hamilton depression scale (HAMD). TSS recorded information on the nature of taste and smell changes (TSCs) and the impact of these changes on the quality of life. LGSRS was used to assess the severity of lower gastrointestinal symptoms; HAMA and HAMD scales were used to reflect the psychosocial state. This study protocol was registered on the Chinese Clinical Trial Registry (No. ChiCTR-2100044643).

RESULTS

Firstly, we found that taste and smell scores were higher in patients with IBS than in healthy controls. Secondly, for FC and IBS patients, LGSRS was significantly correlated with the taste score (Spearman's rho = 0.832, P < 0.001). LGSRS was also significantly correlated with HAMA (Spearman's rho = 0.357, P = 0.017) and HAMD (Spearman's rho = 0.377, P = 0.012). In addition, the taste score was significantly correlated with HAMD (Spearman's rho = 0.479, P = 0.001), while the smell score was also significantly correlated with HAMD (Spearman's rho = 0.325, P = 0.031). Thirdly, 60.87% and 71.43% of patients complained of taste abnormality, while 65.22% and 71.43% had smell abnormality in the FC and IBS groups, respectively. Meanwhile, 47.83% and 47.62% of patients suffered from anxiety, while 43.48% and 57.14% suffered from depression in the FC and IBS groups, respectively. Finally, we found significant differences in the taste, smell, HAMD, and LGSRS scores between the female and male IBS groups (P < 0.050).

CONCLUSIONS

TSCs and psychological disorders are prominent in FC and IBS patients. Taste abnormalities, as well as anxiety and depression, are significantly correlated with LGSRS. Awareness of this high prevalence of taste/smell abnormalities and the psychological changes among patients with FC and IBS may help better predict and understand the severity of symptoms.