A Quantitative Sensory Testing Approach to Pain in Autism Spectrum Disorders

Pain perception in autism. A study of sensory reactivity in children and adolescents with autism using quantitative sensory testing and psychophysiological correlates

Background

Hyper- or hypo-reactivity to sensory input is a diagnostic criterion for autism spectrum disorder; however, it is still not fully characterized, despite its relevance to patients' quality of life. When considering neurodevelopment, sensory reactivity in autism is often assessed through parental reports, with only a few pieces of evidence acquired using standardized protocols. Quantitative sensory testing (QST) is a standardized protocol used to quantify sensory function by assessing perceptive and pain thresholds with calibrated sensory stimuli. To date, only a few studies have used QST to investigate sensory reactivity in autism, with only one taking into account adolescents and none including children in the sample.

Methods

We aimed to study pain perception and in children diagnosed with autism using the QST protocol. Moreover, we sought to measure central reactivity to painful stimuli by recording electroencephalographic (EEG) responses to painful thermal stimuli to explore the relationship between subjective reactivity (i.e., reactions to sensory stimuli) and central processing of sensory stimuli (i.e., EEG responses). Finally, we aimed to explore the relationship between parents' reports, subjective reports, and EEG responses.

Discussion

This study will help to expand our previous knowledge concerning the sensory profile of children and adolescents with autism. Deepening our understanding of the relationship between perceptive thresholds in children with autism and the reactivity of the central nervous system, could help us understand the causal mechanism of the perceptual differences observed in autism.

Study protocol identifier

NCT06659731.

Modifying quantitative sensory testing to investigate tactile sensory function and behavioral reactivity in children with intellectual and developmental disabilities: establishing feasibility and testing sex, autism, and self-injury effects

BACKGROUND

Sensory reactivity differences are common across neurodevelopmental disorders (NDDs), however very few studies specifically examine tactile or pain responses in children with NNDs, especially those with communication challenges. The current study aimed to (a) replicate the feasibility of a modified quantitative sensory test (mQST) with a sample of children with NDDs, (b) assess validity evidence based on behavioral reactivity during mQST application and the corresponding behavioral measurement coding system, and (c) explore group differences in behavioral reactivity to mQST stimuli by demographic (sex), clinical (autism status), and behavioral pathology (self-injury) variables.

METHODS

The mQST protocol was implemented and blindly coded across 47 participants aged 2-12 years (M age = 6.7 years, SD = 2.6; 70% male) with NDDs. Feasibility was measured by completion of the mQST protocol and interobserver agreement. Validity was assessed using paired t-tests investigating differences between behavioral reactivity to active stimuli compared to a sham trial. Boxplots were used to visually explore differences in group characteristics (sex, autism status, and self-injurious behavior), with two-sample t-tests used to further characterize differences in SIB group characteristics in behavioral reactivity to mQST stimuli.

RESULTS

The mQST provided codable data across 91% of stimuli applications with high IOA (84.7% [76.7-95%]). Behavioral reactivity was significantly higher for active vs. sham stimuli. Children reported to engage in self-injurious behavior showed significantly more reactivity to the second half of the repeated von Frey stimulus application compared to children without caregiver-reported self-injurious behavior (M = 6.14, SD = 3.44), t (40)= -2.247, p =.04).

CONCLUSION

The mQST is a feasible approach to investigate tactile reactivity in children with NDDs and complex communication needs. The mQST may be useful in understanding sensory variables in relation to developmental and behavioral outcomes such as self-injurious behavior.

[Pain assessment for children and adolescents with autism spectrum disorders (ASD): A systematic review]

OBJECTIVE

Pain in children and adolescents with autism spectrum disorders remains underdiagnosed due to their inherent communication difficulties. The goal of this review is to identify the most suitable methods for assessing pain in this population and for evaluating the specific perceptions of, or behavioural reactions to, pain whilst considering disorder severity and specifiers (with or without accompanying intellectual impairment, with or without accompanying language impairment).

METHOD

A systematic review and analysis of the international literature was conducted.

RESULTS

Fourteen studies were selected. No difference was found in pain-related behaviours based on the age or gender of children or adolescents with autism. Three studies showed pain-related behaviours in autism spectrum disorders to be similar to control groups. Other studies showed specific behavioural responses in autism spectrum disorders with a longer physiological and behavioural recovery time associated with an episode of acute pain in this population. Similarly, the three studies that focused on sensory perceptions of pain all showed differences in the autism spectrum disorders population compared to control groups. In hospital or daily life contexts, studies essentially showed idiosyncratic expressions, hypervigilance, motor agitation, negative emotional reactions, or vocalizations. Regarding the association of autism severity with hyposensitivity to pain, the results remain unclear even when language disorders or intellectual disabilities are also present (in conjunction with autism). The Non-Communicative Children Pain Checklist and its translation into French and Italian showed good internal validity and was used by almost half of the studies in hetero-assessment, mostly by parents. Studies recommend the inclusion of parents in the assessment in order to optimise the evaluation process. Similarly, analysis of parent/child/caregiver interviews from the studies highlights the importance of personalizing pain assessment of children and adolescents, taking into account subject-specific characteristics, pathology, and context.

CONCLUSION

An integrative and personalized approach to pain assessment appears to be the most appropriate for enhancing the understanding and detection of pain in individuals with autism spectrum disorders. This approach aligns well with a care setting where a nominated professional with a good expertise in autism is responsible for pain assessment. Given the complexity of identifying pain in individuals with autism, further qualitative studies, in conjunction with new pain exploration technologies, are considered necessary as well as a more extensive categorization of the population studies.

Involvement of sphingosine-1-phosphate receptor 1 in pain insensitivity in a BTBR mouse model of autism spectrum disorder

BACKGROUND

Abnormal sensory perception, particularly pain insensitivity (PAI), is a typical symptom of autism spectrum disorder (ASD). Despite the role of myelin metabolism in the regulation of pain perception, the mechanisms underlying ASD-related PAI remain unclear.

METHODS

The pain-associated gene sphingosine-1-phosphate receptor 1 (S1PR1) was identified in ASD samples through bioinformatics analysis. Its expression in the dorsal root ganglion (DRG) tissues of BTBR ASD model mice was validated using RNA-seq, western blot, RT-qPCR, and immunofluorescence. Pain thresholds were assessed using the von Frey and Hargreaves tests. Patch-clamp techniques measured KCNQ/M channel activity and neuronal action potentials. The expression of S1PR1, KCNQ/M, mitogen-activated protein kinase (MAPK), and cyclic AMP/protein kinase A (cAMP/PKA) signaling proteins was analyzed before and after inhibiting the S1P-S1PR1-KCNQ/M pathway via western blot and RT-qPCR.

RESULTS

Through integrated transcriptomic analysis of ASD samples, we identified the upregulated gene S1PR1, which is associated with sphingolipid metabolism and linked to pain perception, and confirmed its role in the BTBR mouse model of ASD. This mechanism involves the regulation of KCNQ/M channels in DRG neurons. The enhanced activity of KCNQ/M channels and the decreased action potentials in small and medium DRG neurons were correlated with PAI in a BTBR mouse model of ASD. Inhibition of the S1P/S1PR1 pathway rescued baseline insensitivity to pain by suppressing KCNQ/M channels in DRG neurons, mediated through the MAPK and cAMP/PKA pathways. Investigating the modulation and underlying mechanisms of the non-opioid pathway involving S1PR1 will provide new insights into clinical targeted interventions for PAI in ASD.

CONCLUSIONS

S1PR1 may contribute to PAI in the PNS in ASD. The mechanism involves KCNQ/M channels and the MAPK and cAMP/PKA signaling pathways. Targeting S1PR1 in the PNS could offer novel therapeutic strategies for the intervention of pain dysesthesias in individuals with ASD.

Social Determinants and Consequences of Pain: Toward Multilevel, Intersectional, and Life Course Perspectives

Despite wide endorsement of a biopsychosocial framework for pain, social aspects of pain remain rarely addressed in the context of pain prevention and management. In this review, we aim to 1) examine the broad scope of social determinants and consequences of pain and their interactions across multiple levels of organization, and 2) provide a framework synthesizing existing concepts and potential areas for future work on social aspects of pain, drawing upon socioecological, intersectional, and life course approaches. Integrating interdisciplinary theory and evidence, we outline pathways through which multilevel social factors and pain may affect each other over time. We also provide a brief summary of intrapersonal aspects of pain, which are thought to operate at the interface between individuals and the social context. Progressing from micro- to macrolevel factors, we illustrate how social determinants of pain can directly or indirectly contribute to pain experiences, expression, risk, prognosis, and impact across populations. We consider 1) at the interpersonal level, the roles of social comparison, social relatedness, social support, social exclusion, empathy, and interpersonal conflict; 2) at the group or community level, the roles of intimacy groups, task groups, social categories, and loose associations; and 3) at the societal level, the roles of political, economic, and cultural systems, as well as their policies and practices. We present examples of multilevel consequences of pain across these levels and discuss opportunities to reduce the burden and inequities of pain by expanding multilevel social approaches in pain research and practice. PERSPECTIVE: Despite wide endorsement of a biopsychosocial framework for pain, social aspects of pain are often unclearly defined, hindering their use in pain prevention, management, and research. We summarize the scope of social aspects of pain and provide a framework synthesizing existing concepts and potential areas for future work.

Understanding the impacts of chronic pain on autistic adolescents and effective pain management: a reflexive thematic analysis adolescent-maternal dyadic study

OBJECTIVE

Sensory elements are core features in chronic pain and autism, yet knowledge of the pain experience in autistic adolescents is limited. Little is known regarding how autistic adolescents experience chronic pain, manage their pain and perceive psychological treatment for their chronic pain.

METHODS

Ten autistic adolescents (6 female, 3 male, and 1 self-identified as agender) with chronic pain and their mothers (n = 10) participated in semistructured interviews concerning their perceptions of living with chronic pain. Participants were recruited from U.K. pain management services. According to preference, interviews were conducted individually (n = 10) or dyadically (n = 10 participants across 5 dyads). Data were analyzed using inductive reflexive thematic analysis.

RESULTS

Two themes were generated. Theme 1, "overstimulated and striving for control" described how adolescents' experience of heightened sensitivity enhanced adolescents' levels of anxiety and subsequent pain, illustrating a reciprocal relationship between anxiety, pain, and sensory elements. Theme 2, "not everyone fits the mold" captured how autistic adolescents positioned themselves as distinct from others due to the unique nature of being autistic and living with pain. This sense of difference negatively impacted adolescents' ability to engage with and benefit from the standard treatment for chronic pain.

CONCLUSIONS

Findings suggest that autistic adolescents living with pain experience pain and face barriers to effective pain treatment. Our results identify the need for educational resources to facilitate clinicians to better understand the experience of autistic adolescents living with pain. In turn, such understanding may improve treatment and outcomes in this population.

Mechanisms of pain in aging and age-related conditions: Focus on caregivers

Pain is a complex, subjective experience that can significantly impact quality of life, particularly in aging individuals, by adversely affecting physical and emotional well-being. Whereas acute pain usually serves a protective function, chronic pain is a persistent pathological condition that contributes to functional deficits, cognitive decline, and emotional disturbances in the elderly. Despite substantial progress that has been made in characterizing age-related changes in pain, complete mechanistic details of pain processing mechanisms in the aging patient remain unknown. Pain is particularly under-recognized and under-managed in the elderly, especially among patients with Alzheimer's disease (AD), Alzheimer's disease-related dementias (ADRD), and other age-related conditions. Furthermore, difficulties in assessing pain in patients with AD/ADRD and other age-related conditions may contribute to the familial caregiver burden. The purpose of this article is to discuss the mechanisms and risk factors for chronic pain development and persistence, with a particular focus on age-related changes. Our article also highlights the importance of caregivers working with aging chronic pain patients, and emphasizes the urgent need for increased legislative awareness and improved pain management in these populations to substantially alleviate caregiver burden.

Undiagnosed Autism Spectrum Disorder in a Child With Chronic Pain: A Case Report

The literature acknowledges the presence of psychiatric comorbidities in pediatric chronic pain populations. Few studies have focused on comorbidity with autism spectrum disorders. We describe the case of a 10-year-old patient at the onset of his care by the chronic pain team. This boy had been experiencing refractory multifocal chronic pain for three years and had undergone multiple medical examinations that had not identified the cause of the pain or provided sufficient pain relief. During our consultations, the behavioral peculiarities (averted gaze, inhibition), the atypical description of this boy's pain (pain in the hair), and sensory peculiarities (intolerance to noise) led us to suspect an autism spectrum disorder. A multidisciplinary approach, including a thorough developmental history and evaluation by an autism resource center, confirmed this suspicion. The diagnosis of an underlying autism spectrum disorder allowed us to guide our management by integrating the specific sensory aspects of this boy. Concurrently, we facilitated the family's better understanding of the young boy's issues and addressed his social and communication difficulties. Through multidisciplinary care and the integration of these various aspects, our patient's clinical situation improved. Multidisciplinary management is essential in chronic pain teams.

Pain assessment in autism: updating the ethical and methodological challenges through a state-of-the-art review

Sensory features of autism include hypo- or hyper-reactivity to pain; however, previous studies on pain in autism lead to conflicting results. Here, we present the state of the art and the methodological challenges concerning pain perception in autism, focusing on studies that used standardized protocol as Quantitative Sensory Testing (QST) to measure perception. Despite there are still scant evidences found with the use of QST, they have challenged the presumed hyposensitivity to pain in autisms, which emerged from parents' reports. Both, peripheral and central mechanisms, have been found involved in typical features of perception in autism. Nonetheless, evidences with controlled protocols are still scarce, and even scarcer are studies focused on children. Overall, complex ethical challenges have to be overcome in order to collect subjective and objective measures from autistic children. With heterogeneous neurodevelopmental features, or intellectual disability, novel or modified protocols are needed.

Headache in Individuals with Neurodevelopmental Disorders

PURPOSE OF REVIEW

Migraine is a common condition affecting an estimated billion people across the world. The incidence in individuals with neurodevelopmental disorders or intellectual disabilities like those seen in severe autism spectrum disorder (ASD) is unknown. This is likely due to the limited capacity to communicate the specifics of pain. The expression of pain with maladaptive behaviors, such as self-injurious behavior (SIB), has been described and can alert the clinician to the presence of untreated pain. This review article serves to educate the reader about clinical and treatment considerations when managing headaches in individuals with severe or non-verbal neurodevelopmental disorders given their communication challenges. It will include some clinical experiences and the gaps in our current knowledge.

RECENT FINDINGS

A comprehensive literature review was conducted using scientific databases, including PubMed, Medline, and Google Scholar. Only 1 article addressed the consideration for headaches in this population. The search was conducted using a combination of the following keywords: headache, intellectual disabilities, autism, pain, and behavior. Headache pain is likely underestimated and represents a disservice to this population of people. The consideration for headache pain should be explored when maladaptive behaviors are otherwise unexplainable. Further studies are needed in the area.

Maternal autistic traits and antenatal pain by cross-sectional analysis of the Japan Environment and Children's Study

The aim of cross-sectional study was to investigate whether the presence of autistic traits in pregnant women was positively associated with the prevalence and severity of antenatal pain. We analyzed 89,068 pregnant women from a Japanese national birth cohort cross-sectionally. Autistic traits were assessed using the Japanese version of the Autism-Spectrum Quotient short form (AQ-10-J). Antenatal pain was measured using the SF-8 bodily pain item (SF-8-Pain). Antenatal pain in the second to third trimester during pregnancy was categorized into three groups: without pain, mild pain, and moderate-to-severe pain. Participants were divided into eight groups by AQ-10-J score: seven consecutive scoring groups (scores 0-6), and those above the cut-off (≥ 7) for probable autistic spectrum disorders. Odds ratios (OR) for the prevalence of mild and moderate-to-severe pain were calculated for each AQ-10-J scoring group (reference: without pain group) using multinominal logistic regression analysis. Autistic traits were positively associated with mild and moderate-to-severe pain in a dose-response manner, but the association with moderate-to-severe pain was strongest. Fully-adjusted ORs (95% confidence intervals) for moderate-to-severe pain were: 1.01 (0.91-1.13) for 1 point, 1.13 (1.02-1.25) for 2 points, 1.16 (1.04-1.29) for 3 points, 1.20 (1.07-1.34) for 4 points, 1.23 (1.09-1.40) for 5 points, 1.27 (1.10-1.47) for 6 points, and 1.24 (1.05-1.46) for ≥ 7 points (AQ-10-J cut-off). We identified an association between maternal autistic traits and antenatal pain. Maternal autistic traits may need to be considered when addressing antenatal pain during healthcare for expectant mothers.

Indifference or hypersensitivity? Solving the riddle of the pain profile in individuals with autism

ABSTRACT

Excitatory-inhibitory (E/I) imbalance is a mechanism that underlies autism spectrum disorder, but it is not systematically tested for pain processing. We hypothesized that the pain modulation profile (PMP) in autistic individuals is characterized by less efficient inhibitory processes together with a facilitative state, indicative of a pronociceptive PMP. Fifty-two adults diagnosed with autism and 52 healthy subjects, age matched and sex matched, underwent quantitative sensory testing to assess the function of the (1) pain facilitatory responses to phasic, repetitive, and tonic heat pain stimuli and (2) pain inhibitory processes of habituation and conditioned pain modulation. Anxiety, pain catastrophizing, sensory, and pain sensitivity were self-reported. The autistic group reported significantly higher pain ratings of suprathreshold single ( P = 0.001), repetitive (46°C- P = 0.018; 49°C- P = 0.003; 52°C- P < 0.001), and tonic ( P = 0.013) heat stimuli that were cross correlated ( r = 0.48-0.83; P < 0.001) and associated with sensitivity to daily life pain situations ( r = 0.39-0.45; P < 0.005) but not with psychological distress levels. Hypersensitivity to experimental pain was attributed to greater autism severity and sensory hypersensitivity to daily stimuli. Subjects with autism efficiently inhibited phasic but not tonic heat stimuli during conditioned pain modulation. In conclusion, in line with the E/I imbalance mechanism, autism is associated with a pronociceptive PMP expressed by hypersensitivity to daily stimuli and experimental pain and less-efficient inhibition of tonic pain. The latter is an experimental pain model resembling clinical pain. These results challenge the widely held belief that individuals with autism are indifferent to pain and should raise caregivers' awareness of pain sensitivity in autism.

Qualitative and quantitative analysis of self-reported sensory issues in individuals with neurodevelopmental disorders

INTRODUCTION

Individuals with neurodevelopmental disorders, such as autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and specific learning disorders (SLD) have various types of sensory characteristics.

METHODS

This study investigated sensory issues in individuals with neurodevelopmental disorders using a web-based questionnaire for qualitative and quantitative analysis, categorized the contents of their three most distressful sensory issues, and evaluated their order of priority.

RESULTS

Auditory problems were reported as the most distressing sensory issue among the participants. In addition to auditory problems, individuals with ASD frequently reported more tactile problems, and individuals with SLD reported more visual problems. Among the individual sensory issues, in addition to aversion to sudden, strong, or specific stimuli, some participants reported confusions regarding multiple stimuli presenting concurrently. Additionally, the sensory issues related to foods (i.e., taste) was relatively more common in the minor group.

CONCLUSION

These results suggest that the diversity of sensory issues experienced should be carefully considered when aiding persons with neurodevelopmental disorders.

Physiological effects of Therapeutic Body Wraps in healthy volunteers: An observational study

INTRODUCTION

The clinical management of severe anxiety is challenging. Along with specific medication, several nonpharmacological treatments exist, among which the Therapeutic Body Wraps (TBW). While TBW is clinically known to be efficient, the absence of objective physiological measurements raised some debates about its harmlessness.

AIMS

This observational study investigated TBW in healthy volunteers.

METHODS

Measurements were done in 26 participants, who experienced TBW, which consisted of tightly wrapping the body in one layer of wet cold sheets and several warm blankets. These were compared to 13 participants, who rested in supine position.

RESULTS

Our results showed increase in the trunk skin temperature by the end of TBW similar to rest. Somatosensory perception as assessed with quantitative sensory testing was stable after both TBW and rest. The heart and breath rates decreased both during TBW and rest. It was accompanied by increase in heart rate variability parameters and decrease in salivary cortisol levels.

DISCUSSION

Our data indicate anxiolytic effect of TBW in healthy participants.

IMPLICATIONS FOR PRACTICE

The TBW is harmless and might be used in patients, who are unable to relax by themselves and/or without anxiolytic medication. Further studies are necessary to investigate physiological response to TBW in clinical population.

The Current View on the Paradox of Pain in Autism Spectrum Disorders

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, which affects 1 in 44 children and may cause severe disabilities. Besides socio-communicational difficulties and repetitive behaviors, ASD also presents as atypical sensorimotor function and pain reactivity. While chronic pain is a frequent co-morbidity in autism, pain management in this population is often insufficient because of difficulties in pain evaluation, worsening their prognosis and perhaps driving higher mortality rates. Previous observations have tended to oversimplify the experience of pain in autism as being insensitive to painful stimuli. Various findings in the past 15 years have challenged and complicated this dogma. However, a relatively small number of studies investigates the physiological correlates of pain reactivity in ASD. We explore the possibility that atypical pain perception in people with ASD is mediated by alterations in pain perception, transmission, expression and modulation, and through interactions between these processes. These complex interactions may account for the great variability and sometimes contradictory findings from the studies. A growing body of evidence is challenging the idea of alterations in pain processing in ASD due to a single factor, and calls for an integrative view. We propose a model of the pain cycle that includes the interplay between the molecular and neurophysiological pathways of pain processing and it conscious appraisal that may interfere with pain reactivity and coping in autism. The role of social factors in pain-induced response is also discussed. Pain assessment in clinical care is mostly based on subjective rather than objective measures. This review clarifies the strong need for a consistent methodology, and describes innovative tools to cope with the heterogeneity of pain expression in ASD, enabling individualized assessment. Multiple measures, including self-reporting, informant reporting, clinician-assessed, and purely physiological metrics may provide more consistent results. An integrative view on the regulation of the pain cycle offers a more robust framework to characterize the experience of pain in autism.

"When I'm in Pain, Everything Is Overwhelming": Implications of Pain in Adults With Autism on Their Daily Living and Participation

Pain sensation in autism spectrum disorder (ASD) has been a growing research field in the last two decades. Existing pain research has focused on pain sensitivity, suggesting either hyposensitivity or hypersensitivity to pain in individuals with ASD. However, research about other aspects of pain experience is scarce. Moreover, most pain-related research in ASD focused on quantitative measures, such as neuroimaging or parental reports. Instead, this paper aimed to illuminate the various aspects of pain experience as perceived by adults with ASD. Its descriptive qualitative research design incorporated semi-structured interviews and deductive thematic analysis. This phenomenological approach captured the subjective pain experience through the lens of people with ASD. Four primary themes emerged from the data: (a) physical pain experience, including the sequence of pain sensitivity, pain awareness, pain-related emotional aspects, and pain communication; (b) direct and indirect coping strategies; (c) function and participation outcomes; and (d) suggestions for Healthcare Providers. The findings echo the crucial role of pain awareness and communication in the pain experience of people with ASD. These two factors have been reported as profoundly influencing coping strategies, function, and participation. The results emphasize the need to expand the exploration of pain in this population, calling for greater understanding, and listening to this population's unique pain profiles and experiences to promote better-suited evaluation, diagnosis, and intervention in pain conditions.

Autistic Traits and Empathy for Others' Pain Among the General Population: Test of the Mediating Effects of First-Hand Pain Sensitivity

Autism spectrum disorders (ASD) are characterized by reduced pain empathy-a process that is grounded in first-hand pain perception. Because autistic traits are continuously distributed in the general population, we hypothesized that first-hand pain sensitivity would mediate the link between autistic traits and pain empathy. After controlling for alexithymia, higher autistic traits were associated with lower cognitive and emotional empathy in response to others' pain, as well as lower sensitivity to cold and heat pain (higher cold pain tolerance and lower laser heat pain-intensity ratings). Importantly, pain sensitivity fully mediated the link between autistic traits and pain empathy. These findings highlight the role of atypical first-hand pain sensitivity in the lack of pain empathy observed in people with high autistic traits or ASD.

Autism and chronic ill health: an observational study of symptoms and diagnoses of central sensitivity syndromes in autistic adults

BACKGROUND

Autistic adults, particularly women, are more likely to experience chronic ill health than the general population. Central sensitivity syndromes (CSS) are a group of related conditions that are thought to include an underlying sensitisation of the central nervous system; heightened sensory sensitivity is a common feature. Anecdotal evidence suggests autistic adults may be more prone to developing a CSS. This study aimed to investigate the occurrence of CSS diagnoses and symptoms in autistic adults, and to explore whether CSS symptoms were related to autistic traits, mental health, sensory sensitivity, or gender.

METHODS

The full sample of participants included 973 autistic adults (410 men, 563 women, mean age = 44.6) registered at the Netherlands Autism Register, who completed questionnaires assessing autistic traits, sensory sensitivity, CSS, physical and mental health symptoms. The reliability and validity of the Central Sensitization Inventory (CSI) in an autistic sample was established using exploratory and confirmatory factor analyses. Chi2 analyses, independent t-tests, hierarchical regression and path analysis were used to analyse relationships between CSS symptoms, autistic traits, measures of mental health and wellbeing, sensory sensitivity, age and gender.

RESULTS

21% of participants reported one or more CSS diagnosis, and 60% scored at or above the clinical cut-off for a CSS. Autistic women were more likely to report a CSS diagnosis and experienced more CSS symptoms than men. Sensory sensitivity, anxiety, age and gender were significant predictors of CSS symptoms, with sensory sensitivity and anxiety fully mediating the relationship between autistic traits and CSS symptoms.

LIMITATIONS

Although this study included a large sample of autistic adults, we did not have a control group or a CSS only group. We also could not include a non-binary group due to lack of statistical power.

CONCLUSIONS

CSS diagnoses and symptoms appear to be very common in the autistic population. Increased awareness of an association between autism and central sensitisation should inform clinicians and guide diagnostic practice, particularly for women where CSS are common and autism under recognised.

Autism and Emotion: A Narrative Review

Autism spectrum disorder (ASD) includes a variety of childhood-onset and lifelong neurodevelopmental condition with an enduring impact on multiple domains of functioning characterized by persistent deficits in social communication, restricted and repetitive behavior interest, and activities. They often find it hard to recognize and control emotions but their emotional expression can be improved by various intervention techniques that in turn can help them understand and respond more appropriately to other people. Problems in the area on emotional reciprocity among individual with ASD involve recognizing, understanding, expressing, and regulating emotions. Their ability in emotional reciprocity is often improved with a comprehensive treatment approach, especially by focused emotional enhancement intervention. In this review, we followed the standard IMRAD (Introduction, Methods, Results, and Discussion) structure to critically examine the condition of autism and its relation with genetic mechanism, and how theories of emotion and theory of mind associated with persons with ASD, some of the widely used assessment tools and future research direction in the emotional development of individuals diagnosed with ASD by using the narrative review method. Records collected through research databases such as Scopus, PubMed, Web of Science, Medline, EBSCO and published books with ISBN (International Standard Book Number), and published test manuals were evaluated in-depth and summarized based on the subtopic of the proposed title. A critical theoretical analysis of the genetic mechanism of emotions, theories of emotions, and theory of mind was explained in connection with ASD.

Microbiome-Specific Statistical Modeling Identifies Interplay Between Gastrointestinal Microbiome and Neurobehavioral Outcomes in Patients With Autism: A Case Control Study

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with unclear mechanisms of pathogenesis. Gastrointestinal microbiome alterations were found to correlate with ASD core symptoms, but its specific role in ASD pathogenesis has not been determined. In this study, we used a case-control strategy that simultaneously compared the ASD gastrointestinal microbiome with that from age-sex matched controls and first-degree relative controls, using a statistical framework accounting for confounders such as age. Enterobacteriaceae (including Escherichia/Shigella) and Phyllobacterium were significantly enriched in the ASD group, with their relative abundances all following a pattern of ASD > first degree relative control > healthy control, consistent with our hypothesis of living environment and shared microbial and immunological exposures as key drivers of ASD gastrointestinal microbiome dysbiosis. Using multivariable omnibus testing, we identified clinical factors including ADOS scores, dietary habits, and gastrointestinal symptoms that covary with overall microbiome structure within the ASD cohort. A microbiome-specific multivariate modeling approach (MaAsLin2) demonstrated microbial taxa, such as Lachnoclostridium and Tyzzerella, are significantly associated with ASD core symptoms measured by ADOS. Finally, we identified alterations in predicted biological functions, including tryptophan and tyrosine biosynthesis/metabolism potentially relevant to the pathophysiology of the gut-brain-axis. Overall, our results identified gastrointestinal microbiome signature changes in patients with ASD, highlighted associations between gastrointestinal microbiome and clinical characteristics related to the gut-brain axis and identified contributors to the heterogeneity of gastrointestinal microbiome within the ASD population.

A Digital Fabrication of Dental Prosthesis for Preventing Self-Injurious Behavior Related to Autism Spectrum Disorder: A Case Report

This case report aimed to demonstrate the prosthetic solution of an autism patient with self-injurious behavior using digital dentistry. A 24-year-old male visited our clinic with chief complaints of severe gingival recession associated with self-injurious behavior. Bilateral fixed prosthesis with denture flange were delivered using a digital workflow for the protection of the gingiva. The patient showed healed gingival tissue, behavioral modification, and acceptable oral hygiene during the follow-up period. Also, his caregivers reported no recurrence of the self-injurious behavior. Autism patients usually show self-injurious behavior, which can damage their oral tissue. With adoption of this prosthesis, behavior modification as well as healing of oral tissue was achieved.

[Nociception pain and autism]

Autistic subjects frequently display sensory anomalies. Those regarding nociception and its potential outcome, pain, are of crucial interest. Indeed, because of numerous comorbidities, autistic subjects are more often exposed to painful situation. Despite being often considered as less sensitive, experimental studies evaluating this point are failing to reach consensus. Using animal model can help reduce variability and bring, regarding autism, an overview of potential alterations of the nociceptive system at the cellular and molecular level.

Increased pain sensitivity and pain-related anxiety in individuals with autism

INTRODUCTION

Individuals with autism spectrum disorder (ASD) often exhibit differences in pain responsivity. This altered responsivity could be related to ASD-related social communication difficulties, sensory differences, or altered processing of pain stimuli. Previous neuroimaging work suggests altered pain evaluation could contribute to pain-related anxiety in ASD.

OBJECTIVES

We hypothesized that individuals with ASD would report increased pain sensitivity and endorse more pain-related anxiety, compared to typically developing controls.

METHODS

We recruited 43 adults (ASD, n = 24; typically developing, n = 19) for 3 heat pain tasks (applied to the calf). We measured heat pain thresholds using a method of limits approach, a pain-rating curve (7 temperatures between 40 and 48°C, 5 seconds, 5 trials each), and a sustained heat pain task with alternating low (42°C) and high (46°C) temperatures (21 seconds, 6 trials each). Individual differences in pain-related anxiety, fear of pain, situational pain catastrophizing, depressive symptoms, and autism-related social communication were assessed by self-report.

RESULTS

There were no group differences in pain thresholds. For suprathreshold tasks, mean pain ratings were higher in ASD across both the pain-rating curve and the sustained heat pain tasks, but responses in the ASD group were more varied. Pain anxiety (PASS-Total) and pain-related fear (FOP-III-Total) were higher in the ASD group and were positively associated with pain ratings.

CONCLUSIONS

Our results suggest that both sensory and cognitive experiences of pain are heightened and interact reciprocally in adults with ASD. Future studies are needed to evaluate the impact of pain-related anxiety on treatment-seeking and pain behaviors, given higher levels of pain-related anxiety in ASD.

Autism Spectrum Disorders: Multiple Routes to, and Multiple Consequences of, Abnormal Synaptic Function and Connectivity

Autism spectrum disorders (ASDs) are a heterogeneous group of neurodevelopmental disorders of genetic and environmental etiologies. Some ASD cases are syndromic: associated with clinically defined patterns of somatic abnormalities and a neurobehavioral phenotype (e.g., Fragile X syndrome). Many cases, however, are idiopathic or non-syndromic. Such disorders present themselves during the early postnatal period when language, speech, and personality start to develop. ASDs manifest by deficits in social communication and interaction, restricted and repetitive patterns of behavior across multiple contexts, sensory abnormalities across multiple modalities and comorbidities, such as epilepsy among many others. ASDs are disorders of connectivity, as synaptic dysfunction is common to both syndromic and idiopathic forms. While multiple theories have been proposed, particularly in idiopathic ASDs, none address why certain brain areas (e.g., frontotemporal) appear more vulnerable than others or identify factors that may affect phenotypic specificity. In this hypothesis article, we identify possible routes leading to, and the consequences of, altered connectivity and review the evidence of central and peripheral synaptic dysfunction in ASDs. We postulate that phenotypic specificity could arise from aberrant experience-dependent plasticity mechanisms in frontal brain areas and peripheral sensory networks and propose why the vulnerability of these areas could be part of a model to unify preexisting pathophysiological theories.

Elevated Thresholds for Light Touch in Children With Autism Reflect More Conservative Perceptual Decision-Making Rather Than a Sensory Deficit

Individuals with autism spectrum disorder (ASD) are often behaviorally hyper-reactive to light touch, but it is unclear to what degree this arises from a fundamental sensory difference vs. higher order systems for attention or emotion processing. Thus far, experimental findings for light touch detection are mixed, and few previous studies have independently considered sensitivity (the ability to discriminate signal from noise) and decision criterion (the overall response bias or tendency to answer "yes" or "no" in a detection task). We tested a large sample of children, adolescents, and adults with ASD (n = 88) and with neurotypical (NT) development (n = 59) using von Frey filaments to derive light touch thresholds at the palm. We calculated signal detection metrics for sensitivity (Az) and response criterion (c) from hit and false alarm rates. Both metrics exhibited significant group differences, such that the ASD group was less sensitive, but had a much more conservative response criterion. We used a best subset model selection procedure in three separate ordinal regressions for the whole group, adults, and children/adolescents. In all selected models, c was by far the most significant predictor of threshold, supplanting effects of diagnostic group that were significant in the baseline models. In contrast, Az was not a significant predictor of threshold in any of the models. Mean values of c were similar for adults with and without autism and for children/adolescents with ASD, but lower (more liberal) in neurotypical children/adolescents. This suggests that children with ASD exhibit a conservatism in their perceptual decision-making that differs from their NT peers but resembles that of adults. Across the sample, the value of c was significantly and positively correlated with age and with autism symptoms (SRS-2 total score), in addition to thresholds. The results of this study suggest that, rather than a sensory difference in detection of light touch, there is a difference in response bias such that children with ASD are more conservative/likely to report "no" if unsure, than their young NT peers. Future work should consider the implications of conservative response criterion in ASD for commonly used forced-choice psychophysical paradigms.

Thermal Perceptual Thresholds are typical in Autism Spectrum Disorder but Strongly Related to Intra-individual Response Variability

Individuals with autism spectrum disorder (ASD) are often reported to exhibit an apparent indifference to pain or temperature. Leading models suggest that this behavior is the result of elevated perceptual thresholds for thermal stimuli, but data to support these assertions are inconclusive. An alternative proposal suggests that the sensory features of ASD arise from increased intra-individual perceptual variability. In this study, we measured method-of-limits warm and cool detection thresholds in 142 individuals (83 with ASD, 59 with typical development [TD], aged 7-54 years), testing relationships with diagnostic group, demographics, and clinical measures. We also investigated the relationship between detection thresholds and a novel measure of intra-individual (trial-to-trial) threshold variability, a putative index of "perceptual noise." This investigation found no differences in thermal detection thresholds between individuals with ASD and typical controls, despite large differences between groups in sensory reactivity questionnaires and modest group differences in intra-individual variability. Lower performance IQ, male sex, and higher intra-individual variability in threshold estimates were the most significant predictors of elevated detection thresholds. Although no psychophysical measure was significantly correlated with questionnaire measures of sensory hyporeactivity, large intra-individual variability may partially explain the elevated psychophysical thresholds seen in a subset of the ASD population.