Objective To test the hypothesis that Joint hypermobility and autonomic dysfunction are over-expressed within neurodevelopmental disorders. Joint hypermobility is a widespread poorly recognized connective tissue condition with affected individuals overrepresented among panic and anxiety disorders, irritable bowel syndrome, fibromyalgia, and chronic fatigue. The relevance of hypermobility to neuropsychiatric disorders of developmental origin is currently unknown, despite anecdotal case reports and clinical suspicion of a link. Autonomic nervous system dysregulation, typically postural tachycardia syndrome is often found in hypermobile individuals. Interestingly, differences in amygdala and superior temporal cortex anatomy have been reported in hypermobile populations and functional abnormalities in patients with autism. Method Thirty-seven adults with neurodevelopmental disorder, 205 patients attending general psychiatric clinics without neurodevelopmental diagnosis and 29 healthy controls were recruited. Hypermobility was assessed using the Beighton scale (BS) and autonomic symptoms using the Autonomic Symptoms and Quality of Life Score (ASQoLS: orthostatic, gastrointestinal, bladder, secretomotor, sudomotor and sleep domains. Results The neurodevelopmental cohort had a mean age of 34.6 years (27 male). Nineteen had Attention Deficit Hyperactivity Disorder (ADHD), 4 Autistic Spectrum Disorder (ASD), 1 Tourette Syndrome (TS) and the remainder combinations of ADHD, ASD and TS. Nine had co-morbid affective disorder. Eighteen patients (48.6%) were classified as hypermobile (BS>=4) compared to 67/204(32.7%) in the general psychiatric group (p=0.048) and 3/29(10.3%) in healthy controls (p=0.007) and this prevalence was also significantly higher that reported in a large general population cohort (1156/6022, 19.19%, p=<0.001). Mean autonomic dysfunction score was significantly higher in the neurodevelopmental cohort compared to controls (mean±SEM: neurodevelopmental disorder patients, 45.8±4.86; controls, 8.5±1.62). This effect was seen across all sub-scales of the ASQoLS. Total autonomic dysfunction score did not differ significantly between neurodevelopmental cohort and the general psychiatric group, however neurodevelopmental disorder patients had significantly higher scores on orthostatic and gastrointestinal disturbance subscales. Conclusion We demonstrate for the first time that rates of hypermobility and symptoms of autonomic dysfunction are particularly high in adults with neurodevelopmental diagnoses. It is likely that the importance of hypermobility and autonomic dysfunction to the generation and maintenance of psychopathology in neurodevelopmental disorders is poorly appreciated. Work underway(autonomic testing, fMRI) will test the hypothesis that autonomic reactivity and interoceptive sensitivity predispose to the expression of psychiatric symptoms, particularly anxiety. It is further hypothesized that inefficient neural co-ordination of efferent autonomic drive with imprecise interoceptive representat...
Objectives/AimsAutism is a neurodevelopmental condition characterised by differences in sensory processing, social communication and restricted/repetitive behaviors. Joint hypermobility is a common connective tissue variant, reportedly overrepresented in Autism. Alexithymia is a personality construct characterised by altered emotional awareness which has notably high rates of overlap with autism spectrum disorder. This study tested whether hypermobility was associated with autistic traits and examined alexithymia as a mediator of this association.MethodForty-two people underwent eligibility assessment for a study of joint hypermobility and anxiety (ISRCTN17018615). Hypermobility was assessed using both the Brighton Criteria for Joint Hypermobilty Syndrome (JHS) and 2017 Hypermobile Ehlers Danlos Syndrome (hEDS) Criteria. Participants completed the Ritvo Autism Asperger Diagnostic Scale-Revised (RAADS R: sensory/motor, language, social relatedness and circumscribed interest domains) to quantify autistic traits. No participant had a prior diagnosis of Autism. Participants also completed the Toronto Alexithymia Scale (TAS-20) to measure alexithymia. The TAS-20 has three domains: difficulty describing feelings, difficulty identifying feelings and externally oriented thinking.ResultsAll 42 participants met criteria for JHS, 26 participants also met criteria for hEDS. Strikingly, 22/42 (52.4%) scored above threshold for suspected Autism (26/42 in the sensory/motor domain; 22/42 in language domain; 22/42 in social relatedness domain; 17/42 in circumscribed interests domain). There were no significant differences in RAADS-R scores depending on hypermobility diagnosis. The number of connective tissue features (hEDS Criterion 2A) correlated with RAADS-R sensory/motor score (r = 0.418, p = 0.006) but not social relatedness nor circumscribed interests sub-scores. Full mediation of the relationship between the number of connective tissue features and RAADs sensory/motor score by TAS-20 externally oriented thinking was found using the method of Baron-Kenny (1986) and estimation of indirect effects (Hayes, 2018; bootstrapped confidence intervals (n = 5000, do not cross zero)). Difficulty identifying feelings and difficulty describing feelings domains did not mediate this relationship.ConclusionThese results add to evidence linking variant connective tissue to neurodevelopmental conditions (including Autism) and interestingly, specifically to sensory processing differences. Our study provides a strong rationale for screening for neurodevelopmental conditions in people with hypermobility and motivates further to understand symptom expression in this group. Our results also provide an insight into the processes underlying this relationship, which maybe important for informing interventions for people with hypermobility and autistic traits.
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