Autism in the context of joint hypermobility, hypermobility spectrum disorders, and Ehlers–Danlos syndromes: A systematic review and prevalence meta-analyses

Increasing research suggests a link between autism spectrum disorders and joint hypermobility, hypermobility spectrum disorders, and Ehlers–Danlos syndromes. However, no study systematically examined the available literature about the relationship between these conditions. A systematic literature search was conducted to identify studies (a) examining the link between autism, joint hypermobility, hypermobility spectrum disorders or Ehlers–Danlos syndrome, and (b) reporting the frequency of autism spectrum disorders in people with joint hypermobility, hypermobility spectrum disorders or Ehlers–Danlos syndrome, or vice versa. Prevalence meta-analyses were performed. Twenty articles met the inclusion criteria. Twelve studies explored joint hypermobility/hypermobility spectrum disorders/Ehlers–Danlos syndrome in autistic people. Six explored autism spectrum disorders/autistic traits in people with hypermobility spectrum disorders/Ehlers–Danlos syndrome. Two studies examined autism spectrum disorders in relatives of patients with hypermobility spectrum disorders/Ehlers–Danlos syndrome, and two explored autistic traits and joint hypermobility in non-clinical samples. Out of 15 studies examining the association between autism spectrum disorders/autistic traits and joint hypermobility/hypermobility spectrum disorders/Ehlers–Danlos syndrome, 12 reported significant results. The overall prevalence of joint hypermobility in autistic individuals was 22.3%, but it was higher (31%) when only studies assessing joint hypermobility clinically (excluding self-reports) were considered. The overall prevalence of hypermobility spectrum disorders/Ehlers–Danlos syndrome in autistic samples was 27.9%, but 39% if hypermobility spectrum disorders/Ehlers–Danlos syndrome were assessed clinically. Despite the heterogeneity of studies, these results suggest an association between autism and joint hypermobility/hypermobility spectrum disorders/Ehlers–Danlos syndrome that should be confirmed in further research.