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