By Dr Michelle Garnett and Prof Tony Attwood
Researchers and clinicians in the autism area have known about the association between hypermobility and autism for a long time (Tantam, Evered & Hersov, 1990), and hypermobility is one common symptom of Ehlers-Danlos Syndrome (EDS). In this week’s blog, we discuss what EDS is, the association between autism and EDS, and why knowing about EDS may be helpful.
What is Ehlers-Danlos Syndrome?
Ehlers-Danlos syndrome is a group of disorders that are genetic, and affect the connective tissues making them weaker, primarily the skin, joints, and blood vessel walls. There are 14 different types of EDS, and the most common one, hypermobile EDS (hEDS), is the one most diagnosed with autism (Kindgren, Quinones Perez & Knez, 2021). Many people have overly flexible joints and may be diagnosed with a hypermobility spectrum disorder (HSD), but EDS comes with a whole range of other issues, which are well-summarised by a lead researcher in the area, Emily Casanova and her colleagues (2020):
- overly stretchy skin, where the weak connective tissue allows the skin to stretch more than usual;
- fragile skin that does not heal quickly or well heal when damaged and stitches in a wound may tear and leave a thin crinkly scar;
- chronic pain, usually in the joints;
- hyposensitivity (less sensitivity) to proprioceptive (where the body is in space, allowing movement and force) and vestibular (where the head is in space, allowing movement to be co-ordinated with balance) input;
- joints that are easily dislocated;
- gastrointestinal disorders;
- cardiovascular conditions (i.e. in Vascular EDS);
Mast Cell Activation Disorder (MCAS) – symptoms of this disorder include a lack of mental clarity that impacts on learning new information, word finding, cognitive processing and difficulties regulating emotions;
Postural Orthostatic Tachyardia Syndrome (POTS) -symptoms include dizziness, feeling faint, especially after getting up quickly, sensitivity to heat, palpitations, chest pain with no heart condition;
Auto immune system disorders, such as coeliac disease, lupus and multiple sclerosis.
How do I find out if I have EDS?
There is no quick screening test for EDS and the diagnostic criteria changed in 2017. This is causing some confusion, and there is a general lack of information about EDS in the community and amongst health professionals. However, if you are concerned that you or a loved one may have EDS, the first step is to visit your GP who will take a family history and conduct a physical exam using the Beighton Scoring System, which essentially measures joint mobility. If your GP determines that EDS is a possibility, you will be referred to a rheumatologist or geneticist for genetic testing via a blood test. It is worth asking for a medical specialist who specialises in EDS, since EDS can be difficult to diagnose.
What is the connection between EDS and autism?
Firstly, there seems to be a connection between autism and EDS because the incidence of EDS in autistic people is higher than in non-autistic people. EDS is considered uncommon because it occurs in less than 1% of the population. Research estimates place the prevalence at between 0.01% and 0.02% of the general population, but clinicians believe that the figure is higher, i.e. greater than 0.05% or 1 in 2000 people (Marshal & Piller, 2022). Whilst there is no research on the prevalence of EDS in the autistic population, Kindgren and colleagues (2021) found that the incidence of autism in their sample of children with EDS or HSD was 6%. This incidence of autism is much higher than the latest prevalence figures for autism in a large sample of 8-year-old boys recently released from the US Centers for Disease Control (Maenner et al, 2023) which was 2.6%, indicating a strong association between the two conditions.
It is not known why autistic people are more likely to have EDS, but there is speculation that since collagen and other connective tissue are part of the foundation of neurological tissue, weaker connective brain tissue may be causative of autism for some autistic people (Castori & Voermans, 2014).
Mothers with EDS or HSD had higher rates of autistic children than mothers who did not have EDS, and similar rates to autistic mothers (Casanova et al, 2020). This data suggests that there may be a genetic link between the conditions. Genetic data indicates that there are similarities between the two conditions at the molecular, cellular and tissue levels as reviewed by Casanova and her colleagues (2020). These authors propose that hereditary connective tissue disorder may represent a subtype of autism, but the prevalence of this subtype is unknown and further research is needed.
Another association between EDS and autism is the large symptom overlap. The following is a list of symptoms that commonly occur in both conditions:
- Learning disorder.
- Developmental coordination disorder.
- Tourette’s syndrome.
- Sensory issues, especially proprioceptive and vestibular differences, and a different perception of pain.
- Mental health issues, including anxiety, depression, bipolar disorder, eating disorders, and suicidal behaviours.
- Autonomic nervous system dysregulation, usually chronic sympathetic hyperarousal and parasympathetic under arousal.
- Sleep disorders.
- Auto immune disorders.
Implications of the association between EDS and Autism
A recommendation from research to date is to integrate the Beighton Scoring System into a standard physical assessment for autistic people with their GP (Casanova, 2020). Those autistic individuals who demonstrably have generalised joint hypermobility could then be referred for further genetic testing and assessments.
Being autistic and discovering that one has EDS can be very helpful in the journey toward self-discovery, providing an explanation for ongoing unexplained symptoms, such as hypermobility, low tone, motor clumsiness, pain, fatigue, and other symptoms as listed above. Clinically, we have found that the journey toward a diagnosis of EDS is commonly torturous and long, but ultimately satisfying for the person when a diagnosis is made because it leads to accurate explanations, treatment, and accommodations. The person often feels vindicated that their symptoms were not “all in their head” or manifestations of poor character or stamina, (which have often been their own perceptions due to ill-informed reactions from others) but instead have a demonstrable physical and genetic base.
A potential benefit of knowing one has EDS is that treatments found to be of assistance for EDS could then be made available for the autistic person, including occupational therapy, physiotherapy, and possibly certain medications for an atypically functioning autonomic nervous system. For example, the use of beta blocker, propranolol, has been used with some success for autistic individuals, but more research is needed. A treatment meeting significant success for treating an atypically functioning ANS in autistic individuals is low frequency, repetitive transcranial magnetic stimulation (rTMS; Casanova et al, 2014; Hakim et al, 2017).
Lastly, more research on the associations between EDS and autism may yield further understandings on the suggested autism/EDS neuro phenotype, which will ultimately lead to more specific recognition, research and treatments/accommodations for this phenotype and thus very real benefits for the autistic person with EDS.
Where to from here?
There is still much to learn about the association between EDS and autism. For more resources on EDS, we recommend:
For more resources on autism across the age span we have developed many unique web-based trainings, each informed by our combined 80+ years’ experience as clinical psychologists specialising in autism, and the current research.
Casanova, M.F.; Hensley, M.K.; Sokhadze, E.M.; El-Baz, A.S.; Wang, Y.; Li, X.; Sears, L. (2014). Effects of weekly low-frequency rTMS on autonomic measures in children with autism spectrum disorder. Front. Hum. Neurosci., 8, 851.
Casanova EL, Baeza-Velasco C, Buchanan CB, Casanova MF. (2020). The Relationship between Autism and Ehlers-Danlos Syndromes/Hypermobility Spectrum Disorders. J Pers Med.;10(4):260. doi: 10.3390/jpm10040260. PMID: 33271870; PMCID: PMC7711487.
Castori, M. & Voermans, N. C. (2014). Neurological manifestations of Ehlers-Danlos syndrome. Emergency Medicine Journal: EMJ, 25(3), 175-176.
Hakim, A.; O’Callaghan, C.; De Wandele, I.; Stiles, L.; Pocinki, A.; Rowe, P. (2017). Cardiovascular autonomic dysfunction in Ehlers-Danlos syndrome—Hypermobile type. Am. J. Med. Genet. Part C Semin. Med. Genet. 175, 168–174.
Kindgren E, Quiñones Perez A, Knez R. Prevalence of ADHD and Autism Spectrum Disorder in Children with Hypermobility Spectrum Disorders or Hypermobile Ehlers-Danlos Syndrome: A Retrospective Study. Neuropsychiatr Dis Treat. 2021 Feb 10;17:379-388. doi: 102147/NDT.S290494. PMID: 33603376; PMCID: PMC7882457.
Maenner MJ, Warren Z, Williams AR, et al. (2023). Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 Years — Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2020. MMWR Surveill Summ 2023;72(No. SS-2):1–14. DOI: http://dx.doi.org/10.15585/mmwr.ss7202a1.
Marshall, T.J.& Piller, A. (2022). Ehlers-Danlos Syndrome and Its Comorbidities as a Co-Occurring Health Issue in Autistic People, Autism Spectrum News, Summer Edition. https://autismspectrumnews.org/ehlers-danlos-syndrome-and-its-comorbidities-as-a-co-occurring-health-issue-in-autistic-people/
Tantam, D., Evered, C. and Hersov, L. (1990) ‘Asperger’s Syndrome and Ligamentous Laxity.’ Journal of the American Academy for Child and Adolescent Psychiatry, 29, 892-896.