Autism and Hypermobility

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It seems science is slowly catching up, searching along both spectrums to find the connection between autism and hypermobility spectrum disorder and other hereditary connective tissue disorders—hypermobility is often a sign of such hereditary connective tissue disorders, the best known and most commonly found being Ehlers-Danlos syndrome.

This is mostly because of the work of scientists like Dr. Emily L.Casanova and the call of patients (many in the autism community) looking for answers about the surprising overlap between autism spectrum disorders and the continuum of joint hypermobility syndrome, hypermobile spectrum disorders, and hypermobile Ehlers Danlos syndrome.

Hypermobility
Hypermobility or joint laxity means an individual has an unusual range of motion in one or more joints in their body. Joint hypermobility is therefore a descriptor not a diagnosis (Castori et al., 2017).
The term localized hypermobility syndrome is used when joint hypermobility is observed at one or two (usually less than five) joints. This condition may be genetic but could also be due to injury or trauma to the joint.
The term generalized joint hypermobility is used when joint hypermobility is present at multiple sites, usually more than five. This condition is usually congenital and sometimes a feature of genetic syndromes like hereditary disorders of the soft connective tissue. The terminology describing disorders involving joint hypermobility—especially when it comes to specific subtypes like hypermobile Ehlers-Danlos syndrome (hEDS)—may be confusing.
A Swedish study (Kindgren et al., 2021) mentions how the diagnostic criteria and international classification of Ehlers-Danlos syndrome (EDS) changed in 2017; with the authors detailing that, in their results, all Ehlers-Danlos syndrome cases could be classified as hypermobile Ehlers-Danlos syndrome (hEDS).
EDS, of which there are 13 types, are a group of hereditary connective tissue disorders which predominantly affect collagen (Demmler et al., 2019). The most common type is the hypermobile variant (hEDS). According to research hEDS may be underdiagnosed and poorly understood by practitioners, leading to patients waiting for many years before finally receiving an accurate diagnosis.

Study researching the link between autism and Ehlers-Danlos Syndrome
The retrospective study mentioned above (Kindgren et al., 2021) found a significant association between attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder (ASD) and hEDS. The authors go on to suggest that children with EDS or hEDS may require routine screening for neuropsychiatric symptoms.

It is important to note that hypermobility does not always indicate an autism risk, and it is not always a symptom of a genetic connective tissue disorder. Hypermobility may be caused by environmental factors, it often runs in families, and sometimes hypermobility may be advantageous in athletic pursuits.

Parents should, however, be aware that rates of hypermobility are particularly high in adults with neurodevelopmental diagnoses (Eccles et al., 2014).

Similarities in presentation of ASD and hEDS
Preliminary research from Casanova et al. (2020) found more than 20% of mothers with EDS/hypermobility spectrum disorders reported having autistic children—this percentage is significant when comparing it to the similar 19% seen in mothers with autism. The authors suggest an interesting possibility, perhaps some forms of autism are hereditary connective tissue disorders. For many with hypermobility related disorders, pain is probably one of the most urgent issues to address.

Chronic pain
Because of the communication deficits in autism we may not recognize and understand pain experienced by individuals with autism. For those with joint hypermobility disorders, pain may be due to laxity or the tendency to dislocate the hypermobile joint. Joint hypermobility means more flexibility but also a predisposition to pain and trauma as the tissue is more fragile.

Research (Hershenfeld et al., 2016) suggests higher rates of pain symptoms in individuals with Ehlers-Danlos syndrome when the condition co occurs alongside psychiatric conditions. Furthermore, mast cell activation syndrome (frequently linked to painful conditions) may be another link between ASD and hypermobility spectrum disorders.
Providing an overview of the link between ASD and hypermobility related disorders, the authors (Baeza-Velasco et al., 2018) suggest disseminating information about the potential link between the two conditions may be beneficial in clinical contexts. It could encourage awareness of pain and pain-related symptoms in a group of people “ in which it is extremely challenging to screen for and manage pain.” (Baeza-Velasco et al., 2018)
Another important aspect of researching the association between hEDS and autism is the particular way both conditions affect females.

Masking, autism and hEDS
Autism may be even more prevalent in those with generalized hypermobility syndrome or EDS if one considers these disorders occur more frequently in women who may be masking their autistic traits. More studies are necessary but researchers are uncovering more data suggesting the outdated idea of EDS, and other joint hypermobility syndromes, being rare disorders only affecting the musculoskeletal system and soft tissues should be revisited (Demmler et al., 2019).

Dr. Casanova, Research Assistant Professor at the University of South Carolina, is one of the research pioneers advocating for more studies concerning Ehlers-Danlos syndromes/Hypermobility spectrum disorders in the autism population. Her team’s research (Casanova et al., 2020) found results reinforcing concepts of an etiological association between autism and generalized hypermobility.

Dr. Casanova et al., (2018) used an online survey finding:
Autistic women with generalized joint hypermobility reported more immune (and endocrine-mediated) conditions than those without generalized joint hypermobility

Autoimmune conditions featured prominently in the autism/generalized joint hypermobility group

Final thoughts
Furthermore, the research (Casanova et al., 2018) also explains how connective tissue regulates the immune system. Perhaps joint hypermobility will become a red flag in diagnosing females on the spectrum. While social communication impairments could be camouflaged, the presence of joint hypermobility and connective tissue disorders should alert clinicians in various specialties to the possibility of neuropsychiatric conditions.

Alternatively, awareness should be promoted of the possibility that a child may be misdiagnosed as being on the spectrum because of a condition like hEDS’s symptoms overlapping with those found in ASD. Sensory difficulties, preference for lying down, and stereotypic movements could be explained by joint hypermobility or connective tissue disorders.

Austic children may have severe difficulty communicating about pain and related symptoms, often leading to self-injurious and other challenging behavior. In some cases joint hypermobility may be the only clue that a child on the spectrum has a hypermobility related disorder, the only clue that a child is suffering with little means to let us know they’re in pain.

I preferred it when autism was just a different brain wiring. Now it seems to have more physical features associated with it than downs syndrome.

I think in the long run what they're going to discover is that neurodivergence overlaps heavily with a number of other things and that some of the labels we've been using actually only describe parts of people's symptom sets that actually have common causes. There does seem to be a high potential for other issues to exist alongside ND diagnoses so it's worth trying to untangle what the relationship is, it might only be coincidence, it might be similar root causes or it might something more complicated.

Let's face it, lots of the time when people like us try to describe something that's wrong we're invalidated and get told to stop whining/being dramatic/lazy/difficult/crazy/weird/etc so it's likely that at least a portion of people who get evaluated for some issues are choosing to ignore other ones and that if they were to be given enough time and attention to unpack everything that they'd end up with more labels.

1.1 Anxiety
1.2 Brain fog
1.3 Bipolar disorder
1.4 Bowel disease
1.5 Depression
1.6 Developmental coordination disorder
1.7 Epilepsy
1.8 Fragile X syndrome
1.9 Gender dysphoria
1.10 Abnormal folate metabolism
1.11 Abnormal redox metabolism
1.12 Neurotransmitter anomalies
1.13 Mitochondrial diseases
1.14 Neurofibromatosis type I
1.15 Neuroinflammation and immune disorders
1.16 Neuropathies
1.17 Nonverbal learning disorder
1.18 Obsessive–compulsive disorder
1.19 Obsessive–compulsive personality disorder
1.20 Psychosis and schizophrenia
1.21 Schizoid personality disorder
1.22 Sensory problems
1.23 Reduced NMDA‐receptor function
1.24 Sleep disorders
1.25 Tinnitus
1.26 Tourette syndrome
1.27 Tuberous sclerosis
1.28 Vitamin deficiencies
1.29 Other mental disorders
1.30 Intellectual disability
1.31 Attention-deficit hyperactivity disorder