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Nearly three-quarters of autistic children also have a further medical or psychiatric condition, according to autism studies (Simonoff et al, 2008).

This is called co-existing, or clinically, a ‘co-morbidity’. Co-existing conditions to autism include anxiety disorders, attention-deficit/hyperactivity disorder, depressive disorders, Fragile X syndrome, gastrointestinal symptoms, intellectual disability and developmental delays.

Here at, we don’t tend to focus on the more negative sides to autism. Many people already seemingly regard autism as a terrible disability, rather than the difference in processing and seeing the world that autism is. But we can’t get away from the fact that the common ‘co-existing conditions’ that are associated with autism can be at the very least, debilitating, and in many cases, considerably life-changing. So here, we have detailed some of the most common.

Anxiety disorders & autism

One study found that thirty nine per cent of autistic adolescents had criteria for ‘A lifetime history of an anxiety disorder.) (Mazefsky et al, 2013).

According to, for autistic children, anxiety might show up as stimming more often, asking questions over and over again, hurting themselves, or having trouble getting to sleep. They state that about 40-60% of autistic children also have anxiety.

A well-known anxiety disorder for example is Obsessive compulsive disorder (OCD); people with OCD behave in repetitive and compulsive ways.

Boy draws, to illustrate childhood autism articleAn oft-quoted study on autism and co-existing conditions states: ‘Psychiatric disorders are common and frequently multiple in children with autism spectrum disorders. Co-morbid conditions can appear at any time during a child’s development. Some might not appear until later in adolescence or adulthood. Sometimes these co-morbid conditions have symptoms that affect how well ASD (autism spectrum disorders) therapies and interventions work.’

Attention deficit hyperactivity disorder (ADHD) & autism

According to the National Autistic Society (NAS), ADHD is common in autistic people. The NAS asked experts from The South London and Maudsley Hospital to explain how ADHD can affect children and adults, and the article may be found at the NAS website. The experts stated that while autism and ADHD share some common characteristics, like the autist not seeming to listen when people speak, interrupting, or intruding on other people’s personal space, if someone has ADHD, they predominantly struggle with impulsivity, hyperactivity and inattention.

Often, children with ADHD have difficulty focusing on one activity or task; they may be easily distracted; they are often physically unable to sit still. The ‘attention deficit’ wording may be misleading, as this element could be described as an ‘interest’ deficit – eg. the individual can hold their attention easily on something, if they’re interested in it. As with ASC, children with ADHD often have difficulty moving their attention to other activities, when they are asked to do so. (Source – Children and Adults with Attention-Deficit/Hyperactivity Disorder, or CHADD).

Read our blog on a dual diagnosis of autism and ADHD here – 

A dual diagnosis of autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) – what are the implications?

Depression and dysthymia & autism

Studies definitively link depressive symptoms with autism. One study examined the potential relationship between co-existing depression or anxiety in adolescents with [as was then described as] high-functioning ASD, and found that 32% of autistic adolescents met criteria for ‘A lifetime history of a co-morbid depressive disorder’.

Two females talking _ to illustrate communication between NTs and autistics: ASC ASD‘Findings of co-morbid depressive and anxiety disorders in this study support previous research indicating that these disorders are common among individuals with ASD’, the researchers found.

Likely linked to the individual’s constant struggle to ‘process’ and socialise in a neurotypical world, depressive symptoms like low mood, lack of motivation, trouble sleeping and poor appetite are common signs in autists. It is proposed that depressive symptoms increase with one’s awareness of one’s own autistic social difficulties.

(An interesting research document can be found here (Rai, 2018). The author states: ‘Individuals with ASDs, especially those without intellectual disability, had a greater risk of a depression diagnosis in young adulthood than the general population and their non-autistic siblings.’)

Dysthymic Disorder & autism

Dysthymia, also known as Dysthymic Disorder or Persistent depressive disorder (PDD), is a relatively unknown condition of chronic depression.

Woman- to illustrate that Autistic burnout - Burnout is a physiological symptom of system overload

Dysthymic Disorder can be characterised as a chronic low-grade depression.

According to, Dysthymic Disorder can be characterised as a chronic low-grade depression, persistent irritability, and a state of demoralisation, often with low self-esteem.

However there’s little information available regarding its prevalence with autism. Anecdotally though, it does seem to be fairly common in autistic individuals.

Fragile X syndrome & autism

Fragile X is a genetic disorder and intellectual disability, and children with the condition have trouble communicating. Autism is relatively common in children with Fragile X, so autism can be described as a co-existing condition of Fragile X. You can read more about it at the Fragile X Society’s website – they state: ‘Fragile X Syndrome is the underlying cause of up to 1 in 20 diagnoses of autism’ – and more information may be found here – Budimirovica et al, 2011.

Gastrointestinal symptoms & autism

Common gastrointestinal symptoms for autistic people are constipation, abdominal pain, diarrhoea and stomach bloating. One recent study (Hsiao, 2-14) found evidence of ‘Emerging evidence for a gut-brain connection in autism, wherein GI [gastrointestinal] dysfunction may contribute to the pathogenesis or severity of ASD symptoms.’

Proposed reasons for GI symptoms in autists include altered gut bacteria, low fibre intake, intolerance and food sensitivities, as well as some autist’s restricted diets. Stress is well-known to affect digestive health, and this is undoubtedly a further relevant factor.

Intellectual disability and developmental delays & autism

As opposed to the theory that intellectual disabilities are highly co-existing conditions of autism (a seemingly common preconception or myth!), it could be conversely said that individuals with intellectual disability are definitively at risk for autism.

(While some figures point to an estimated 38% of autistic children having an intellectual disability – see this by no means indicates that autism = intellectual disability. This pre-conception, that ALL autists are intellectually challenged, is something that autists face consistently.

A study (Sappok et al, 2013), describes intellectual disability as being: ‘Diagnosed when a child who is six years or older and has an IQ below 70, as well as difficulties with daily tasks. In children under six years, the term ‘developmental delay’ is used when children have significant cognitive and language delays.’

In terms of how common intellectual disability is in autistic children, about one per cent of the general population is thought to have an intellectual disability, and about 10% of individuals with intellectual disability are autistic or autistic traits.

However, a much higher percentage of autistic individuals have Intellectual Disability. (The resource states that in studies, 38% of autistic children were found to have intellectual disability.) Since America’s Centers for Disease Control (CDC) has been measuring prevalence rates of ASD and co-occurring intellectual disability, the rate of individuals with ASD who DO NOT have co-occurring intellectual disability has been rising. Eg there are now more individuals WITHOUT intellectual disability being diagnosed in the USA.

Anorexia nervosa & autism

Could anorexia nervosa be considered a co-existing condition of autism? We have left it until last in our article, as the condition isn’t currently widely considered to be a common co-existing condition of autism. But should it be? The latest research certainly pinpoints a link. The charity Autistica said ‘findings’ suggest one in five women presenting to UK clinics with anorexia may also be autistic; health watchdog the National Institute for Health and Clinical Excellence (NICE) conservatively said in response that more research is required.

Autism’s propensity for rigidity and obsession

Woman with eyes closed _ to illustrate article on communication between NTs and autisticsIt is proposed that some autists develop anorexia due to autism’s propensity for rigidity and obsession, e.g. developing a set of rules about calorie intake. Autistica’s director of science, Dr James Cusack, is calling for new guidelines from NICE.

The two conditions have been researched over the years. The document: ‘Autism Spectrum Disorder in Anorexia Nervosa: An Updated Literature Review’ has the main study resources. The ‘Current Psychiatry Reports’ review finds that ‘Studies consistently report over-representation of symptoms of ASD in AN. Co-morbid AN and ASD may require more intensive treatment or specifically tailored interventions.’

Spectrum News reports that: ‘People with anorexia often have difficulties making friends and sustaining social relationships even before the onset of their condition. Because high levels of social discomfort and withdrawal persist even after they begin eating regularly and return to a normal weight, these social difficulties are not likely to have been caused by anorexia or malnutrition.’

Other co-existing conditions associated with autism

There are a number of other co-existing conditions associated with autism that include Epilepsy, Tourette Syndrome, Dyslexia, Dyspraxia, and Downs Syndrome – here are some resources, for further reading:

The National Autistic Society

Synapse (Australia)

Maski et al, 2011

A little disclaimer – here at we don’t claim to be experts about Autism; the information we post here is based purely on our own exposure and experiences. We’d also love your feedback on our posts!

Read a further blog here –

Autism Foundation Posts – Spectra.Blog’s FAQs and key posts and articles on autism spectrum disorders

Also published on Medium.