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New research reveals more and more children are presenting with both disorders.

DeAnny Wry’s 12-year-old son, T.J., was diagnosed with autism spectrum disorder (ASD) last year, three years after he was first diagnosed with attention deficit hyperactivity disorder (ADHD).

"Our journey has been a long one," the mother-of-two from Dawson Creek, B.C. tells HuffPost Canada. "We did not know the issues we dealt with from birth were red flags for ADHD and autism."

That may be about to change.

Up until 2013, it was not possible to diagnose ASD in a child with ADHD, or ADHD in a child with ASD. But new research is showing more and more children are presenting with both disorders and that they may share the same rare gene, prompting recommendations by scientists and clinicians that children with ASD be tested for ADHD at the time of their first diagnosis, and vice versa.

“Studies show that between 30 and 50 per cent of individuals with ASD manifest ADHD symptoms (particularly at pre-school age),” reports the Journal of Frontiers in Human Neuroscience. “Similarly, estimates suggest two-thirds of individuals with ADHD show features of ASD.”

What’s more, notes the report, a “co-occurrence of ADHD and ASD is associated with a lower quality of life and poorer adaptive functioning than in any one of these conditions.”

So what’s the difference?

It’s important to know if your child has both neurodevelopmental disorders early on, but what’s the difference between the two and how do doctors tell them apart?

“People with ASD tend to have communication deficits, such as responding inappropriately in conversations, misreading nonverbal interactions, or having difficulty building friendships appropriate to their age,” notes the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

Additionally, people with ASD may be “overly dependent on routines, highly sensitive to changes in their environment, or intensely focused on inappropriate items.”

Conversely, according to the DSM-5, ADHD symptoms include behaviours such as “failure to pay close attention to details, difficulty organizing tasks and activities, excessive talking, fidgeting, or an inability to remain seated in appropriate situations.” These symptoms are also present in multiple settings, such as at school and the home.

Additionally, unlike ADHD, people with ASD “fall on a continuum,” meaning there is a spectrum where some individual's symptoms are more severe than others. Symptoms of ASD also appear in early childhood, whereas ADHD symptoms can present as late as age 12.

Despite these clear differences, it can still be difficult for doctors and parents to distinguish between the two disorders.

ADHD diagnosis can overshadow ASD

T.J. was on the move from the time he could crawl. He was a busy toddler who was “constantly on the go, loud, hyper, energetic, goofy and had a temper,” says Wry. At age three, T.J. began speaking backwards. By the time school started, he was using accents and different voices, interrupting and talking back to his teachers. In Grade 2, T.J.’s teacher recommended further testing.

“She didn't come out and say ADHD to us,” says Wry. “But she strongly recommended testing for his inattention, distractibility and hyperactivity.”

T.J. was diagnosed with ADHD just prior to the start of Grade 3 and began taking medication. Though treatment made vast improvements with T.J.’s ability to focus and his impulse control, other symptoms previously overshadowed by his ADHD became more pronounced, causing further disruptions. As a result, Wry says T.J. spent much of Grade 3 wandering the halls or sitting in one of the quiet rooms.

“He couldn’t handle assemblies, lights or loudness in the classroom and peers in his personal space,” says Wry. “By the end of Grade 3, he was experiencing anxiety attacks.”

Frustrated by a lack of support, Wry decided to homeschool T.J. the following year. At home, T.J. would rock back and forth, bang his head, repeat himself, randomly shriek, and speak with an Irish or Western accent.

“He lacked social skills, was obsessed with the weather, took things literally, felt empathy to the extreme, had difficulty transitioning from one activity to the next, [had] meltdowns and aggressive behaviours,” says Wry.

The mom then decided to get T.J. evaluated by a neuropsychologist, which recommended the boy be tested for autism. At age 10, T.J. was referred for testing at the B.C. Autism Assessment Network and was diagnosed on the autism spectrum disorder in 2016.

ADHD and ASD go hand-in-hand

“We are finding that the brains of kids with ADHD and autism are much more similar than they are different,” Dr. Evdokia Anagnostou, Senior Clinician Scientist at the Holland Bloorview Kids Rehabilitation Hospital, tells HuffPost Canada. “One of the trademarks of autism in brain imaging studies is that the brain is not efficiently connected, and now we have evidence that the connectivity of the brain in ASD and ADHD is quite similar.”

Dr. Anagnostou was a co-author of a Canadian study published last July in the American Journal of Psychiatry which showed no major differences between the brains of kids with ASD and ADHD. Anagnostou believes ongoing research in this area will change the way ADHD and autism are treated.

“Ultimately, we need to find treatments that go after the underlying biology,” says Anagnostou. “As we do that, it would not make much difference whether you have ASD or ADHD, it would matter more what kind of biology you have.”

More research is needed

Dr. Doron Almagor is the President of Canadian ADHD Resource Alliance (CADDRA) and founder of the Possibilities Clinic for ADHD in Toronto. Though comorbidity is nothing new to him, he says a lot of the research is still forthcoming and that we really need to understand how to better diagnose children with autism and ADHD.

“We’re working in a vacuum in terms of what we know,” Almagor tells HuffPost Canada. “But the number of dual diagnoses is high enough to know that if someone has ADHD, they should be screened for autism and if they have autism, they should be screened for ADHD.”

Alina Kislenko, registered psychotherapist and founder of the ADHD and Asperger’s Clinic in Guelph, Ont., would take it even one step further.

“If I could reorganize the autism spectrum, I would add ADHD on the most high-functioning end,” Kislenko tells HuffPost Canada. “ADHD and Asperger’s [one of four disorders of ASD] have very similar neurology, social skill issues and stress sensitivity. There’s so much overlap.”

Despite the delayed diagnosis, Wry says T.J. is doing well. He’s in the sixth grade at a private school where he is able to receive more one-on-one support and will soon begin autism therapy.

“We take it one day at a time. Difficult does not even begin to describe parenting a child with ADHD and autism,” says Wry. “I just wish a doctor could have told us that our son’s quirks were atypical when he was a toddler. That knowledge may have saved us such a long road, gotten us early intervention and prevented damage to my son’s self-esteem going undiagnosed for so long.”

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