Quelle est la fréquence de la comorbidité entre le TDAH et le TSA ?

30 à 50 % des personnes autistes ont également un TDAH, comparé à seulement 5 % dans la population générale. Inversement, 20 à 30% des personnes avec TDAH présentent aussi des traits autistiques significatifs.

Depuis quand est-il possible de diagnostiquer simultanément le TDAH et le TSA ?

Depuis 2013, avec la publication du DSM-5, il est officiellement possible de poser un double diagnostic TDAH + TSA. Auparavant, le DSM interdisait de diagnostiquer les deux troubles simultanément car ils étaient considérés comme mutuellement exclusifs.

Pourquoi le TDAH et le TSA coexistent-ils si fréquemment ?

La fréquence élevée de cette comorbidité a des bases neurobiologiques et génétiques documentées. Des études de génétique moléculaire ont identifié des gènes communs aux deux troubles, notamment des gènes impliqués dans la synaptogenèse (formation des connexions neuronales).

Qu'est-ce que la comorbidité TDAH-TSA implique pour l'accompagnement ?

Cette comorbidité fréquente et souvent méconnue crée des profils complexes qui nécessitent un double accompagnement et des professionnels capables de voir les deux troubles en même temps. Les deux conditions se chevauchent, s'amplifient mutuellement et créent des profils d'une complexité particulière.

Comment les troubles TDAH et TSA interagissent-ils entre eux ?

Le TDAH et le TSA coexistent fréquemment, se chevauchent et s'amplifient mutuellement. Cette interaction crée des profils d'une complexité particulière qui nécessitent une compréhension approfondie de leurs mécanismes et manifestations concrètes.

Pourquoi est-il important de comprendre la comorbidité TDAH-TSA ?

Comprendre cette comorbidité — ses mécanismes, ses manifestations concrètes et son accompagnement — est devenu indispensable pour tout professionnel ou parent concerné, car elle représente une réalité clinique observée depuis des décennies et reconnue officiellement depuis 2013.

🧩 Neurodevelopment — ADHD & ASD Series

ADHD and ASD comorbidity: understanding the overlap

30 to 50% of autistic people also have ADHD. This frequent and often overlooked comorbidity creates complex profiles that require dual support — and professionals capable of seeing both disorders at the same time.

For a long time, the DSM prohibited making both diagnoses simultaneously — ADHD and autism were considered mutually exclusive. Since the DSM-5 in 2013, this rule has been abandoned, recognizing a clinical reality that practitioners have observed for decades: ADHD and ASD frequently coexist, overlap, mutually amplify, and create profiles of particular complexity. Understanding this comorbidity — its mechanisms, its concrete manifestations, and its support — has become essential for any concerned professional or parent.

30–50%

of autistic people also have ADHD — vs 5% in the general population

20–30%

of people with ADHD also exhibit significant autistic traits

2013

year since which the DSM-5 officially allows the dual diagnosis of ADHD + ASD

1. Why do ADHD and ASD coexist so often?

The high frequency of ADHD + ASD comorbidity is not a coincidence — it has documented neurobiological and genetic bases. Molecular genetics studies have identified common genes for both disorders, including genes involved in synaptogenesis (formation of connections between neurons) and in dopaminergic and serotonergic neurotransmitter systems. A parent may carry ADHD susceptibility genes that combine, in the child, with ASD susceptibility genes carried by the other parent.

Neurologically, both disorders share anomalies in fronto-striatal circuits (involved in executive control and behavioral regulation), even though their profiles of impairment are distinct. This partially common neurological basis explains why the same brain can express both conditions simultaneously.

🧬 Shared genetics: what research reveals

A study published in Nature Genetics (2019) analyzed genomic data from over 200,000 individuals and confirmed that ADHD and autism share a significant portion of their genetic architecture. Genetic variants associated with one also increase the risk of the other. This does not imply that the two disorders are "the same thing" — but explains their frequent co-occurrence in the same families and individuals.

2. Concrete manifestations of the dual diagnosis

The profile of a child or adult with a dual diagnosis of ADHD + autism is characterized by internal contradictions that make support particularly complex — and can confuse professionals and parents who are not well acquainted with both disorders.

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Impulsivity + rigidity

ADHD generates impulsivity (acting without thinking) while autism often generates procedural rigidity (need to do things in a precise way). Result: the child acts impulsively BUT insists that this action be carried out exactly according to their internal rules.

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Hyperfocus + distraction

Autism generates intense hyperfocus on areas of interest; ADHD generates distraction on everything else. The child may spend 6 hours reading about dinosaurs (autism) but cannot maintain attention for 5 minutes during a lesson that does not interest them (ADHD).

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Routine + novelty

Autism generates a strong need for routine and predictability; ADHD generates a need for stimulation and novelty. The child suffers from changes in schedule (autism) but quickly gets bored with the same activities (ADHD) — an internal conflict that causes great frustration.

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Overload + emotional impulsivity

Sensory and social overload (autism) combined with poor emotional regulation (ADHD) creates particularly intense and sudden emotional outbursts — often interpreted as "tantrums" when they reflect an unregulated accumulation of stress.

Daily life at school

A child with a dual diagnosis at school presents a particularly difficult picture for untrained teachers to manage. They may work with remarkable concentration on a project that interests them (autistic hyperfocus) but disengage immediately in other subjects (ADHD). They may violently resist a change of classroom or schedule (autistic rigidity) while being unable to sit still during a lesson (ADHD hyperactivity). They may have very rigid social rules that they apply to themselves and others (autism) but repeatedly and impulsively break classroom rules (ADHD).

⚠️ In adolescence: the peak of vulnerability

When both disorders amplify each other

Adolescence is often the most challenging period for individuals with a dual diagnosis. Social demands increase (navigating the complex codes of peer groups) while autistic masking becomes exhausting. Simultaneously, ADHD symptoms may worsen in adolescence due to stress and new academic demands. The risks of depression, anxiety, and autistic burnout are significantly higher in this profile than in either disorder taken separately.

3. Diagnosis: why the two disorders mask each other

The dual diagnosis is frequently underestimated because the two disorders can mask each other depending on the evaluation context. In a typical child psychiatry office, ADHD hyperactivity may capture all clinical attention and overshadow more subtle autistic indicators. Conversely, in a specialized autism center, the focus on autistic criteria may neglect a significant ADHD component.

🔬 Comprehensive evaluation

The necessary tools to see both profiles

A comprehensive assessment for suspected dual diagnosis must include:

• For ADHD: ADHD screening test, selective attention test, complete CPT or TOVA, Conners (for children) or ASRS (for adults), WISC/WAIS with index profile

• For autism: ADOS-2 (direct observation), ADI-R (parent interview), sensory evaluation

• For both: comprehensive clinical interview covering developmental history since birth, school profile, assessment of comorbidities (anxiety, depression, sleep disorders)

4. Dual support: principles and practices

Supporting a person with a dual diagnosis requires simultaneous consideration of both sets of needs — which implies coordination among the various professionals involved and specific training for parents and teachers.

The main principles

✔ Principles of dual support ADHD + autism

Always address autism first in accommodations: reducing sensory overload and respecting routines stabilizes the environment enough for ADHD strategies to be effective
ADHD medications with caution: methylphenidate may be used but often at lower doses due to increased sensitivities; some autistic patients tolerate non-stimulants (atomoxetine) better
Explicit structures: making transitions, rules, and expectations visible and predictable — meets the need for autistic predictability AND helps compensate for ADHD organizational deficits
Task breakdown: small, clearly defined steps with immediate feedback — helps maintain ADHD attention AND allows autistic sequencing to progress
Consistency among all stakeholders: school, therapists, parents — an inconsistent message is particularly destabilizing in this profile

At school

The PAP (Personalized Support Plan) or the PPS (Personalized School Project) must integrate accommodations for both disorders. Extra time for exams (ADHD), isolated exam room (autism + ADHD), desk away from distractions (ADHD), advance notice of schedule changes (autism), access to a calm decompression space (autism), AESH trained in both disorders. Teacher training is crucial — DYNSEO offers specific training to support these profiles in institutions.

🎯 Dual support DYNSEO — ADHD + autism

DYNSEO offers resources designed for dual diagnosis:

• Non-medical ADHD Test — free assessment

• Selective Attention Test — objective attention profile

• Training "Supporting a child with ADHD"

• Training "Supporting a child with autism"

• DYNSEO cognitive tools — suitable for both profiles

Dual support DYNSEO →

FAQ

What is the frequency of comorbidity ADHD + autism?

30 to 50% of autistic individuals also have ADHD, compared to 5% in the general population. Conversely, 20 to 30% of individuals with ADHD exhibit significant autistic traits. The DSM-5 officially recognized the dual diagnosis in 2013.

How does the dual diagnosis manifest concretely?

Paradoxical internal contradictions: need for routine (autism) + need for novelty (ADHD), hyperfocus (autism) + global distraction (ADHD), impulsivity (ADHD) + procedural rigidity (autism). These profiles generate great distress and require support that encompasses both logics.

How to treat the dual diagnosis?

Multidisciplinary approach: ADHD medications with caution (often lower doses), speech therapy, occupational therapy, adapted CBT, combined school accommodations (PAP/PPS). Consistency among all stakeholders is essential.

Which professionals to consult for a dual diagnosis?

Neuropsychologist or child psychiatrist experienced in both disorders. The evaluation must include ADHD tools (CPT, Conners, ASRS) AND autism (ADOS-2, ADI-R). Assessments in specialized neurodevelopment centers are preferable for these complex profiles.

Why do the two disorders mask each other?

ADHD hyperactivity can focus clinical attention and overlook the underlying autism. Conversely, the rigid autistic profile may misinterpret impulsivity as resistance. A comprehensive assessment with specific tools for both disorders is essential.

Conclusion: dual diagnosis = dual support

The comorbidity of ADHD + autism is not a rarity — it is a common clinical reality affecting tens of thousands of children and adults in France. Recognizing this comorbidity, diagnosing it correctly, and implementing support that simultaneously addresses both sets of needs is a challenge — but a challenge that can be met with the right tools and professionals.

DYNSEO supports families, teachers, and health professionals in this dual understanding. Start with the DYNSEO evaluation tests and explore dedicated training to build truly tailored support.