ADHD (F90.0, F90.1, F90.2) centers on attention and impulse control; autism spectrum disorder (F84.0) centers on social communication differences and restricted, repetitive behaviors. They overlap and can co-occur, and DSM-5 permits coding both.
Quick Comparison
| Feature | ADHD (F90.x) | Autism (F84.0) |
|---|---|---|
| Core feature | Attention regulation and impulse control | Social communication and restricted, repetitive behavior |
| Social difficulty cause | Inattention and impulsivity (missed cues, interrupting); social motivation intact | Core social-communication deficit; difficulty reading and using social signals |
| Repetitive behavior | Motor restlessness, fidgeting, driven by hyperactivity | Restricted interests, insistence on sameness, stereotyped movements |
| ICD-10 code | F90.0, F90.1, F90.2 | F84.0 |
Same overlap, different roots. ADHD and autism can look alike on the surface (both may struggle socially and both may move a lot), but the underlying mechanism differs. That mechanism, not the surface behavior, is what drives the correct diagnosis and code.
Where They Overlap
ADHD and autism share several features, which is why they are so often confused and why careful differential reasoning matters:
- Attention: both can present with attention that looks atypical. In ADHD attention is poorly regulated and easily diverted; in autism attention may be narrowly and intensely fixed on preferred topics, which can look like distractibility when the child is pulled away from an interest.
- Social difficulty: both groups can struggle in social settings. Children with either condition may have fewer friendships and more peer conflict, even though the reason differs.
- Executive function: both conditions involve executive-function challenges, including planning, working memory, task initiation, and shifting between activities. Difficulty with transitions and organization is common to both.
Because the surface picture overlaps, a presentation should never be coded on behavior alone. The clinical work is identifying the mechanism behind the shared feature.
How to Tell Them Apart
Two questions do most of the differential work: what is driving the social difficulty, and what is driving the repetitive behavior.
Social motivation versus social-communication deficit. In ADHD, the child typically wants and understands social connection, but inattention and impulsivity get in the way: interrupting, missing cues because attention drifted, or acting before thinking. Social motivation and the underlying grasp of reciprocity are intact. In autism, the difficulty is a core social-communication difference: reading and using nonverbal signals, understanding another person's perspective, and sustaining reciprocal interaction. The deficit is in the social-communication machinery itself, not in attention.
Restlessness versus restricted interests. The repetitive behavior of ADHD is hyperactive restlessness: fidgeting, an inability to stay seated, feeling driven by a motor. It is not tied to specific content. In autism, repetitive behavior is restricted and patterned: intense, narrowly focused interests, insistence on sameness and routines, and stereotyped movements. The behavior is content-specific and serves predictability, not discharge of physical energy.
Practical framing: ask whether the child struggles socially because attention got in the way (points to ADHD) or because reading and using social communication is itself hard (points to autism); and whether the repetitive behavior is undirected restlessness (ADHD) or a focused need for sameness and special interests (autism).
How to Code Each
ADHD. Code ADHD by presentation within the F90 family. Match the code to the pattern of symptoms documented in your assessment:
| Code | Description | Notes |
|---|---|---|
| F90.0 | ADHD, predominantly inattentive presentation | Inattention predominates; hyperactivity minimal |
| F90.1 | ADHD, predominantly hyperactive-impulsive presentation | Hyperactivity and impulsivity predominate |
| F90.2 | ADHD, combined presentation | Both inattentive and hyperactive-impulsive criteria met |
| F90.9 | ADHD, unspecified type | Temporary placeholder only |
Autism spectrum disorder. Autism uses a single ICD-10-CM code regardless of level of support needs:
| Code | Description | Notes |
|---|---|---|
| F84.0 | Autistic disorder (autism spectrum disorder) | Single code for the full spectrum in ICD-10-CM |
One code, spectrum detail in the note: ICD-10-CM has a single autism code (F84.0). Capture severity, level of support needs, and any co-occurring intellectual or language impairment in your documentation, since the code alone does not convey them.
When Both Are Present
DSM-5 allows a dual diagnosis of ADHD and autism. The DSM-IV rule that prohibited diagnosing ADHD in the presence of autism was removed in 2013, and the two conditions co-occur often. When a client independently meets criteria for each, code both: F84.0 plus the relevant F90 code.
| Code Pairing | Description | Notes |
|---|---|---|
| F84.0 + F90.2 | Autism with combined-presentation ADHD | Most common co-occurring pattern |
| F84.0 + F90.0 | Autism with inattentive ADHD | Inattention may be masked by restricted interests |
| F84.0 + F90.1 | Autism with hyperactive-impulsive ADHD | Restlessness distinct from stereotyped movement |
There is no combined code for co-occurring ADHD and autism. Bill both diagnoses, list the primary focus of treatment first, and document how each condition independently meets criteria so the pairing supports medical necessity.
Do not force a single label. When features of both are genuinely present, choosing only one code undercodes the presentation and can misdirect treatment. If each condition meets its own threshold, code both rather than collapsing them into one.
Documentation
Strong documentation for an ADHD-versus-autism differential should include:
Nature of the social difficulty: whether the social problems stem from inattention and impulsivity (with social motivation intact) or from a core social-communication deficit, with concrete examples.
Nature of the repetitive behavior: whether it is undirected hyperactive restlessness or content-specific restricted interests, insistence on sameness, and stereotyped movements.
Developmental history: age of onset and early social-communication milestones, which help separate a lifelong autism profile from an attention-regulation profile.
ADHD presentation: which F90 presentation the symptoms support (inattentive, hyperactive-impulsive, or combined) and the settings in which impairment appears.
Co-occurrence rationale: when coding both F84.0 and an F90 code, a brief note on how each condition independently meets criteria and which is the primary focus of treatment.
Frequently Asked Questions
- Can you have both ADHD and autism?
- Yes. DSM-5 explicitly permits a dual diagnosis of ADHD and autism spectrum disorder; the earlier DSM-IV rule that barred coding both was removed in 2013. The conditions co-occur frequently, and when a client meets criteria for each you code both. In ICD-10-CM that means F84.0 for autism spectrum disorder plus the matching F90 code for ADHD (F90.0, F90.1, or F90.2).
- What is the ICD-10 code for autism?
- Autism spectrum disorder is F84.0 in ICD-10-CM. This single code covers the full spectrum; ICD-10-CM does not use separate codes for what were once called Asperger's disorder or PDD-NOS. Document the level of support needs and any co-occurring intellectual or language impairment in the note rather than in the code itself.
- What is the code for ADHD?
- ADHD is coded in the F90 family by presentation: F90.0 for the predominantly inattentive presentation, F90.1 for the predominantly hyperactive-impulsive presentation, and F90.2 for the combined presentation. F90.9 (unspecified) exists as a temporary placeholder but should be replaced with a specific presentation code once your assessment supports it.
- How do you tell ADHD from autism?
- Focus on the nature of the social difficulty and the nature of the repetitive behavior. In ADHD, social problems usually stem from inattention and impulsivity, such as interrupting or missing cues, while social motivation and the underlying grasp of social communication are intact. In autism, the social difficulty is a core communication difference, and repetitive behavior takes the form of restricted, intense interests and a need for sameness rather than restlessness.
- Does one diagnosis rule out the other?
- No. Neither diagnosis excludes the other under current criteria. When features of both are present and each independently meets its diagnostic threshold, the correct approach is to diagnose and code both (F84.0 plus the relevant F90 code) rather than forcing the presentation into a single label.
Accurate differentiation comes down to mechanism: attention and impulse control point to ADHD (F90.0, F90.1, F90.2), while a core social-communication difference with restricted, repetitive behavior points to autism (F84.0). When both are genuinely present, DSM-5 permits coding both, so record each clearly and code F84.0 alongside the matching F90 code.