Yes, autism can be misdiagnosed as ADHD. Studies have found that 20 to 40 percent of people with autism also meet the criteria for ADHD, but many others receive an ADHD diagnosis first before their autism is identified. The two conditions share several core traits, which makes telling them apart genuinely difficult even for experienced clinicians.
Why Do Autism and ADHD Get Confused So Often?
Both conditions affect how the brain processes information and manages attention. A child who seems distracted and impulsive might have ADHD, or they might be overwhelmed by sensory input from autism. The outward behavior looks the same even when the root cause is different.
Research published in the journal Autism found that about 15 percent of children diagnosed with ADHD later received an autism diagnosis. Many clinicians still operate under the old belief that a person cannot have both conditions. The American Psychiatric Association removed that restriction in 2013, but practice has been slow to catch up.
Social difficulties are another big overlap. A child who does not make eye contact or struggles with back-and-forth conversation could fit either diagnosis. The key difference is often why the behavior happens. In ADHD, social problems usually come from impulsivity or inattention. In autism, they come from differences in understanding social cues and communication.
What Are the Core Differences Between Autism and ADHD?
There is real overlap, but the two conditions have distinct features that help doctors tell them apart. The table below shows the main differences based on diagnostic criteria from the DSM-5.
| Trait | Autism | ADHD |
|---|---|---|
| Attention | Intense focus on specific interests; difficulty shifting attention | Easily distracted; difficulty sustaining attention on non-preferred tasks |
| Social interaction | Difficulty understanding social rules, nonverbal cues, and reciprocal conversation | May interrupt or miss social cues due to impulsivity or inattention |
| Repetitive behaviors | Hand-flapping, rocking, lining up objects, insistence on routines | Fidgeting, restlessness, but generally not repetitive in the same patterned way |
| Sensory issues | Common and often intense; over- or under-reaction to sounds, textures, lights | Possible but less central to the diagnosis |
| Hyperactivity | Less common as a primary feature | Core symptom in many cases |
No single trait seals the diagnosis. Clinicians look at the pattern over time and across settings. A child who has intense special interests and struggles with changes in routine is more likely autistic. A child who is restless in every situation and cannot finish tasks is more likely ADHD.
How Often Does Autism Get Misdiagnosed as ADHD?
The exact rate is hard to pin down because studies use different methods. But the numbers are significant enough that the National Institute of Mental Health has called for better diagnostic training.
A 2020 study in the Journal of Autism and Developmental Disorders looked at over 1,500 children. It found that roughly 25 percent of children with an initial ADHD diagnosis actually met the criteria for autism when evaluated more thoroughly. That is one in four children who might be treated for the wrong condition.
Adults face an even higher risk of misdiagnosis. Many adults with autism have learned to mask their symptoms over years of social pressure. They may appear to have ADHD because they struggle with organization and focus, but the underlying reason is autistic burnout or sensory overload rather than a deficit of attention.
Girls and women are especially likely to be misdiagnosed. Research shows that girls with autism often present differently than boys. They may have fewer obvious repetitive behaviors and more social imitation, which leads clinicians to diagnose ADHD or anxiety instead.
Can a Person Have Both Autism and ADHD?
Yes, and it is common. The CDC reports that about 30 to 50 percent of autistic people also have ADHD symptoms significant enough for a diagnosis. Having both conditions is not rare, and it changes how symptoms show up.
When both are present, the traits can blend in confusing ways. A person might have the intense focus of autism and the impulsivity of ADHD at the same time. They might need routines for comfort but struggle to stick with them because of inattention. This combination can make diagnosis harder because neither condition looks textbook.
Some studies suggest that having both conditions is linked to greater functional challenges. People with both may have more trouble with executive function, emotional regulation, and daily living skills than people with either condition alone. Getting the right diagnosis for both is important for finding the right support.
Clinicians who specialize in neurodevelopmental conditions are more likely to recognize both. A general practitioner or a therapist who mainly treats anxiety may miss the signs. If you suspect both conditions are at play, seeking an evaluation from a specialist with experience in autism and ADHD is the most reliable path.
What Happens When Autism Is Misdiagnosed as ADHD?
Treatment for ADHD focuses on managing attention and impulsivity. Stimulant medications like methylphenidate are common. For someone with autism who does not have ADHD, these medications may not help and can cause side effects including increased anxiety, irritability, and sleep problems.
Behavioral therapies for ADHD target organization, time management, and impulse control. These can be helpful for some autistic people too, but they miss the core needs. An autistic person may need support with sensory regulation, social communication, and managing rigid thinking patterns. Without addressing these, the person may continue to struggle even if their attention improves.
Misdiagnosis also delays access to autism-specific services. Early intervention for autism makes a meaningful difference in communication and daily functioning. A child who is treated only for ADHD may miss years of speech therapy, occupational therapy, or social skills training that could have helped more.
Emotionally, a wrong label can be damaging. People with autism who are told they have ADHD may internalize the idea that they just need to try harder to focus. This can lead to years of self-blame and frustration when standard ADHD strategies do not work.
How Can You Tell the Difference Between Autism and ADHD?
There is no single test that separates the two. A thorough evaluation takes time and looks at multiple sources of information. The process typically includes:
- Developmental history — when did symptoms first appear? Autism signs often show up before age three. ADHD can be noticed later once demands for sustained attention increase.
- Social communication patterns — does the person struggle with the back-and-forth of conversation or miss nonverbal cues? This is more specific to autism.
- Restricted interests and routines — intense focus on specific topics and distress over small changes strongly point toward autism.
- Sensory responses — strong reactions to sounds, lights, textures, or smells are more characteristic of autism.
- Response to treatment — if ADHD medication does not work or causes bad side effects, it is worth revisiting the diagnosis.
A good clinician will also rule out other conditions that can look similar, including anxiety disorders, obsessive-compulsive disorder, and learning disabilities. The evaluation should involve interviews with family members, school or work observations, and standardized assessment tools like the ADOS-2 for autism or the Conners rating scales for ADHD.
If you are unsure about a current diagnosis, a second opinion from a specialist is reasonable. Many autism assessment centers offer comprehensive evaluations that can clarify whether autism, ADHD, or both are present.
Common Misconceptions About Autism and ADHD Misdiagnosis
A common myth is that autism and ADHD are completely separate and cannot occur together. This belief was officially outdated in 2013 but still influences how some clinicians diagnose. The reality is that they co-occur frequently, and having both is not a mistake or a rare exception.
Another misconception is that autism is obvious in childhood. Many autistic people, especially those with average or above-average intelligence, learn to mask their traits. They may appear socially typical but feel exhausted from the effort. Clinicians who rely on surface-level observations may miss autism entirely.
Some people believe that if ADHD medication works, the person cannot have autism. This is not true. Stimulant medications can help with attention in autistic people who also have ADHD. A positive response to medication does not rule out autism.
There is also a belief that autism is a childhood condition that people outgrow. Autism is lifelong. Symptoms may change with age and support, but the underlying differences in brain wiring remain. An adult who was never diagnosed as a child can still be autistic.
Frequently Asked Questions
Can autism be mistaken for ADHD in adults?
Yes, this happens often because adults with autism may have learned to mask social difficulties while still struggling with focus and organization that looks like ADHD.
What is the best way to get an accurate diagnosis?
A comprehensive evaluation by a specialist in neurodevelopmental conditions using standardized tools and developmental history interviews is the most reliable approach.
Can ADHD medication make autism symptoms worse?
For some people, stimulant medications can increase anxiety, irritability, or repetitive behaviors, especially if autism is present without ADHD.
How long does it take to tell the difference between autism and ADHD?
A thorough evaluation typically requires multiple sessions over several weeks to gather history, observe behavior, and rule out other conditions.
