How Autism & ADHD Can Be Misdiagnosed as Anxiety

In Australia, autism and ADHD are sometimes misdiagnosed as anxiety – especially in women and girls, whose symptoms are more likely to be masked or overlooked. While these are distinct conditions, autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and anxiety disorders can share overlapping symptoms. Shared symptoms of autism, ADHD, and anxiety include difficulty in concentration, emotional overload, and feelings of restlessness.

A study published in The Lancet in 2024 found that 25% of autistic adults felt that they had been misdiagnosed before receiving their autism diagnosis, and over 40% felt their diagnoses did not fully reflect their experiences. Without an accurate diagnosis, people may be treated for the wrong condition – delaying access to appropriate support, therapy, or services like the NDIS.

Differences Between Autism, ADHD, and Anxiety

On the surface, some symptoms of autism, ADHD, and anxiety may appear very similar. However, the differences lie in the underlying causes of these behaviours. Anxiety is a psychological condition, whereas ASD and ADHD are neurodevelopmental conditions.

Anxiety disorders are marked by persistent worry and fear. This leads to a state of hypervigilance and a tendency to avoid situations related to fears.

Individuals with autism are not primarily affected by fear or worry. Instead, autism is characterised by differences in social communication, behavioural patterns, and sensory sensitivity, such as a need for routines or a hyperfocus on specific interests. Autism is sometimes mistaken for social anxiety as people may appear withdrawn, quiet, or unsure in social situations, but this is not usually due to fear of judgment. It is more often linked to difficulty reading social cues, processing conversations in real-time, or finding the interaction meaningful.

Individuals with ADHD face challenges with attention and impulsivity due to differences in brain development, rather than fear and worry. When someone struggles to focus on tasks, it can be easily mistaken for psychological worry, but in reality, the root cause is neurological.

How Common is Co-Occurrence for Autism, Anxiety, and ADHD?

It is possible for individuals to be diagnosed with more than one condition, which can often complicate both diagnosis and treatment.

“AuDHD” is a popular informal term for the co-occurrence of autism and ADHD. According to research published by Frontiers in Psychiatry in 2022, between 50-70% of individuals with autism also met the criteria for ADHD. Meanwhile, a study published in Autism Research in 2024 found that 9.8% of children with ADHD also met the criteria for autism.

The co-occurrence of ADHD and anxiety is also well documented. A 2015 study by Tsang et. al. found that 31% of children with ADHD had at least one comorbid anxiety disorder, most commonly generalised anxiety disorder, followed by social anxiety, and obsessive-compulsive disorder.

These overlaps in symptom presentations highlight the need for comprehensive assessments of these conditions.

How Autism & ADHD Can Be Misdiagnosed as Anxiety

Getting the Right Diagnosis for Anxiety, ASD, and ADHD

Working with a qualified psychologist or medical professional is the only way to get an accurate diagnosis for anxiety, ASD, and ADHD. Online self-diagnosis questionnaires are not a reliable way to differentiate between conditions with overlapping symptoms.

Each condition has a specific diagnostic process that is designed to identify key traits and rule out other conditions.

Diagnosis for Anxiety

Psychologists often use standardised assessment tools such as the Beck Anxiety Inventory (BAI) and the Depression Anxiety Stress Scales (DASS-21) to diagnose the level and type of anxiety symptoms. These tools are typically administered during an in-clinic consultation and form part of a broader clinical interview based on DSM-5 criteria.

Diagnosis for ASD

The diagnosis for ASD starts with an initial screening session with a psychologist. During this screening session, the psychologist will explore presenting concerns and determine whether a full assessment is necessary.

A full assessment will involve the use of tools such as the Autism Diagnostic Observation Schedule (ADOS-2) and Adaptive Behaviour Assessment System (ABAS-3), used in combination with behavioural observations, developmental history, and information from caregivers, teachers, or family members.

Diagnosis for ADHD

An ADHD diagnosis will also start with a one-hour initial screening session to determine whether a full assessment is required.

A comprehensive ADHD assessment will include a clinical interview, behavioural questionnaires and cognitive testing, using tools such as the Behaviour Assessment System for Children (BASC-3), Adult ADHD Self-Report Scale (ASRS), Wechsler Intelligence Scale (WISC-V, WAIS-IV ) and more.

The Risks of Misdiagnosis

When neurodevelopmental conditions like ASD and ADHD are misdiagnosed as psychological conditions like anxiety, these individuals miss out on getting the crucial support they need. A professional diagnosis is essential for receiving the right treatment and medication, as well as accessing government-funded support programs like the NDIS.

Psychological treatment for anxiety will not address the core needs of individuals with ADHD and autism. For example, treatment for anxiety may focus on reducing fear or worry, while overlooking executive functioning challenges, sensory sensitivities, or social communication differences that are central to ADHD and autism. In the long term, the wrong treatment approach can be ineffective or even harmful, leading to frustration, low self-esteem or worsening mental health.

How Tailored Treatment Can Help

For any treatment to be effective, it must be tailored to the individual’s condition. Having an accurate diagnosis for autism, ADHD, or both will allow psychologists to create a treatment plan that addresses the specific needs of the individual.

For example, treatment for ADHD may involve behavioural coaching and attention management strategies, while autism treatment may cover social skills training and sensory integration therapy.
At New Vision Psychology, we offer tailored autism assessments and ADHD assessments in Sydney at our clinics. Our professional psychologists provide compassionate, evidence-based care to help you better understand your needs and find the right path forward. Our initial screening sessions provide an ethical and cost-effective way to check for signs of ADHD and ASD without having to commit to a full assessment upfront. Get in touch with us to learn more.