AuDHD

*Research shows that 60–70% of autistic people also have ADHD.

Embrace Autism website has articles on AuDHD

AuDHD is an unofficial but popular term used to describe individuals who are Autistic and ADHD. This means that an AuDHDer has been self/formally diagnosed with autism and ADHD because they have traits characteristic of both conditions.

AuDHD is a colloquial term, but it does not exist as an official diagnosis. This means that an AuDHDer who has a formal diagnosis will have documents listing both conditions separately; it will likely say that they have ADHD and autism.

 The diagnostic criteria conceptualise ADHD as an attentional deficit. However, ADHDers are perhaps better described as having a form of hyper-attention.

 ADHDers experience all stimuli at once and these stimuli all fight for our attention, making it difficult to attend to any one thing. 

The exception is when we are absorbed in something interesting. In this case, ADHDers experience hyperfocus just like autistics do.

*The Prevalence of Attention Deficit/Hyperactivity Disorder Symptoms in Children and Adolescents With Autism Spectrum Disorder Without Intellectual Disability: A Systematic Review (Eaten et al., 2023)

Article 

There is a strong link between autism and ADHD, with both having high heritability 

and genetic overlap. 

Common traits shared in ADHD and autism include:

Sensory differences, Executive dysfunction, Hyperfocus and intense interests.

Rejection sensitivity, Social challenges, Sleep problems.

Differences in eye contact, Difficulties with interoception, such as noticing when you are hungry.

Although there are many similarities, differences exist; ADHD individuals may crave novelty and exhibit impulsivity, while autistic people often seek routine and similarity.

If someone is autistic and has ADHD, which some people refer to as AuDHD, they may experience an internal struggle between these contrasting traits.

An AuDHD person is likely to experience a heightened version of the shared autism and ADHD characteristics, such as an intense focus on hobbies and interests, or experience challenges socialising with neurotypical people.

• Someone with ADHD is more likely to seek out novelty and make more impulsive decisions, whereas an autistic person is more likely to crave routine and structure.

• If someone is autistic and has ADHD, known as AuDHD, they may experience an internal struggle between their competing autistic and ADHD traits and a heightened experience of shared traits.

There is evidence that for some Clients with AuDHD, the autistic aspect of the brain can lead to  being more sensitive to stimulant side effects.

These side effects could be : 

• Increased irritability, mood changes, or anxiety.
• Appetite suppression (with greater impact in those with sensory-based feeding challenges).
• Sleep disturbance.
• Heightened repetitive or stereotyped behaviours in some individuals.
• Risk of sensory overstimulation (amplifying hypersensitivity).

Our clinic has extensive experience in helping our AuDHD clients test out their ADHD medication 

in a slower and longer time period to help them when finding the correct dose.

Overstimulation in autistic adults reflects neurobiological differences in how the brain filters, amplifies, integrates, and recovers from input. It is not a failure of coping or emotional control; it is a systems-level load problem.

(References are listed on last page)

1. Reduced sensory filtering (thalamocortical gating)

The thalamus acts as the brain’s sensory “gatekeeper,” prioritising and dampening incoming information before it reaches the cortex.

• In many autistic adults, sensory gating is less efficient
• Background input (noise, light, movement) is not filtered out
• Result: everything arrives at once and at full strength

➡️ The brain must consciously process information that is automatic for others, rapidly consuming cognitive resources.

2. Excitation–inhibition imbalance

Neural signalling relies on a balance between:

• Excitatory activity (glutamate)
• Inhibitory control (GABA)

In autism, evidence suggests reduced inhibitory modulation in key cortical circuits.

• Sensory signals are amplified
• Neural “volume control” is limited
• Habituation (getting used to stimuli) is slower or absent

➡️ Sensory input does not fade into the background; it stays loud.

3. Hyper-reactive salience and threat detection

The amygdala and salience networks evaluate what matters and what is threatening.

• In autistic adults, ambiguous or intense sensory input may be tagged as high salience
• This drives autonomic arousal (sympathetic nervous system activation)
• The brain shifts into threat-readiness, even without danger

➡️ Overstimulation is experienced as urgency, panic, or “I need to escape now.”

4. Prefrontal cortex overload (executive collapse)

The prefrontal cortex (PFC) manages:

• Attention allocation
• Emotional regulation
• Behavioural inhibition
• Masking and social monitoring

When sensory and emotional input exceeds capacity:

• PFC resources are diverted to basic regulation
• Executive functions drop offline
• Speech, planning, and impulse control degrade

➡️ This produces shutdown (withdrawal, mutism) or meltdown (loss of behavioural control).

5. Network inefficiency and slower recovery

Autistic brains often show:

• Less synchronised long-range connectivity
• Higher local processing demand
• Increased metabolic cost for everyday tasks

After overload:

• Neural recovery is slower
• Sensory thresholds remain lowered
• Further input triggers overload more quickly

➡️ This explains cumulative overload across the day or week.

6. The cost of masking

Masking requires continuous top-down control from the PFC:

• Monitoring social cues
• Suppressing natural responses
• Translating internal experience into acceptable output

Neurologically, this:

• Raises baseline cortical load
• Reduces reserve capacity
• Lowers the threshold for overstimulation

➡️ Masking doesn’t prevent overload—it brings it closer.

Putting it together

Overstimulation occurs when:

1. Too much input enters the system
2. Too little is filtered
3. Too much is flagged as important or threatening
4. Executive regulation runs out
5. Recovery capacity is exceeded

The outcome is a neurological overload state, not a psychological choice.

There are many clinicians who explain Autism from a Differences perspective.

Autism is usually written in deficit-based context and pathological in nature.

Clinical definition:

Autism is characterised by persistent difficulties in communication and social interactions and restricted, repetitive patterns of behaviour, interests or activities. 

Neurodivergent Insights website written and created by the exceptional Dr. Megan Anna Neff 

explains Autism in a visual way.

Reframing Autism website has extensive resources and help explanations 

Autism podcast & featuring detailed website on female presentation of Autism by Dr Henderson

Embrace Autism website 

All the key Autism self report assessments can be accessed and results given 

immediately. Helpful perspectives on Autistic strengths.
From the authors: “Dissatisfied with the lack of information available on autism in adults, in 2018 we founded Embrace Autism, which we intended as a platform to distribute research and experience-based information on autism. We did this as a way to empower ourselves and fellow autistics. Because for many of us, we don’t come to fully understand and appreciate ourselves until we find out that we are autistic”.

Autism Awareness Australia website 

Interoception. Perceiving & interpreting signals from own bodies. Website 

Alexithymia: Challenges with identifying and describing  feelings. Website 

Nociception: Autistic Experiences of Pain. Website 

Hypermobility and Autism: Website 

Self identifying as Autistic  Website

Communication: Practical tips for fostering a meaningful approach  Website

Eye Contact : Understanding Autistic Differences Website 

Avoidant Restrictive Food Intake Disorder (ARFID). Website 

Anorexia Vs. ARFID: Differences In Neurodivergent Eating Disorders.  Website

Autistic Inertia: Stranded in the Moment.  Website 

Autism and Emotions: Autistic People Process Emotions Differently. Website 

Situational Mutism: A Guide for Allies. Website 

Hypersensitive & Hyper focused: An Autistic Experience of Sensory Anxiety. Website

RMC is happy to signpost Clients to 

Psychologistswho are highly skilled in understanding Autism assessments.

Camouflaging Autistic Traits Questionnaire 

25 Questions.
The CAT-Q measures camouflaging in general, as well as three subcategories:

1. Compensation — Strategies used to actively compensate for difficulties in social situations.

Examples: copying body language and facial expressions, learning social cues from movies and books.

2. Masking — Strategies used to hide autistic characteristics or portray a non-autistic persona.

Examples: adjusting face and body to appear confident and/or relaxed, forcing eye contact.

3. Assimilation — Strategies used to try to fit in with others in social situations.

Examples: Putting on an act, avoiding or forcing interactions with others
It may be used to identify autistic individuals who do not currently meet diagnostic criteria due to their ability to mask their autism.

Social camouflaging is defined as the use of strategies by autistic people to minimise the visibility of their autism during social situations. Social camouflaging encompasses an explicit effort to ‘mask’ or ‘compensate’ for autistic characteristics; and to use conscious or unconscious techniques which result in a less autistic behavioural presentation article

The Ritvo Autism Asperger Diagnostic Scale–Revised (RAADS‑R) 

80 Questions. 

This is a validated instrument that helps identify autism in adults by examining lifelong patterns of cognition, perception, and behaviour. It’s especially helpful for those who relate to autistic traits but were not recognised due to masking, gender bias, or late-identified neurodivergence. It is designed to uncover developmental, social, sensory, and communication traits that may indicate autism, especially in adults who were missed or misdiagnosed earlier in life.

The Autism Spectrum Quotient (AQ) is a self-administered questionnaire used to measure autistic traits in adults (age 16+). 50 questions. The AQ measures 5 areas often associated with autism spectrum conditions:

1. Social Skill – comfort and ability in social situations.
2. Attention Switching – flexibility in shifting attention.
3. Attention to Detail – preference for and noticing of small details.
4. Communication – ease of verbal interaction.
5. Imagination – ability to imagine and empathize with others.

Autism Spectrum Disorder 

AuDHD: why Autism is so difficult to diagnose in girls & women with ADHD

Video

Divergent Voices YouTube Channel  video 

Autism & Eating Disorder Challenges  video by Divergent Voices 

Autism & ADHD  video by Divergent Voices 

Could I be on the Autism Spectrum ? video

Overlook traits of Autism in Women  video

Late Autism Diagnosis in Women  video by Divergent Voices 

Baron-Cohen, S., Ashwin, E., Ashwin, C., Tavassoli, T., & Chakrabarti, B. (2009). Talent in autism: Hyper-systemizing, hyper-attention to detail and sensory hypersensitivity. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1522), 1377–1383. https://doi.org/10.1098/rstb.2008.0337

Cascio, C. J., Woynaroski, T., Baranek, G. T., & Wallace, M. T. (2016). Toward an interdisciplinary approach to understanding sensory function in autism spectrum disorder. Autism Research, 9(9), 920–925. https://doi.org/10.1002/aur.1612

Green, S. A., & Ben-Sasson, A. (2010). Anxiety disorders and sensory over-responsivity in children with autism spectrum disorders. Journal of Autism and Developmental Disorders, 40(12), 1495–1504. https://doi.org/10.1007/s10803-010-1005-z

(Widely extrapolated to adults in later literature)

Excitation–inhibition imbalance

Rubenstein, J. L. R., & Merzenich, M. M. (2003). Model of autism: Increased ratio of excitation/inhibition in key neural systems. Genes, Brain and Behavior, 2(5), 255–267. https://doi.org/10.1034/j.1601-183X.2003.00037.x

Robertson, C. E., & Baron-Cohen, S. (2017). Sensory perception in autism. Nature Reviews Neuroscience, 18(11), 671–684. https://doi.org/10.1038/nrn.2017.112

Thalamocortical filtering & sensory amplification

Nair, A., Treiber, J. M., Shukla, D. K., Shih, P., & Müller, R.-A. (2013). Impaired thalamocortical connectivity in autism spectrum disorder: A study of functional and anatomical connectivity. Brain, 136(6), 1942–1955. https://doi.org/10.1093/brain/awt079

Woodward, N. D., Giraldo-Chica, M., Rogers, B., & Cascio, C. J. (2017). Thalamocortical dysconnectivity in autism spectrum disorder. Journal of Autism and Developmental Disorders, 47(8), 2540–2547. https://doi.org/10.1007/s10803-017-3166-1

Salience network, amygdala, and autonomic activation

Uddin, L. Q., Menon, V., & Pelphrey, K. A. (2013). Dynamic reconfiguration of structural and functional connectivity across core neurocognitive brain networks with development. Journal of Neuroscience, 33(12), 5247–5258. https://doi.org/10.1523/JNEUROSCI.3712-12.2013

Green, S. A., Hernandez, L., Tottenham, N., Krasileva, K., Bookheimer, S. Y., & Dapretto, M. (2015). Neurobiology of sensory overresponsivity in youth with autism spectrum disorders. JAMA Psychiatry, 72(8), 778–786. https://doi.org/10.1001/jamapsychiatry.2015.0737

(Mechanisms generalise to adult models of overload)

Executive function collapse & cognitive load

Just, M. A., Keller, T. A., Malave, V. L., Kana, R. K., & Varma, S. (2012). Autism as a neural systems disorder: A theory of frontal-posterior underconnectivity. Neuroscience & Biobehavioral Reviews, 36(4), 1292–1313. https://doi.org/10.1016/j.neubiorev.2012.02.007

Hill, E. L. (2004). Executive dysfunction in autism. Trends in Cognitive Sciences, 8(1), 26–32. https://doi.org/10.1016/j.tics.2003.11.003

Masking, burnout, and cumulative overload

Hull, L., Petrides, K. V., Allison, C., Smith, P., Baron-Cohen, S., Lai, M.-C., & Mandy, W. (2017). “Putting on my best normal”: Social camouflaging in adults with autism spectrum conditions. Journal of Autism and Developmental Disorders, 47(8), 2519–2534. https://doi.org/10.1007/s10803-017-3166-1

Raymaker, D. M., Teo, A. R., Steckler, N. A., et al. (2020). “Having all of your internal resources exhausted beyond measure”: Defining autistic burnout. Autism in Adulthood, 2(2), 132–143. https://doi.org/10.1089/aut.2019.0079