ADHD and Autism (AuDHD): Understanding Co-Occurring Diagnosis in the UK

ADHD and autism share surface-level similarities that can confuse both clinicians and individuals. Both involve difficulties with executive function, sensory processing differences, social challenges and emotional regulation. However, the underlying reasons often differ. An autistic person may struggle with social situations because of differences in processing social cues, while someone with ADHD may struggle socially because of impulsivity or inattention during conversations.

The masking effect works in both directions. ADHD's impulsivity and novelty-seeking can hide autistic traits - the person appears socially outgoing rather than rigidly routine-driven. Conversely, autistic coping strategies like careful planning and list-making can disguise the core symptoms of ADHD such as disorganisation and forgetfulness. The result is often a person who appears to cope well on the surface but is exhausted from the effort of managing two competing neurological profiles.

Women and girls are disproportionately affected by missed dual diagnoses. Both ADHD and autism present differently in women compared to the stereotypical male presentation that diagnostic criteria were historically built around. Women are more likely to develop sophisticated masking behaviours, to internalise rather than externalise their difficulties, and to receive alternative diagnoses such as anxiety, depression or personality disorders before either ADHD or autism is considered.

Our guide to ADHD in women covers the specific ways ADHD is missed in female patients. When you layer autistic masking on top of ADHD masking, the chances of accurate diagnosis drop further. Many women with AuDHD are not identified until their thirties, forties or later, often after a child's diagnosis prompts them to examine their own experiences.

In the UK, ADHD and autism assessments are typically run as separate processes, often by different teams within the same trust. An ADHD assessment is usually carried out by a psychiatrist, while an autism assessment is carried out by a multidisciplinary team that may include a clinical psychologist, speech and language therapist and occupational therapist.

If you suspect you have both conditions, it is worth pursuing both assessments. You can request them simultaneously through your GP, though they will likely be processed by different services with different waiting lists. Some private providers now offer combined neurodevelopmental assessments that assess for both ADHD and autism in a single process, which can be more efficient and produces a more integrated clinical picture.

NHS waiting times for autism assessment are often longer than for ADHD - in some areas, three to five years. Right to Choose applies to ADHD assessment in England but is more limited for autism, as fewer providers are set up to accept NHS-funded autism referrals under the patient choice framework.

Medication decisions become more nuanced with a dual diagnosis. Stimulant medications commonly prescribed for ADHD can sometimes increase sensory sensitivity or anxiety, both of which may already be heightened in autistic people. This does not mean medication is unsuitable - many people with AuDHD benefit significantly from ADHD medication - but it does mean that titration should be approached carefully, with close monitoring of sensory and anxiety responses alongside the standard ADHD symptom tracking.

Beyond medication, therapeutic approaches for AuDHD often need to address both sets of needs. Standard ADHD coaching focused on novelty and motivation may clash with an autistic need for routine and predictability. Similarly, autism support strategies that rely on rigid structure may not account for ADHD's need for flexibility. The most effective support tends to come from practitioners who understand both conditions and can tailor strategies accordingly.

Sensory processing differences are common in both ADHD and autism, but they manifest differently. ADHD-related sensory issues tend to involve difficulty filtering background noise or becoming overwhelmed in busy environments. Autistic sensory issues can be more specific - certain textures, lights, sounds or smells may be intensely uncomfortable or even painful.

With AuDHD, these sensory profiles combine in ways that can be unpredictable. A person might seek out intense sensory experiences (an ADHD trait) while simultaneously being overwhelmed by certain sensory input (an autistic trait). Understanding your own sensory profile is one of the most practical things you can do after a dual diagnosis. Conditions like rejection sensitive dysphoria can also intensify when both neurotypes are present, as emotional regulation is affected by both ADHD and autism.

Executive function - the brain's ability to plan, prioritise, start tasks and manage time - is typically affected by both conditions, but in different ways. ADHD executive dysfunction is often about motivation and initiation, while autistic executive dysfunction may relate more to transitions and flexibility. Recognising which type of difficulty you are experiencing in a given moment can help you choose the right coping strategy.