Reflective Practice: Are We Seeing the Overlaps Between ADHD and ASC?

Expertise in one field does not carry over into other fields. But experts often think so. The narrower their field of knowledge, the more likely they are to think so.

Robert A HeinLein, sci-fi author

Over a 3-month period (mid-Jan 2023 to mid-March 2023), I received 98 requests from adults for diagnostic assessment of autism spectrum condition (ASC). More practitioners, particularly in Britain, Australia and Canada, are using the term ‘condition’ rather than ‘disorder’, which refers to the atypical neurological development in autism without classifying it as a disorder. This term acknowledges that there are both strengths and weaknesses in learning and information processing. Approximately 20% of the requests for assessment said they had recently been diagnosed with attention deficit hyperactivity disorder (ADHD), either combined or inattentive subtypes (mostly inattentive). However, they went on to say that the diagnosis did not explain the social interaction difficulties they had experienced and continued to experience. In some cases, the prescribed stimulants did not have any effect and they had stopped taking them. What intrigued me as a practitioner who sees many adults on the autistic spectrum (level one mild) with comorbid ADHD, is how few practitioners diagnosing ADHD in adults recognise ASC as a comorbid presentation.

Prevalence

There are behaviours that are recognised to be predominantly part of ADHD, as there are characteristics that are predominantly part of ASC. The US Centers for Disease Control and Prevention (Brooks, 2023) estimated the prevalence rate of autism among 8-year-old children as one in 36 children. In NZ, Bowden et al. (2020) used administrative health data sources to identify ASC among children and young people, suggesting the prevalence among 8-year-old children was one in 102 children. Interestingly, co-occurring mental health or related problems were noted in 68% of the total group of 9555 individuals with ASC aged under 24 years. Co-occurring mental health conditions were noted in 14% of those with ADHD. Bowden et al. noted gathering data in this way most likely underestimated the cases of ASC in NZ.

A US study found ADHD prevalence in children aged 2–17 years was one in 10 (Danielson et al., 2018). The prevalence of ADHD is common in those who have ASC, and often worsens the developmental trajectory of ASC. Rong et al. (2021) estimated the current and lifetime prevalence of ADHD among people with ASC based on 63 articles and 56 studies and reported a prevalence of 38.5%–40.2%. Rong et al. made a plea for clinicians to consider this high prevalence, especially in school-age children and adolescents, and invited clinicians to improve their assessment and tracking system processes. Diagnosing this comorbidity makes for better and targeted interventions at an earlier life stage and has potential to reduce the significant suffering in those diagnosed in adulthood.

Gender, Ethnicity and Social Deprivation

It is only in the last 10 years that a higher than previously considered rate of women with neurodiversity are being seen and recognised (Beck et al., 2020). The ‘camouflaging’ characteristics of assimilation, masking and compensation have meant many have not been noticed, and it often means focused understanding is needed by the practitioner as to how women do this (Young et al., 2020). This assists the person in understanding what they have been doing and can account for accumulated high anxiety and stress levels when presenting at the diagnostic assessment.

Bowden et al. (2020) used the integrated data infrastructure method and reported that a high number of Pākehā children in urban settings were diagnosed with ASC. Although there were no substantive deprivation-related differences in the identification rate, that study noted other factors (e.g. the history of institutional racism) had led to disparities and inequalities in many health areas. Although no local studies on prevalence rates among LGBTQI or transgender groups are available, my clinical experience suggests these groups have camouflaged in a similar way to women and are therefore missed or not seen for their neurodiverse characteristics potentially with the explanations of their presentation relating to their sexual or gender preferences.

Strengths and Challenges of Having ADHD and ASC

A person who presents with autistic and ADHD traits has several strengths. They can have high energy, be creative and can be charismatic and fun to be with, including a quirky sense of humour. They can be hyper-fixated with great enjoyment and success from their careers. They can be highly compassionate. In my experience, if ADHD is dominant, the person may have difficulties in directing and maintaining attention to what is needed (distractible), there is a tendency towards inhibiting responses and risk-taking behaviours (impulsive), challenges with completion of tasks, missing social cues and errors because of distractibility, planning and initiation (procrastination) and poor working memory, especially auditory working memory. If ASC is dominant, the person may find identifying the ‘unwritten’ social code difficult, they may be cognitively rigid and inflexible, and have a need for routine and a single-track mind (perseveration). Anxiety around unexpected change is high. They are good at systems, patterns and spotting errors. Their detailed focus means that they can have difficulty grasping the bigger picture (‘weak central coherence’; Tassini et al., 2022) and they may have a slower processing speed for verbal and social information. Clients with both ADHD and ASC frequently have sensory processing difficulties, both seeking and avoiding certain sensations. Their attention is focused when the stimulus is novel or interesting to them. They can be both hyper-focused and interrupt before the other person has completed saying what they need to say, and have difficulty managing emotions. There is often a layer of shame associated with poor time perception and management. They experience rejection sensitivity, motor restlessness, challenges in sustaining and maintaining friendships, insomnia and being prompt dependent.

The challenges can be considerable for people with autism plus ADHD. Clients have described it as like ‘a war on the inside’. For example, making spontaneous plans (ADHD) but also becoming very upset if those plans are interrupted (ASC). Struggling to organise daily life/tasks (ADHD) but also having a strong need for order (ASC). Struggling to be on time (ADHD) but upset when others are a few minutes late (ASC). Hyper-fixating on a wide variety of topics (ADHD), and also having long term special interests (ASC). Gargaro et al. (2011) asked ‘Can the comorbidity of ASC and ADHD truly be established by considering executive functions alone?’ Attentional impairments in autism tend to be more of the ‘not listening’ and difficulty ‘shifting focus’ type than of the ‘short attention span’ and ‘excessive distractibility’ type. These distinct clinical particulars suggest distinct attentional symptoms inherent to ASC, rather than resulting from comorbid ADHD. Hours et al. (2022) concluded that rather than it being a comorbidity, this attentional trait should be included in the clinical definition and description of ASC instead of ADHD being the explanation.

Craig et al. (2016) identified three types of executive functions that differentiated ADHD and ASD. The only executive function difficulty experienced by the ADHD group and not the autistic group was ‘difficulty with response inhibition (impulsivity)’. The two executive function difficulties experienced by the autistic group and not the ADHD group were ‘difficulty with flexibility’ and ‘difficulty with planning’. In a workshop on autism and ADHD (held in May 2023), Professor Tony Attwood and Dr Michelle Garnett offered the following quote from Noah, who had both.

One of the biggest challenges I face is that my brain often works in non-linear ways. I can see connections and patterns that others miss, and I have a natural ability to think creatively and come up with unique solutions to problems. But at the same time, I also struggle with organisation, executive functioning and other challenges that can make it difficult for me to bring my ideas to fruition.

When both ADHD and ASC are present, clients typically have significantly poorer cognitive performance and social/adaptive abilities (Rosello et al., 2022). Dual diagnosed clients are more likely to develop emotional/behavioural difficulties, especially externalising problems, and have impairments in executive and social processing. These greater impairments in executive functioning extend to theory of mind abilities, difficulties reading non-verbal communication and empathy.

Implications for Practice

There is a strong need for practitioners to be skilled in the assessment of both ASC and ADHD. However, there are several key questions to consider as follows. How can we accomplish this? Is this a matter of identifying the practitioners who are skilled in both and bringing them together to have a healthy exchange of their clinical observations? Can they then become the trainers of others either through a series of video teaching modules or having practitioners sit in and observe the ASC/ADHD assessments? Do we need a focused series of online training sessions? How can we grow this expertise to be available? What information needs to be out there in the community of practitioners (psychiatrists, psychologists, psychotherapists, counsellors)? Currently we have organisations that attend to one or other condition, such as ADHD NZ or Autism NZ. Is it we, the practitioners, that need to inform these organisations, researchers and the public?

Support for people with ADHD and ASC is also needed in developing executive functioning skills and self-regulation practices, including in the workplace, where managers often want to know how to support people with ADHD and ASC. People with both ADHD and ASC need accommodations so they can work to the best of their capacity. Although more resources are available for the younger person (under 18 years), it is when entering the adult world of tertiary education and employment and relationships that many of these characteristics in the ADHD/ASC person become stronger, and therefore the difficulties experienced become more prevalent. It is vital that we are aware of the ‘war inside’ and can guide and counsel wisely to reduce the significant suffering these people experience. For too long they have been invisible and silenced.