Clinical insights: what happens in an autism assessment? Understanding the process & its role in diagnosis
22nd January 2025 / Written by Harbor London
Autism spectrum disorder (ASD) affects more than 1 in 100 people in the UK, according to the National Autistic Society, meaning there are around 700,000 individuals1 currently living with autism. However, despite growing awareness, many adults remain undiagnosed – possibly as many as a further 750,0002 – which can create significant personal and societal challenges.
Autism is a type of neurodiversity that influences how individuals perceive the world and interact with others, presenting a spectrum of strengths and challenges. For adults, receiving a diagnosis often provides clarity and validation after years3 of navigating misunderstood behaviours and cognitive patterns. With that said, the diagnostic process can feel daunting for many.
As medical and clinical professionals, it’s important to guide clients through this journey, ensuring they understand what to expect and how to prepare. This article provides an in-depth look at autism assessments and their vital role in delivering accurate diagnoses and tailored support.
Interested in learning more about Harbor London’s whole-person approach? Contact us →
The challenges of living with undiagnosed autism
Many adults with undiagnosed autism may find communication challenging, experience sensory sensitivities, or tend towards rigid routines without ever understanding the underlying cause4. These issues can lead to misdiagnosis, often as anxiety, depression, or personality disorders.
From a clinical perspective, undiagnosed autism increases vulnerability to mental health conditions5. Studies indicate that up to 70% of autistic individuals also experience co-occurring mental health conditions6, such as generalised anxiety disorder (GAD) or major depressive disorder (MDD); without a diagnosis, people may develop maladaptive coping mechanisms.
Additionally, many adults report certain challenges in building and maintaining relationships, whether at work or within their families. For example, challenges with non-verbal cues or sensory overwhelm may lead to misunderstandings, contributing to isolation or frustration7. In severe cases, these struggles may result in burnout, particularly when individuals mask certain behaviours in order to fit societal norms.
Early diagnosis and intervention, ultimately, are critical, for helping individuals access the tools they need to thrive.
What autism means, and what it doesn’t
Autism is not a disease, neurological, or mental health condition8. It reflects neurodiversity, a concept recognising the natural variations in human brain development. People with autism often experience heightened attention to detail, strong pattern recognition, and unique problem-solving skills9.
However, autism can also involve challenges, particularly in areas such as communication, sensory processing, and executive functioning10. These can vary widely, which is why autism is referred to as a “spectrum” condition. While some individuals may require significant support, others lead highly independent lives, excelling independently in their personal and professional pursuits.
Autism is not thought to be caused by parenting style, trauma, or external environmental factors. Current research supports a genetic predisposition11, with studies identifying a complex interplay between genetic and environmental influences during prenatal development.
As a clinical and wider social community, it’s vital to approach autism without bias; rather emphasising its diversity. An accurate understanding helps individuals and their families view ASD with perspective and knowledge, paving the way for informed support strategies.
The neurobiology and neurochemistry
Autism is rooted in differences in brain structure and function, particularly within the cerebral cortex, amygdala, and cerebellum12. Neuroimaging studies have revealed altered connectivity in the default mode network (DMN), which governs self-referential thinking and social cognition13. These differences may explain challenges with social communication and theory of mind.
At the neurochemical level, serotonin dysregulation and glutamate-GABA imbalance are key areas of focus14. Elevated serotonin levels in the brain’s synaptic spaces are often observed, potentially contributing to sensory sensitivities and repetitive behaviours. Meanwhile, a hyperexcitable glutamatergic system can result in heightened arousal and specific challenges with sensory integration.
Studies also indicate that autistic brains exhibit reduced synaptic pruning during early childhood, which may lead to overconnectivity in certain regions15. This neurobiological complexity underpins the diversity of autism, highlighting the importance of individualised diagnostic and therapeutic approaches.
The importance of accurate diagnosis
An accurate autism diagnosis provides individuals with clarity, helping them better understand their experiences16. Diagnosis also enables access to appropriate support services, including accommodations at work, educational adjustments, and targeted therapeutic interventions.
Clinically, diagnosis ensures that co-occurring conditions such as ADHD, OCD, or mood disorders are recognised and addressed. It also prevents misdiagnosis, reducing the risk of inappropriate or ineffective treatments.
Furthermore, early intervention – regardless of age – can significantly improve quality of life, enabling individuals to build on their unique strengths.
What happens in an autism assessment?
An autism assessment is a multi-step process involving interviews, observations, and standardised tools designed to evaluate behaviour, communication, and developmental history. In general, individuals can expect:
Initial referral and pre-assessment questionnaires
The process often begins with a referral to a specialist team or clinic. Individuals are typically asked to complete detailed questionnaires about their experiences, challenges, and developmental history. Family members or close contacts may also provide input to offer additional context.
Clinical interview
A key component of the assessment is the clinical interview, which explores the client’s history, behaviours, and individual presentation17. This is conducted by trained clinicians, such as psychologists or psychiatrists, who use structured frameworks like the Autism Diagnostic Interview-Revised (ADI-R)18.
Standardised assessments
Tools such as the Autism Diagnostic Observation Schedule (ADOS-2) are often used19 to observe behaviours and communication skills. These assessments are designed to identify core characteristics of autism, such as individual challenges with social reciprocity or restricted interests.
Developmental and medical history review
For adult individuals, clinicians may explore childhood behaviours, educational experiences, and family medical history to identify patterns indicative of autism. This thoroughness ensures that other factors, such as trauma or mental health conditions, are also considered.
Feedback and diagnosis
Once the evaluation is complete, the clinician provides detailed feedback, discussing the findings and whether the criteria for ASD have been met. Clients are given a diagnostic report, which outlines strengths, challenges, and recommendations for support.
Tips to help clients prepare
Healthcare professionals can help clients approach an autism assessment by sharing these practical tips:
- Encourage honesty: advise clients to describe their experiences openly, even if they seem unrelated. Accurate reporting helps clinicians form the most complete picture.
- Organise records: individuals should gather any relevant documentation, such as childhood medical or educational records, ahead of time, to assist with the developmental history review.
- Prepare questions: encourage clients to note down any questions or concerns they may have about the process or diagnosis.
- Manage expectations: explain that the assessment is thorough, and may take some time, but is a critical step toward clarity and support.
Private, curated & whole-person autism management
An autism diagnosis serves as a pivotal foundation for understanding an individual’s unique strengths and challenges20. At Harbor London, we offer discreet and curated care that prioritises both confidentiality and a whole-person approach; helping with the management of ASD, as well as treating co-occurring mental health conditions.
Importantly, we don’t aim to ‘treat’ autism. Rather, with our expert assistance and clinical guidance, we help develop management strategies. In the context of ASD, this involves a multifaceted strategy tailored to each person’s profile. Therapeutic interventions play a central role21, with approaches such as CBT, speech therapy, and occupational therapy helping to address specific challenges, while psychoeducation is another component of effective care22, fostering a sense of empowerment and acceptance.
For many individuals, particular attention on enhancing communication and building stronger relationships23 is valuable. Targeted programs address difficulties in interpreting social cues, expressing emotions, or initiating interactions, helping individuals form meaningful connections.
Equally important are lifestyle adjustments designed to accommodate sensory sensitivities or rigid routines, which are common features of autism. By creating supportive environments, either at home, in educational settings, or within workplaces, individuals can better manage potential stressors while pursuing their goals.
At Harbor London, we believe that no two journeys with autism are alike, and every individual deserves a curated plan that celebrates their individuality and unlocks their full potential.
To learn more about our services or to make a referral, contact our dedicated team today.
References
- https://www.autism.org.uk/advice-and-guidance/what-is-autism
- https://www.autism.org.uk/advice-and-guidance/professional-practice/under-diagnosis-of-autism-in-england-a-population#:~:text=The%20researchers%20estimate%20that%20the,would%20exceed%201.2%20million%20people.
- https://www.theguardian.com/society/2016/nov/19/autism-diagnosis-late-in-life-asperger-syndrome-john-harris
- https://pmc.ncbi.nlm.nih.gov/articles/PMC9790627/
- https://www.autismparentingmagazine.com/undiagnosed-autism-in-adults/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6669096/
- https://www.helpguide.org/mental-health/autism/adult-autism-and-relationships
- https://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-asd
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6127767/
- https://www.autistica.org.uk/what-is-autism/challenges-autistic-people-face
- https://www.niehs.nih.gov/health/topics/conditions/autism
- https://pmc.ncbi.nlm.nih.gov/articles/PMC5192959/
- https://pubmed.ncbi.nlm.nih.gov/29034353/
- https://pubmed.ncbi.nlm.nih.gov/39636522/?utm_source=SimplePie&utm_medium=rss&utm_campaign=pubmed-2&utm_content=1HaIafHQm-66xWEi1RW0VGTB1_3R-Bbzd8yH4m7zkklDodwsl6&fc=20220523105801&ff=20241205181754&v=2.18.0.post9+e462414
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8526836/
- https://www.psychologytoday.com/gb/blog/living-neurodivergence/202307/making-sense-of-the-past-as-a-late-diagnosed-autistic-adult
- https://www.autism.org.uk/advice-and-guidance/topics/diagnosis/assessment-and-diagnosis/criteria-and-tools-used-in-an-autism-assessment
- https://www.sciencedirect.com/topics/medicine-and-dentistry/autism-diagnostic-interview-revised
- https://www.sciencedirect.com/topics/medicine-and-dentistry/autism-diagnostic-observation-schedule
- https://www.autismspeaks.org/expert-opinion/should-i-pursue-autism-diagnosis-adult
- https://www.sciencedirect.com/science/article/abs/pii/S1750946718300485
- https://pubmed.ncbi.nlm.nih.gov/28929582/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7670840/