Who Is in the Room? The Hidden Diagnostic Risks When Autism Assessment Teams Work Without Breadth

This week I attended training on selective mutism, organised by Diagnostics CEN and delivered by Libby Hill and Abigail Mance, speech and language therapists whose depth of knowledge and quiet expertise in this area genuinely stopped me in my tracks. It was one of those rare CPD experiences that does not merely inform but prompts genuine reflection: on what good clinical practice looks like, on where the gaps exist in the services I work within and alongside, and on the professional responsibility we all carry when conducting complex diagnostic work. I left feeling inspired and also a little unsettled, in the best possible way.

That discomfort is worth sitting with. Because what Libby and Abigail's training made visible, for me at least, was not just how much there is to know about selective mutism specifically, but how often that knowledge is absent from the very settings where it matters most: autism assessment services and clinics. And that absence, I think, is part of a broader and largely unaddressed problem.

Autism assessment has become, quite rightly, a topic of significant public and policy attention in recent years. Waiting lists are long, demand is high, and the pressure on services to move quickly and efficiently is real. But alongside the volume challenge sits a quieter and, I would argue, more serious one: the clinical breadth of the professionals conducting and formulating those assessments.

Because autism does not exist in a diagnostic vacuum. It sits within a landscape of presentations that can look remarkably similar on the surface, and which require knowledge, experience, and a degree of intellectual humility to disentangle. And right now, too many assessment teams are navigating that landscape without the full map.

Selective Mutism: The Diagnosis Most Assessment Clinicians Have Not Been Trained to Recognise

Selective mutism is characterised by a consistent failure to speak in specific social situations, most commonly school or formal settings, in children and adults who speak fluently in others. It is rooted in severe situational anxiety, not in social motivation deficits, sensory processing differences, or the communicative profile that underpins autism. And yet, it is routinely missed, misattributed, or folded into an autism formulation without adequate consideration.

The surface presentation can be deceptively similar. A child who does not speak during an assessment, who avoids eye contact, who appears withdrawn and does not engage with the professionals in the room, can look, to an untrained eye, like a child who fits an autistic profile. The critical difference, that this child communicates freely and relationally in familiar, safe contexts, often goes unexplored.

The consequences of missing selective mutism are not trivial. An inappropriate autism diagnosis, or a formulation that fails to identify situational anxiety as the primary driver of communication behaviour, leads to the wrong interventions, delayed access to effective support, and, in many cases, further entrenchment of anxiety through approaches that are not fit for purpose. For clinicians working with adults, the picture is even more opaque, as selective mutism in adulthood is still widely underrepresented in training curricula and clinical awareness.

Developmental Language Disorder: Present in the Room, Invisible to the Team

Developmental Language Disorder, or DLD, affects approximately 7.6% of children. That is roughly two young people in every classroom, and it is one of the most under-identified neurodevelopmental conditions in clinical and educational practice. When it intersects with autism assessment, the consequences can be significant.

DLD is a persistent and significant difficulty with language that cannot be explained by other known conditions. It affects vocabulary, grammar, sentence processing, inference, and the ability to follow and generate connected discourse. Children and adults with DLD often experience genuine social communication difficulties, not because of reduced social motivation or atypical social cognition, but because language is the medium through which social interaction is conducted, and that medium is impaired.

Pragmatic difficulties, conversational breakdowns, difficulties understanding implied or figurative meaning, and reduced narrative ability can all feature in DLD presentations. To a clinician without specialist language knowledge, these features may read as consistent with autism. The risk of diagnostic substitution, or of DLD being absorbed into an autism formulation without independent recognition, is high in teams where speech and language therapy expertise is absent or underutilised.

DLD and autism can, of course, co-occur. The challenge is not to treat them as mutually exclusive, but to ensure that each is identified on its own terms, with implications for the support a person receives.

Trauma and Mental Health: The Contextual Blind Spots

The overlap between trauma responses and autism presentations is well-documented in the research literature, but far less well-embedded in the practice of clinicians who have not had dedicated training in trauma-informed frameworks.

Complex developmental trauma, adverse childhood experiences, disorganised attachment, and conditions such as Reactive Attachment Disorder can produce presentations that include social withdrawal, hypervigilance interpreted as sensory sensitivity, rigid and controlling behaviours as coping strategies, and difficulties with trust and reciprocal relating. These are not autistic traits in their origin. They are adaptive responses to environments that were unsafe or unpredictable. Misattributing them to autism without adequate exploration of developmental history, relational context, and trauma exposure risks compounding the harm already experienced.

Similarly, mental health conditions, including social anxiety disorder, OCD, depression, and PTSD, can significantly alter communication and social behaviour in ways that superficially align with autism criteria. Adults seeking assessment are particularly vulnerable here, where years of lived experience, masking, and accumulated anxiety may obscure the original presentation and create a layered, complex clinical picture.

Assessment formulations that do not actively interrogate these possibilities are not comprehensive. They are, at best, incomplete, and at worst, harmful.

The Speech and Language Therapist: Not a Supplement but a Requirement

Speech, language, and communication are not peripheral to autism assessment. They are central to it. The diagnostic criteria for autism are substantially rooted in social communication and interaction, domains that sit at the core of speech and language therapy expertise.

NICE guidance has long recognised the importance of SLT involvement in autism assessment, and yet, in practice, many MDTs operate without it, particularly in adult services. Where SLTs are present, their role is sometimes narrowly conceived: a communicative assessment, a language screen, a report to add to the pile. This is not the same as genuine MDT integration, where clinical reasoning, differential formulation, and the nuanced interrogation of language and communication profiles shape the diagnostic outcome from the beginning.

SLTs bring specific expertise that other professions, however skilled, cannot replicate: the ability to assess and interpret language processing, pragmatic communication, communicative intent, contextual variability of speech and language, and the distinction between social communication difficulties rooted in language disorder, anxiety, trauma, or autistic neurology. Without that expertise actively present in the formulation process, those distinctions are at risk.

Every autism assessment MDT should include a speech and language therapist. Not as an optional addition, not as an occasional consultant, but as an integral clinical voice with equity in the room.

CPD Is Not Optional: It Is a Professional and Ethical Obligation

The gaps described here are not failures of character or commitment. Many clinicians working in neurodevelopmental services are working exceptionally hard under significant systemic pressure. But knowledge gaps in selective mutism, DLD, trauma, and mental health presentations are not acceptable when the stakes are diagnostic accuracy and appropriate intervention access.

Continuing professional development in these areas must be treated as a clinical governance priority, not a personal aspiration. For psychologists, psychiatrists, paediatricians, nurses, and occupational therapists working in autism assessment, training in selective mutism and DLD awareness, trauma-informed assessment frameworks, and the functional presentation of mental health conditions is not supplementary knowledge. It is essential.

For SLTs, that same commitment applies in the other direction: deepening expertise in autism, ADHD, mental health, and trauma to enable meaningful contributions to complex differential formulations rather than narrowly scoped communication screens.

Reflective MDT practice, regular joint training, case-based learning across professional boundaries, and active engagement with organisations such as SMIRA, RADLD, and the RCSLT all offer routes forward. Services commissioning neurodevelopmental assessments have a responsibility to ensure that the teams they fund and oversee are trained and structured to meet this standard.

Closing Thought

Getting an autism assessment right, or more precisely, getting the formulation right, matters enormously. It shapes how a person understands themselves, what support they receive, and what narrative is written about them, sometimes for life. That responsibility demands clinical breadth, intellectual honesty, and a genuine commitment to knowing what we do not yet know.

The question is not only whether we are assessing for autism. It is whether we are truly equipped to recognise what else might be present, absent, or mistaken for it.

First published on LinkedIn on 1 July 2026.