Why the increase in autism diagnoses?

Our understanding of autism has changed dramatically in recent years. Once thought of as a condition (or even disease) that impacted a person in terms of what they can’t do, autism is now recognised as it’s own neurotype, a natural variation in how brains work, think, feel, and connect.

a Broader, more inclusive definition

You may have noticed that autism diagnoses have increased in recent years, with a broader range of people now being recognised and identified. Two key factors have contributed to this: a broadening of the diagnostic criteria, and a deeper understanding of internalised or less visible presentations of autism.

The DSM-5

The Diagnostic and Statstical Manual of Mental Disorders (DSM-5) is the most commonly used tool to identify and diagnose autism. It provides a set of criteria that looks at patterns in how a person thinks, communicates, and experiences the world, through the lens of the autistic neurotype.

In 2013, the DSM-IV was revised to broaden the diagnostic criteria for autism, aiming to make diagnoses more accurate and inclusive worldwide. This updated version is known as the DSM-5, and it remains the criteria used today. The following criteria were added, broadening the definition to better reflect the many ways the autistic neurotype can present:

Four diagnostic labels were merged into one. Asperger’s Syndrome, Pervasive Developmental Disorder (not otherwise specified), Childhood Disitegraive Disorder and Autistic Disorder were combined under the one diagnosis – Autism Spectrum Disorder.

Sensory differences were included. For the first time, sensory experiences became part of the official criteria. These include things like:

Being very sensitive to sounds, smells, or textures
Food intolerances
Seeking of movement like running, spinning or jumping
Difficulty recognising internal cues like hunger, thirst, pain or the need to use the toilet
Fascination with lights, movement, or certain sensations

The separate diagnostic criterion of social interaction and communication were combined into a single criterion, Social Communication, as understanding grew around how closely these areas are linked for Autistic people

A “support needs” scale was added. It was recognised that not all Autistic people need the same kind of help. So now, the diagnosis includes levels including:

Level 1: needs some support
Level 2: needs substantial support
Level 3: needs very substantial support

These levels aren’t about how “autistic” someone is, they provide a guide to what kind of support might be helpful for them.

It was clarified that, while signs of autism must have been present in early development, they may not have been obvious at the time. Some traits only become noticeable later, especially when social or learning demands increase, such as starting school or as friendships and social dynamics mature.

In earlier editions, co-diagnoses like Autism and ADHD were not permitted, meaning a person couldn’t be formally diagnosed with both. The revised DSM-5 now recognises that a neurotype can include a combination of traits, allowing for a dual diagnosis of Autism and ADHD (often informally referred to as AuDHD).

Internalised autism & HigH Masking Profiles

Another of the key reasons more people are being diagnosed with autism today is because we’ve become better at recognising internalised and less visible presentations. These profiles have always existed but until recently, they were often missed, misunderstood, or misdiagnosed.

For many autistic people, their traits may not match the traditional or stereotypical picture of autism. Instead of outward behaviours, their differences are more subtle or internalised, and they may work very hard to mask or camouflage their autistic traits to blend in with peers or meet social expectations. An internalised experience of autism can mean that a person may not even be aware they are masking, a process known as unconscious masking, until they are supported with the opportunity to reflect and recognise their internal experience.

Internalised autism might show up as:

High anxiety or perfectionism
Social exhaustion or emotional shutdowns after school or social, work or social events
Preference for being in control & difficulty coping with change or unpredictability
More subtle stimming or other natural self-regulation behaviours (eg: chewing gum, tapping foot, twirling hair, rubbing fingers)
More mainstream special interests (fashion, TV shows, hair, animals)
Being seen as shy, quiet, sensitive, or well-behaved — while internally overwhelmed
Strong empathy and a desire for connection, paired with social confusion or burnout

Because a high masking individual can often appear to be coping, or because they don't present with more obvious autistic traits, their need for support can go unseen, sometimes for years. But with growing understanding, clinicians are now better equipped to identify how these internalised traits meet the diagnostic criteria.

The Best is yet to come

While this deeper understanding of autism is a welcome advancement, many Autistic people and professionals within the neurodiversity space acknowledge that the deficit-based language of the DSM-5 still falls short in capturing the strengths, identity, and positive lived experiences of Autistic individuals. Many diagnosticians, while following the DSM-5 criteria, choose to share their clients’ stories through the strength-based lens of the neurodiversity-affirming paradigm. It is hoped that future revisions of the DSM will reflect this approach more fully.