Why the increase in autism diagnoses?

Our understanding of autism has changed dramatically in recent years. Once thought of  as a condition or disorder 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 process and engage in the world around them.

So why are there so many more autistic people being diagnosed? For the same reason there seem to be so many more stars in the sky since we invented telescopes.

The stars were always there. We simply developed better tools to see them.

Likewise, 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: changes to the diagnostic criteria and a deeper understanding of internalised or less visible presentations of autism.

The DSM-5

The Diagnostic and Statistical Manual of Mental Disorders (not a great name 😬 ) 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 better reflect emerging research and improve consistency in autism diagnosis worldwide. This updated version is known as the DSM-5, and it remains the criteria used today. The following changes were introduced 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 Disintegrative 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 (but not limited to):

• Being very sensitive to sounds, smells, or touch

• Sensitivities to the taste, texture, and smell of food

• Seeking out sensory experiences like movement or deep pressure

• Difficulty recognising internal cues like hunger, thirst, pain or the need to use the toilet

The separate diagnostic criterions 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 the experience of Autistic people is incredibly diverse, with support needs varying from person to person. 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, instead,  they guide the kind of support that might be helpful for them.

It was clarified that, while signs of autism must have been present in early development, traits 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 and high masking profiles

Another of the key reasons more people are being diagnosed as autistic 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:

• Anxiety

• Perfectionism

• Social exhaustion, emotional meltdowns or shutdowns after school, 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 social motivation, 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.