Has Autism Diagnosis Lost Its Meaning?

Uta Frith has researched autism since 1966, and laid the groundwork for Theory of Mind

A leading autism researcher argues today’s spectrum may be two different conditions

STUDY: Frith U, Autism spectrum disorder: has it lost its meaning and is it leading to misdiagnosis? Psychological Medicine 2026

STUDY TYPE: Editorial

FUNDING: Independent

Background

Autism first entered the diagnostic manuals in 1980, defined by social aloneness, language delay, and insistence on sameness. Each revision since has widened the net: Asperger disorder joined in 1994, and the 2013 manual folded everything into one spectrum that applies at any age or intelligence level, even when symptoms only show up by historical report.

Uta Frith, who helped shape the original criteria, now asks whether that widening has gone too far.

Summary

Frith argues that autism is a real disorder that starts in childhood and causes a triad of social impairments:

1. Social Interaction

• Difficulty making friends
• Not understanding unwritten social rules
• Appearing detached or indifferent to others
• Struggling to take turns in a conversation

2. Social Communication

• Trouble with body language and facial expressions
• Taking language very literally (missing sarcasm or jokes)
• Unusual changes in tone of voice
• Delays in language

3. Social Imagination and Flexibility

• Preferring strict daily routines
• Getting very upset by sudden changes
• Intense, narrow special interests
• Difficulty predicting what will happen next or understanding other viewpoints

Although it is highly heritable, autism does not have a single biological fingerprint, suggesting there are different types under the same umbrella of Autism Spectrum Disorder. However, Frith believes the overlap implied by the “spectrum” concept applies to different types of autism, but should not be misinterpreted as a continuum between neurotypical and autistic.

Rising Rates, Changing Presentations

In the UK, autism has risen 44-fold since 1966, from 4 in 10,000 children to 1 in 57. There are many causes:

1. Broadening of criteria
2. Looser interpretation of criteria
3. Allowing cases with few overt symptoms who mask or compensate
4. Social contagion (including online screening tests and TikTok videos)

Everyone masks their true self in social interactions, and the process can be exhausting, but that is not a reliable basis to make a diagnosis, argues Frith. She clarifies that “social contagion is not ‘faking it’; rather, it is a survival mechanism to align with the tribe,” but medicalizing this process risks overdiagnosis.

Most of the rise is due to later onset diagnoses and milder cases. Since the 1960’s rates of intellectual disability have fallen from 70% to 7% in autism. Women are also overrepresented in later diagnosed patients, but Frith is skeptical of the widely accepted hypothesis that girls are better able to mask the symptoms. We need better explanations, she argues.

Frith also notices a pattern in this diagnostic expansion that points to two unique subtypes.

Two Types of Autism?

Those diagnosed later in life differ from those diagnosed as children.

Until recently, we thought that late-diagnosed autism reflected milder cases that weren’t picked up in childhood, but a 2025 genetic study in Nature challenges that. Those diagnosed later (age 7-14, as opposed to 1-6) did not have problems as children, suggesting this wasn’t an early onset disorder that was detected late.

The two groups also differed in genetic markers. The early diagnosis group had genetic links related to social and repetitive-behavior traits, while the late-diagnosed genetics overlapped more with ADHD, depression, and PTSD, suggesting they had other disorders that were misclassified as autism.

Other researchers have tried to subtype autism based on social and sensory symptoms, or neuroimaging markers, but Dr. Frith did not think those held together. The DSM divides autism not by subtype but by severity (levels 1-3).

Practice Implications

1. Late-diagnosed adult is likely different from a child who met criteria at age four.
2. Look for collateral information to make the diagnosis, and screen for other causes of social impairments.
3. Here’s more from the Mayo Clinic on how to diagnose high-functioning autism in adults.