What explains the rise in autism diagnoses?

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What explains the rise in autism diagnoses?

The sub-stack post argues that the numerical rise is mostly a measurement story rather than a sudden surge in the underlying condition. Three mechanisms are put forward:

Broader diagnostic criteria – especially after successive DSM revisions – have widened the net of behaviours that qualify as Autism Spectrum Disorder (ASD) [1].

Diagnostic substitution – children who would once have been given other labels (e.g., “intellectual disability” or “language delay”) are now more often classified as autistic [1].

Greater awareness and active screening by schools, paediatricians and parents mean that milder cases are detected where they would once have been missed [1].

The post does not claim that every additional diagnosis is artefactual; it concedes some possibility of a genuine increase, but holds that the bulk of the rise can be explained without invoking a new environmental trigger [1].

Conflicting views noted in the source

Robert F. Kennedy Jr. maintains that vaccines are the principal cause of the rise.
The author, citing mainstream epidemiological work (e.g., Emily Oster), rejects this and attributes the increase to the three measurement factors listed above [1].

Thus there is a clash between an environmental-toxin narrative (vaccines, mercury, etc.) and a diagnostic-practice narrative. The post sides decisively with the latter.

Public discourse and its evolution (as described in the source)

1990s–early 2000s – Concerns about thimerosal in childhood vaccines emerge; the idea that “vaccines cause autism” starts to circulate.
Mid-2000s – Vaccine safety becomes a prominent culture-war topic; RFK Jr. becomes one of its most visible advocates [1].
2010s – Large observational studies fail to find evidence supporting a vaccine–autism link; attention in academic circles moves toward genetics and early-brain-development research. The broader public conversation, however, still features periodic flare-ups driven by political figures and social media [1].
2023 – RFK Jr.’s presidential bid briefly returns the controversy to front-page news; commentators such as Arnold Kling review the evidence and again point to changes in diagnosis as the main explanation [1].

(Only milestones explicitly mentioned or implied in the source are listed.)

Summary

According to the cited post, the apparent surge in autism prevalence is best understood as the result of broader definitions, label substitution and heightened vigilance, not as proof of a new, widespread environmental assault on children’s health [1]. The vaccine hypothesis remains a high-profile minority view that is strongly contested by the epidemiological mainstream.

Notes on further research

The article points out that there remains scientific interest in subtle environmental contributors, but these have not yet been demonstrated at a population level. Genetic architecture, parental age effects and perinatal factors continue to be investigated, and new data could shift the balance of explanations in the future [1].

Sources

Question

What explains the rise in autism diagnoses?