As Donald Trump gives oxygen to unproven theories about what might be behind a recent rise in autism cases, experts repeatedly point to the changing nature of how autism is diagnosed and viewed.

A key moment in the history of autism diagnosis was the publication in 1994 of a new version of the Diagnostic and Statistical Manual of Mental Disorders. It's a reference book of psychiatric conditions and how to diagnose them, used by psychiatrists and psychologists around the world.

In this episode, Andrew Whitehouse, a professor of autism research at the University of Western Australia, explains why this shift in autism diagnosis happened in the 1990s, what impact it had, and what it's meant for the support autistic people get.

This episode was produced by Katie Flood, Mend Mariwany and Gemma Ware. Sound design and mixing by Michelle Macklem and theme music by Neeta Sarl. Read the full credits for this episode and sign up here for a free daily newsletter from The Conversation.

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