Autism is today’s hot topic in the middle of medicine and society, sparking conversations on everything from parents and public health to new theories of social interaction and technological innovation. But how did this once-obscure condition become an “epidemic”?

Gil Eyal answers this question by tracing the social history of autism, arguing that we can learn more about why it is common today by asking why it used to be rare. His work highlights three key changes in the mental health system. First, treatment for autism shifted from clinics and institutions to special education at home and in the community. Second, specialists stopped looking for complete “bundles” of symptoms to diagnose autism, turning instead to a checklist of individual behaviors, identified by parents and falling across a wide spectrum. Finally, these changes in practice taught parents and doctors to look for progress in small steps through treatment, rather than a complete “cure” for autism; it is now seen as a lifelong condition.

Eyal argues that these changes didn’t create new knowledge or skills among the experts, but instead made a new kind of autism expertise by changing the social relationships among parents, therapists, researchers, and activists. Now parents are encouraged to actively participate in the diagnosis and treatment of their children, with their observations taken more seriously by doctors. Thus, autism diagnoses have been supported by a broader social network and increased over time, while other conditions that required specific clinical treatments without the parents—like childhood schizophrenia—have decreased. While autism now occurs more frequently, at least part of the epidemic lies in the way our society sees mental health.