Keith Joyce came across leucovorin last December while trying to find ways to improve the life of his 4 1/2-year-old autistic grandson, Jose. He spent the next few months researching the drug and talking to neurologists. In April, he took his research to Jose Behavel’s development specialist, who agreed to prescribe the drug.

In the five months since he started treatment, Jose went from being generally nonverbal to constantly babbling.

“Within a few days, I started seeing another one,” Joyce told Wired. Before taking leucovorin, “he struggled with two-word sentences, and last night I had a three or four minute conversation about family with him.”

Joyce wanted to share his research with others because there are so few resources online, I know he started the Leucovorin for Autism Group on Facebook in May.

There was some interest in the group initially, and by August, about 8,000 people had joined, Joyce said. But then it came out that the Trump administration and U.S. Secretary of Health Robert F. Kennedy Jr. were going to recommend leucovorin as a possible treatment for autism — the group exploded. In the week following Makary’s annotation, Joyce’s group membership jumped to nearly 60,000 people.

Even before the official announcement, tens of thousands of new members had joined based on Spectar’s drug.

Then, last month, President Donald Trump pushed baseless claims that the active ingredient in Tylenol and vaccines could contribute to an autism diagnosis. FDA chief Marty Makary announced September 22 that the agency approved the use of leukovorin to treat brain fly deficiency, a deficiency that some people with autism symptoms have.

“Leukovorin is something that has been prescribed for many years for autistic people in general, with inconsistent results,” says Matthew Lerner, program manager of the Life Course Outcomes Research Program at the Aj Drexel Autism Institute at Drexel University. “There have been a few small studies to date, also with pretty inconsistent results. But strongly, we don’t know much, even from those studies, in terms of what would be an optimal dose, what would be an optimal time period.”