Health and Human Services Secretary Robert F. Kennedy Jr. has long been focused on the growing "epidemic" of autism in children, with particular attention devoted to uncovering the potential causes of and possible treatments for the condition.

On Monday, Kennedy and other Trump officials announced that approval had been granted for an old drug to be repurposed as a treatment for some children diagnosed with autism, according to People magazine.

That drug is known as leucovorin, or folinic acid, a form of vitamin B, but while some people were thrilled about the prospect of a new treatment for some autistic children, others expressed caution or downplayed the significance of the new federal approval.

New approval for possible autism treatment

The Food and Drug Administration announced on Monday that it had approved the use of leucovorin calcium tablets as a treatment for patients diagnosed with cerebral folate deficiency, or CFD, which is a neurological condition that negatively affects the transportation of folate to the brain.

CFD often results in developmental delays, particularly for those also diagnosed with autism, and can be evidenced by poor social communication skills, sensory processing, behavioral issues, coordination and movement problems, and seizures, among other things.

Yet, some studies have shown that taking leucovorin to boost folic acid in the brain has had positive results for individuals diagnosed with CFD.

"We have witnessed a tragic four-fold increase in autism over two decades," FDA Commissioner Dr. Marty Makary said. "Children are suffering and deserve access to potential treatments that have shown promise. We are using gold standard science and common sense to deliver for the American people."

A "groundbreaking" step in treating some autism cases

Some healthcare professionals who work with children diagnosed with autism in conjunction with CFD are excited about the possibility that leucovorin may be a key to treating the condition and improving the daily lives of those patients.

Dr. Richard Frye, of the Autism Discovery and Treatment Foundation, told TIME magazine, "I think [leucovorin] is a major step forward to get many children treated and improve their ability to function."

"It is particularly groundbreaking in the fact that many do not think that autism can be treated at its core," he continued. "This treatment fixes core biological deficits and therefore could be disease-modifying. It is not a cure, but can improve the function of many children substantially."

Some skeptics have been dismissive of the apparent breakthrough, however, but Frye said in response, "I personally wouldn’t consider it experimental. I would prescribe it as a treatment that has good evidence as effective." He did, though, note that leucovorin shouldn't be considered a "first-line treatment" but rather should be used after and in conjunction with other therapies and certain issues are addressed.

TIME noted that Dr. Markary, during Monday's press conference, said, "Autism may also be due to an autoimmune reaction to a folate receptor on the brain not allowing that important vitamin to get into the brain cells," and added of leucovorin, "We have a duty to let doctors and the public know we are going to change the label to make it available. Hundreds of thousands of kids, in my opinion, will benefit."

Some remain skeptical

Not all autism-focused healthcare professionals are pleased with this development and the approved relabeling of a drug commonly prescribed to treat the negative effects of chemotherapy for cancer patients since the 1950s.

USA Today reported that Alycia Halladay, of the Autism Science Foundation, lamented that "The studies on leucovorin in autism so far have been very small, not replicated, or have found inconsistent findings, and not used the same dose," and noted that her foundation "does not consider this a treatment for autism."

Hallady told TIME, "I think it’s incredibly premature to say leucovorin is anything more than a potential idea that has yet to get any real scientific data. Most autism experts I know would not prescribe leucovorin and would not advise [families] to take it."

"The reality is that we don’t have the safety data yet. We need larger studies" to determine the long-term impact, she added, along with her concerns that the new excitement about leucovorin could detract from other ongoing research and clinical trials, as well as other treatment approaches involving behavioral modifications and other drugs that already have sufficient scientific support.