Researchers at Yale University have identified a low-cost prescription drug already on the market that could help ease symptoms of autism spectrum disorder (ASD) in some people.
And if you’re thinking it’s leucovorin — a vitamin B–derived drug hyped as a possible remedy — you’d be wrong.
In the study, researchers compiled a database of 774 FDA-approved drugs and tested how they affected the behavior of zebrafish genetically modified to exhibit autism-like traits.
The choice of test subject may sound unusual, but these tiny tropical swimmers have become one of science’s most powerful research tools in recent years.
Humans and zebrafish share about 70% of the same genes, and roughly 84% of genes linked to human disease have an equivalent in the animal, making it a powerful model for studying conditions ranging from muscular dystrophy and melanoma to epilepsy and Parkinson’s.
Of the 774 FDA-approved drugs tested, the researchers narrowed the list down to 520 that were non-toxic and showed significant effects on zebrafish behavior.
From that group, one drug in particular stood out as a potential candidate for treating ASD.
Sold under the brand name Carnitor, levocarnitine is currently used to treat low carnitine levels, a condition in which the body cannot properly convert fat from food into energy.
But in the new analysis, the drug — which costs about 44 cents per pill — appeared to go beyond that.
Researchers found that levocarnitine helped restore more normal function in zebrafish carrying mutations in two key genes tied to brain development and autism-related traits, SCN2A and DYRK1A.
The drug appeared to “reverse” disruptive behaviors in the animals, while also promoting more balanced metabolism and more typical patterns of brain activity.
But before you get too excited, there’s a bit of a catch.
While mutations in SCN2A and DYRK1A are known risk factors for the neurodevelopmental condition, they appear to be relatively rare in the broader ASD population.
Research suggests SCN2A may account for roughly 1 in 333 autism cases, while experts estimate fewer than 1% of diagnosed people carry DYRK1A mutations.
Taken together, the findings suggest levocarnitine would likely only benefit a small subset of people with ASD who carry specific mutations in those genes.
Still, the team at Yale say their findings underscore the importance of studying known autism risk genes — more than 800 of which have been identified — in the search for potential treatments.
They also hope their open-source, searchable database of drugs will help pave the way for future discoveries.
“Our findings lay the groundwork for investigating these drug mechanisms as potential targets for individuals carrying mutations in select autism risk genes,” Dr. Ellen Hoffman, a psychiatric geneticist, neurobiologist and senior author of the study, said in a press release.
The research comes amid a steady rise in ASD cases across the US.
Diagnoses have climbed sharply in recent years, from 1 in 150 children in 2000 to 1 in 31 by 2022. Adults ages 26 to 34 have also seen a 450% increase in diagnoses between 2011 and 2022.
Scientists attribute the rise to expanded diagnostic criteria, improved screening tools and greater awareness.
Autism symptoms can include difficulty making eye contact, communication struggles, trouble reading others’ emotions, challenges forming friendships, repetitive behaviors, intense interests in specific objects and sensory sensitivities.
Currently, there is no medication that can cure ASD or a one-size-fits-all treatment to relieve its symptoms.
For now, the Yale researchers caution against seeking out levocarnitine as a treatment, stressing that the drug still needs to be tested in humans.
