UCLA researchers found that a single dose of rapamycin, an existing immunosuppressant drug, reversed several autism-associated brain and behavioral changes in adult mice within about two hours, according to a study published July 23 in Nature Communications.
The team, led by Dr. Harley Kornblum with first author Dr. Janel Le Belle and co-senior author Dr. Neil Harris, exposed pregnant mice to mild inflammation early in gestation. Offspring later developed chronic inflammation, mild brain overgrowth, overactive mTOR pathway signaling, and autism-like traits including repetitive behaviors, heightened sensory sensitivity, and elevated seizure risk.
After adult mice received a single rapamycin dose, hyperactive brain cells calmed, connectivity between brain regions reorganized, seizure susceptibility dropped, and repetitive and sensory behaviors eased — all within roughly two hours. "The adult brain may be more adaptable than we assumed, even when underlying structural changes remain," the researchers noted.
The effects were temporary, and repeated dosing lost effectiveness while raising toxicity concerns, so rapamycin itself is not a viable human treatment. But the findings suggest autism-related brain circuitry stays more flexible into adulthood than previously thought, potentially opening the door to future drugs targeting the same mTOR pathway.