Researchers at Newsnationnow discovered that brain and behavioral effects linked to autism may be temporarily reversible in adults using a single dose of the immunosuppressive drug rapamycin. The study, published in Nature Communications, challenged the long-held scientific belief that structural brain changes associated with autism are completely locked in by the time an individual reaches adulthood.
UCLA Health Study Shows Rapid Reversal of Autism-Like Traits in Mice
To conduct the research, scientists exposed pregnant mice to a mild inflammatory stimulus to induce physiological and behavioral changes in their offspring. The offspring subsequently developed persistent inflammation in the brain and body, abnormal brain growth, seizures, and heightened sensitivity to sensory input.
How a Single Dose of Rapamycin Alters Brain Function
Once the mice reached adulthood, investigators administered a single dose of rapamycin. Within roughly two hours, the treatment significantly improved brain signaling and behavioral symptoms. The intervention caused unusually active neurons to calm down, eased repetitive behaviors and sensory overresponsivity, and helped poorly communicating brain regions display more typical patterns.
Rapamycin is a prescription immunosuppressant and mTOR inhibitor primarily used to prevent organ transplant rejection. In this context, mTOR stands for the mechanistic target of rapamycin, acting as a master switch for cell growth, metabolism, and survival. According to Technology Networks, electrical recordings confirmed that the mice originally possessed hyperactive brain cells prone to seizures, which the drug successfully quieted.
Insights Into Adult Brain Adaptability and Gene Expression
By analyzing gene activity before and after treatment, scientists concluded that rapamycin altered electrical activity and brain function rather than rebuilding underlying physical structures, which typically takes longer. The drug reversed abnormal patterns of gene expression tied to autism, epilepsy, and ion channel function, with the strongest effects seen in excitatory neurons.
The level of functional normalization achieved over this short time suggests new mechanisms by which possible treatments may act,
said study senior author Dr. Harley Kornblum, director of the UCLA Intellectual and Developmental Disabilities Research Center in the Semel Institute for Neuroscience and Human Behavior, according to Labroots. It suggests the adult brain may be more adaptable than we assumed, even when the underlying structural changes from early development are still there.
Dr. Janel Le Belle, an associate professor in the UCLA Department of Neurosurgery and first author of the study, noted that the findings reframe how symptoms might be addressed by focusing on functional circuitry rather than physical anatomy.
Limitations and Implications for Future Therapies
Despite the promising outcomes, researchers emphasized that rapamycin itself is not a viable direct treatment for humans. The benefits of a single dose were strictly temporary, with behavioral abnormalities returning fully after 72 hours. Furthermore, the drug is toxic with repeated use, and mice developed a tolerance to it after several weeks of daily treatment, causing the benefits to become far less prominent.
Co-senior author Dr. Neil Harris, a professor in the UCLA Department of Neurosurgery, explained that the work serves as a foundational jumping-off point for future medical strategies rather than advocating for rapamycin usage. Researchers aim to direct future therapeutic targets toward sensory circuit neuromodulation and balancing neuronal inhibition and excitation.
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