Columbia, Oct 3 — A University of Missouri study has found that a low dose of the drug rapamycin improved brain blood flow in healthy middle-aged adults carrying the APOE4 gene variant.

Participants aged 45 to 65 took 1mg of rapamycin daily for four weeks. Only APOE4 carriers showed improved cerebral blood flow; non-carriers did not. Female carriers saw the largest gains, a key finding since women account for nearly two-thirds of Alzheimer’s cases.

APOE4 is the strongest known genetic risk factor for late-onset Alzheimer’s. One copy triples lifetime risk; two copies can increase it twelvefold.

The findings were published in the Journal of Cerebral Blood Flow & Metabolism. Lead researcher Ai-Ling Lin said slowing brain aging in high-risk people may reduce their risk.

Rapamycin is currently prescribed for organ transplant rejection. Researchers stress the work is early and not a treatment recommendation. The researchers say the approach could preserve cognitive function for those at highest risk. Larger trials are needed before any clinical use.