A new study from University of California, San Francisco and Imperial College London researchers (on 28 healthy participants who had never taken psilocybin) found that a single high dose of the mushroom caused anatomical and functional changes in brain structure still visible a month later—a finding that researchers called “remarkable.” Special scans indicated that some brain nerve tracts had become denser and more robust after the drug was taken. Although the findings are preliminary, the scientists noted the opposite changes in…