Repeated low doses of LSD are safe and well tolerated in older adults. In a double-blind, placebo-controlled trial, 48 healthy volunteers aged around 63 received either 5, 10, or 20 micrograms of LSD or a placebo every four days for three weeks. LSD was undetectable in the blood at the 5 microgram dose, while peak levels for higher doses occurred within 30 minutes. Adverse events were no more frequent than with placebo, and tests of cognition, balance, and proprioception showed no impairment. These results support further clinical development of low-dose LSD for treating or preventing Alzheimer's disease.
LSD doses of 50, 75, and 100 micrograms are tolerable and safe in healthy adults when administered in a novel group-based intervention paradigm with one attendant per participant. Thirty-two adults (mean age 28.8 years) received LSD or placebo across open-label and double-blind designs. No serious adverse events occurred; 28% of participants reported at least one mild expected adverse event and one moderate event. Peak blood plasma levels appeared 1.2 to 2 hours after administration, with an apparent half-life of 2.8 to 4.3 hours. LSD produced greater subjective effects than placebo, including mystical-type experiences. Further research is needed in clinical populations.