The connections between neurons and areas in the brain Sherbrooke Connectivity Imaging Lab (SCIL)/Getty

Psychedelic drugs such as LSD seem to make brain cells grow branches and form new connections.

The finding in rats and fruit flies could explain why psychedelics seem to evoke long-lasting changes after a single dose, and why they may be able to help treat mental health disorders.

The psychedelics include psilocybin, found in magic mushrooms, and DMT, found in the South American plant brew ayahuasca. In recent years, numerous studies have investigated these drugs as a possible treatment for depression, and small …