Psychedelics use is not without its risk, with more research needing to be done on potentially adverse side effects. A study from the Imperial College London and the University College San Francisco sought to evaluate the cognitive and perceptual changes associated with delusional ideation, magical thinking and hallucinogen persisting perception disorder (HPPD). 

The results concluded negligible correlation between psychedelic use and delusional ideation and magical ideation. About a third of participants (32.7%) in the 654 person study experienced HPPD-related symptoms, such as intensified colors. Only two people in that group perceived these symptoms as distressing; associated distress is linked with the diagnosis of HPPD, possibly explaining the generally low rate of HPPD diagnosis. Still, more research should be done on topics related to psychedelics use and HPPD before any definite conclusions can be drawn. 

Details about how the study was conducted, as well as background on psychedelic use and its possible effects can be read here.