Scientists conventionally accept research as being statistically significant if the likelihood that differences are due to chance is less than 1 in 20. There have been studies since the Dishotsky et al. paper. Not all drug experiences turn out as anticipated. Any potentially enjoyable event may prove to be a disappointment, as when rainy weather spoils a picnic. But the special quality of drug-induced bad trips is that they cannot easily be terminated.
Flashbacks are sudden and unexpected recurrences of aspects of an earlier drug experience.
Flashbacks have not been shown to be dangerous and, in fact, are often self- induced. Matefy et al. It's like getting high all over again. Some authors have reported permanent cerebral deficit in LSD users. In any event, there are no relevant experimental studies, but only comparisons of users with nonusers.