Flashbacks among soldiers discharged as unfit who abused more than one drug.
Of 280 soldiers discharged from military service in 1971 as unfit, 207 reported the heavy use of at least one drug (most of these abused more than one drug) and 146 (52%) reported having flashbacks. Most flashbacks were of a simple visual nature, but repeat "trips," complex subjective experiences, and persistent difficulties in concentration were often reported. The prevalence and severity of flashbacks increased with drug use, particularly with hallucinogens and marijuana. Because psychological, social, and physiological factors may all contribute to flashback phenomena, other populations need to be studied to determine the extent to which these findings can be generalized.