It wasn't until the Vietnam War era and the 1980 inclusion of PTSD in the DSM-III that the flashback became the "hallmark" symptom we recognize today—defined by a vivid, sensory "here-and-now" reliving of events.
For a deep dive into how "flashbacks" have shifted from a drug-culture term to a psychiatric staple, the most interesting paper is (Jones et al., 2003). Flashbacks! Evolution!
When researchers examined medical records of UK servicemen from the Boer War and World Wars I and II, they found that flashbacks were virtually non-existent . Instead, soldiers then expressed trauma through physical symptoms (somatization) like tremors or "effort syndrome". It wasn't until the Vietnam War era and
This paper explores the of the flashback as a clinical concept, arguing it is a "culture-bound" symptom rather than a universal human reaction to trauma. Key Insights from the Paper National Institutes of Health (
Flashbacks and post-traumatic stress disorder: the genesis of a 20th-century diagnosis. National Institutes of Health (.gov)
The term "flashback" was originally coined in the 1960s to describe the recurring visual hallucinations experienced by LSD users .