I flashback dovuti all'assunzione dell' LSD, si possono verificare nei giorni seguenti all'assunzione della sostanza.
Confermo ciò che ha detto terrorman, sono attimi al massimo alcuni secondi ma non di più.
Quello a cui fai riferimento tu, ovvero la presenza continua degli effetti anche dopo molti giorni dall'assunzione di LSD, è una sindroma chiamata Hallucinogen Persisting Perception Disorder (HPPD).
Questa sindrome differisce dai flashbacks perchè persiste nel tempo ed è del tutto visiva, ma si presenta solo in soggetti che già soffrivano di disturbi della psiche.
Riporto un breve estratto da wikipedia per farti avere un quadro completo.
E' in inglese, se dovessi avere problemi di traduzione non esitare a chiedere
Flashbacks and HPPD
"Flashbacks" are a reported psychological phenomenon in which an individual experiences an episode of some of LSD's subjective effects long after the drug has worn off, usually in the days after typical doses. In some rarer cases, flashbacks have lasted longer, but are generally short-lived and mild compared to the actual LSD "trip". Flashbacks can incorporate both positive and negative aspects of LSD trips, and are typically elicited by triggers such as alcohol or cannabis use, stress, caffeine, or sleepiness. Flashbacks have proven difficult to study and are no longer officially recognized as a psychiatric syndrome. However, colloquial usage of the term persists and usually refers to any drug-free experience reminiscent of psychedelic drug effects, with the typical connotation that the episodes are of short duration.
No definitive explanation is currently available for these experiences. Any attempt at explanation must reflect several observations: first, over 70 percent of LSD users claim never to have "flashed back"; second, the phenomenon does appear linked with LSD use, though a causal connection has not been established; and third, a higher proportion of psychiatric patients report flashbacks than other users. Several studies have tried to determine how likely a user of LSD, not suffering from known psychiatric conditions, is to experience flashbacks. The larger studies include Blumenfeld's in 1971 and Naditch and Fenwick's in 1977, which arrived at figures of 20% and 28%, respectively.
Although flashbacks themselves are not recognized as a medical syndrome, there is a recognized syndrome called Hallucinogen Persisting Perception Disorder (HPPD) in which LSD-like visual changes are not temporary and brief, as they are in flash-backs, but instead are persistent, and cause clinically significant impairment or distress. The syndrome is a DSM-IV diagnosis. Several scientific journal articles have described the disorder.
HPPD differs from flashbacks in that it is persistent and apparently entirely visual (although mood and anxiety disorders are sometimes diagnosed in the same individuals). A recent review suggests that HPPD (as defined in the DSM-IV) is rare and affects only a distinctly vulnerable subpopulation of users. However, it is possible that the prevalence of HPPD is underestimated because most of the diagnoses are applied to people who are willing to admit to their health care practitioner that they have previously used psychotropics, and presumably many people are reluctant to admit this.
There is no consensus regarding the nature and causes of HPPD (or flashbacks). A study of 44 HPPD subjects who had previously ingested LSD showed EEG abnormalities. Given that some symptoms have environmental triggers, it may represent a failure to adjust visual processing to changing environmental conditions. There are no explanations for why only some individuals develop HPPD. Explanations in terms of LSD physically remaining in the body for months or years after consumption have been discounted by experimental evidence. Some say HPPD is a manifestation of post-traumatic stress disorder, not related to the direct action of LSD on brain chemistry, and varies according to the susceptibility of the individual to the disorder. Many emotionally intense experiences can lead to flashbacks when a person is reminded acutely of the original experience. However, not all published case reports of HPPD appear to describe an anxious hyper-vigilant state reminiscent of post-traumatic stress disorder. Instead, some cases appear to involve only visual symptoms.
Fonte: en.wikipedia.com
