FLASHBACKS
The issue of flashbacks, or posthallucinogen
perception disorder (PITPD), is
clearer. Flashbacks are the reemergence of some aspect of the hallucinogenic experience in the absence of the drug. They
are most commonly reported in frequent
I.SD users, although isolated case reports exist about flashbacks in individuals after use of other
serotonin-like hallucinogens. The most
common form includes altered visual images, wavering, altered borders to visual images, or trails of light. While
flashbacks can occur after a single
use of the drug, they may become increasingly common as the number of hallucinogenic experiences
increases. Use of other drugs, like marijuana and alcohol, and even extreme
fatigue, can trigger this phenomenon.
The overall incidence is hard to judge because use of other drugs or psychiatric conditions must be ruled out.
By our best guess, incidence for the
common user is low.
People's reactions to flashbacks vary widely. Some
users experience anxiety and
depression while others view flashbacks as an acceptable side effect of an otherwise positive experience. In many
cases, flashbacks diminish with
abstinence, although symptoms that persist for years have been reported.
Persistent symptoms might actually reflect
long-term changes in how the brain
processes sensory images. Studies of vision of habitual LSD users (when they are not under the influence of the
drug) show that their brains may
continue to respond to visual stimuli after the stimuli are removed. This
response suggests that repeated LSD usage may cause some neuroplastic changes that persist. In the
"Brain Basics" chapter, we discuss the brain's capacity to remember all sorts of experiences, including
repeated drug applications.
