HPPD, or Hallucinogen Persisting
, is essentially
recurrence of disturbances
in perception experienced by people who
have been under the influence
a hallucinogenic drug
. It is the
term for the more commonly
used name, flashback
The disturbances commonly include visual
hallucinations such as geometric shapes,
peripheral-field images, flashes or
intensification of colors,
"trails" (images that remain
in the path of a
moving object) and halos.
The symptoms can also include a changed
mind set, appearing to be similar to the
effect of the drug when originally
ingested. While the effects can come
suddenly and unexpectedly, some people
find them pleasant, while others
find them more disturbing and frightening
(possibly because their unknown origin).
Symptoms may abate after a few months,
but people have reportedly experienced them
after as much as 5 years.
The origin of these symptoms is a bit of a mystery.
Many tend to consider the disorder
psychological in nature, as no traces of the
psychedelic drugs can be found in the
victim's body. Another
possible explanation could be alternations
of neurochemical processes in the brain,
although the latter seems unlikely.
These effects have been reported after use
of most of the psychedelics
(e.g. LSD, MDMA / Ecstasy,
Mescaline, DMT et al.), but LSD
seems to be the most common culprit.