A crew of British military were each given LSD-25 (Acid)
This is a British army sous-titre archives of the 60′s and it demonstrates the effect of drugs on our brain.
Several soldiers were given LSD
and then monitored.
Under the influence of LSD, the ability to make sensible judgments and see common dangers is impaired, making the user susceptible to personal injury, which can be fatal. After an LSD trip, the user may suffer acute anxiety or depression, and may also experience flashbacks, which are recurrences of the effects of LSD days or even months after taking the last dose. A flashback occurs suddenly, often without warning, usually in people who use hallucinogens chronically or have an underlying personality problem. Healthy people who use LSD occasionally may also have flashbacks. Bad trips and flashbacks are only part of the risks of LSD use.
LSD users may also manifest relatively long-lasting psychoses, such as schizophrenia or severe depression.
LSD produces tolerance, so some users who take the drug repeatedly must take progressively higher doses to achieve the state of intoxication that they had previously achieved. This is an extremely dangerous practice, given the unpredictability of the drug.