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The Effects of LSD on the Brain

Drug Alters User's Perceptions, Sensations


Updated May 20, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Effects of LSD
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LSD obviously affects the brains of those who use it, distorting and altering their perceptions and sensations, but science really does not understand specifically all of the effects the drug has on the human brain.

What we do know is that LDS (d-lysergic acid diethylamide) is one of the most potent mood-altering drugs available. It causes profound distortions in the user's perception of reality that can last up to 12 hours.

Trippin' Since 1938

Although the use of LSD reached its peak in the 1960s and 1970s, the drug has been around since it was discovered in 1938, although that date is debatable. It was synthesized from ergot, a fungus that grows on grains, such as rye.

LSD is usually sold in tablets or capsules, but sometimes in liquid form. The liquid is sometimes applied to absorbant paper, called "window pane" or "blotter" acid, which is cut up into individual doses.

No Controlled Studies

Despite the fact LSD has been around for more than 70 years, there are few, if any, properly controlled research studies about the specific effects LSD has on the brains of those who use it. The research that does exist is comprised of smaller studies and case reports.

Scientists believe that the drug works by influencing the receptors involved in regulation of serotonin, a neurotransmitter in the brain. Serotonin is involved in the control of behavioral, perceptual and regulatory systems, including mood, motor control, sensory perception, hunger, body temperature and sexual behavior.

The Nature of Hallucinations

When this system is disrupted by taking LSD, it can cause profound distortions in the user's perception of reality, or in other words, hallucinations. LSD users see images, hear sounds and feel sensations that seem to be very real, but they are not real at all.

These sensory hallucinations can be accompanied by rapid and intense emotional swings. Consequently, an LSD "trip" can go from being a pleasant experience to a very unpleasant one very quickly, making the effect of the drug extremely unpredictable.

The Effects of LSD

Some of the most dramatic effects of LSD reported by researchers in smaller or case studies include:

  • Dramatic changes in sensations and feelings.
  • Feeling several different emotions at once.
  • Swing rapidly from one emotion to another.
  • Altered sense of time.
  • Altered sense of self.
  • Crossover senses, synesthesia (hearing colors, seeing sound)

Bad Trips and Flashbacks

These altered perceptions and sensations can cause panic in LSD users. Some experience terrifying thoughts, feelings of despair, fear of losing control, fear of insanity and fear of death. These experiences are what is known as having a "bad trip."

Scientists have also not been able to explain why some LSD users have flashbacks - a sudden recurrence of aspects an LSD trip without warning. These flashbacks can happen within a few days of the original use of the drug or sometimes more than a year later.

LSD Is Unpredictable

The problem for LSD users is that all of these effects, pleasant or unpleasant, are unpredictable. The same dose of the same batch of LSD can affect one person completely differently from another person. Moreover, a user can be affected differently from one trip to the next taking the same amount and same kind of LSD.

You never know when you might have a bad trip.

Fortunately, LSD is not addictive and most users eventually get tired of it and simply quit voluntarily, or decrease their use over time. However, users can build up a tolerance to the drug, requiring them to take higher amounts to achieve the same state the previously achieved, which can be dangerous due to the unpredictability of the drug.

National Institute on Drug Abuse. "NIDA InfoFacts: Hallucinogens - LSD, Peyote, Psilocybin, and PCP." Revised June 2009.

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