At the top of the brain stem is a neurotransmitter called dopamine, which relays messages of pleasure to nerve fibers in the limbic structure. Mood altering drugs override the limbic system by tricking the nerve cell into thinking it is being stimulated by a natural neurotransmitter. Since this neurotransmitter helps control feelings of pleasure, drugs make a person feel pleasure. People tend to repeat activities that induce pleasure, which is why drugs are so addictive. Some drugs, like heroin, mimic the effects of a natural neurotransmitter. Others, like LSD, block receptors and thereby prevent neuronal messages from getting through. Still others, like cocaine, interfere with the process by which neurotransmitters are sucked up by the neurons that release them. Others, like caffeine and PCP, exert their effects by interfering with the way messages proceed from the surface receptors into the cell interior.2 In a research project conducted by Dr. Jacqui Rodgers, participants who were addicted to certain drugs showed memory damage. Dr Rodgers said, "Cannabis use seems to lead to problems with everyday memory, such as remembering what you have done earlier that day. The more you smoke the more this appears to be the case." She also said that Ecstasy use also tended to interfere with the ability to remember events in the future, such as an appointment.4
Bibliography
Bellenir, Karen. Drug Information for Teens: Health Tips about the Physical and Mental