Reply #21: Yes. It lowers your white blood cell count, and interferes with short term [View All]

memory.

http://health.yahoo.com/topic/addiction/other/article/pt/Psychology_Today_articles_pto_term_marijuana

What happens after a person smokes marijuana?

Within a few minutes of inhaling marijuana smoke, the user will likely feel, along with intoxication, a dry mouth, rapid heartbeat, some loss of coordination and poor sense of balance, and slower reaction time. Blood vessels in the eye expand, so the user's eyes look red.

For some people, marijuana raises blood pressure slightly and can double the normal heart rate. This effect can be greater when other drugs are mixed with marijuana; but users do not always know when that happens.

As the immediate effects fade, usually after 2 to 3 hours, the user may become sleepy.

How is marijuana harmful?

Marijuana can be harmful in a number of ways, through both immediate effects and damage to health over time.

Marijuana hinders the user's short-term memory (memory for recent events), and he or she may have trouble handling complex tasks. With the use of more potent varieties of marijuana, even simple tasks can be difficult.

Because of the drug's effects on perceptions and reaction time, users could be involved in auto crashes. Drug users also may become involved in risky sexual behavior. There is a strong link between drug use and unsafe sex and the spread of HIV, the virus that causes AIDS.

Under the influence of marijuana, students may find it hard to study and learn. (14) Young athletes could find their performance is off; timing, movements, and coordination are all affected by THC.

Some of the more long-range effects of marijuana use are described later in this document.

How does marijuana affect driving?

Marijuana affects many skills required for safe driving: alertness, the ability to concentrate, coordination, and reaction time. These effects can last up to 24 hours after smoking marijuana. Marijuana use can make it difficult to judge distances and react to signals and sounds on the road.

There are data showing that marijuana can play a role in crashes. When users combine marijuana with alcohol, as they often do, the hazards of driving can be more severe than with either drug alone.

Health Hazards

THC changes the way in which sensory information gets into and is processed by the hippocampus, a brain component that is crucial for learning, memory, and the integration of senses with emotions. Learned behaviors also deteriorate.

Long-term use of marijuana produces changes in the brain similar to those seen after long-term use of other major drugs.

Someone who smokes marijuana regularly may have many of the same respiratory problems as tobacco smokers.

Regardless of the THC content, the amount of tar inhaled by marijuana smokers and the level of carbon monoxide absorbed are three to five times greater than among tobacco smokers.

Does using marijuana lead to other drugs?

Long-term studies of high school students and their patterns of drug use show that very few young people use other drugs without first trying marijuana. The risk of using cocaine has been estimated to be more than 104 times greater for those who have tried marijuana than for those who have never tried it. Although there are no definitive studies on the factors associated with the movement from marijuana use to use of other drugs, growing evidence shows that a combination of biological, social, and psychological factors are involved.

Marijuana affects the brain in some of the same ways that other drugs do. Researchers are examining the possibility that long-term marijuana use may create changes in the brain that make a person more at risk of becoming addicted to other drugs, such as alcohol or cocaine. While not all young people who use marijuana go on to use other drugs, further research is needed to determine who will be at greatest risk.

Stats on children and use http://www.nida.nih.gov/Infofacts/marijuana.html

(same page lists health effects; this one is important -- )

Other Health Effects

Some of marijuana's adverse health effects may occur because THC impairs the immune system's ability to fight disease. In laboratory experiments that exposed animal and human cells to THC or other marijuana ingredients, the normal disease-preventing reactions of many of the key types of immune cells were inhibited14. In other studies, mice exposed to THC or related substances were more likely than unexposed mice to develop bacterial infections and tumors15,16.