Marijuana has been used as a drug since the beginning of time, yet there are still many mysteries about its health effects on humans. Marijuana, or cannabis sativa, is a preparation of the crushed flower or buds of the female hemp plant. The existence of the plant has been reported as early as 1500-2000 BC in China, and cannabis has been described as an analgesic as early as 200 AD. Since then, an overwhelming number of studies have attempted to explain the physical and psychological effects of cannabis on humans.
Physically, cannabis is relatively harmless. Studies have observed interesting results, including that it causes structural changes in the brain, depresses male sperm counts, and damages the lungs. Most of these claims,however, have been unreplicated in humans or contradicted by other work. Various studies have claimed that cannabis destroys brain cells. However, several other studies have found no structural or neurochemical atrophy in the brain at all. One study found a correlation between cannabis use and low sperm counts in human males. This is misleading because a decrease in sperm count has not been shown to have a negative effect on fertility and because the sperm count returns to normal after cannabis use has stopped. The most serious physical danger of using cannabis is in smoking it. Inhaling any sort of burnt plant matter is not very good for the lungs. Smoking cannabis through a water-bong will filter out some of the water soluble carcinogens and will also greatly cool down the smoke. Cannabis has also been known for its many therapeutic uses, including the treatment of open angle glaucoma, asthma, and the nausea associated with chemotherapy. It has also been described as a tumor retardant, an antibiotic, a sleep-inducer, and a muscle relaxant.
The psychological effects of cannabis are the user feels the onset of the "high" between 7 seconds (when smoking) and up to thirty minutes(after eating). This involves a relaxed and peaceful, yet sometimes euphoric state of mind. At high doses, it can cause hallucinations. The effects last from 2 to 4 hours after the drug is ingested, and it usually leaves the user in a relaxed state for several hours after the high. One of the main intoxicating properties is that short term memory is inhibited for the duration of the high. Thoughts may seem unclear, and it might be difficult for a user to concentrate on logical, complicated concepts like mathematics.
Whether cannabis use causes permanent physical or psychological changes in its users is still under question.