Marijuana, or cannabis, a drug created from the hemp plant, has been used throughout the world for centuries. Most commonly smoked, but sometimes eaten or brewed as tea, the drug is illegal in a number of countries. The possibility of a connection between marijuana and brain damage has been studied by researchers but results are inconclusive. Some studies appear to show long-term marijuana use causing changes in the structure of the brain, while others show no such brain injury. Other research has indicated that marijuana alters the function of the brain over time, but it is uncertain how these changes might affect an individual's ability to think.
Using marijuana causes a number of physical symptoms, such as raised heart rate, dry mouth, inflamed eyes and increased appetite. In the mind, what are described as cognitive symptoms occur, including feelings of well-being and relaxation and heightened sensations. Less positive cognitive symptoms, such as distorted perceptions of distance and time, poor concentration and reduced short-term memory, could lead to accidents. In the longer term, difficulties in thinking, memory, and concentration caused by marijuana use can affect an individual's performance in work and social situations. There is no conclusive evidence that this is the result of irreversible brain damage and it could merely be a consequence of continued marijuana use.
Researchers investigating a possible connection between marijuana and brain damage have found that long-term users participating in studies are difficult to assess. They might use other drugs, may be experiencing withdrawal symptoms, and could have mental disorders which have led to their drug use. There is also the problem of determining what a person's intellectual abilities might have been before marijuana use began.
Some research has shown that, in long-term marijuana users, memory loss returns to normal a few weeks after quitting the drug. Other scientists found that marijuana's effects on the brain accumulate, becoming progressively worse over time. More studies need to be carried out to answer the questions surrounding the issue of marijuana and brain damage.
A positive link between marijuana and brain damage exists where the brain cells in question are cancerous. Scientists researching possible treatments for brain cancer have discovered that marijuana can cause brain cell death when the cells involved are malignant tumor cells. The malignant brain cell damage is brought about by a chemical in marijuana, known as THC, that causes tumor cells to digest themselves. This property of THC could lead to the development of new treatments for currently incurable brain cancers.