Effects of Cannabis - Long-term Effects

Long-term Effects

Though the long-term effects of cannabis have been studied, there remains much to be concluded; debated topics include the drug's addictiveness, its potential as a "gateway drug", its effects on intelligence and memory, and its contributions to mental disorders such as schizophrenia and depression. On some such topics, such as the drug's effects on the lungs, relatively little research has been conducted, leading to division as to the severity of its impact. However, a study funded by the US government on the long term lung-related effects of marijuana has concluded that moderate marijuana use does not impair pulmonary function.

More research is no guarantee of greater consensus in the field of cannabis studies, however; both advocates and opponents of the drug are able to call upon multiple scientific studies supporting their respective positions. Cannabis has been correlated with the development of various mental disorders in multiple studies, for example a recent 10 year study on 1923 individuals from the general population in Germany, aged 14–24, concluded that cannabis use is a risk factor for the development of incident psychotic symptoms. Continued cannabis use might increase the risk for psychotic disorder.

Other studies differ widely as to whether cannabis use is the cause of the mental problems, whether the mental problems encourage cannabis use, or whether both the cannabis use and the mental problems are the effects of some other cause. Still other studies even encourage the use of cannabis in treating schizophrenia. Similarly, efforts to prove the "gateway drug" hypothesis that cannabis and alcohol makes users more inclined to become addicted to "harder" drugs like cocaine and heroin have produced mixed results, with different studies finding varying degrees of correlation between the use of cannabis and other drugs, and some finding none. Some, however, believe the "gateway effect," currently being pinned on the use of marijuana, should not be attributed to the drug itself but rather the illegality of the drug in most countries. Supporters of this theory believe that the grouping of marijuana and harder drugs in law is, in fact, the cause of users of marijuana to move on to those harder drugs.

Finally, many clinical studies done on the practice of smoking marijuana or cannabis have shown that this does not lead to any kind of addiction. Indeed, according to one of the earliest and most famous studies on the issue, the La Guardia Committee of 1944, smoking marijuana would help to get out of the addiction from substances like cocaine or morphine.