Cloudscape

There has long been controversy about whether or not marihuana causes psychosis. The correlation that has been found between marihuana and psychosis is indisputable, but it is unclear whether marihuana causes psychosis or vice versa.

It is probably a bit of both: marihuana use can be out of a need to flee from reality, meaning that beside marihuana, the person will also seek other ways of fleeing from reality, which is basically synonymous to psychotic diathesis. It can also be because of isolation, or to find distraction from stress. Stress, isolation and a tendency to flee from reality happen to be the three most important factors of psychosis. At the same time, however, marihuana may also cause a person to flee even further from reality, become even more isolated, and because of this, eventually go through even more stress.

As a result of this, the increased risk of psychosis caused by heavy marihuana use is probably not as high as anti-drug activists are inclined to believe, but also not as low as marihuana users are inclined to believe. Studies indicate that the risk of psychosis in marihuana users is 2 to 8%, compared to 1% in the general population — an increase of 100 to 800 percent. If the correlation is bidirectional, the risk of psychosis would increase with heavy marihuana use, but not by 800 percent.

It may seem hard to find out by how much the risk of psychosis is really increased by marihuana, since there is no way one can subject a random sample of the population to heavy marihuana use and see what happens, but there can be another way:

The researchers should ask not for subjects who are already using marihuana, but for subjects who claim to be interested in using marihuana but have never used it. The subjects would then be split in two groups, both of which would be subject to regular drug tests. In one group, the control group, subjects that are found to have used marihuana are eliminated from the study. In the other group, subjects that have found not to have used marihuana will be eliminated from the study, though not before the end of the follow-up. To prevent the study from manipulating the subjects' behavior, all subjects would be paid the same amount of money at the end of the study, even if they were eliminated at an early stage. At the study's conclusion, it is important that the user group (that is, the group where all non-users have been eliminated) is subdivided into separate groups according to how heavily they used marihuana, and the percentage of psychosis be mentioned for each subdivision. This study would last for at least years and at most decades.