Quote Originally Posted by beachguy in thongs
Here's the site: www.hnrc.ucsd.edu

Some references may be brief. Adult Language, Nudity, and Violence.

Tests may have been done in 2001, but it was published in 2003.

They included three groups: heavy Cannabis users (recently), past heavy users (but, not recently), and a group of controls (very limited exposure to Cannabis).

Eight neurocognitive ability areas were tested. Six indicated that the effect could not be distinguished from zero. Learning and forgetting were the other two. The numbers of the differences being .21 for learning and .27 for forgetting (I don't know how to read those numbers, but I know that .21 means 1/5 of 1).
"These results can be interpreted in several ways. A statistically reliable negative effect was observed in the domain of learning and forgetting, suggesting that chronic long-term cannabis use results in a selective memory defect. While the results are compatible with this conclustion, the effect size for both domains was of a very small magnitude. The 'real life' impact of such a small and selective effect is questionable."

They asked the groups to abstain from cannabis and took urine analyses for the next month. "They were tested on days zero, 1, 7, and 28. After 28 days, all the heavy-users had undetectable THC levels. They noted subtle impairments on several neurocognitive tests in the active-users, who had just become abstinent. However, by 28 days, the active-users who had abstained for almost a month were indistinguishable from former heavy-users or non-using controls."

I forgot the rest.
The .21 and .27 numbers are most likely the adjusted R^2 (pronounced R-Squared) refer to the experiments "explaining power." (1 being perfect explaining power.) For example, a perfect correlation with a perfect R^2 of 1.00 means that the two effects are directly correolated (i.e. when it rains its wet outside) .21 and .27 are relatively weak R^2 numbers and they basically mean that memory loss can be correlated with long-term heavy cannabis users but it only explains about 20% of all possible variables that could be affecting memory loss. Basically, to a very small extent, cannabis could be attributed partially to why these users suffered memory loss. An acceptable R^2 (and this is opinionated, but most professionals agree) is around .5 or .6 and that offers a reasonable amount of explaining power. BUT the study does not mention anything about the direction of causality. Is it that cannabis causes memory loss, or do people apt to memory loss tend to smoke cannabis? (basically, does cannabis cause memory loss, or does memory loss cause people to be more susceptible to smoking cannabis) For example, does it rain because it's wet outside, or is it wet outside because it rained. The direction of causality is really important, and isn't as clear cut as the example i just gave. Although the numbers aren't very high, they are statistically different from zero, which means that cannabis (to some extent) may be related to memory loss.
GhostFace2K Reviewed by GhostFace2K on . Hey, I wrote this down. Some sites, I know, say several weeks for affected memory Here's the site: www.hnrc.ucsd.edu Some references may be brief. Adult Language, Nudity, and Violence. Tests may have been done in 2001, but it was published in 2003. They included three groups: heavy Cannabis users (recently), past heavy users (but, not recently), and a group of controls (very limited exposure to Cannabis). Eight neurocognitive ability areas were tested. Six indicated that the effect could not be distinguished from zero. Learning and forgetting were the other Rating: 5