> Single cases always make an emotional argument to involved just as > personal experience does, but that's a total aside. > If you can find that reference, I'd appreciate it. Not that it means > anything to me, but a reference is always good when a discussion like > this comes up. And you KNOW it will again. and again. and again.
You can always do a scholar.google search: here's a link to the search I just used: http://tinyurl.com/nclt97 and a few relevant studies from it: http://archpsyc.ama-assn.org/cgi/content/abstract/58/10/909 - differences seen initially in a set of standard neuropsych tests, but no differences between heavy daily users, former users and controls were found after 28 days. http://tinyurl.com/kohhcb found deficits for very heavy long term users (7 or more times per week) but not medium users with non users. http://tinyurl.com/llgsxf found no differences. http://tinyurl.com/nezkrv studied Ecstasy, but in the subjects table is very interesting on cannabis use. To quote from the discussion section: -- Ecstasy users also had taken a greater number of other illicit drugs than did the control subjects, although the latter group had an appreciable exposure to cannabis and cocaine. However, cumulative lifetime doses did not correlate with rCBF for any of these drugs. These results indicate that even prolonged exposure to Ecstasy and a variety of other drugs is not necessarily associated with detectable regional alterations on the neurophysiologic level. -- http://tinyurl.com/mgpdz7 - fMri study found no real differences from the abstract: -- Cannabis users and controls performed equally well during the working memory task and the selective attention task. Furthermore, cannabis users did not differ from controls in terms of overall patterns of brain activity in the regions involved in these cognitive functions. However, for working memory, a more specific region-of-interest analysis showed that, in comparison to the controls, cannabis users displayed a significant alteration in brain activity in the left superior parietal cortex. -- Note the region of interest analysis at the time was subject to very problematical type I and II errors, so I am not confident of those results. http://tinyurl.com/kvylo4 review study - found significant short term but not long term effects. http://tinyurl.com/lk7rwq from the abstract: -- Despite similar task and cognitive test performance compared with control subjects, active and abstinent marijuana users showed decreased activation in the right prefrontal, medial and dorsal parietal, and medial cerebellar regions, but greater activation in various frontal, parietal and occipital brain regions during the visual-attention tasks (all with P ⤠0.001, corrected, cluster level). However, the BOLD signals in the right frontal and medial cerebellar regions normalized with duration of abstinence in the abstinent users. Active marijuana users, with positive urine tests for THC, showed greater activation in the frontal and medial cerebellar regions than abstinent marijuana users and greater usage of the reserve network (regions with load effect), suggesting a neuroadaptive state -- Problem with many of these studies is that they don't mention other drug use in either the controls or the different experimental groups. Frequently the sample sizes are quite small, in several there were age or SES differences that could also explain some of the experimental results. I could go on and about the drawbacks to this area but you'd be terminally bored. In general then the results are all over the board. larry ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Want to reach the ColdFusion community with something they want? Let them know on the House of Fusion mailing lists Archive: http://www.houseoffusion.com/groups/cf-community/message.cfm/messageid:300861 Subscription: http://www.houseoffusion.com/groups/cf-community/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.5
