Marijuana can cause cognitive effects such as:
* Short or long-term psychosis/schizophrenic disorders that begin in some young users <a target=_blank class=ftalternatingbarlinklarge href="http://www.timesonline.co.uk/article/0,,3561-1565337,00.html">http://www.timesonline.co.uk/a...,,3561-1565337,00.html</a>
* Varying amounts of paranoia and anxiety in some users (usually when overdosed or anxious before use) <a target=_blank class=ftalternatingbarlinklarge href="http://www.guide4living.com/drugabuse/cannabis-effects.htm
">http://www.guide4living.com/dr...bis-effects.htm
</a>
* Some studies report the loss of coordination and distorted sense of time in some users <a target=_blank class=ftalternatingbarlinklarge href="http://www.nhtsa.dot.gov/PEOPLE/INJURY/research/job185drugs/cannabis.htm">http://www.nhtsa.dot.gov/PEOPL...b185drugs/cannabis.htm</a> , while others fail to find effects on time perception and reaction time. <a target=_blank class=ftalternatingbarlinklarge href="http://www.qmc.ufsc.br/qmcweb/artigos/maconha/papers/comparative_effects_alchool_marijuana.pdf
">http://www.qmc.ufsc.br/qmcweb/...l_marijuana.pdf
</a>
* Impairment of short-term memory in some heavy users (7 cigarettes a week and more) (H. G. Pope Jr and D. Yurgelun-Todd, The residual cognitive effects of heavy marijuana use in college students, Journal of the American Medical Association, Vol. 275 No. 7, February 21, 1996)
* Auditory or visual hallucinations at high doses in some users <a target=_blank class=ftalternatingbarlinklarge href="http://www.wrongdiagnosis.com/sym/hallucinations.htm
">http://www.wrongdiagnosis.com/...lucinations.htm
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* Increased mental activity, like metacognition and introspective or meditative states of mind in most users (Joseph Owens, Dread, The Rastafarians of Jamaica, 1974)
* Entheogenesis (e.g. per Rastafarian users, more "Jah-Vibrations") in some users (Joseph Owens, Dread, The Rastafarians of Jamaica, 1974)
Additionally, cannabis use was observed to affect blood flow to the brain, by narrowing blood vessels analogous to how heart disease affects blood flow, though blood flow was shown to improve again after one month's abstinence in light to moderate users. <a target=_blank class=ftalternatingbarlinklarge href="http://news.bbc.co.uk/2/hi/health/4244489.stm
">http://news.bbc.co.uk/2/hi/health/4244489.stm
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Playing devils advocate:
There is some conclusive scientific evidence about the long-term effects of human cannabis consumption. <a target=_blank class=ftalternatingbarlinklarge href="http://www.mth.kcl.ac.uk/~streater/cannabis.html
">http://www.mth.kcl.ac.uk/~streater/cannabis.html
</a>
The most significant confounding factor is the use of other drugs, including alcohol and tobacco, by test subjects in conjunction with cannabis. When subjects using only cannabis were combined in the same sample with subjects using other drugs as well, researchers could not reach a conclusion as to whether their findings were caused by cannabis, other drugs, or the interaction between them. In addition, research using cannabis is heavily restricted in many countries, making it difficult to get new studies funded or approved. Since there are so many different compounds in cannabis, it is difficult to predict or accurately measure its effects. Some conclusions established with some degree of certainty that cannabis is less likely to cause emphysema or cancer than tobacco <a target=_blank class=ftalternatingbarlinklarge href="http://www.mapinc.org/drugnews/v05/n1106/a09.html?275821">http://www.mapinc.org/drugnews.../n1106/a09.html?275821</a> ; that it is unlikely to cause birth defects or developmental delays in the children of users,(J.S. Hayes, R. Lampart, M.C. Dreher, L. Morgan (1991). "Five-year follow-up of rural Jamaican children whose mothers used marijuana during pregnancy". West Indian Medical Journal 40 (3): 120-3. and M.C. Dreher, K. Nugent, R. Hudgins (1994). "Prenatal Marijuana Exposure and Neonatal Outcomes in Jamaica: An Ethnographic Study". Pediatrics 93 (3): 254-260.) and in a study done by the University of California Los Angeles in 2006, that even heavy cannabis smokers do not increase their risk for lung cancer. <a target=_blank class=ftalternatingbarlinklarge href="http://www.washingtonpost.com/wp-dyn/content/article/2006/05/25/AR2006052501729_pf.html">http://www.washingtonpost.com/...R2006052501729_pf.html</a> According to a United Kingdom government report, using cannabis is less dangerous than both tobacco and alcohol in social harms, physical harm and addiction. <a target=_blank class=ftalternatingbarlinklarge href="http://news.bbc.co.uk/1/shared/bsp/hi/pdfs/31_07_06_drugsreport.pdf
">http://news.bbc.co.uk/1/shared...drugsreport.pdf
</a>
I really don't care either way. There's facts for each so whatever you decide your body can put up with.
*shrug