[All this week, GS will be covering stories on Marijuana - its traditional uses, basic biology, criminalization, neurological effects and more. Join us all this week for our in depth study of this fascinating, controversial plant!]

Many marijuana users believe that there are no significant negative repercussions to smoking cannabis. In fact, many believe the practice to be good for them; it calms them, it brings them to a happier place, and, if they did their research, it relieves nerve pain. Although these claims may hold true to users, marijuana does far more than just “bring you to a happy place.”

Almost one year ago, researchers from ORYGEN Research Centre and the Melbourne Neuropsychiatry Centre performed magnetic resonance imaging (MRI) on 15 men that had smoked 5 joints daily for more than 10 years. The results of these men (average age of 39.8 years) was compared with the MRIs of 16 individuals who were not cannabis users (average age of 36.4 years). The participants of the survey were also required to take a verbal memory test and checked for symptoms of psychotic disorders, such as schizophrenia and psychosis.

The hippocampus, which regulates emotion and memory in the brain, and the amygdala, which influences fear and aggression, was shown to decrease with cannabis users. The hippocampus had an average volume of 12% less in cannabis users than nonsmokers, and the amygdala’s volume was reduced around 7.1%. Cannabis users were found to have more sub-threshold symptoms for psychotic disorders, and they also had inferior performance on the verbal memory test. The authors explained that the regional brain volume differences did not contribute to the significant discrepancy on verbal memory test performance. The authors also mention that mild to modest use of cannabis does not have significant neurotoxic effects.

Cannabis proves to be much more harmful to teens and young adults. Researchers discovered that young users have abnormal brain development, resulting in anomalies “in areas of the brain that interconnect brain regions involved in memory, attention, decision-making, language and executive functioning skills.” To a teen or young adult, this is extremely detrimental due to the brain development and maturation that occurs in this stage of life. Certain critical areas of the brain that develop in the latter stages of adolescence are heavily damaged in cannabis users.

Fourteen users of cannabis and fourteen healthy controls, both groups with an average age of 19, had their results of diffusion tensor imaging (DTI) compared. DTI is a form of MRI scanning that measures water movement through brain tissues. The myelin sheath that surrounds neurotissues and brain cells was either damaged or had arrested development in cannabis users. Myelin contributes color to the white matter of the brain and covers fibers that connect brain regions. The study leader, Dr. Manzar Ashtari, explained “Abnormal white matter development could slow information transfer in the brain and affect cognitive functions.”

Regular use of cannabis may increase the risk of stroke as well, in part due to the aforementioned consequences of cannabis use. Marijuana use also has a slew of cardiovascular effects such as tachycardia (rapid heartbeat), excessively high or low blood pressure, and loss of oxygen-carrying ability for red blood cells. A protein which raises levels of blood fats related to stroke and heart attack is also raised as a cannabis smoker. Also, within an hour of smoking marijuana, the smoker’s chance of getting a heart attack is quadrupled.

The negative effects of marijuana seem to greatly outweigh its positive effects, unless the user has been prescribed medicinal marijuana for a particular condition. With all of these potential risks, marijuana users may need to ask themselves, “is this ‘happy place’ really worth it?”

Discussion Question: Why do you think so many marijuana users are unaware of the dangers of marijuana?
Articles:
http://www.sciencedaily.com/releases/2008/06/080602160845.htm
http://www.sciencedaily.com/releases/2009/02/090202175105.htm
Journal References:

http://archpsyc.ama-assn.org/cgi/content/short/65/6/694
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T8T-4V74K3P-2&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=0201e5732b322070f213eb381e4af414