RECENTLY LEGALISED IN the Washington and Colorado, marijuana has medical and recreational uses but can also be damaging to our bodies and minds.
The high you get from marijuana comes from a chemical called Tetrahydrocannabinol, also known as THC, which is found in varying potency.
Most of THC’s effects happen in the brain, where the chemical interacts with receptors on brain cells called cannibinoid receptors. Our bodies actually make chemicals very similar to THC, which are used in normal brain function and development. THC co-opts these natural pathways to produce most of its effects.
General manager David Martinez labels containers of retail marijuana, behind a sales bar fitted with a brochure available to customers, at 3D Cannabis Center in Denver. (AP Photo/Brennan Linsley)
The active ingredient in marijuana acts in the part of the brain called the hippocampus to alter the way information is processed and how memories are formed. Animal studies have shown that this is particularly true while the brain is still developing — specifically why the legal smoking age is 21 in the states that have legalised it.
This blockage of memory formation can cause cognitive impairment in adulthood if use happens during adolescence, at least in rats. It can also quicken age-related brain cell loss, though marijuana has been shown to slow the progression of Alzheimer’s disease.
THC messes with brain areas called the cerebellum and basal ganglia, which regulate balance, posture, coordination, and reaction time. When these brain areas are disturbed, the user has a harder time walking and talking correctly, becoming quite clumsy. It also impacts their ability to drive.
Although there is no conclusive evidence that marijuana makes users depressed (it’s just as likely that people who are depressed use pot), one recent study from the Netherlands found that smoking cannabis increases the risk of depression for young people who have a genetic vulnerability to the mental illness.
In the long-term, smoking marijuana increased depressive symptoms in subjects with a special serotonin gene responsible for increased risk of depression.
Somewhere between 20 and 30 percent of recreational marijuana users react with intense anxiety after taking the drug, making it one of the most commonly reported side effects.
Marijuana users who have taken large doses of the drug may experience acute psychosis, which includes hallucinations, delusions, and a loss of the sense of personal identity. These episodes may be related to the link between marijuana use and psychosis, but are distinct.
When THC hits brain cells, it causes them to release dopamine, a feel-good brain chemical. This is a part of the brain’s reward system, which makes you feel good when you do things that ensure the survival of yourself and your offspring. These things include eating and having sex.
When over-excited by drugs, the reward system creates feelings of euphoria.
Marijuana use can prevent epileptic seizures, a 2003 study showed.
Robert J. DeLorenzo of Virginia Commonwealth University, gave marijuana extract and synthetic marijuana to epileptic rats. The drugs rid the rats of the seizures for about 10 hours. Cannabinoids like the active ingredient in marijuana, tetrahydrocannabinol (also known as THC), control seizures by binding to the brain cells responsible for controlling excitability and regulating relaxation.
The findings were published in the Journal of Pharmacology and Experimental Therapeutics.
Patients with inflammatory bowel diseases like Crohn’s disease and ulcerative colitis could benefit from marijuana use, studies suggest.
University of Nottingham researchers found in 2010 that chemicals in marijuana, including THC and cannabidiol, interact with cells in the body that play an important role in gut function and immune responses. The study was published in the Journal of Pharmacology and Experimental Therapeutics.
THC-like compounds made by the body increase the permeability of the intestines, allowing bacteria in. The plant-derived cannabinoids in marijuana block these body-cannabinoids, preventing this permeability and making the intestinal cells bond together tighter.
Marijuana may be able to slow the progression of Alzheimer’s disease, a study led by Kim Janda of the Scripps Research Institute suggests.
The 2006 study, published in the journal Molecular Pharmaceutics, found that THC, the active chemical in marijuana, slows the formation of amyloid plaques by blocking the enzyme in the brain that makes them. These plaques are what kill brain cells and cause Alzheimers.
One chemical found in marijuana, called cannabidiol, prevents cancer from spreading, researchers at California Pacific Medical Center in San Francisco reported in 2007.
Cannabidiol stops cancer by turning off a gene called Id-1, the study, published in the journal Molecular Cancer Therapeutics, found. Cancer cells make more copies of this gene than non-cancerous cells, and it helps them spread through the body.
The researchers studied breast cancer cells in the lab that had high expression levels of Id-1 and treated them with cannabidiol. After treatment the cells had decreased Id-1 expression and were less aggressive spreaders.
- Jennifer Welsh, Dina Spector, and Randy Astaiza
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