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What Marijuana Does To Your Brain And Body

It’s 4/20. For those not in the know, “4/20” is the unofficial holiday for pot smokers and marijuana legalization activiists around the world to celebrate by lighting up on April 20. 

The Huffington Post’s Ryan Grim traced the term back to 1971. A group of California high school friends, known as the “Waldos,” used “4/20” as a codeword to refer to the time of the day when they would smoke outside of school. 

The term was popularised in stoner communities, courtesy of the Grateful Dead. It eventually went mainstream, much to the dismay of police, parents, and lawmakers.   

The drug, best-know for it’s “feel-good” effects and touted for its uses for multiple diseases, can also be damaging to our bodies and minds.

Marijuana comes from the cannabis sativa plant, and is the dried and shredded leaves, stems seeds and flowers. The high you get from marijuana comes from a chemical called Tetrahydrocannabinol, also known as THC. Some strains contain more or less THC — making them more or less potent.

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.

Marijuana makes you feel good

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.

.. but that's not all good

When the rewards system is overstimulated, for example with drugs of abuse like cocaine, it can go haywire and cause a dependence (and in extreme cases addiction) on whatever is providing the rewarding feeling, and also take away from how rewarding normal things, like eating, are.

This can cause apathy and dependence on the drug.

It blocks memory formation

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 legalized it.

This blockage of memory formation can cause cognitive impairment in adulthood if use happens during adolescence, at least for 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 your balance

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.

Cannabis use may increase the risk of depression

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.

Intense anxiety, fear, distrust, or panic are common side effects

Somewhere between 20 and 30 per cent of recreational marijuana users react with intense anxiety after taking the drug, making it one of the most commonly reported side effects.

Marijuana users may experience psychosis

Marijuana users who have taken large doses of the drug may experience an 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.

Audio and visual hallucinations are common

It robs you of sleep

There are five stages of sleep, which get progressively deeper as the night goes on. The first four stages are called rapid eye movement, or REM. THC, the main active chemical in marijuana, has been shown to interrupt the later phases of REM sleep, the point during the night that is most crucial to making the body feel re-energized when you wake up.

Inhaling marijuana causes your heart rate to increase

Within a few minutes of inhaling marijuana, your heart rate increases, sometimes by 20 to 50 beats per minute (normal is 70 to 80 beats per minute). In some cases, like when taking other drugs with marijuana, heart rate can double.

This heart rate increase usually subsides relatively quickly, in about 20 minutes.

Red eyes

The traditional red eyes of a marijuana user -- Visine anyone? -- come from blood vessels expanding in the eye.

Dry mouth

On uncomfortable effect of smoking weed is dry mouth or thirst.

The common side-effect, equivalent to the feeling of having a bunch of cotton balls shoved in your mouth, is not just the result of inhaling in hot smoke. It turns out cannabinoids receptors are located where our saliva is produced. When these receptors are activated by cannabis use, they inhibit the production of saliva.

The munchies

After marijuana intake, most people feel the need to eat. And eat a lot. The drug increases food enjoyment and interest in food, increasing appetite. This is thought to be caused by the THC interacting with the cannibinoid receptors in a brain area called the hypothalamus.

Interestingly, a link has been drawn between milk products and cannibinoids. Some researchers think that these cannibinoids in milk play an important role in infant survival, because they stimulate the child's appetite and cause them to eat more and suckle, which could be why THC has a similar effect in adults.

The drug is also touted for its health benefits

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