Recently legalized in 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.
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, by the abuse of drugs like cocaine, it can go haywire and cause a dependence (or in extreme cases addiction) on whatever is providing the rewarding feeling. It can also diminish how rewarding normal things, like eating, feel.
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 in rats. It can also quicken age-related brain cell loss, though marijuana has been shown to slow the progression of Alzheimer's disease.
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