Marijuana is the dried leaves and flowers of the Cannabis sativa or Cannabis indica plant.
Stronger forms of the drug include high potency strains - known as sinsemilla (sin-seh-
me-yah), hashish (hash for short), and extracts including hash oil, shatter, wax, and
budder.
Of the more than 500 chemicals in marijuana, delta-9-tetrahydrocannabinol, known as
THC, is responsible for many of the drug's psychotropic (mind-altering) effects. It's this
chemical that distorts how the mind perceives the world. In other words, it's what makes
a person high.
Strength and Potency
The amount of THC in marijuana has increased over the past few decades. In the early
1990s, the average THC content in marijuana was less than 4 percent. It is now about 15
percent and much higher in some products such as oils and other extracts (see below).
Scientists do not yet know what this increase in potency means for a person's health.
Some people adjust how they consume marijuana (by smoking or eating less) to
compensate for the greater potency. There have been reports of people seeking help in
emergency rooms with symptoms, including nervousness, shaking and psychosis (having
false thoughts or seeing or hearing things that aren't there), after consuming high
concentrations of THC.
Marijuana Extracts
Smoking extracts and resins from the marijuana plant with high levels of THC is on the
rise. There are several forms of these extracts, such as hash oil, budder, wax, and shatter.
These resins have 3 to 5 times more THC than the plant itself. Smoking or vaping it (also
called dabbing) can deliver dangerous amounts of THC and has led some people to seek
treatment in the emergency room. There have also been reports of people injured in fires
and explosions caused by attempts to extract hash oil from marijuana leaves using butane
(lighter fluid).
What happens to your brain when you use marijuana?
All drugs change the way the brain works by changing the way nerve cells communicate.
Nerve cells, called neurons, send messages to each other by releasing chemicals called
neurotransmitters. These neurotransmitters attach to molecules on neurons called
receptors. (Learn more about how eurotransmitters work.) Drugs affect this signaling
process.
When marijuana is smoked or vaporized, THC quickly passes from the lungs into the
bloodstream, which carries it to organs throughout the body, including the brain. Its effects begin almost immediately and can last from 1 to 3 hours. This can affect decision
making, concentration, and memory for days after use, especially in people who use
marijuana regularly.1 If marijuana is consumed in foods or beverages, the effects of THC
appear later—usually in 30 minutes to 1 hour—and may last for many hours. Some
people consume more and more waiting for the "high" and end up in the emergency room
with uncomfortable symptoms from too much THC.
As it enters the brain, THC attaches to cells, or neurons, with specific kinds of receptors
called cannabinoid receptors. Normally, these receptors are activated by chemicals
similar to THC that occur naturally in the body. They are part of a communication
network in the brain called the endocannabinoid system. This system is important in
normal brain development and function.
