“You can study, study, study it, but it’s THC (Delta-9-tetrahydrocannabinol) – that is the active ingredient,” Franson said. “And there are certain things that happen to everyone who takes THC.”
These, she said, are a feeling of pleasure or high, motor instability, decreased reaction time, attention deficit and increased heart rate.
“People think it mellows them out, but it causes an average increase in heart rate of 16 beats per minute,” Franson said. “That’s why people who take high doses they are unaccustomed to can experience significant anxiety or paranoia.”
Other THC effects commonly experienced are increased appetite, decreased nausea, decreased motivation and decreased pain perception.
Additional typical effects are bloodshot eyes, decreased pressure inside the eye (it’s used to treat glaucoma), heightened sensory perception (intense colors and sounds), distorted sense of time and sometimes a dry mouth.
“The cannabinoid receptor system is one of the biggest systems. Your brain is chock-full of them,” said Dr. Christian Hopfer, an associate professor of psychiatry at University of Colorado Hospital’s Center for Dependency, Addiction and Recovery.
“You need (the body’s natural cannabinoids), and it has an effect when you’re messing with those receptors,” Hopfer said.
THC mimics the body’s cannabinoids. Both interact with the same receptors. When THC binds to the receptor, it interferes with normal brain function, such as dopamine regulation.
Dopamine is part of the body’s natural reward system and a key molecule in many brain functions, such as attentiveness, motivation, learning, memorization and motor control. THC increases dopamine in the short term, but ultimately interferes with the body’s own reward circuit.
With chronic cannabis consumption, the body decreases the number of receptors for its cannabinoids. Researchers have found that this results in reduced blood flow – and glucose and oxygen – to the brain. This could manifest as attention-deficit, memory loss and other impaired mental abilities.
“There is evidence you don’t recover all your mental capacity when you quit using,” said Hopfer, who treats marijuana and other addictions. “It’s a very insidious addiction. It’s very hard to treat. Its effects are subtle, gradual and less dramatic. And it’s been trivialized.”