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What is Marijuana?

Marijuana is dried leaves, flowers, stems, and/or seeds of the cannabis plant. Marijuana is used by smoking, eating, drinking, inhaling the vapors and applying to the skin. Two components of marijuana are THC and CBD. THC is the active, mind-altering ingredient in marijuana that causes the high effect. Over the years, the amount of THC in marijuana has increased. CBD is often associated with medicinal use however there is continued research on the claimed positive impacts of CBD.

Prevalence

Thirty-eight percent (38%) of high school students report having used marijuana in their life.

It is assumed that more than 82% of college students used marijuana in the last 30 days. However, only 19% of students actually used.

Effects

  • Immediate effects include:
    • Impairment of cognition and coordination (which impacts driving)
    • Production of anxiety and psychotic symptoms
    • Irregularity in function of both the cardiovascular and respiratory systems
    • Increased risk of developing a respiratory infection
  • Long-term effects include:
    • Cannabis dependence, or Cannabis Use Disorder
    • Impairments in cognition
    • Higher rate of development of mental health conditions like schizophrenia and bipolar disorder, or exacerbation of preexisting mental health conditions
    • Decreased respiratory function
    • Increased risk for cardiovascular disease and cancer

Myths and Marijuana

Marijuana Frequently Asked Questions

Marijuana and Memory

The memory issues come from the way marijuana hits the hippocampus, the region of the brain that regulates short-term memory. The effect of cannabis temporarily prevents the brain from developing new memories and learning new things, which is a form of short-term memory.

Researchers who published their findings in the Molecular Psychiatry journal discovered that heavy cannabis users are at risk for developing false memories, even if those users had gone without smoking pot for over a month.

Such a finding is one of a number that suggests people who were regular marijuana smokers in their teenage years are more likely to have memory problems as adults. One such study was published in the Hippocampus journal, which found that teenagers who smoked pot every day for three years had “abnormally shaped” hippocampal regions when they reached their early 20s. Those individuals “performed around 18 percent worse in long-term memory tests,” compared to other test subjects who had never smoked marijuana.

Another study published noted the same thing, with researchers surprised that there was “a consistent association with verbal memory for chronic exposure to marijuana,” even when cigarettes and alcohol were accounted for. As past years of marijuana use went up, verbal memory scores went down; or in other words, 50 percent of pot smokers tended to remember one fewer word from a list of 15 words. One of the study's authors worried that this effect could damage how the brain processes information and how that information is recalled later.

There is a lot more research that suggests people who smoke marijuana on a daily basis for a number of years, struggle with cognitive tasks more than those who either do not smoke marijuana or who do so infrequently and/or for shorter periods of time. According to one researcher speaking to Reuters Health, people who smoke marijuana occasionally and then give up the habit have a lower risk of developing problems with their thinking power and memory. Nonetheless, he warned that cannabis is still a drug, and all drugs have some level of harm to them, especially if they are consumed under certain circumstances.

Page last modified July 27, 2026