Addiction
Some people think that marijuana is not truly “addictive” or that people can’t become “hooked” on the drug, but research shows that about 1 in 10 marijuana users will become addicted. For people who begin using before the age of 18, that number rises to 1 in 6
Some of the signs that someone might be addicted include:
Unsuccessful efforts to quit using marijuana.
Giving up important activities with friends and family in favor of using marijuana.
Using marijuana even when it is known that it causes problems fulfilling everyday jobs at home, school or work
Brain Health
Marijuana use directly affects the brain — specifically the parts of the brain responsible for memory, learning, attention, decision making, coordination, emotions, and reaction time.
Short-term effects of marijuana on the brain
Heavy users of marijuana can have short-term problems with attention, memory, and learning, which can affect relationships and mood.
Long-term effects of marijuana on the brain
Marijuana also affects brain development. When marijuana users begin using as teenagers, the drug may reduce attention, memory, and learning functions and affect how the brain builds connections between the areas necessary for these functions
Cancer
There is mixed evidence about whether marijuana can cause cancer, partly because most people who use marijuana also use tobacco, a substance that does cause cancer. Researchers have found an association between current, frequent, or chronic marijuana smoking and testicular cancer (non-seminoma-type).More research is needed to understand the full impact of marijuana use on cancer