7. Marijuana use is linked to improved mental health.
A number of studies reported by NIDA have shown an association between chronic marijuana use and mental illness, including a worsening or earlier onset of psychosis, schizophrenia, depression, anxiety, and substance use disorders. The amount of marijuana used and age of first use, as well as genetic predisposition to a mental illness may play a role. Link: (There is a Link Between Marijuana Use and Psychiatric Disorders)
Compared to non-users, heavy marijuana users report not only poorer mental health, but also less physical health, life satisfaction, and more relationship problems, according to NIDA. Link: (Marijuana and Disorders)
A study published in Health examining national adolescent samples from Canada and the US found that marijuana users report reduced mental and physical health which is permanent, particularly if they were once regular smokers or began before the age of 15 or 20. Link: (Health)