The nearly 11% annual prevalence rate of marijuana use in North America is dramatically higher than the global rate of 9.9%.
When someone injects heroin intravenously this is called mainlining.
Large amounts of dopamine in the brain as a result of a methamphetamine may lead to irreparable brain damage, because the drug destroys natural dopamine production sites.
It is never recommended to stop taking Valium abruptly without medical intervention, and there are drug rehab facilities which can perform a safe medical detox and get individuals off of the drug.