Marijuana is widely known as weed and is the most commonly abused illicit drug in the United States. Delta-9-tetrahydrocannabinol, or THC for short, is the main active chemical in marijuana.
THC produces many effects in the brain by rapidly passing from the lungs into the bloodstream carrying the chemical to the brain and other organs. When marijuana is used, the brain has cannabinoid receptors that kick off a series of cellular reactions that lead to the “high” that the user experiences. The part of the brain that has the most cannabinoid receptors is the part that controls pleasure, memory, thinking, concentrating, sensory and time perception, and coordinated movement. Marijuana’s adverse impact in a chronic user is on learning and memory. Researchers say that effects could last for days or weeks after the initial effects of the drug wear off.
Increased rates of anxiety, depression, and schizophrenia have been found in studies of chronic marijuana users. Schizophrenia and/or related disorders have been linked to marijuana use and are the strongest evidence that has been reported by researchers that link mental illness and marijuana.
Some consistent alterations to the brain of chronic users have been found according to brain imaging studies. Compulsive drug seeking and abuse despite the know harmful effects upon functioning in the context of work, school, family, and recreational activities, known as addiction, has been linked to long-term marijuana abuse. Nine percent of users become addicted to marijuana and this number climbs to about 17 percent among those who start at a young age. The estimate for daily users is 25-50 percent.
Those who try to quit marijuana abuse have reported withdrawal symptoms which include irritability, anxiety, drug craving, sleeplessness which begin within one day following abstinence and can last up to 2 weeks. All of these symptoms make it difficult to remain abstinent.