How Does Marijuana Affect the Brain?

Introduction

According to the National Institutes of Health, marijuana is the most abused illegal drug in the United States. Derived from the hemp plant Cannabis sativa, the active ingredient in marijuana is delta-9-tetrahydrocannabinol, which is also called THC. Marijuana looks like a "dry, shredded green and brown mix of flowers, stems, seeds, and leaves," according to the National Institutes of Health. Marijuana can be used in multiple ways, according to the NIH. While marijuana is commonly smoked by using a pipe or joint, users also brew marijuana as a tea or mix it into their food to get high.

Spread of THC to the Brain

According to the National Institutes of Health, when marijuana is smoked, THC quickly passes from the lungs to the blood stream. Once THC has entered the blood stream, THC can move to any organs in the body, including the brain. Within the brain, there are multiple receptors that result in a person's perception of pleasure or pain. THC acts upon the cannabinoid receptors in the brain; when cannabinoid receptors receive THC, it results in the drug high associated with marijuana. According to the National Institutes of Health, each part of the brain has different amounts of cannabinoid receptors. Brain regions that are responsible for pleasure, memory, thoughts, concentration, perception, movement and coordination have the largest number of cannabinoid receptors. Thus, the use of marijuana has a profound effect on these brain functions.

Effects on the Brain

Once THC has entered the brain, it temporarily affects brain function. Examples of marijuana effects on the brain are distorted perception, impaired coordination, difficulty with thinking and problem solving, and learning and memory problems, according to the NIH. In addition, the NIH notes that learning and memory problems as a result of marijuana use can last for days or weeks. While the long-term effects of marijuana are debated, the NIH states that changes from marijuana abuse to the brain are similar to effects of long-term abuse of other drugs. For example, dopamine receptors, which are involved in the reward system in the brain, get affected by all abused drugs. The Drug Policy Alliance Network notes that some marijuana users may experience some psychological effects, such as anxiety, paranoia and panic. In rare cases, large amounts of ingested marijuana can result in temporary toxic psychosis.