Marijuana's Neuroscience, Effects, and Treatment Guide

The Neuroscience of Marijuana

Cannabis sativa (marijuana) is a plant that contains a chemical compound called delta-9-tetrahydrocannabinol, commonly known as THC. According to the National Institute on Drug Abuse (NIDA, 2010), smoking marijuana — the most common form of intake — causes THC to "rapidly pass from the lungs into the bloodstream, which carries the chemical to the brain and other organs throughout the body." The smoking process therefore delivers THC quickly to the brain, where it is received by cannabinoid receptors.

Cannabinoid receptors are physical sites distributed throughout the brain, concentrated mainly "in parts of the brain that influence pleasure, memory, thinking, concentrating, sensory and time perception, and coordinated movement" (National Institute on Drug Abuse, 2010). When THC binds to these receptors, it triggers "a series of cellular reactions that ultimately lead to the 'high' that users experience when they smoke marijuana" (National Institute on Drug Abuse, 2010).

Although the high feels momentarily pleasurable, evidence indicates that marijuana "is harmful to the brain" ("Marijuana's Lasting Effects on the Brain," 2012). One longitudinal study found that people who smoked marijuana regularly from age 13 to age 38 experienced an average drop in IQ score of 8 points. A control group in the same study did not smoke marijuana and showed no drop in IQ score over the same period ("Marijuana's Lasting Effects on the Brain," 2012). There is also evidence that smoking marijuana can cause neural impairment that may be permanent even after a person stops using the drug. However, cessation does lead to improvements in cognitive and neural functioning.

Many people become psychologically addicted to marijuana and continue using it to experience the high. When a person stops, the brain reacts with negative symptoms. "Long-term marijuana abusers trying to quit report withdrawal symptoms including: irritability, sleeplessness, decreased appetite, anxiety, and drug craving, all of which can make it difficult to remain abstinent" (National Institute on Drug Abuse, 2010).

Psychological Effects of Cannabis Use

When THC reaches the brain, it does more than create a euphoric high. Each person reacts differently — some feel emotionally calm and stable, while others feel anxious and distracted. The drug can also "cause distorted perceptions, impaired coordination, difficulty with thinking and problem solving, and problems with learning and memory" (National Institute on Drug Abuse, 2010). Regular or heavy cannabis users "show deficits in memory, concentration, and overall brainpower in relation to their peers, and the effects are greater the earlier a person starts smoking marijuana on a regular basis" (Gardner, 2012).

The high lasts a relatively short time, but the negative effects persist much longer. According to NIDA, "marijuana's adverse impact on learning and memory can last for days or weeks after the acute effects of the drug wear off. As a result, someone who smokes marijuana every day may be functioning at a suboptimal intellectual level all of the time."

Some users experience serious psychological illness. Research reveals "an association between chronic marijuana use and increased rates of anxiety, depression, and schizophrenia" (National Institute on Drug Abuse, 2010). High doses are especially detrimental for individuals who are already genetically prone to mental illness. Marijuana contains many chemicals beyond THC, including cannabidiol (CBD), which mitigates some of THC's adverse side effects. One research study found that "the men who had taken THC had more psychotic symptoms like altered thinking (paranoid and delusional thoughts) than men who'd taken either CBD or placebo" (Walton, 2012).

In terms of physiological effects, increased heart rate and red eyes are the primary physical symptoms (Taylor, 1996). According to NIDA (2010), "marijuana increases heart rate by 20–100% shortly after smoking; this effect can last up to 3 hours."

Demographics: Who Uses Marijuana

There is no single type of person who uses marijuana because it is a widely consumed substance. In fact, "marijuana is the most commonly abused illicit drug in the United States" (National Institute on Drug Abuse, 2010), meaning a large and diverse population is affected. According to SAMHSA (2012), a government agency that tracks drug use patterns, white and Black Americans use marijuana in roughly equal proportions, as do males and females overall. The primary demographic difference is that non-white females tend to use marijuana less than non-white males (SAMHSA, 2012).

White males are more likely than other groups to be found in treatment facilities for marijuana use. According to NIDA (2010), "marijuana admissions were primarily male (74%), white (49%), and young (30% were in the 12–17 age range)." The age groups most likely to have ever used marijuana are between 18 and 59 years old, among whom roughly half report having used it at least once. Interestingly, higher educational attainment is associated with a greater likelihood of having tried marijuana (SAMHSA, 2012).

References

Gardner, A. (2012). Pot smoking may leave mark on teen brains. CNN. August 27, 2012.

"Marijuana's Lasting Effects on the Brain." (2012). National Institute on Drug Abuse.

MedlinePlus. (2012). Marijuana. U.S. National Library of Medicine.

National Institute on Drug Abuse. (2010). Drug facts: Marijuana.

SAMHSA. (2008). Marijuana. Substance Abuse and Mental Health Services Administration.

Taylor, H. G. (1996). Analysis of the medical use of marijuana and its societal implications.

Walton, A. G. (2012). The neuroscience of pot: Researchers explain why marijuana may bring serenity or psychosis. Forbes.