Marijuana is a natural plant substance that is typically ingested by smoking.
According to the National Institute on Drug Abuse, about 30 percent of people who use marijuana have some level of marijuana use disorder, also known as addiction.
People can become addicted to marijuana.
Although marijuana has a reputation for being harmless with little potential for addiction, some people who use marijuana experience some level of dependency and abuse. About four million people in the U.S. met the criteria for marijuana use disorder in 2015, and approximately 138,000 people sought treatment for marijuana abuse.
Marijuana dependency develops when the brain becomes accustomed to the presence of THC in the body and reduces the production and sensitivity to its own endocannabinoid neurotransmitters. Tetrahydrocannabinol (THC) is the main active ingredient in cannabis and is a crystalline compound.
Dependency can turn into addiction when a person cannot stop using a substance despite negative consequences in their life. They begin to participate in compulsive drug-seeking behaviors to obtain and consume more of the substance of choice.
The U.S. Drug Enforcement Administration currently lists marijuana as a Schedule I drug, meaning that it has no currently accepted medical use and a high potential for abuse. This places marijuana in the same category as heroin and ecstasy.
Despite this classification, many people believe that marijuana is harmless and poses little risk for addiction.
While marijuana does not pose the same risk for fatal overdose and serious physiological addiction as other highly potent drugs of abuse such as opioids or stimulants, marijuana can impact the brain and body in significant ways. People can develop addiction problems with regular marijuana consumption.
Research from animal and human studies have indicated that marijuana use can have some adverse impacts on the brain, particularly during early development.
The hippocampus is the area of the brain that is responsible for memory and information processing. This is the area of the brain that is affected by THC use early in life. The changes there are responsible for some of the negative outcomes in cognitive functioning noted in research about marijuana use.
Rats who are exposed to THC early in life develop problems with learning and memory tasks later in life. These impacts, as well as other cognitive impairments, are associated with structural and functional changes that occur in the hippocampus during development. These studies also show that exposure to THC impacts the brain’s reward system, making it more likely that subjects will choose to take other rewarding drugs when presented with the opportunity.
Studies in humans have offered conflicting results. There is some evidence that THC use alters brain functioning in areas of cognitive functions like memory, processing speed, and overall operation. The degree of impairment appears to be dependent on the age at which use began as well as how much was used and how long use continued.
One study found that marijuana use disorder in adolescence was associated with a loss of six to eight IQ points that are not recovered in adulthood. Those who began marijuana use in adulthood did not lose IQ points.
This further supports the notion that early exposure to marijuana poses the most risk for individuals over the long term.
NIDA states that about nine percent of people who use marijuana will develop a dependency on the drug. Dependency is measured by the presence of withdrawal symptoms when people stop using a substance.
Addiction is different than dependency. Addiction is assessed by examining drug-seeking behaviors that accompany dependency. People may become dependent on marijuana and experience withdrawal symptoms when they stop using it, but they may not necessarily experience uncontrollable drug-seeking behaviors that often accompany reliance on other, more potent drugs.
Opioids, for example, are highly addictive. Nearly everyone who uses opioids for a prolonged period of time will become dependent on them because of their interaction with the opioid receptors in the brain and the painful symptoms associated with withdrawal.
The American Society of Addiction Medicine states that 23 percent of people who use heroin will develop an opioid addiction. People who develop an opioid dependency will experience the compulsive behaviors that characterize addiction because the symptoms of opioid withdrawal are so painful and distressful that they feel a physiological need to ingest more opioids for relief from withdrawal symptoms.
Studies of marijuana are complicated by the fact that many people may be using more than one substance, such as alcohol or other drugs, as well. This makes it difficult for researchers to be able to make determinations about exactly what the cause for certain results may be. Furthermore, some studies use measures of dependency like the presence of withdrawal symptoms as a proxy for addiction, but addiction and dependency are not the same conditions and people can have a dependency without having an addiction.
The addictive potential surrounding drug abuse is often linked to the distressful symptoms of withdrawal that occur when people try to stop using a substance they have been regularly consuming. The withdrawal symptoms associated with quitting marijuana are not nearly as intense and painful as the symptoms of withdrawal from other drugs such as heroin. Thus, marijuana poses less of a risk than other more potent drugs, such as opioids and cocaine, in terms of the potential for developing an addiction.
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However, more people use marijuana than other drugs of abuse, which means that in absolute numbers, there may be more people with marijuana dependency than other substance dependencies.
The National Institutes of Health reports that 2.5 percent of adults, or nearly 6 million people in the U.S., experienced marijuana use disorder in the past year, and 6.3 percent of adults met the criteria at some point in their lives.
In comparison, according to NIDA, about 913,000 people in the U.S. met criteria for cocaine dependency or abuse in the past year, with about 1.5 million current users. People with addictions to prescription pain relievers and heroin numbered approximately 2.5 million in 2015.
Estimations about the rates of substance use disorders are also complicated by the presence of polysubstance abuse. Many people may use more than one substance, such as marijuana and alcohol, which can impact the severity of symptoms of withdrawal as well as other compulsive behaviors associated with addiction. A study from Human Psychopharmacology found that the majority of people with non-alcohol substance use disorders had at least one other co-occurring substance use disorder.
Marijuana use is particularly concerning among those who begin to use as adolescents. There could be implications for brain development when exposed to marijuana as well as the potential for the development of tolerance and dependency.
Adolescents who start using marijuana when they are younger are at risk for further problems with marijuana as they get older. People who start using marijuana before they are 18 years old have a four and seven times higher likelihood of developing an addiction to marijuana than those who start using the drug as adults.
There are other risks associated with marijuana use that have implications for other areas of health and wellness. A 2015 study found that long-term use of marijuana can result in the following:
Marijuana may be less dangerous overall than other commonly used drugs of abuse in regard to the potential for severe withdrawal symptoms and overdose fatalities. However, it is not without risks and does have the potential to become habit-forming.
Another concern with the current trends in the marijuana industry is the rise in the potency of the THC content in marijuana supplies. The THC content in confiscated marijuana samples has quadrupled from about 3.8 percent in the early 1990s to 12.2 percent in 2014 samples.
Products that contain THC extracts that are now sold in legal markets may contain 50 to 80 percent THC. This has concerned some addiction and policy experts, as the increasing potency of marijuana could mean more consequential outcomes for people with marijuana use disorders and the potential for marijuana to be more highly addictive than it has been in the past.
People who have a personal or family history of addiction should not use marijuana because they may have a higher risk of developing addiction with prolonged use.
Those with mood or personality disorders and other mental health conditions should not use marijuana, as they are also at increased risk for developing a potentially problematic marijuana use disorder.
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