Right out of the gate, asking about the signs someone is addicted to weed is going to cause a firestorm.
We get it. Marijuana has a healthy contingent of defenders, to the point that, at times, it’s difficult to have a civil conversation about it. Like any other mind- or mood-altering substance, discussing the potential for addiction to marijuana isn’t a value judgment about the substance itself. It is, like any other drink or drug, an assemblage of chemical compounds that affects everyone in different ways.
In the case of marijuana, thousands of individuals partake with absolutely no consequences, meaning it never develops into a problem. In fact, marijuana has a great many advocates who tout its benefits as a holistic alternative to pharmaceutical medicine, and there are indeed some scientific studies that have demonstrated its medicinal effectiveness.
Addiction, however, is a process that takes place in the brain of afflicted individuals, many of whom are biologically or genetically predisposed to it regardless of what substances they consume — from heroin to cocaine to alcohol to, yes, marijuana. The signs someone is addicted to weed may not lead them to the bitter ends of other addictive substances, but the entire concept of recovery is built around quality of life.
In that regard, marijuana can have a negative impact and lead to problems that worsen the quality of life for those who become addicted to it rather than enhancing it, as it may do for some. Those individuals shouldn’t be shamed for wanting to do something about it.
So how does marijuana affect the brain? When did we, as a species and a culture, develop an affinity for it? And what ARE the signs someone is addicted to weed? Let’s dive in.
Weed 101: What Is It?
Pot, reefer, weed, grass, ganja, herb, Mary Jane … marijuana has been saddled with a number of slang terms over the years, but for the sake of this particular blog, they all come down to one thing: cannabis, and specifically the chemical compound delta-9 tetrahydro-cannabinol, commonly referred to as THC. Cannabis is the name of the plant from which weed comes — specifically, cannabis sativa, which “grows wild in many of the tropical and temperate areas of the world. It can be grown in almost any climate, and is increasingly cultivated by means of indoor hydroponic technology,” according to the University of Washington’s Alcohol and Drug Abuse Institute .
THC is the chemical compound that gives cannabis consumers the “high” that they desire. While there’s been an explosion of THC-related products as marijuana has been legalized in a number of states, the three main forms of cannabis, according to the University of Washington, are “marijuana, hashish and hash oil. Marijuana is made from dried flowers and leaves of the cannabis plant. It is the least potent of all the cannabis products and is usually smoked or made into edible products like cookies or brownies. Hashish is made from the resin (a secreted gum) of the cannabis plant. It is dried and pressed into small blocks and smoked. It can also be added to food and eaten. Hash oil, the most potent cannabis product, is a thick oil obtained from hashish. It is also smoked.”
Granted, those three are not the end-all, be-all of products derived from cannabis, and we’ll get into some of the more modern consumables later on. The focus here is on THC, which is the chemical that can pose problems. Those who show signs someone is addicted to weed are really addicted to the effects THC has on the brain.
So how does it affect the brain? For starters, THC mimics a naturally occurring brain chemical called anadamide, according to the National Institute on Drug Abuse (NIDA) , which function as neurotransmitters that relay messages between nerve cells: “They affect brain areas that influence pleasure, memory, thinking, concentration, movement, coordination, and sensory and time perception. Because of this similarity, THC is able to attach to molecules called cannabinoid receptors on neurons in these brain areas and activate them, disrupting various mental and physical functions.”
These cannabinoid receptors, according to the website BrainFacts.org , “exists in brain areas that are critical for learning, memory, pain perception, and reward processing,” and the introduction of THC causes a number of things to happen, the NIDA points out:
- Because it affects the hippocampus and the orbitofrontal cortex, “areas that enable a person to form new memories and shift his or her attentional focus … using marijuana causes impaired thinking and interferes with a person’s ability to learn and perform complicated tasks.”
- THC also affects normal functioning in the cerebellum and the basal ganglia, “brain areas that regulate balance, posture, coordination, and reaction time.”
- Finally, through those natural cannabinoid receptors, THC “also activates the brain’s reward system, which includes regions that govern the response to healthy pleasurable behaviors such as sex and eating. Like most other drugs that people misuse, THC stimulates neurons in the reward system to release the signaling chemical dopamine at levels higher than typically observed in response to natural stimuli. This flood of dopamine contributes to the pleasurable ‘high’ that those who use recreational marijuana seek.”
Signs Someone Is Addicted to Weed: A Brief History
Again, it’s important to frame this conversation as one about a certain segment of the population who develop a problem with marijuana. If you’re seeking signs someone is addicted to weed, it’s easy to take every physical symptom as a harbinger of doom, but ancient civilizations have used cannabis “in medicine, magic, religion and recreation,” according to High Times magazine , the authority on all things weed since 1974. Some of those civilizations, High Times writer Alan Sumler detailed in 2017, included:
- The Assyrians and Babylonians of Mesopotamia, where “it was used for treating depression, as well as in different medical recipes. Under the name kunubu, it was one of the ingredients in their religious incense, which they traded with Egypt and Judaea.”
- In Bactria — what’s now Afghanistan and Turkmenistan — “Zoroastrian priests prepared the plant as an ingredient in their religious drinks.”
- In ancient India, cannabis was called bhang and ganjha (twisted rope). Their pharmaceutical texts (ca. 1600 BCE) prescribe the plant for treating anxiety, among other common ailments.”
- Cannabis and hemp were present in ancient Egypt, and in nearby Judaea, “cannabis appears as one of the ingredients in holy incense and anointing oil under the name kaneh bosm.”
- “The ancient Greek historian Herodotus (5th century BCE) wrote about the nomadic Scythians and their fumigation of cannabis flowers.”
- The Subeixi, which flourished in the contemporary Chinese province of Xinjiang, “ancient cannabis remains of 16 intact female plants were found in a grave, lain across the deceased body as a burial shroud. Another grave in a nearby cemetery contained a little under two pounds of processed and cut cannabis.”
- “The Roman naturalist Pliny (23-79 CE) mentioned cannabis in several passages, including medical usages.”
By the 16th century, cannabis had expanded westward, according to the DEA Museum , “where Spaniards imported it to Chile for its use as fiber” circa 1545. “In North America cannabis, in the form of hemp, was grown on many plantations for use in rope, clothing and paper.” It was in the 19th century, according to History.com , that cannabis began to appear as a component of Western medicine when “Sir William Brooke O’Shaughnessy, an Irish doctor studying in India, found that cannabis extracts could help lessen stomach pain and vomiting in people suffering from cholera. By the late 1800s, cannabis extracts were sold in pharmacies and doctors’ offices throughout Europe and the United States to treat stomach problems and other ailments.”
In the early part of the 20th century, however, marijuana began to be seen in a different light. According to Eric Schlosser, writing in 1994 for the publication Atlantic , “The political upheaval in Mexico that culminated in the Revolution of 1910 led to a wave of Mexican immigration to states throughout the American Southwest. The prejudices and fears that greeted these peasant immigrants also extended to their traditional means of intoxication: smoking marijuana.” Law enforcement and government officials began to demonize weed, and headlines like this 1925 one in The New York Times  were common: “Mexican, Crazed by Marihuana, Runs Amuck With Butcher Knife.”
In 1937, the federal government passed the Marijuana Tax Act, “the first federal U.S. law to criminalize marijuana nationwide,” according to History.com . “The Act imposed an excise tax on the sale, possession or transfer of all hemp products, effectively criminalizing all but industrial uses of the plant.” That was repealed in 1970 with the introduction and passage of the Controlled Substances Act, which “listed marijuana as a Schedule I drug — along with heroin, LSD and ecstasy — with no medical uses and a high potential for abuse. It was identified in anti-drug programs like D.A.R.E. (Drug Abuse Resistance Education) as a ‘gateway drug.’”
States began to push back against such a draconian measure in 1996, when California, which passed the “Compassionate Use Act of 1996, became the first state to legalize marijuana for medicinal use by people with severe or chronic illnesses.”
As of 2020, according to Esquire magazine , there are 11 states (plus the District of Columbia) that have legalized weed (Alaska, California, Colorado, Illinois, Maine, Massachusetts, Michigan, Nevada, Oregon, Vermont and Washington) for personal use, and another 22 have legalized it for medical use only. Although still technically considered a Schedule 1 drug at the federal level, it remains completely illegal in 17 states: Alabama, Georgia, Idaho, Indiana, Iowa, Kansas, Kentucky, Mississippi, Nebraska, North Carolina, South Carolina, South Dakota, Tennessee, Texas, Virginia, Wisconsin and Wyoming.
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Signs Someone Is Addicted to Weed: Is It Addictive?
Short answer: It can be for some people. According to the NIDA , “Marijuana use can lead to the development of problem use, known as a marijuana use disorder, which takes the form of addiction in severe cases. Recent data suggest that 30 percent of those who use marijuana may have some degree of marijuana use disorder. People who begin using marijuana before the age of 18 are four to seven times more likely to develop a marijuana use disorder than adults.” To put a finer point on those numbers, the Centers for Disease Control puts it this way : “Yes, about 1 in 10 marijuana users will become addicted. For people who begin using younger than 18, that number rises to 1 in 6.”
At the risk of sounding like a broken record, that doesn’t mean everyone who blazes up is going to be curled up in a fetal position a few weeks later, trying to inject the marijuanas into their arm. It’s amusing to poke fun as marijuana addiction as seemingly impossible, but that undercuts the very nature of addiction itself: It’s not about the specific substance. As the NIDA points out , “No one factor can predict if a person will become addicted to drugs. A combination of factors influences risk for addiction. The more risk factors a person has, the greater the chance that taking drugs can lead to addiction.”
In a 2017 article for Live Science , contributor Knvul Sheikh interviewed Dr. Hitoshi Morikawa, an associate professor of neuroscience at the University of Texas at Austin, who explained it in laymen’s terms: “As individuals continue with addictive habits or substances, the brain adapts. It tries to reestablish a balance between the dopamine surges and normal levels of the substance in the brain, Morikawa said. To do this, neurons begin to produce less dopamine or simply reduce the number of dopamine receptors. The result is that the individual needs to continue to use drugs, or practice a particular behavior, to bring dopamine levels back to ‘normal.’ Individuals may also need to take greater amounts of drugs to achieve a high; this is called tolerance.
“Without dopamine creating feelings of pleasure in the brain, individuals also become more sensitive to negative emotions such as stress, anxiety or depression, Morikawa said … eventually, the desire for the drug becomes more important than the actual pleasure it provides. And because dopamine plays a key role in learning and memory, it hardwires the need for the addictive substance or experience into the brain, along with any environmental cues associated with it — people, places, things and situations associated with past use.”
While weed may not seem to be the harbinger of addiction that drugs like heroin, meth and cocaine might be, it does lead to long-term brain changes, according to a 2016 Live Science article : “In a study published in November 2014 in the journal Proceedings of the National Academy of Sciences, researchers looked at 48 adults who used the drug at least three times a day, for an average of eight or nine years, and 62 people who didn't use marijuana. It turned out that the people who had been smoking pot daily for at least four years had a smaller volume of gray matter in a brain region called the orbitofrontal cortex, which previous research had linked to addiction.” (As a sidenote: Those same chronic marijuana users showed greater brain connectivity, a measure of how well information travels across different parts of the brain.)
But that’s not all: Over time, marijuana can have lasting effects on the brains reward centers: “In a paper published in Human Brain Mapping, researchers demonstrated for the first time with functional magnetic resonance imaging that long-term marijuana users had more brain activity in the mesocorticolimbic-reward system when presented with cannabis cues than with natural reward cues. ‘This study shows that marijuana disrupts the natural reward circuitry of the brain, making marijuana highly salient to those who use it heavily. In essence, these brain alterations could be a marker of transition from recreational marijuana use to problematic use,’ said Dr. Francesca Filbey, director of Cognitive Neuroscience Research in Addictive Disorders at the Center for BrainHealth and associate professor in the School of Behavioral and Brain Sciences.” 
Can Weed Be Harmful?
Of course it can, but again, that statement needs to be qualified: “Harmful” is a relative term, and there’s a world of difference between “harmful” and “deadly.” It bears mentioning, however, that death isn’t the arbiter of whether marijuana can be problematic for some people. And given the short-term effects of weed that many consider to be beneficial, according to the University of Washington , it’s difficult to see how it can be considered harmful at all: “feeling of well-being; talkativeness; drowsiness; loss of inhibitions; decreased nausea; increased appetite.” There are, of course, some minuses — “loss of coordination; bloodshot eyes; dryness of the eyes, mouth, and throat; anxiety and paranoia” — but by and large, a cursory glance at the short-term effects make weed seem fairly benign.
But what about long-term effects? Those are still being studied, but the research suggests, at the very least, caution: “The biggest risk related to the use of marijuana is the increased risk of psychosis," Dr. Scott Krakower, assistant unit chief of psychiatry at Zucker Hillside Hospital in Glen Oaks, New York, told Live Science . The article goes on to point out that “another significant risk, for those who use marijuana during their teenage years, is an increased likelihood of an IQ drop. ‘It is safe enough to say that people who smoke marijuana,’ especially when they are young, are more likely have a reduction in their IQ later in life,” according to Krakower.
Such studies have, for the most part, been consistent over the years. Last August, a group of researchers, writing for the journal Addiction , pointed out that while “evidence regarding other cognitive domains and neurological consequences, including cerebrovascular events, is limited and inconsistent,” heavy use by those who are dependent on weed “is consistently associated with a high prevalence of comorbid psychiatric disorders and learning and memory impairments that seem to recover after a period of abstinence.”
It should be noted, too, that scientists and researchers often temper their findings with acknowledgement of the benefits of cannabis, both anecdotal ones and those touted by their peers. In a January 2017 evidence review in the journal Pediatric Neurology , Dr. David Mandelbaum and Dr. Suzanne M. de la Monte find that while “the touting of its medicinal values stems from anecdotal reports related to treatment of a broad range of illnesses including epilepsy, multiple sclerosis, muscle spasms, arthritis, obesity, cancer, Alzheimer disease, Parkinson disease, post-traumatic stress, inflammatory bowel disease, and anxiety” … “the literature and reported case provide strong evidence that chronic cannabis abuse causes cognitive impairment and damages the brain.”
And that doesn’t begin to address the potential long-term effects of high-potency THC products that have as much resemblance to weed as heroin does to Tylenol. Consider, according to the NIDA : “In the early 1990s, the average THC content in confiscated marijuana samples was roughly 3.8 percent. In 2014, it was 12.2 percent. The average marijuana extract contains more than 50 percent THC, with some samples exceeding 80 percent.”
And that potency isn’t limited to just smokable weed. According to the website Wired , “Extracts are more popular than ever. Dispensaries that use the cannabis database Leafly to organize their inventories have added 300,000 concentrate items to their offerings since the beginning of the year — an almost 600 percent increase over the same period last year.” These products go by various names — shatter, wax, cannabis oil and more — but they come down to the oily extract of the cannabis plant that can be potentiated to produce much higher levels of THC than can be found in the plant’s natural state, some “that can approach 90 percent” — or higher.
So What ARE the Signs Someone Is Addicted to Weed?
The current edition of the Diagnostic and Statistical Manual of Mental Disorders — DSM-5 — lays out 12 criteria for cannabis use disorder — all of which can be interpreted as signs someone is addicted to weed. An individual’s cannabis use is problematic, and can lead to “clinically significant impairment or distress,” when two or more of the following signs take place within a 12-month period :
- Weed is used in greater amounts or over a longer period of time than the consumer originally intended;
- Someone who uses weed wants to cut down or control their use but is unable to do so;
- Someone spends an inordinate amount of time getting weed, using weed or recovering from its use;
- The individual experiences strong urges, or cravings, to use;
- Using weed interferes with vocational, educational or personal responsibilities;
- The individual refuses to stop smoking/consuming weed despite problems at work, school or home that are caused by it;
- The person cuts back or gives up entirely other social, recreational or vocational activities because they interfere with smoking weed;
- They use weed in situations that are physically dangerous to do so;
- They continue to smoke even though they’ve been told certain physical or psychological problems are made worse by weed.
- Their tolerance causes them to consume greater amounts to achieve the effects they desire;
- They show obvious psychological — and in rare cases, physical — signs of withdrawal if they stop using weed.
According to the DSM, the severity of an individual’s cannabis use disorder is graded on a scale of mild (if two to three signs are present), moderate (four to five signs) or severe (if someone presents with six or more of the above criteria).
At the risk of redundancy, this information isn’t meant to stoke the flames of marijuana panic. These signs someone is addicted to weed shouldn’t be a carte blanche comparison to other, deadlier substances. “Cannabis intoxication most often does not require medical management and will self-resolve,” according to writers for the peer-reviewed health professionals journal StatPearls , and in many cases, “using cannabis for experimentation is associated with less use and fewer problems. Factors such as enjoyment, habit, activity enhancement, and altered perception or perspectives are associated with heavier use and more problems.”
Applying some nuance to that last word — problems — is key to acceptance and understanding of the signs someone is addicted to weed. While it may be benign, or even beneficial, for a great many people who partake, science and medicine both agree that it cannot be given a blanket label of harmlessness. The segment of the population who develops a dependence on cannabis are deserving of as much consideration to their issues as those who become addicted to cocaine or heroin — because, one more time for the people in the back, addiction isn’t about a the substance as much as it is the unmanageability of a life consumed by those substances.
And, just like other substances, drug and alcohol treatment can be effective for those who develop those problems. Jason Patel and Raman Marwaha, writing for StatPearls , point out that “supportive treatment may be provided during detoxification; enabling access to psychiatric services allows addressing underlying disorders; psychological counseling can modify behavior, develop healthier coping skills in the face of stressors, and enlighten them as to their temperament.” And, they add, “for individuals with marked intoxication or withdrawal, or cannabis use disorder, the goal should be a cessation of the drug altogether.”