Marijuana Use Disorder Overview
Marijuana, also known as cannabis, hashish, or hash, is one of the most widely used psychoactive substances worldwide. Its primary psychoactive effects are produced by delta-9-tetrahydrocannabinol (THC), a cannabinoid that varies in concentration across different preparations. Potency is commonly measured by the percentage of THC present.
After use, THC reaches the brain within minutes and binds primarily to cannabinoid CB1 receptors. These receptors are concentrated in areas involved in reward, motivation, memory, and cognition. Activation of the mesolimbic dopamine system is believed to contribute to the reinforcing and pleasurable effects associated with marijuana.
During the 1960s and 1970s, most marijuana strains contained relatively low levels of THC, typically between 0.4% and 1%. Over time, selective cultivation techniques have increased THC concentrations substantially, with some modern strains reaching 25% or higher. This increase in potency has raised concerns regarding its potential relationship to marijuana use disorders and possible neurological or psychological effects.
For readers considering treatment for marijuana use disorder or other substance use concerns, it can be helpful to learn how to compare rehab options in Thailand, including factors such as therapeutic approaches, facility standards, clinical oversight, and aftercare support, to make an informed decision about the most appropriate care pathway.
The legal status of marijuana varies across countries and regions, including differences between recreational and medical use. Research suggests that approximately 10% of individuals who use marijuana regularly may develop marijuana use disorder. This condition has been associated with cognitive impairment, mood disturbances, psychosis, and difficulties in occupational, social, and family functioning.
Clinical Manifestations of Marijuana Use Disorder
Marijuana use disorder is characterized by a persistent pattern of use that leads to clinically significant impairment or distress in at least two areas of functioning within a 12-month period.1 These impairments may include abandoning previously valued activities, reduced work or academic performance, or the development of health-related complications.
Unlike some other substance use disorders, diagnosis is not based solely on the quantity or frequency of use. Instead, clinicians focus on functional impairment and behavioral patterns. Diagnostic assessment may include evaluation of denial of use despite corroborating evidence from family members, employers, or biological testing.
Trends in Marijuana Use Prevalence
The prevalence of marijuana use differs significantly across countries and regions. Higher rates of use are often observed in areas where marijuana has been decriminalized, legalized, or approved for medical use. Cultural norms, societal attitudes, and regulatory frameworks also influence patterns of consumption.
Marijuana Use in the United States
Attitudes and laws surrounding marijuana use in the United States have shifted substantially over recent decades. These changes have prompted researchers to examine whether marijuana use and marijuana use disorder have increased concurrently.
A large epidemiological study conducted by the National Institute on Alcohol Abuse and Alcoholism examined marijuana, alcohol, and other drug use among more than 36,000 U.S. adults, along with associated psychiatric conditions.2
The study compared nationally representative data from 2012-2013 with findings from 2001-2002 using DSM-IV diagnostic criteria. Results indicated that 9.5% of adults reported marijuana use in the past year, while 2.9% met criteria for marijuana use disorder. This represented approximately 6.8 million individuals, or about three out of ten marijuana users.
Both marijuana use and marijuana use disorder increased compared to earlier findings. However, the overall risk of developing a disorder among users appeared to decrease slightly, suggesting that the rise in prevalence was largely driven by an increase in the number of users rather than individual susceptibility.
These findings are consistent with other reports indicating increased use, potentially influenced by legislative changes and higher THC potency. Further research is needed to clarify the relationship between potency, frequency of use, and long-term outcomes.
Marijuana Use in the United Kingdom
In the United Kingdom, approximately one-third of adults report having tried marijuana. Among individuals aged 16 to 29, an estimated 2.5 million reported use within the past year. National drug misuse data from 2015-2016 indicated that marijuana was the most commonly used illicit drug, with 6.5% of adults reporting past-year use.
Research specifically examining marijuana use disorder in the UK is limited. A notable review by psychiatrist Adam R. Winstock highlighted changes in cannabis preparations over the past decade, particularly a shift toward high-potency products with elevated THC levels.3
Despite widespread use, only a small proportion of individuals seek treatment for marijuana-related problems. Many who are diagnosed with marijuana use disorder present for care due to secondary concerns such as anxiety, depression, respiratory symptoms, impaired concentration, or legal and employment issues rather than marijuana use itself.
How High-Potency Cannabis May Affect the Brain
Research conducted by investigators at King’s College London has explored the relationship between high-potency cannabis use and changes in brain structure.5 One study examined white matter integrity, particularly within the corpus callosum, which facilitates communication between the brain’s hemispheres.
Brain imaging of individuals treated for psychosis and a control group revealed differences in white matter density. Reduced white matter integrity may impair neural communication and has been associated with cognitive difficulties such as memory impairment and reduced attention.
The findings suggested a correlation between frequency of high-potency cannabis use and greater white matter changes. However, the study did not establish causation, and the mechanisms underlying these associations remain unclear.
Marijuana Use in Canada
Marijuana is among the most commonly used psychoactive substances in Canada. While recreational use was historically illegal, medical use has been permitted under specific regulatory frameworks. Data from 2022 indicated that approximately 27% of Canadians reported marijuana use within the past year.6
Earlier surveys found high rates of experimentation among adolescents, with concerns raised about potential long-term cognitive, physical, and mental health effects associated with chronic use.
A national study published in 2012 reported that 21.6% of Canadians met criteria for a substance use disorder, with marijuana accounting for 6.8% of cases, following alcohol at 18.1%.7
Marijuana Use in Australia
Marijuana use in Australia increased notably after the 1970s and peaked during the 1990s. Although prevalence has declined since then, marijuana remains the most commonly used illicit drug in the country.
National surveys have reported that approximately one-third of Australians aged 14 and older have tried marijuana at least once. More recent household studies have documented ongoing regular use among a subset of the population, particularly among adults in their 20s and 30s.8
Impact of Marijuana Use
Occasional marijuana use is not generally associated with significant harm for most individuals. However, use can produce measurable changes in cognition, perception, and physiological function. Risks may increase with heavy or prolonged use, particularly in individuals with co-occurring mental health conditions.
Physical and Psychological Effects of Marijuana Use
Marijuana can be consumed through smoking, vaporization, ingestion, or infusion. Effects typically begin within minutes when inhaled and may last several hours. Common short-term physical effects include:
- Increased heart rate
- Changes in blood pressure
- Altered blood sugar levels
- Shallow or altered breathing
- Dilated pupils and red eyes
- Dry mouth and dizziness
- Slowed reaction time
Psychological effects may include:
- Altered perception of time
- Anxiety
- Paranoia
- Depressive symptoms
Long-term effects vary and may depend on frequency of use, potency, and individual vulnerability. Reported associations include hormonal changes, fertility issues in men, and exacerbation of certain medical conditions. In some individuals, long-term use has been linked to mental health symptoms such as hallucinations, delusions, or psychosis.9
Addictiveness of Marijuana
Marijuana use can progress to marijuana use disorder in some individuals, although not all users develop dependence. Factors such as genetics, environment, early life experiences, and co-occurring health conditions may influence risk. Additional information on substance use disorders can be found in this overview of substance abuse.
Individuals with marijuana use disorder may experience withdrawal symptoms upon cessation, including irritability, reduced appetite, sleep disturbances, cravings, and restlessness.10 These symptoms are generally described as mild to moderate and typically resolve within one to two weeks.
Psychosocial interventions such as cognitive behavioral therapy, counseling, structured exercise, and mindfulness-based practices have been reported as helpful. When co-occurring mental health conditions are present, psychiatric evaluation and treatment may be appropriate.
Impact of Marijuana Use on Quality of Life
The effects of marijuana use on relationships and daily functioning remain a subject of ongoing debate. Some clinicians suggest that marijuana use may interfere with interpersonal dynamics, while others emphasize the importance of individual and contextual factors.
Marijuana use disorder may affect multiple areas of life, including:
- Personal wellbeing
- Friendships and social networks
- Intimate relationships
- Family responsibilities
- Work or academic performance
The extent to which marijuana use contributes directly to these outcomes is complex and may involve additional predisposing factors. Further research is needed to better understand these relationships.
- American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5)
- Prevalence of Marijuana Use Disorders in the United States Between 2001-2002 and 2012-2013
- Assessment and management of cannabis use disorders in primary care
- Statistics on Drug Misuse: England, 2017
- Effect of high-potency cannabis on corpus callosum microstructure
- Marijuana Use in Canada
- Mental and substance use disorders in Canada
- 2016 National Drug Strategy Household Survey
- Adverse Health Effects of Marijuana Use
- Is Marijuana Addictive?
