Cognitive effects

Long-term use of marijuana, especially in large quantities, can lead to problems with short-term memory and executive functions such as planning or decision-making. For example, users may have difficulty remembering new information. Studies indicate that people who start using at a young age have a higher risk of permanent brain changes, but many deficits can be reversible after 4-6 weeks of abstinence.

Mental health implications

Marijuana can increase the risk of psychosis and schizophrenia, especially with daily use of high-THC varieties. A study published in The Lancet Psychiatry found that daily smoking of high potency marijuana can increase the risk of a psychotic episode by almost five times. The relationship with anxiety and depression is more complex, with some users reporting relief and others reporting worsening symptoms.

Physical effects

Smoking marijuana over a long period of time can lead to chronic bronchitis, coughing and phlegm production, but evidence for lung cancer is mixed. It may also increase the risk of heart attack and stroke, especially in people with heart disease, although research is limited.

Unexpected detail

While the negative effects are often reported, some studies suggest that reducing marijuana use can improve sleep quality and mood in people with depression, a lesser-known aspect.

A detailed review of the long-term effects of marijuana intake

With the increasing legalization of marijuana around the world, both for recreational and medical use, there is growing interest in its long-term effects. While marijuana is often seen as a low-risk substance, scientific studies reveal that its regular and long-term use can have significant effects on physical and mental health. In this article, we will look at the latest research on the long-term effects of marijuana use, focusing on cognitive, mental health, physical health, and social-behavioral aspects, based on an analysis of sources such as the National Institute on Drug Abuse (NIDA), Harvard Medical School, The Lancet Psychiatry and others.

Survey methodology

The analysis included a review of scientific articles, medical reports and discussions on forums such as Reddit, with a focus on current data (through April 2025). Key sources included NIDA, Harvard Health, PMC, the American Lung Association and others, which provided detailed information on the effects of marijuana on various aspects of health.

Cognitive effects

Long-term marijuana use, especially in large quantities, can lead to problems with short-term memory, attention and executive functions such as planning, organization and decision-making. Studies, such as those from Harvard Health, show that regular users may experience difficulty remembering new information while on THC. For example, marijuana users may have trouble concentrating on tasks that require attention.

Research indicates that the hippocampus - the area of the brain responsible for memory - may undergo temporary structural changes in people who smoke daily for years. The good news? After 4-6 weeks of abstinence, these functions usually return to normal, according to research from PMC. However, people who started using marijuana at a young age, especially before age 18, have a higher risk of permanent changes in the prefrontal cortex, which can affect decision-making and impulse control.

The table below summarizes key studies on cognitive effects:

Mental health implications

One of the most debated topics is the link between marijuana use and mental disorders such as psychosis and schizophrenia. Numerous studies indicate that regular use of marijuana, especially high THC varieties, increases the risk of developing psychosis. A study published in The Lancet Psychiatry found that daily smoking of high potency marijuana can increase the risk of a psychotic episode by almost five times (The Lancet Psychiatry). People with a genetic predisposition, such as a variant of the COMT gene, and those who started using at a young age are particularly vulnerable.

In addition, there is a link between marijuana use and anxiety and depressive disorders, although the relationship is complex and ambiguous. Some users report relief from anxiety and depression symptoms due to the relaxing effects of CBD and THC at low doses, while others experience an exacerbation of these conditions, especially at high doses (PMC). Studies indicate that reducing marijuana use can improve sleep quality and mood in people with depression, a lesser-known aspect (Wikipedia).

The table below summarizes key studies on mental health:

Physical effects

The way marijuana is taken has a huge impact on its long-term physical effects.

Respiratory system

Smoking marijuana, like smoking tobacco, can lead to chronic bronchitis and other respiratory problems. Users often report coughing, phlegm production and wheezing (American Lung Association). Studies indicate that smoking marijuana can damage the lining of the airways, leading to chronic coughing and an increased risk of bronchitis. While the evidence for a link between marijuana and lung cancer is mixed, there is no conclusive evidence of an increased risk compared to tobacco.

Cardiovascular system

Marijuana can affect the cardiovascular system, causing temporary increases in heart rate and blood pressure. Long-term use may increase the risk of heart attack and stroke, especially in people with existing heart conditions (Harvard Health). Studies suggest that the risk of heart attack is several times higher in the hour after smoking marijuana, which is a red flag for people with a history of heart disease.

The table below summarizes key studies on physical effects:

Social and behavioral influence

Long-term use of marijuana affects not only the body, but also daily life.

Motivation and productivity

There is a stereotype of the "lazy smoker," but scientific evidence on the effects of marijuana on motivation and productivity is mixed. Some studies, such as those from Imperial College London, suggest that long-term use can lead to reduced motivation through changes in dopamine production, which may explain the lack of interest in work or daily activities (Imperial College London). On the other hand, research from the University of Cambridge finds no significant differences in motivation between users and non-users (University of Cambridge).

Addiction

Some 9% marijuana users develop an addiction, according to a NIDA study (NIDA). Withdrawal symptoms, such as irritability, insomnia and loss of appetite, are usually mild and pass after 1-2 weeks.

Potential benefits

While most of the long-term effects are negative, the potential benefits are worth mentioning. Marijuana is used medically to treat chronic pain, nausea caused by chemotherapy, and inflammation (Cleveland Clinic). Some studies suggest that reducing marijuana use can improve sleep quality and mood in people with depression, a lesser-known aspect (Wikipedia).

Long-term marijuana use can have a variety of effects, including cognitive problems, increased risk of mental disorders, respiratory and cardiovascular problems, and potential impacts on motivation and productivity. While some of these effects may be reversible once use is discontinued, others, especially in those starting at a young age, may be more permanent. As such, it is important for users to be aware of the potential risks and approach marijuana use with caution, especially in the context of high THC doses and early onset.

Marijuana under a magnifying glass - what happens years later?

Marijuana has stirred emotions for years - some see it as a miracle drug, others warn of its dangers. But what really happens to your body and mind when you use it for a long time? As a cannabis expert, I looked at the latest research and user experiences to shed light on the long-term effects of taking cannabis. From effects on the brain to physical health to daily functioning, this article is a comprehensive look at a topic that continues to divide scientists and the public.

Long-term effects of marijuana intake - What does the science say?

Brain and cognitive function

Marijuana, specifically THC (tetrahydrocannabinol), acts on the endocannabinoid system, which regulates memory, mood and concentration. Long-term use can have both positive and negative effects:

• Short-term memory: Regular users often report difficulty remembering new information while on THC. Studies show that the hippocampus - the area of the brain responsible for memory - can undergo temporary changes in structure in people who smoke daily for years. The good news? After 4-6 weeks of abstinence, these functions usually return to normal.
• Tolerance and brain plasticity: Continuous use leads to tolerance - the brain adapts, reducing the number of cannabinoid receptors. This means you need more marijuana to achieve the same effect. However, a break (known as a "tolerance break") can reverse this process.
• Young users: People starting before the age of 18 are at greater risk of permanent changes in the prefrontal cortex, which can affect decision-making and impulse control. After age 25, when the brain is fully developed, this risk decreases.

Mental health - Facts and myths

The topic of marijuana and mental health is a real storm of opinion. Here's what we know:

• Anxiety and depression: In some, cannabis relieves symptoms of anxiety and depression due to the relaxing effects of CBD and THC in low doses. But in others, especially at high doses, it can exacerbate anxiety or lead to paranoid episodes. Long-term use does not appear to unequivocally cause depression, but may exacerbate existing problems.
• Psychosis and schizophrenia: Studies indicate a link between heavy marijuana use and an increased risk of psychosis, especially in those with a genetic predisposition (e.g., a variant of the COMT gene). However, the cause-and-effect relationship is not certain - marijuana may be a "trigger" for those who were exposed anyway. The key factor? Early onset and high doses of THC.
• Emotional stability: Users report that marijuana helps them cope with stress, but over-reliance on it can weaken natural coping mechanisms to deal with emotions.

Physical health - Lungs, heart and more

The way marijuana is taken has a huge impact on its long-term physical effects:

• Lungs: Smoking joints or bongs for years can lead to respiratory irritation, chronic coughing and an increased risk of bronchitis. Vaporization and edibles are gentler on the lungs, but research on their long-term effects is still ongoing. Interestingly, there is no conclusive evidence of a link between marijuana and lung cancer, unlike tobacco.
• Cardiovascular system: THC temporarily raises heart rate and blood pressure, which is not a problem in healthy people. However, in people with heart disease, long-term use may increase the risk of cardiac incidents, although data are limited.
• Immune system: Cannabinoids, especially CBD, have anti-inflammatory properties, which can promote immunity. On the other hand, smoking marijuana can weaken the immune response in the lungs.

Daily functioning and lifestyle

Long-term use of marijuana affects not only the body, but also daily life:

• Motivation: The myth of the "lazy smoker" has a grain of truth - regular use, especially of indica varieties, can lower energy and motivation for action. However, this effect depends on personality and context - many users lead active lives.
• Sen: Marijuana helps you fall asleep and prolongs the deep sleep phase, but long-term use can disrupt the REM (dream phase) cycle, which affects mental recovery. After withdrawal, users often report vivid dreams for several weeks.
• Tolerance and addiction: Approximately 9% users develop behavioral addiction (not physical, as with opioids). Withdrawal symptoms - irritability, insomnia, lack of appetite - are mild and pass after 1-2 weeks.

Potential long-term benefits

It's not all black - marijuana also has positive sides:

• Chronic pain: Patients with diseases like multiple sclerosis and neuropathy report pain relief after years of using medical marijuana.
• Inflammatory conditions: CBD and other cannabinoids can reduce chronic inflammation, which holds promise for treating autoimmune diseases.
• Creativity: Some artists and thinkers claim that marijuana supports their creative process, although this effect is subjective and difficult to measure.

Factors affecting the effects of

Not everyone experiences marijuana the same way. The key variables are:

• Frequency: Daily use increases the risk of side effects compared to occasional use (e.g., once a week).
• Dosage: High concentrations of THC (e.g., in 80%+ concentrates) are more aggravating than mild varieties (10-15% THC).
• Method of consumption: Smoking carries more risk to the lungs, edibles to the psyche (harder to control the dose), and vaporization seems to be the golden mean.
• Age and genetics: Young users and those with a family history of mental illness are more likely to experience negative effects.

How to minimize the risk?

• Take breaks: Regular "tolerance breaks" (2-4 weeks) reset tolerance and reduce the impact on the brain.
• Choose wisely: Use balanced (THC:CBD) varieties and avoid concentrates if you want milder effects.
• Monitor health: Regular examinations (lungs, heart) will help catch any problems.
• Listen to yourself: If you notice a decrease in motivation or an increase in anxiety, consider downsizing.

Balance the key to everything

The long-term effects of marijuana use are a mix of potential benefits and risks that depend on how, when and how much you use it. Science still doesn't have all the answers - some effects are reversible, while others can leave a mark, especially in young users or predisposed individuals. One thing is certain: with a conscious approach, moderation and customization, you can enjoy cannabis without major health costs. It's not a magic plant or a devilish invention - it's a tool that requires prudent use.