by Lisa O’Mary – works for WebMD – contributor to Medscape, LinkedIn, int. al – April 21, 2025

Forwarded by Herschel Baker <hmbaker1938@hotmail.com> 14 May 2025 04:45

A newly published large-scale study has cast serious doubt on the long-term safety of cannabis. Based on data from more than 6 million Canadians, the research shows that adults who had used cannabis and been hospitalized or visited an emergency room were up to four times more likely to develop dementia within five years, compared to non-users.

The findings have sparked concern among researchers and public health experts, especially given the sharp rise in cannabis-related hospital visits in recent years.

“The data is too compelling to ignore” – they recommend that one should “Add cannabis to the list of things now linked to a heightened risk of dementia.” the study’s authors said, according to WebMD.

Cannabis users who visited the emergency room or were hospitalized were up to four times as likely as people in the general population to be diagnosed with dementia within five years, according to a large new study.

 

Is Marijuana Safe for Teens?

How does it affect their grades, their mental health, and more?

While the study can’t say that cannabis use causes dementia – a progressive disease that affects memory, thinking, and language, along with emotions and behavior – its findings are compelling enough to capture attention from both the public and the medical community.

Here’s what to know about those findings, what’s still being investigated, and why it matters to you.

What the Study Found

The most well-known biological feature of dementia is the presence of brain plaques that kill neurons. Age is the biggest risk factor, but strong links have also been made to things like high blood pressure, diabetes, poor diet, heart and sleep problems, and lack of physical activity.

Published in JAMA Neurology, the study found that:

• Cannabis users who went to the ER were 23% more likely to be diagnosed with dementia within five years, compared with nonusers who also went to the ER.
• Among hospital patients, those who used cannabis had a 72% greater risk of dementia within five years, compared with cannabis abstainers.
• The rate of people seeking ER or hospital care with documented cannabis use skyrocketed between 2008 and 2021, increasing five-fold. The rate among people ages 65 and older increased nearly 27-fold.

Does This Research Apply to You?

The study only included Canadian adults ages 45 and older who had no prior dementia diagnosis. It’s garnered a lot of respect in medical circles because of its size – more than 6 million people’s health data was included, making the results more reliable than past, smaller marijuana studies.

Marijuana Addiction and Abuse

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Is Marijuana Addictive?

Addiction is more common in drugs like alcohol or cocaine. But it’s possible to get hooked on marijuana, also known as cannabis. That means you can’t stop using it, even if you want to. Studies show about 1 in 10 adults who use marijuana can get addicted. Your chances go up to 1 in 6 if you use it before age 18.

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What Is Cannabis Use Disorder (CUD)?

You might have this condition if smoking marijuana causes physical, emotional, or social problems. It’s also called marijuana use disorder. CUD can range from mild to severe.

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How Do You Know If You Have CUD?

Do you use marijuana every day or almost every day? Have you tried to quit but can’t? Do you get unwanted symptoms when you stop, like anxiety, crankiness, or trouble sleeping? Do those go away when you use marijuana again? Do you have a strong urge, or craving, to use it? Do you keep using it even though bad things happen, like problems at work, school, or with friends and family? If you answered yes to any of these, you may have CUD.

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Problems Linked to CUD

Marijuana use can make it hard to think, learn, or pay attention. If you drive while high, you’re more likely to have a car wreck. If you already have mental health problems, CUD can worsen them. People who use marijuana a lot are more likely to be jobless and not happy with life. If you use it every day, you might get withdrawal symptoms a day or two after stopping. These include insomnia, mood problems, or cravings you can’t control.

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Who Gets CUD?

Early use may lead to marijuana problems. Genes and environment also play a role. You’re more likely to get CUD if you misuse other drugs, like alcohol. Your chances also go up if you use marijuana a lot and by yourself. Mental health issues, like an anxiety or a mood disorder, can raise your chances, too.

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How Does CUD Happen?

Marijuana has THC, or tetrahydrocannabinol as the primary psychoactive ingredient. It triggers receptors in your brain called endocannabinoid receptors. When you use addictive drugs like marijuana a lot, you can change circuits in your brain. Over time, you become less sensitive to the chemicals in marijuana. You might make less endocannabinoid, which your body produces on its own. That means you may need to use more of the drug to feel “normal,” or you may feel stressed out when you’re not using it.

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How to Avoid CUD

The only sure way to stop CUD from happening is to never use marijuana. Not using drugs when you’re young might lower your chances. If you have children, make sure they know marijuana can be harmful. Keep a close eye on your kids if you get divorced, move, or have to send them to a different school. Teenagers tend to use drugs when faced with uncertain changes or stressors.

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How to Treat CUD

Most people with CUD don’t seek treatment. But you may get better if you try psychotherapy, or talk therapy. That includes cognitive behavioral therapy (CBT), motivational enhancement therapy (MET), and contingency management (CM). These can help you change thoughts and behaviors that make it hard to quit. You could also try to set limits such as only using marijuana  on certain days of the week, like the weekends. If you have trouble sticking to self imposed limits, it may indicate a problem. Meditation or other stress relieving activities may also help you use less.

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Treatment for Teens with CUD

Psychotherapy can help young people too. But they may do better when loved ones are involved in treatment. That’s how multidimensional family therapy (MDFT) works. If you’re a caregiver, you can go to MDFT with your teen.

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Can Medicine Help With CUD?

If you’re dependent on cannabis, you could go through withdrawal for weeks or relapse after you quit. That’s why experts are studying how medicine can ease withdrawal symptoms like bad mood, anxiety, restlessness, and sleep issues. They’re looking at antidepressants, cannabinoid agonists, mood stabilizers, and insomnia medication, but there are no FDA-approved meds for CUD. Some of these may treat mental health problems that worsen CUD.

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Marijuana Abuse and Sleep

You may use cannabis to help you doze off at night. But in the long run, marijuana can do a lot of harm to your sleep. And heavy use may cause a lot of problems when you try to quit. You might have nightmares, insomnia, or bad sleep quality. If this happens to you, talk to your doctor about how to treat these symptoms.

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CUD and Pregnancy

Experts aren’t sure how cannabis affects your baby. But animal studies show it may change how their brain grows. More research is needed to know what’ll happen after they’re born. But if they’re exposed to marijuana daily, they may have a hard time learning or paying attention when they get older. If you’re pregnant or want to be, ask your doctor for help on how to give up cannabis

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How to Use Medical Marijuana

In some states, doctors can prescribe cannabis. There’s research into its health benefits. It’s used to treat pain that doesn’t go away and may help with symptoms of Parkinson’s disease, multiple sclerosis, or glaucoma. Write down what type of cannabis you use. (For example, is it an edible, a joint, or an oil?) Keep track of how it makes you feel. Tell your doctor about any bad side effects. They may be able to recommend a different kind or dose or whether you should be using it at all.

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Medical Marijuana and Pregnancy

You may have heard that marijuana helps with morning sickness. But there’s no scientific evidence this is safe. If you’re pregnant, you shouldn’t use medical marijuana unless your doctor says it’s OK.

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Medically Reviewed by Poonam Sachdev on October 11, 2023

But there are some important limitations and context to consider:

• Most people in the study were included for comparison purposes, and the number of cannabis users was only about 16,000. The average age among users was 55, and their age varied a lot. About 60% were men.
• The cannabis users were getting medical care for reasons related to their cannabis use – including mental and behavioral illness due to cannabis use, poisoning or adverse effects of cannabis or its derivatives, and cannabis addiction.
• About 5% of cannabis users in the study were diagnosed with dementia within five years, compared to 3.6% of people who went to the ER or hospital for other reasons. The rate of dementia in a general population comparison group was 1.3%.
• Looking 10 years after the ER or hospital visit, 19% of users were diagnosed with dementia, compared to 15% of nonusers who got the same level of medical care.
• Cannabis use was linked to a 31% lower risk of dementia within five years, compared to people who were treated in the ER or hospital due to alcohol use, the researchers found.

• Related:Binge Drinking: How Much Is Too Much?

What’s Still Being Investigated

There’s still a lot we don’t understand about the possible link between dementia and cannabis use. What researchers still don’t know:

• Whether the link still exists for people who use cannabis without needing medical care
• How the complex interaction of genetics, lifestyle, and other health conditions combine with cannabis use to increase a person’s risk of having dementia

The Bigger Picture

This is just the latest in a string of recent studies shedding long-awaited light on the health impacts of cannabis use.

How Marijuana Affects Your Body

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It Makes You High

Let’s be honest: This is why most people use marijuana. THC is what causes the high. When you smoke marijuana, THC goes from your lungs to your bloodstream and then makes its way to your brain. There it connects to parts of certain cells called receptors. That’s what gives you those pleasant feelings. You can also get marijuana in things like cookies, gummies, and brownies. These are called edibles. They get into your blood through your digestive system.

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Brain

You might find it harder to focus, learn, and remember things when you use marijuana. This short-term effect can last up to 24 hours after you stop smoking. Long-term use, especially in your teens, may have more permanent effects. Imaging tests that take pictures of the brain show fewer connections in areas linked to alertness, learning, and memory. Tests show lower IQ scores in some people.

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Lungs

Marijuana smoke can inflame your lungs. If you’re a regular user, you could have the same breathing problems as a cigarette smoker. That means a cough, sometimes long lasting, or chronic. It might produce colored mucus, or phlegm. You could also be more likely to get lung infections. Inflamed lung tissue is part of the reason, but THC also seems to affect the way some people’s immune systems work.

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Heart

Your normal heart rate of 50 to 70 beats per minute can rise by 20 to 50 beats or more for up to 3 hours after you use marijuana. Scientists think that this, along with tar and other chemicals in the drug, may raise your chance of a heart attack or stroke. The risk could go up further if you’re older or you already have heart problems.

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Mental Health

Anxiety and paranoia are common complaints among marijuana users. Clinical anxiety and depression are also more likely, but scientists aren’t yet sure exactly why. The drug can make symptoms of more serious mental illness like psychosis and schizophrenia worse. It’s also linked to a higher likelihood of substance abuse. These effects could be worse if your genes make you more likely to get a mental illness or an addiction.

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Appetite

Regular marijuana users often refer to this as the munchies.  Some reports suggest this increased appetite might help you gain weight lost to illnesses like AIDS or cancer, or because of treatment for those diseases. Scientists are still studying when and if the treatment works or if it’s safe.

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Stomach

By itself, THC (marijuana’s active ingredient) seems to ease nausea, especially if your symptoms are from chemotherapy treatment for cancer. Some people say the stomach-settling effects work better when you use marijuana instead of THC alone. This may be because other chemicals enhance the effects of THC. But long-term marijuana use can have the opposite effect and cause more vomiting. Cannabinoid hyperemesis syndrome can occur in regular users and leads to frequent vomiting.

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Eyes

Some evidence suggests that marijuana, or chemicals in it, can lower the eye pressure that’s a main symptom of glaucoma. The problem is the effect only lasts 3 to 4 hours. To keep it low, you’d have to get the drug into your bloodstream 6-8 times a day. Doctors have yet to come up with a form of the drug that’s safe to use as a glaucoma treatment. And though marijuana does seem to lower eye pressure, it also might reduce the blood supply to your eye, which could make glaucoma worse.

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Chronic Pain

Both marijuana and a pill version of THC called dronabinol seem to help relieve pain by attaching to parts of brain cells called cannabinoid receptors. Some studies suggest CBD oil could ease pain from arthritis, nerve damage (neuropathy), and muscle spasms, among other causes. Scientists continue to study how and when and if this works in people.

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Multiple Sclerosis

A version of THC that you spray up your nose called nabiximols is available in Canada, the U.K., and other countries. It seems to help calm muscle spasms, lessen nerve pain, and improve sleep for many people with multiple sclerosis. It may also help with other illnesses, like cancer. The FDA is working to test the drug for use in the U.S.

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Inflammation

Though smoking marijuana can inflame your lungs, substances called cannabinoids seem to lessen the swelling in certain other tissues. Cannabidiol may be a good choice because it doesn’t cause the same high as THC. In animal tests, it shows some promise in the treatment of rheumatoid arthritis and conditions that inflame the digestive tract, like ulcerative colitis and Crohn’s disease.

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Seizures

There’s good evidence that marijuana, or drugs made from it, may help lessen seizures in some people with epilepsy. The FDA has even approved a drug made with cannabidiol for that purpose (Epidiolex). But the agency only recommends it for two rare forms of childhood epilepsy called Lennox-Gastaut syndrome and Dravet syndrome.

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Medically Reviewed by Jabeen Begum, MD on March 16, 2024

A lack of scientific research has led many people to form their understanding of marijuana’s health effects based on limited evidence from their own or others’ experiences. Medical experts have long warned that the true health impacts of marijuana are largely unknown, and in recent years, some of the first rigorous studies have offered new information, including links between cannabis and:

• Cardiovascular problems, like strokes and heart attacks
• Early death
• Reduced brain function during tasks that involve mental skills

Those risks are along with the already well-established understanding that cannabis use is particularly risky among youths and young adults, whose brains are still developing. The American Psychiatric Association says there’s evidence that cannabis use can speed up the start of mental illness, particularly in young adulthood. People with depression who use cannabis are at an increased risk of suicidal thoughts or attempts. Risks increase based on how much and how long a person uses.

Source: https://www.webmd.com/mental-health/addiction/news/20250421/new-study-links-cannabis-and-dementia-heres-what-that-means