As cannabis use increases among older Americans, experts at Stanford Medicine warn that today’s cannabis products are much more potent than many people realize and may carry serious health risks.
Eloise Theisen never expected to become a medical cannabis expert. A geriatric nurse currently focusing on cannabis therapy at Stanford University, she first turned to cannabis on her own after a serious car accident left her with chronic pain that other treatments failed to alleviate.
When I later returned to work at an oncology clinic, I realized that many patients were already using or considering using cannabis without the guidance of a medical professional.
“We find that patients use it whether their healthcare provider approves or not,” Theisen said. “Many of our patients were older and had risks that needed to be assessed and addressed before they began using cannabis.”
Cannabis use is increasing among older adults
Medical and recreational marijuana use continues to increase across the United States, including among adults 65 and older. But researchers still have big unanswered questions about how cannabis affects the body and brain. One reason for this is that cannabis remains federally illegal, making certain types of research difficult.
Many older adults use cannabis in hopes of relieving chronic pain, insomnia, and anxiety. However, Smita Das, MD, clinical associate professor of psychiatry and behavioral sciences at Stanford University, said there is still no widespread medical consensus that cannabis effectively treats these conditions.
Experts say older adults face unique risks from regular cannabis use. These include an increased chance of heart disease, certain cancers, addiction, cognitive problems, and dangerous drug interactions. Also, today’s cannabis products are much more potent than the cannabis many people encountered decades ago, increasing the risk of accidental overuse.
Stanford Medicine experts shared five important things seniors should know before using cannabis.
1. Cannabis today is much more powerful than before
Medical marijuana is legal in 40 states and the District of Columbia, while recreational marijuana is legal in 24 states and Washington, DC. Regular use among older adults is still relatively rare, but the number is rapidly increasing. According to the National Survey on Drug Use and Health, in 2023, 7% of adults 65 and older reported recent cannabis use, compared to less than 5% in 2021.
Many older adults may not realize how dramatically the potency of cannabis has changed. In the 1970s, marijuana typically contained 1% to 4% tetrahydrocannabinol (THC), the compound responsible for the drug’s psychoactive effects. Currently, legal cannabis flower contains about 20% THC on average, with some strains containing as much as 35% THC.
Other cannabis products can be further concentrated. Oils, edibles, and concentrates can contain levels of THC approaching 90%. Synthetic marijuana products such as Spice and K2 are even more potent and have been linked to heart problems. These products are illegal in California and many other states.
“We’re just catching up on our understanding of how the sudden increase in psychoactive components is affecting the brain and body,” said Dr. Claudia Padura, assistant professor of psychiatry and behavioral sciences.
The increased strength of cannabis products may also help explain the rise in accidental overdoses among older adults. A Canadian study comparing emergency department visits before and after legalization nationwide found that cases of cannabis poisoning among adults 65 and older increased nearly threefold.
“There are so many different formulations, so many different strengths,” Das said. “This isn’t really ’70s cannabis.”
2. Cannabis may increase risk of heart disease and cognitive impairment
Cannabis research is still evolving, but some studies have shown a link between regular cannabis use and cardiovascular disease.
Joseph Wu, MD, director of the Stanford Heart and Vascular Institute, and Simon H. Stelzer, MD, professor of medicine and radiology, said this is especially concerning for older adults because heart disease remains the leading cause of death in the United States.
Wu’s research team found that THC causes inflammation of blood vessels in animal studies. Epidemiological studies have also revealed an association between cannabis use and some forms of heart disease in humans. According to these studies, regular cannabis use is associated with a 29% increase in heart attacks and a 20% increase in the risk of stroke.
Although these risks are lower than those associated with heavy tobacco or alcohol use, Wu noted that many cannabis users smoke cigarettes, drink alcohol, or both. Combining these substances may further increase cardiovascular risks. Smoking marijuana has also been linked to lung cancer and head and neck cancer.
Wu said that while edibles are not without risks, smoking or inhaling cannabis appears to promote inflammation more than edible products.
“There is no safe amount of cannabis; low doses and occasional use are still associated with vascular inflammation,” he said. “Abstinence is the safest option for heart health.”
Theisen also notes other complications in older patients who use cannabis, such as dizziness, confusion, falls, and worsening of cognitive problems such as dementia.
Older people metabolize cannabis more slowly than younger people, which means the drug stays in their system longer and its effects can last longer than expected. Slower metabolism also increases the chance of interactions with prescription drugs.
One example includes cannabidiol (CBD), a non-intoxicating cannabis compound. CBD can interfere with enzymes involved in breaking down medications such as blood thinners. This can increase drug levels in the body and increase the risk of bleeding after an injury or fall. In some cases, cannabis can also make medicines less effective.
3. Cannabis is addictive
Although it is widely believed that cannabis is not addictive, Das said research suggests otherwise.
Research shows that approximately 30% of regular cannabis users may develop cannabis use disorder. Like other substance use disorders, this condition is diagnosed based on how strongly the drug affects a person’s daily life. Signs may include withdrawal symptoms, needing higher doses over a longer period of time, or cannabis interfering with relationships or responsibilities.
Even though cannabis addiction rates are lower than alcohol addiction rates, many health care providers may not routinely ask older adults about cannabis use, Das said.
“We are aware that older adults may not necessarily disclose their cannabis use to their providers unless specifically asked, and this is not a population that we traditionally think of in terms of cannabis use,” Das said. “If someone came to me for another reason, like depression or alcohol use disorder, I might be the first person to ask about their cannabis use.”
For people struggling to lose weight or quit smoking, Das says it’s important to have an open conversation with your doctor or addiction specialist. Treatments such as cognitive behavioral therapy have been shown to be effective.
“Empowering individuals by helping them understand the criteria for substance use disorder can help them decide, ‘Do I want to talk about this?'” Das said. “On the clinician side, there’s a lot we can do to make drug use part of the conversation. What are they using cannabis for? And if someone wants to stop using, we need to be there for them through the hard part of quitting.”
Padura also studies how the brains of people with cannabis use disorder and other addictions respond to environmental cues. Her research using functional MRI scans found that people who relapse after treatment often exhibit hypersensitivity to drug-related signals in their surroundings.
4. Cannabis may improve some symptoms, but research is still limited
Research shows that different age groups use cannabis for different reasons.
A 2017 Padura-led study of licensed medical marijuana users at San Francisco dispensaries found that adults between the ages of 18 and 30 were more likely to use marijuana when bored or in a social setting. Middle-aged users commonly reported insomnia as a reason for use, and adults aged 51 to 72 more often used cannabis for cancer, chronic pain, or other long-term medical conditions.
The Food and Drug Administration has not approved cannabis itself for medical purposes. However, it has approved two cannabis-related compounds for specific uses. CBD has been approved for certain forms of childhood epilepsy, and the synthetic cannabis compound dronabinol is used to treat nausea and loss of appetite in cancer and HIV/AIDS patients.
Cannabis compounds have also been shown to be effective against muscle spasms caused by multiple sclerosis. Some countries have approved cannabis for that purpose, but the United States has not.
CBD products are now widely marketed for pain, sleep disorders, anxiety, and substance use disorders, but evidence supporting many of these uses remains limited.
Research on cannabis for chronic pain has yielded mixed results. Although some studies have reported pain relief, researchers have also observed significant placebo effects. Mr. Das helped author the American Psychiatric Association’s statement against cannabis as a psychiatric treatment, as there is currently no evidence to show that cannabis effectively treats mental disorders.
Theisen sees this issue a little differently in his work with palliative care patients facing life-threatening illnesses. Many of these patients use cannabis to manage cancer-related symptoms, including pain, and want an alternative to opioid drugs, which can cause severe side effects and dependence. Research shows that chronic pain patients who use cannabis may reduce their use of opioids.
Theisen also said that many patients appreciate the euphoria that cannabis brings.
“Though THC has gotten a bad rap over the years, it can have therapeutic effects in very small amounts,” she says. “There’s also a lot of stigma about the effects of euphoria. For patients who have months to years to live, being able to still experience joy is very important.”
5. Doctors say honest conversations are most important.
Experts may differ on how useful cannabis is medically, but they do agree that older adults should have an honest discussion with their health care provider before using it.
Theisen said she would prefer patients to discuss cannabis with a medical professional rather than relying on the advice of pharmacy staff or experimenting on their own.
During the early years of legalization, she frequently heard of patients accidentally ingesting extremely high doses of THC edibles because they did not receive proper instructions.
“Sometimes patients end up in the emergency room, and sometimes they think, ‘This doesn’t work for me’ and don’t want to come back,” she says.
Finding reliable information about cannabis can still be difficult. Doctors can help patients assess whether cannabis is right for them, discuss possible alternatives, and identify risks associated with existing medical conditions or medications.
“Your doctor will be aware of your medical condition and any other medications you may be taking,” Padula says. “Talk to your doctor and tell them not only what they’ve prescribed you, but also what you’re using recreationally, to help establish a way to do it in the safest way possible.”
