As more older adults turn to cannabis to alleviate medical ailments like pain, insomnia, and anxiety, many physicians are hesitant to ask their patients about the topic or advise them about possible health impacts.
The lack of questioning is concerning for both doctors and patients: while moderate use of cannabis and cannabidiol (CBD) may be safe on their own when combined with certain medications, the substance can cause serious side effects. Older adults may also be more sensitive to the drug.
The problem is magnified by a sharp increase in cannabis consumption among older Americans resulting from its legalization in 38 states across the country. One study found that use of cannabis by adults 65 years and older in the United States jumped sevenfold in the past decade. In states like California, the stark increase has resulted in a 1808% jump in the rate of cannabis-related visits by seniors to the emergency room, according to a study published this past January in the Journal of the American Geriatric Society.
As cannabis grows in popularity, doctors need to inform patients about the potential harms and benefits, experts said.
Marijuana can have serious interactions with blood-thinning medications like warfarin, resulting in a risk for internal bleeding. Its use may also cause harmful interactions with the anti-epileptic medication clobazam (Sympazan, Onfi). Use of cannabis also decreases the efficacy of smoking cessation medications like theophylline, clozapine, and olanzapine.
Anesthesia requirements are also greater in those who regularly use cannabis; therefore, if a patient is going into surgery the doctor needs to have an accurate understanding of regular use, said Peter Grinspoon, MD, a primary care physician and instructor at Harvard Medical School in Boston.
“If you don’t have open communication between a doctor and patient then cannabis use can be dangerous,” said Grinspoon, the author of Seeing Through the Smoke: A Cannabis Specialist Untangles the Truth About Marijuana. If doctors are aware of a patient’s cannabis use, they can adjust their medications, he said.
Many physicians are hesitant to advise their patients on cannabis use because they weren’t taught about it in medical school, Grinspoon said. Only about 15% of US medical schools teach about medical marijuana and the endocannabinoid system, through which cannabis works in the body. Cannabinoid receptors are found throughout the body in tissue and organs, and they are most numerous in the brain. When cannabis is in the system it acts on these receptors, which then release brain chemicals that impact appetite, pain, mood, and memory.
“We’re doing a huge disservice to doctors by not educating them on the basics of how cannabis works,” Grinspoon said.
Seniors may also turn to cannabis to help with their depression and anxiety, said Thomas Kosten, MD, a professor of psychiatry at Baylor College of Medicine in Houston. The drug also can serve as an appetite stimulant in depressed patients who aren’t eating well and are losing weight as a result.
An April 2020 study published in the American Journal of Geriatric Psychiatry found that anxiety was among the most common reasons why older patients use cannabis and that patients found it effective for alleviating symptoms. Kosten notes that older patients may sometimes experience anxiety over concerns around aging or loneliness.
Although cannabis may reduce symptoms of depression and anxiety, doctors must look below the surface at what’s causing the symptoms. “Cannabis may improve your appetite but it won’t necessarily make the depression that’s causing it any better,” Kosten said. “For that, patients may need an antidepressant.”
Kosten noted that older military veterans may turn to cannabis to help ease post-traumatic stress disorder (PTSD). Some evidence points to benefits of cannabis for PTSD, including a study published in the journal Psychiatry and Neuroscience in March 2019.
Many patients turn to cannabis because the side effects are more tolerable than other medications, Grinspoon said. Even so, doctors need to be aware of these side effects and act accordingly. “There’s no free lunch,” he said. “All medications have side effects.”
Sara Novak is a science writer based in South Carolina who has written for a variety of publications, including WebMD, Medscape, Scientific American, and New Scientist.