Cannabis and its documented use for medicinal purposes have been available for thousands of years. As of April 2021, a majority of states have passed laws allowing the use of cannabis for medical purposes, and a growing number of states have also passed laws allowing use for personal and recreational use. The impacts of using cannabis in an older person are not well known by the general public and are poorly understood or recognized in the medical community.
By definition, an elderly person generally means a person who has reached the chronological age of 65 and older. It can be further classified as early elderly (65-74 years of age) and late elderly (75 years of age and older). Generally speaking, as a person ages, they commonly will develop age-related diseases, which include neurodegenerative diseases (Alzheimer’s, Parkinson’s), cardiovascular diseases, cancer, immune system disorders, and musculoskeletal disorders.
The number of people over the age of 65 has increased over time and is expected to continue to rise into the foreseeable future. This growing and aging population, along with the expansion of cannabis programs across the United States, has inevitably led to the consumption of cannabis by more elderly persons for reported “medical” purposes as well as for personal use. By far, the most cited reason for “medical” use is “pain.”
The amount of medical literature for the use of cannabis for pain is sparse. A large pain organization recently concluded that “due to the lack of high-quality clinical evidence, the International Association for the Study of Pain (IASP) does not currently endorse general use of cannabis and cannabinoids for pain relief.” This was soon followed by the Faculty of Pain Medicine of the Australian and New Zealand College of Anesthetists position that “the clinical use of cannabinoid products cannot be ethically recommended outside of a properly established and registered clinical trial environment, until high-quality evidence for specific indications is published.” Large reviews[4] of the benefits of cannabis have already been completed. The conclusions were that a small number of reviews of cannabis use showed cannabis provided a benefit for reducing pain; other reviews were sub-optimal, making it difficult to know how consistent the findings are when considering pain in general. Results from the included reviews were mixed, with most reporting an inability to draw conclusions due to inconsistent findings and a lack of rigorous evidence. Mild "harms" were frequently reported, and it is possible the "harms" of cannabis-based medicines may outweigh the benefits. Anecdotes of patients weaning off opioids and replacing opioids with cannabis do not equate to scientific evidence, and/or the results from research.
The United States is in the midst of an opioid epidemic and over time the number of people dying from drug overdoses has continued to rise, strongly correlating with more states legalizing cannabis for medical and recreational purposes. This is incongruent with the concept of using cannabis as an opioid substitute or pain reliever. For instance, Colorado has had medical cannabis since 2001 and nearly 90% of the recommendations for use are “pain,” yet the finalized 2020 data from the Colorado Department of Public Health and Environment showed another record number of drug overdoses. Since the legalization of cannabis for recreational use in Colorado, drug overdose deaths have increased significantly: prescription opioid deaths increased 136%, fentanyl deaths increased 864%, methamphetamine deaths increased 364%, cocaine deaths increased 195%, and heroin deaths increased 45%. Cannabis is not helping the drug crisis in Colorado and similar trends are seen in most other states.
More concerning is the fact that products purchased in legal medical and recreational markets have not been well-studied, effectively regulated, or proven to be effective. For example, the 2019 cannabis audit report by the State of Oregon concluded that “test results are unreliable and products may be unsafe for human consumption.” Because of inadequate state oversight and regulation, cannabis products may contain undisclosed adulterants (i.e., sildenafil ) and contaminants (i.e., arsenic ) which may be harmful to an already “at-risk” patient population. Other contaminants have been found in regulated cannabis markets, including fungus, mold, pesticides, rodenticides, and other poisons.
Cardiovascular disease is more common in the elderly, and people 65 years of age and older are more likely to suffer from a heart attack or stroke. The American Heart Association’s statement, in August 2020 concluded that people who use cannabis may be at risk of sudden death, heart attack, arrhythmia, and stroke. Caution should be made in elderly people using cannabis who have cardiovascular disease.
As we age, it is not uncommon that the number of prescribed medications may increase. Along with this comes the risk of potential drug-drug interactions (DDIs). Most medical providers, as well as patients, do not consider possible interactions between cannabis and commonly prescribed medications. This may be due to not asking the patient about their cannabis use or the patient failing to disclose they are using cannabis products.
The cannabis plant has over 300 components and the most commonly known and understood ones are tetrahydrocannabinol (THC) and cannabidiol (CBD). There are known serious, and potentially life-threatening drug interactions with cannabis and prescription medications. For example, the blood thinner, warfarin, is used for people with atrial fibrillation and blood clots, which is more commonly seen in the elderly. There is a known interaction between warfarin and cannabis components where life-threatening thinning of the blood may occur. There are many more potential interactions[16, 17] with more commonly prescribed medications, such as anti-inflammatories, cholesterol agents, and pain relievers. These include serious interactions between prescription medications and CBD, which is perceived as benign.
The elderly population may develop problems with memory, cognition, and balance; and components of cannabis may have significant impacts across these domains, potentially putting seniors at risk of falls, serious injury, and inadequate safety. Using a substance, such as cannabis, which may potentially cause impairment, should be seriously considered in the elderly. There is data which has demonstrated that past-year injury rates were 18.9% for cannabis non-users and 28.8% for cannabis users, and past-year emergency department (ED) visit rates were 23.5% for cannabis non-users and 30.9% for cannabis users. Cannabis use was associated with injury and injury was associated with ED visits. Cannabis use increases the likelihood of ED visits through increased injury risk. Any possible benefit of using cannabis should be weighed against possible harm in an older person.
There is evidence that may suggest a benefit in conditions more common in the elderly, such as Parkinson’s disease. A recent review of the literature, however, concluded there is insufficient evidence to support the use of cannabinoids as a therapeutic alternative to patients with Parkinson’s disease. Patients with Parkinson’s disease are more likely to be taking other prescription medications and drug interactions may be more concerning.
Cannabis use in the elderly can interfere with the ability to perform daily tasks such as driving a car, because cannabis components can impair one’s abilities, such as depth perception, divided attention, and reaction time, which may already become a problem with aging in general. Recent data suggests that medical cannabis law enactment in US states appears to have been associated with increased prevalence of driving under the influence of cannabis, but not alcohol. Other data suggests that cannabis containing equivalent concentrations of CBD and THC appears no less impairing than THC-dominant cannabis, and in some circumstances, CBD may actually exacerbate THC-induced driving impairment.
Alcohol is commonly used in the older population and there can be serious issues combining alcohol with cannabis as both are central nervous system depressants. Recent data shows drivers who combine cannabis with alcohol, compared with those who use only alcohol, were more likely to engage in nearly all of the risky behaviors measured in the survey, including driving under the influence of alcohol. These also include speeding on residential streets, aggressive driving, intentional red-light running, and texting while driving. Compared with those who neither drink nor use cannabis, those who use only cannabis were more likely to drive under the influence of prescription drugs and ride with an intoxicated driver.
In summary, the aging population and those caring for the elderly should be mindful of not only the inevitable changes in mental and physical health as we grow older, but the potential impact of adding a substance that may interfere and adversely impact those changes. There should be a nationwide effort to support the development of cannabis-based medications that are proven to work, particularly in the elderly, who are under-represented in the medical literature. There needs to be a push to develop dosing guidelines of cannabis-based medications for use in the elderly and encouragement for insurance and pharmaceutical companies to cover the cost of these medications, which may be difficult for the elderly due to possible income limits and the requirement of multiple prescriptions.
Dispensary cannabis should not be considered for use in the elderly as it has not been proven and carries with it potential problems outlined above. Current evidence may show benefits with products unavailable in the United States or with well-studied synthetic cannabinoids. Any perceived or real benefit of cannabis use may be outweighed by potential harm.
Care must be taken by an elderly person, their medical providers, and caregivers, as to whether or not the addition of a cannabis product is in the best interest and safety of that person.
