We are thrilled that an NPR story by Jim Zarroli included clips from his interview with Dr. Lori Zucker of PTCannabisInfo and one of her patients. The story, “Concerns are Raised About Whether Cannabis is Safe for Older Users” can be heard here:
A full report about the use of cannabis for medical conditions and its known benefits and risks for older people is well beyond the scope of this post. However, we want to offer up a few key points that may be helpful to clinicians as they encounter patients who ask about cannabis.
Cannabis: THC and CBD
THC, CBD, and other phytocannabinoids are found in cannabis. THC and CBD have been studied the most, with scientists having a good, if not a complete understanding of the effects that these chemicals have on our brains and bodies. For now, it is well accepted that THC has intoxicating effects and CBD does not.
It is important however, to be aware that when people use the term cannabis they may be referring to products that only contain THC (Delta-9-tetrahydrocannabinol) OR only contain CBD (cannabidiol) OR contain different ratios of THC and CBD. Knowing this difference is important for being able to read scientific reports, understand product labels, and be able to predict effects.
Cannabis is Stronger and More Potent Today
Many people raise concerns that today’s cannabis is much “stronger” than the cannabis of the 60s and 70s and generally speaking, it’s true. That’s in part because cannabis growers developed plants with higher concentrations of THC, the chemical that gets you “high”. However, with the legalization of medical cannabis, many growers have moved towards cannabis plants that provide a wider range of phytocannabinoids such as CBD, CBN, and CBG, which may have beneficial effects and are certainly different than THC’s effects. Nevertheless, everyone should be aware that dry cannabis flowers, available in dispensaries have on average 14-18% THC, whereas cannabis in the 70s contained 3%.
Well, it’s important to know that in general, today’s cannabis is stronger than decades ago, however, cannabis products that are now legally available in dispensaries report the amount of THC, CBD, and other endocannabinoids found in their product whether it be a cartridge, joint, edible, etc. This reporting gives consumers some knowledge and control over dosing and their consumption. Yes, there are scientific papers that call to question the quality control of some products, but at least for now, purchasing labeled cannabis products in a dispensary is a good strategy for being able to “start low and go slow” once a decision is made to introduce cannabis for medical purposes.
Cannabis and Older Adults: Falls
It is prudent to be concerned about the intoxicating and sedative effects of cannabis in older adults, especially since normal aging changes can account for declines in strength, balance, and reaction time. Together, this has the potential to increase instability and the risk of falling. That’s why it’s important to talk with people about the reason(s) they are using cannabis and how they can minimize their safety risks. This is not all that different from millions of older adults who are using sedative-hypnotic medications such as benzodiazepines, barbiturates, and anxiolytics, to treat a range of conditions. Prescriptions for these medications, come with a long list of precautions and recommendations to lessen the safety risk of these drugs.
Cannabis and Older Adults: Cardiovascular Disease
The American Heart Association reports that the incidence of cardiovascular disease in US men and women between the ages of 60-79 is approximately 75%. That’s 3 out of 4 people! And the incidence is higher (86%) in those over 80 years of age. Researchers have found definitively that smoking cannabis acutely increases heart rate and blood pressure, and this poses an increased risk for people with cardiovascular disease. However, in a small study that included people aged 65-75 with pain, all of whom were taking anti-hypertensive medication, researchers found that 3 months of cannabis treatment was associated with reductions in systolic and diastolic blood pressure, heart rate, and rate product pressure. The mean total daily dose of THC and CBD was 21mg each, with 77% using cannabis oil rather than smoking. (Abuhasira et al 2021).
With conflicting reports, differences among patient populations, and options regarding delivery methods, it can be challenging to make sound clinical recommendations about cannabis use in older adults. MacCallum and colleagues (2021) offer some useful categories of considerations, precautions, and contradictions that includes older adults.
Precautions and Considerations
Cannabis and Older Adults: Polypharmacy
The Centers for Disease Control and Prevention report that 83% of US adults in their 60s and 70s have used one prescription drug in the past month and 33% regularly take 5 or more prescription medications. Using multiple medications (polypharmacy) creates a risk of unintended drug interactions and increases the risk of cognitive impairment, falls, and other negative outcomes.
Knowing that older adults are more often than not taking prescription drugs to treat different health conditions, adding cannabis to their list of medications carries an inherent safety risk. MacCallum and colleagues (2021) recommend screening for prescription and over-the-counter depressants such as alcohol, opioids, and benzodiazepines because cannabis may worsen sedation and cognitive impairment.
In two case studies of individuals, one using of THC and the other using CBD for epilepsy, TCH and CBD were found to increase the effects of warfarin, a blood thinner (Damkier et al 2019). Unfortunately, specific drug interaction studies have not been done, so at this time, precautions must be observed when and if cannabis is recommended for people taking blood thinners.
There have been some observations that CBD can increase liver enzymes and that this may indicate liver damage. Indeed, the FDA warns that CBD can cause liver damage because, in clinical studies of Epidiolex (a CBD medication prescribed for 2 rare forms of epilepsy), some participants experienced high levels of liver enzymes, and treatment needed to be stopped. However, therapeutic levels of Epidiolex may require 10mg/kg twice a day, which means that a 150 lb. person would need to take 1,360mg of CBD daily. This far exceeds the amount typically consumed with over-the-counter CBD products.
Cannabis and Older Adults
With all medications, there are potential risks and benefits, and not all people respond to medications in the same way. When cannabis is considered a medicine, the same is true. When people want to include cannabis, along with their other medications to achieve or maintain health and well-being healthcare providers should be ready to advise them with the best available evidence given their own individual health status and goals.
Abuhasira, R., et al. (2021). Cannabis is associated with blood pressure reduction in older adults – A 24-hours ambulatory blood pressure monitoring study. European Journal of Internal Medicine, 86, 79–85. https://doi.org/10.1016/j.ejim.2021.01.005
Damkier, P., Lassen, D., Christensen, M. M. H., Madsen, K. G., Hellfritzsch, M., & Pottegård, A. (2019). Interaction between warfarin and cannabis. Basic & clinical pharmacology & toxicology, 124(1), 28–31. https://doi.org/10.1111/bcpt.13152
MacCallum, C. A., Lo, L. A., & Boivin, M. (2021). "Is medical cannabis safe for my patients?" A practical review of cannabis safety considerations. European Journal of Internal Medicine, 89, 10–18. https://doi.org/10.1016/j.ejim.2021.05.002