Cannabis (marijuana) products are widely used. Cannabis is now fully legal in 24 states, legal if medically prescribed in 15 and partially legal (depending on the composition) in seven. In only four states is it still completely illegal.
Among 176,000 primary-care patients in a Los Angeles clinic, 17% reported regular use. Not surprisingly, use was commoner in younger people than older ones: 31% of those 18-29 used cannabis, while only 8.5% of those 60 and older reported use.
A large percentage of cannabis users say they do so to treat symptoms, largely stress, insomnia and pain.
Cannabis can be inhaled or eaten. Smoking gets the active ingredients into you faster, but the effects of edible (“gummies”) products are similar.
Do cannabis products help? Our evidence base is flimsy. The fact that cannabis is still classified at the federal level as “Class 1,” with no approved medical use, means funding for large, well-done studies is limited.
Many of the studies of the benefits rely on self-reported use and are uncontrolled. An analysis of the use of cannabis for chronic pain found seven large studies, including 13,000 patients, that were “observational” (uncontrolled) and 18 randomized, placebo-controlled trials – but these were very small, averaging fewer than 100 subjects in each trial.
What we can gather from studies to date is that some cannabis products do help with insomnia, but this is countered by deterioration in sleep if use is stopped.
The evidence seems to show that cannabis has moderate effectiveness for chronic pain, but the benefit is countered by sedation and a marked increase in dizziness and falls.
What about the risks? Cannabis use by women during pregnancy results in increased likelihood of low birthweight, preterm birth and need for intensive care by the newborns.
Regular long-term use starting in adolescence and continued into middle age was accompanied by a fall in IQ and evidence of shrinkage of the part of the brain known as the hippocampus.
Participants in the United Kingdom Biobank (a large, respected observational trial) who were regular, heavy cannabis users, followed for an average of 12 years, had a higher mortality, both overall and from cancer and heart disease.
Older people should be particularly cautious, as side-effects such as dizziness and sedation are more likely. After cannabis was legalized in Ontario, Canada, the number of older adults treated in emergency departments for cannabis side-effects rose four-fold.
My take-aways? First, cannabis should be strongly discouraged in adolescents and young adults, whose brains are still developing, and in pregnant women.
It should be discouraged in older adults, where side-effects are more common and more likely to lead to falls and injury.
In the middle? Be cautious and minimize your use.
Finally, I do support the removal of cannabis from Class 1 to a lower class, so that proper studies can be done with federal funding. Only large, randomized, placebo-controlled trials can determine whether cannabis has a role in treating symptoms.
Edward Hoffer MD is Associate Professor of Medicine, part-time, at Harvard.
What Does The Doctor Say?
By Dr. Edward Hoffer