People with chronic migraines who use cannabis products are much more likely to suffer from "rebound headaches" than those who don't use the drugs, a preliminary study suggests.
However, though a link has been uncovered, it's still unclear whether cannabis directly triggers the rebound headaches, the study authors told Live Science. The study also didn't specify what types of cannabis products the patients used, so it's unknown whether certain products show a greater correlation to rebound headaches than others.
A rebound headache, also known as a medication-overuse headache (MOH), happens when a person who already has a headache disorder, such as chronic migraine, either develops a new kind of headache or their existing headaches significantly worsen over time because they are taking headache medication too frequently, according to the International Classification of Headache Disorders (ICHD 3).
A formal diagnosis of rebound headaches means that a person has regularly overused one or more drugs to treat their headaches for more than three months. That usually means taking pain-relieving or antimigraine medications more than two or three days a week, according to Harvard Health. In addition, a diagnosed person will have experienced headaches on 15 or more days each month. The rebound headaches usually resolve if patients stop overusing the medications.
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These headaches affect about 1% to 3% of people in the general population and nearly one-third of the patients who seek treatment for headaches at specialized clinics, such as the Stanford Headache Center, study author Dr. Niushen Zhang, a clinical assistant professor and director of the Headache Fellowship Program at Stanford University School of Medicine, told Live Science in an email.
Now, in their new study, Zhang and her colleagues found that people with chronic migraines appear six times more likely to experience rebound headaches if they use cannabis, as compared with migraine patients who don't use the drug. The scientists will present the unpublished research at the American Academy of Neurology's 73rd Annual Meeting, to be held virtually in April.
"This study shows that there is some kind of association between cannabis use and medication-overuse headache in people with chronic migraine," Zhang said.
However, the research is still in its early days, and "it is unclear at this time whether patients are using cannabis to treat medication-overuse headache or if cannabis is contributing to the development [of] medication-overuse headache, or both," Zhang said. Future studies will be needed to determine whether cannabis contributes to the emergence of rebound headaches, and if so, what that means for those with chronic migraines, she said.
For now, "it is too early to provide any clinical recommendations based on the current findings," Zhang added.
Zhang and her colleagues launched their study after noticing that a number of their patients with both chronic migraines and MOH also used cannabis products, she said. As there is very little research on cannabis use and these headache disorders, the team decided to explore the association further.
"Our study is the first of its kind to assess the risk of medication-overuse headache in chronic migraine patients who use cannabis," Zhang said.
The team pulled data from the Stanford Research Repository Cohort Discovery Tool, collecting information on chronic migraine patients treated between 2015 and 2019. They included 368 adults who had experienced chronic migraine for at least a year; 150 reported using cannabis products, and 218 did not use any.
The team then assessed which patients had been diagnosed with MOH, taking other variables into account, such as how often they got migraines, how long they'd been using cannabis, when they got diagnosed with MOH and what other medications they took for headaches.
They found that 212 patients had MOH, and that patients who reported cannabis use were far more likely to be diagnosed with the disorder. There was also a significant link between cannabis use, opioid use and rebound headaches, they found. "Some of the patients in the study who were using cannabis were also taking, or had a history of taking, opioids," Zhang said.
Again, future studies will need to investigate if and how these drugs raise the risk of rebound headaches, as well as what happens when people take them simultaneously.
The cannabinoids in cannabis products bind to receptors in the body that regulate the perception of pain, and there is evidence that cannabis products can help alleviate certain types of chronic pain, Live Science previously reported. That said, since this new study reveals a potential link between the drugs and rebound headaches, more research will be needed to see whether cannabis sets migraine patients up for worse headaches, Zhang said.
Again, for now, it's too early to say for sure.
Originally published on Live Science.