Young adults hospitalized for a stroke are much more likely to be admitted for a recurrent stroke if they have cannabis use disorder (CUD), new observational research suggests.

Research suggests CUD — defined as the chronic habitual use of cannabis — is more prevalent in the young adult population. But Jain said the population of marijuana users is “a changing dynamic.”

Cannabis use has been linked to an increased risk for first-time stroke or transient ischemic attack (TIA). Traditional stroke risk factors include hypertension, diabetes, and diseases related to blood vessels or blood circulation, including atherosclerosis.

Young adults might have additional stroke risk factors, such as behavioral habits like substance abuse, low physical activity, and smoking, oral contraceptives use among females, and brain infections, especially in the immunocompromised, said Jain.

Research from the American Heart Association (AHA) shows stroke rates are increasing among adults 18 to 45 years of age. Each year, young adults account for up to 15% of strokes in the United States.

Prevalence and risk for recurrent stroke in patients with previous stroke or TIA in cannabis users have not been clearly established, the researchers point out.

For this new study, Jain and colleagues used data from the National Inpatient Sample from October 2015 to December 2017. They identified hospitalizations among young adults 18 to 44 years of age with a previous history of stroke or TIA.

They then grouped these patients into those with CUD (4,690) and those without CUD (156,700). The median age in both cohorts was 37 years.

The analysis did not include those who were considered in remission from CUD.

Results showed that 6.9% of those with CUD were hospitalized for a recurrent stroke, compared with 5.4% of those without CUD (P < .001).

After adjustment for demographic factors (age, sex, race, household income), and pre-existing conditions, patients with CUD were 48% more likely to be hospitalized for recurrent stroke than those without CUD (odds ratio, 1.48; 95% CI, 1.28 – 1.71; P < .001).

Compared with the group without CUD, the CUD group had more men (55.2% vs 40.2%), more African American people (44.6% vs 37.2%), and more use of tobacco (73.9% vs 39.6%) and alcohol (16.5% vs 3.6%). They also had a greater percentage of chronic obstructive pulmonary disease, depression, and psychoses.

But a smaller percentage of those with CUD had hypertension (51.3% vs 55.6%; P = .001) and diabetes (16.3% vs 22.7%; P < .001), which is an "interesting" finding, said Jain.

“We observed that even with a lower rate of cardiovascular risk factors, after controlling for all the risk factors, we still found the cannabis users had a higher rate of recurrent stroke.”

He noted this was a retrospective study without a control group. “If both groups had comparable hypertension, then this risk might actually be more evident,” said Jain. “We need a prospective study with comparable groups.”

Living in low-income neighbourhoods and in northeast and southern regions of the United States was also more common in the CUD group.

The study did not investigate the possible mechanisms by which marijuana use might increase stroke risk, but Jain speculated that these could include factors such as impaired blood vessel function, changes in blood supply, an increased tendency of blood clotting, impaired energy production in brain cells, and an imbalance between molecules that harm healthy tissue and the antioxidant defences that neutralize them.

As cannabis use may pose a different risk for a new stroke, as opposed a previous stroke, Jain said it would be interesting to study the amount of “residual function deficit” experienced with the first stroke.

The new study represents “foundational research” upon which other research teams can build, said Jain. “Our study is hypothesis-generating research for a future prospective randomized controlled trial.”

A limitation of the study is that it did not consider the effect of various doses, duration, and forms of cannabis abuse, or use of medicinal cannabis or other drugs.

Robert L. Page II, PharmD, professor, Departments of Clinical Pharmacy and Physical Medicine/Rehabilitation, University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, provided a comment on this new research.

A CUD diagnosis provides “specific criteria” with regard to chronicity of use and reflects “more of a physical and psychological dependence upon cannabis,” said Page, who chaired the writing group for the AHA 2020 cannabis and cardiovascular disease scientific statement.

He explained what sets people with CUD apart from “run-of-the-mill” recreational cannabis users is that “these are individuals who use a cannabis product, whether it’s smoking it, vaping it, or consuming it via an edible, and are using it on a regular basis, in a chronic fashion.”

The study received no outside funding. The authors report no relevant disclosures.

International Stroke Conference 2022. Abstract 139.

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