A new study suggests frequent marijuana use may worsen seizures in people with hard-to-treat epilepsy.Researchers reviewed the medical records of 64 adults with drug-resistant epilepsy admitted to an inpatient unit where doctors monitored their seizures in real time.Twenty-two of them reported using marijuana at least 20 days a month.The difference between the two groups was significant. 91% of frequent users experienced convulsive seizures compared with 57% of nonusers.Frequent users also had more than twice as many convulsive seizures per year and became resistant to antiseizure drugs faster.On average, they needed specialized inpatient monitoring to adjust medications or consider surgery just five years after their first seizure, compared with 18 years for nonusers.But these findings show an association, not cause and effect, which is why researchers are planning a follow-up study to help patients understand their risk.The lead author says, "Larger studies will help us give them a real answer — how much matters and whether stopping helps — so they can make an informed decision."Source: EpilepsiaAuthor Affiliations: Washington University in St. Louis, University of Wisconsin–Madison, University of South Dakota, University of Helsinki .Sign up for our weekly HealthDay newsletter