A study in Germany suggests that the repeated use of drugs called proton pump inhibitors (PPIs) to treat stomach ailments may raise the risk of dementia.

The researchers who conducted the trial analyzed medical records from 2004 through 2011 of 73,000 patients, mostly women, who were age 75 or older, reports Reuters. A total of 2,950 patients were labeled as regular PPI users, which meant they filled one prescription for the drug every four or five months over an 18-month period .

Overall, the scientists found 29,510 people had developed dementia during the study. An estimated 44 percent had a higher chance of developing the neurological disorder compared with patients who weren’t taking these medications.

Senior author Britta Haenisch told Reuters the research team was only able to provide, “statistical association between PPI prescriptions and occurrence of dementia in the elderly,” but couldn’t prove PPIs were the direct cause.

Furthermore, the team didn’t know if certain individuals they looked at were already at risk for dementia. The research was published in the journal JAMA Neurology.

Other studies have said PPIs are linked to an increased risk of chronic kidney disease or heart conditions. PPIs are taken by an estimated 15 million Americans, according to NPR