Some popular heartburn and acid reflux medications could raise the risk of dementia in seniors, a new study has found.

Proton Pump Inhibitors (PPI) reduce the amount of acid in the stomach. The most common brand names are Nexium, Prilosec, and Prevacid.

German researchers found patients over 75 who took the medications had a 44 percent increased risk of dementia, according to multiple reports. However, the study only found an association and not a cause-and-effect link. The researchers said more study was needed.

Women taking the medication for at least 18 months were most at risk.

The study was published Monday in the journal JAMA Neurology.