MONDAY, Feb. 15, 2016 (HealthDay News) -- A popular class of heartburn medications might raise a senior's risk of dementia, a new study suggests.

Called proton pump inhibitors (PPIs), this group of drugs includes Prilosec, Nexium and Prevacid. They work by lowering the amount of acid produced by the stomach.

But German researchers found that people 75 or older who regularly take the medications had a 44 percent increased risk of dementia, compared with seniors not using the drugs. The study only found an association, however, and not a cause-and-effect link.

"To evaluate cause-and-effect relationships between long-term PPI use and possible effects on cognition in the elderly, randomized, prospective clinical trials are needed," said corresponding author Britta Haenisch, from the German Center for Neurodegenerative Diseases in Bonn.

In the meantime, "Clinicians should follow guidelines for PPI prescription, to avoid overprescribing PPIs and inappropriate use," Haenisch said.

The report was published Feb. 15 in the journal JAMA Neurology.

The results are surprising enough that at least one leading expert on aging, Dr. Malaz Boustani, plans to share the findings with older patients who are using PPIs.

Boustani said earlier studies have linked another type of antacid, H2 blockers, with an increased risk of dementia. Up to now, he's recommended that patients use PPIs to treat acid reflux and steer clear of H2 blockers like Tagamet, Pepcid and Zantac.

"I'm going to disclose the finding to my patients and then let them decide whether they will take the risk or not," said Boustani, a professor of medicine with the Indiana University Center for Aging Research and a spokesman for the American Federation for Aging Research. "On Monday I have clinic, and if I have patients taking a PPI or an H2 blocker I will tell them exactly what I'm telling you, and then they can decide."

More than 15 million Americans used prescription PPIs in 2013, at a total cost of more than $10 billion, according to a report by the IMS Institute for Healthcare Informatics. Several popular PPIs -- Prilosec, Prevacid and Zegerid -- also are available over-the counter, further boosting their use.