The drugs, known as proton pump inhibitors (PPIs), include lansoprazole (Prevacid), manufactured by Novartis, as well as esomeprazole (Nexium) and omeprazole (Prilosec), both manufactured by AstraZeneca.
The current study can only provide a statistical association between PPI prescriptions and occurrence of dementia in the elderly. It can’t prove that PPIs actually cause dementia, said senior author Britta Haenisch of the German Center for Neurodegenerative Diseases in Bonn, Germany.
“In our analysis we focused on long-term regular PPI prescription for at least 18 months,” Haenisch told Reuters Health by email.
The researchers examined medical records from 2004 through 2011 from more than 73,000 patients age 75 and older, mostly women.
They classified 2,950 of those patients as regular PPI users, meaning they had at least one prescription for one of the drugs every four or five months over an 18-month period.
During the study period, 29,510 people developed dementia.
Regular PPI users were 44 percent more likely to develop dementia than those who were not receiving the drugs, the authors reported in JAMA Neurology.
The researchers couldn’t know whether some of the people in the study were at increased risk for dementia to start with, Haenisch said.
PPI use and dementia may both be influenced by similar risk factors, Dr. Lewis H. Kuller of the University of Pittsburgh wrote in an editorial accompanying the results.
In the Women’s Health Initiative, for example, women who took PPIs were more often obese, had arthritis, and had poorer health generally than others, which may increase dementia risk, Kuller wrote.
The drugs do carry an increased risk of kidney disease, fracture, low magnesium levels, gastrointestinal infections, Clostridium difficile infection and pneumonia, Kuller told Reuters Health by email.
Some PPIs are available without a prescription, but prescriptions are needed for long-term use, he said.
“PPIs used for the treatment of gastroesophageal reﬂux disease and peptic ulcers work by reduction of gastric acid production,” Haenisch said. “The underlying mechanism by which PPIs might influence cognition is yet to be determined.”
Some of the drugs may cross the blood-brain barrier and interact with brain enzymes, or they may be associated with vitamin B12 deficiency, which may promote neurological damage, she said.
“Patients should take the drugs according to their doctor’s instructions,” Haenisch said. “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.”
Doctors should take care not to overprescribe PPIs, which is reported frequently, she said. One study found that up to 70 percent of the drugs prescriptions were inappropriate for the patient, she said.