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Alzheimer's Disease Health Center

Acid Blockers Linked to Mental Decline

H2 Blockers May Raise Risk of Age-Related Cognitive Impairment
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WebMD Health News
Reviewed by Louise Chang, MD

Aug. 3, 2007 - Long-term use of H2 blockers, including Axid, Pepcid, Tagamet, and Zantac, may increase the risk of mental decline in later life.

H2 blockers, available over the counter as well as by prescription, belong to a family of drugs that reduce stomach acid.

The finding -- which must be confirmed by additional studies -- comes from Indiana University researcher Malaz Boustani, MD, MPH, and colleagues.

"We demonstrate a simple association for taking these medications for a long time -- more than two years -- and the chance of having dementia or mild cognitive impairment," Boustani tells WebMD. "Patients had two to two-and-a-half times the odds of having a deficit in their cognitive performance. It ranged from mild to potentially severe dementia similar to Alzheimer's disease."

Boustani, a gerontologist, noticed that his elderly patients sometimes appeared confused after taking over-the-counter H2 blockers.

He's not the first to notice this. Histamine-blocking drugs such as some kinds of antihistamines or H2 blockers often contribute to mental confusion, says neurologist Charles J. Duffy, MD, PhD, director of cognitive and behavioral neurology at the University of Rochester, N.Y. Duffy was not involved in the Boustani study.

"We have known for some time that H2 blockers have an impact on cognitive capacity and can contribute significantly [as one of many factors] in delirium -- particularly in the elderly or in those with brain pathology," Duffy tells WebMD.

Long-Term Use of H2 Blockers

Boustani wondered whether long-term use of H2 blockers might cause more permanent mental effects. To test the idea, he looked at the use of H2 blockers among 1,558 over-65 African-Americans enrolled in a study of aging.

The study showed that after taking into account other factors, elderly people who reported "continuous use" of H2 blockers had a 2.4-fold higher chance of some form of cognitive impairment.

Boustani notes that previous studies looking at H2 blockers have come up with conflicting data. Some show no effect, some show a negative effect, and some even show a positive effect.

"We think we have a study that adds a piece to the puzzle to make the picture a little clearer," Boustani says. "At a minimum, this finding needs confirmation. We don't want people to stop taking these medications and have worse outcomes from ulcer bleeds and so on."

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