Recently we talked about the two-way connection between the brain and the small and large intestines (aka the gut). This week, Savvy Psychologist Dr. Ellen Hendriksen continues our journey through the gut by investigating the link between heartburn drugs and dementia.
Our small and large intestines, collectively known as the gut, do more than just provide a long, twisting joyride for our food. As we heard in last week’s episode, our gut, plus the trillions of bacteria that live there, influence our mood, our health, and even our personalities. Indeed, when you hear what it can do, the gut sounds more like a superhero than an internal organ: with a surface area the size of a basketball court, it secretes acid strong enough to burn your skin!
That burn is what you feel when you have acid reflux, better known as heartburn. We all feel the burn after, say, fried chicken doused in sriracha with chaser of coffee, but in the event that reflux becomes chronic, we may find ourselves with a prescription for a proton pump inhibitor, or PPI. Popular examples include Prilosec and Prevacid; another, Nexium, was the top-selling prescription drug in 2012, with nearly $6 billion in sales.
But recent studies have rung the alarm on the side effects of PPI, most specifically the risk of dementia. The loudest warning call came from a study in the journal JAMA Neurology that included almost 75,000 people age 75 and older. At the beginning of the study, none of the participants had dementia. But after an average of 5 years passed, almost 30,000 had some sort of cognitive decline, including dementia and Alzheimer’s disease. The researchers found that those receiving regular PPI medication were 44% more likely to develop dementia than those who didn’t take PPIs.
How in the world would having less stomach acid put one at risk for dementia? Here’s the breakdown. PPIs are designed to block acid production in the stomach, but they also impede acid production elsewhere in the body. As luck would have it, cells in the brain called microglia act as the brain’s street sweeper, zapping infectious agents, damaged cells, and, importantly, protein tangles and plaques that are thought to cause dementia. How do the microglia break down all this brain junk? Acid. Therefore, when PPIs cross the blood-brain barrier and inhibit acid production in the microglia, protein accumulation results.
But the study isn’t enough to seal the PPI-dementia deal. The big asterisk is that the researchers didn’t inquire about drinking or smoking, two huge risk factors for acid reflux, both of which also independently raise dementia risk. It’s possible that the PPIs were just a red herring because they may have been prescribed more often to people who drank or smoked.
But the findings do match up with studies in mice where PPIs increased a protein called beta-amyloid in their brains, the hallmark of Alzheimer’s disease.
Okay, stinks to be those mice, you might say, but I’m not a mouse, nor a human over 75. Well, another study looked at the impact of PPIs in 20-26-year-olds and found that while PPIs certainly didn’t make college kids develop Alzheimer’s, they did impact their cognitive functioning, including impairment in visual memory, attention, working memory and planning, and executive functioning. And this was after just a week of PPI exposure.
Now, this was a small study—just 60 people in all—but what was particularly interesting was that the study looked at all five classes of PPIs and found that omeprazole, sold under the brand name Prilosec, was the worst, negatively impacting seven of the nine neuropsychological tests administered to the participants. Esomeprazole, sold under the brand name Nexium, was comparatively better, with negative impact on only three of the nine tests. But still, I don’t think any of us can afford to have one-third of our abilities take a few hits.
The bottom line? We can’t say yet whether PPIs cause dementia, though we can say there’s a link between the two. And given that 110 million Americans have a prescription for a PPI, that’s nothing to shake your sriracha at.
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