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Medications for enlarged prostate may also protect against dementia with Lewy bodies
Last reviewed: 02.07.2025
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A new study suggests that some drugs commonly used to treat an enlarged prostate may also reduce the risk of developing dementia with Lewy bodies (DLB). The observational findings may seem surprising, but they mirror previous work by a University of Iowa Health team linking these drugs to a protective effect in another neurodegenerative disorder, Parkinson's disease. The new findings were published online in the journal Neurology.
The UI researchers believe that the specific side effect of these drugs targets a biological defect common to DLB and Parkinson's disease, as well as other neurodegenerative diseases, raising the possibility that they have broad potential to treat a variety of neurodegenerative conditions.
“Diseases like Lewy body dementia, Parkinson’s disease, or Alzheimer’s disease are debilitating, and we don’t really have good treatments that can change the course of the disease. We can treat the symptoms, but we can’t slow the disease itself,” explains lead study author Dr. Jacob Simmering, an assistant professor of internal medicine at the UI.
"One of the most exciting things about this study is that we are finding the same neuroprotective effect that we saw in Parkinson's disease. If there is a broadly protective mechanism, these drugs could potentially be used to manage or prevent other neurodegenerative diseases."
DLB is a neurodegenerative disease that causes significant and rapid cognitive decline and dementia. Although less common than Parkinson's disease, DLB affects about one in 1,000 people per year and accounts for 3 to 7% of all cases of dementia. Because aging is a key risk factor for DLB, it is likely that the disease will become more common as the population ages.
For the new study, UI researchers used a large database of patient information to identify more than 643,000 men with no history of DLB who started taking one of six drugs used to treat benign prostatic hyperplasia (enlarged prostate).
Three drugs, terazosin, doxazosin, and alfuzosin (Tz/Dz/Az), have an unexpected side effect; they can boost energy production in brain cells. Preclinical studies suggest that this ability may help slow or prevent neurodegenerative diseases such as PD and DLB.
Other drugs, tamsulosin and two 5-alpha reductase inhibitors (5ARIs), finasteride and dutasteride, do not increase energy production in the brain and therefore serve as good comparisons for the effect of Tz/Dz/Az drugs.
The team then followed the men from the time they started taking the drugs until they dropped out of the database or developed Lewy body dementia, whichever came first. On average, the men were followed for about three years.
Because all the participants were selected to start taking medications to treat the same condition, the researchers believed that the men were likely similar to each other when they started treatment. The researchers also matched the men using scores for characteristics such as age, year they started taking the medications, and other medical conditions they had before starting treatment to further reduce differences between the groups.
“We found that men taking Tz/Dz/Az were less likely to develop a diagnosis of dementia with Lewy bodies,” Simmering says. “Overall, men taking drugs like terazosin had about a 40% lower risk of developing a diagnosis of DLB compared to men taking tamsulosin, and about a 37% lower risk compared to men taking 5-alpha-reductase inhibitors.”
This was an observational study, and therefore the results only show an association between Tz/Dz/Az treatment and a reduced risk of developing DLB, rather than a cause and effect relationship.
Additionally, the study included only men because the drugs are prescribed for prostate problems, meaning the researchers don’t know whether the findings would apply to women. However, Simmering and his colleagues are excited about the potential of these drugs, which are already FDA-approved, inexpensive, and have been used safely for decades.
"If terazosin and similar drugs can help slow this progression—if not prevent the disease entirely—it would be important for preserving cognitive function and quality of life in people with DLB," Simmering concludes.