Prostate drugs may find role in dementia, say US scientists

Dementia with Lewy bodies (DLB) may not be as well-known as other forms like Alzheimer’s, but is just as devastating, so the discovery that commonly used drugs may reduce the risk of the disease is a beacon of hope for patients and their carers.

The main finding of the observational study, published in the journal Neurology, suggests that alpha-blocker drugs used to treat urinary symptoms caused by an enlarged prostate gland may reduce the risk of DLB, which accounts for between 3% and 7% of all dementia cases.

While observational studies only show an association between two factors and cannot show causality, the new data backs up an earlier finding that the drug class seems to reduce the risk of Parkinson’s disease. That could point to a possible common mechanism behind the two neurodegenerative diseases and certainly builds the case for them to be studied in clinical trials.

Jacob Simmering and colleagues at the University of Iowa carried out the study using health records of over 600,000 men who were taking different types of drug treatment for benign prostatic hyperplasia (BPH). Subjects were followed for an average of three years to see who developed DLB.

The researchers found that people taking alpha-1 blockers – terazosin, doxazosin, and alfuzosin – were around 40% less likely to develop DLB than people taking other prostate drugs, namely tamsulosin, finasteride, and dutasteride.

They interpret the result as suggesting that the benefits of the alpha-blockers are linked to an ability to boost energy production in brain cells that is not shared with other BPH drug classes. In diseases like DLB and Parkinson’s, neurons show deficits in the function of mitochondria, the energy-producing organelle in cells.

“If terazosin and these similar medications can help slow this progression – if not outright preventing the disease – this would be important to preserving cognitive function and quality of life in people with DLB,” said Simmering.

Moreover, there is a broadly protective mechanism, the drugs could potentially be used to manage or prevent other neurodegenerative diseases, he added. Alpha-blockers have been used for decades, have a good safety profile and are very cheap, so could have a big role to play in dementia around the world if found to be effective.

DLB is the third most common form of dementia after Alzheimer’s and vascular dementia, and affects around 1 in 1,000 people, with an estimated 1.4 million cases in the US and 100,000 in the UK. It is more common in people over 65 and is expected to become ever more burdensome with the ageing of the world’s population.

At the moment, there are no drugs available which can stop or even slow the progression of the disease.

Commenting on the new study, Alzheimer’s Research UK’s head of research strategy, Dr Julia Dudley, said: “It’s encouraging to see large studies exploring whether drugs already licensed for other medical conditions could have a protective effect for the diseases that cause dementia.”

“As these drugs have already been shown to be safe for use in people, this could potentially speed up the process of testing in clinical trials,” she added.

There are still a lot of unanswered questions, however. For example, the DLB study only involved men – even though alpha-blockers are also used to treat urinary symptoms in women – which Dudley said highlights the need for future research to include wider groups of people.

Another limitation of the study is that dementia with Lewy bodies can be difficult to diagnose, so it’s possible that not all people with dementia with Lewy bodies were correctly diagnosed.