Men’s nocturnal urge to urinate could point to dementia
The correlation is documented by a scientific study from Aarhus University.
Many men over the age of 60 sleep poorly because a benign prostate enlargement forces them to get up regularly at night to urinate.
This irresistible urge to pee means their sleep is broken up, which is stressful in itself.
Most worrying of all, however, is the fact that the fragmented sleep pattern also seems to put this group of night-urinating men at increased risk of developing dementia.
This is documented in a new scientific study conducted by researchers from Aarhus University and Stanford University in the US. The study is supported by the Lundbeck Foundation, amongst others, and the findings have been published in the scientific journal EClinicalMedicine.
‘To put it very briefly, our study shows that this group of men, measured over a ten-year period, statistically has a 21 percent higher risk of developing dementia than men of the same age who do not have these prostate problems,’ says Mette Nørgaard, professor at the Department of Clinical Epidemiology at Aarhus University (AU).
She has led the scientific study, which is based on studies of health information from a total of 1.4 million Danish men – information that the researchers have inter alia accessed through the Danish National Patient Registry and the Danish National Prescription Registry.
At the same time, the new knowledge points to the possible benefits of focusing on sleep patterns in men diagnosed with benign prostatic hyperplasia, says Mette Nørgaard:
‘This could take the form of medication, but it could also involve various exercises – cognitive behavioural therapy – which can also increase the chances of getting a more continuous night’s sleep. And finally, there are various good, down-to-earth tips that can also help, such as the classic: Don’t drink too many liquids in the hours before bedtime.’
Brain cleansing
In dementia research, there has been a focus for a long time on the hypothesis that there could be a link between persistent sleep disturbances and an increased risk of dementia.
The core of the hypothesis is the brain’s ‘washing machine’: the glymphatic system, which ensures that our brains are flushed by cerebrospinal fluid while we sleep.
Later, when this fluid drains out of the brain via the nerves and lymphatic vessels, the brain’s waste products are flushed out along with this.
If this ‘brainwashing’ fails to work properly, there will be a build-up of waste products in the brain. This, in turn, is thought to lead to various forms of dementia, according to the hypothesis – which often refers to Alzheimer’s as a possible example, because in this form of dementia, a build-up of the protein fragment beta-amyloid can be seen in the brain.
However, when we wish to conduct scientific studies to elucidate a possible link between sleep disorders and dementia, a methodological challenge arises: How can we actually investigate it?
It is a thorny problem, and Professor Mette Nørgaard and her colleagues thought for some time before coming up with an idea that seemed realistic, she says:
‘It occurred to us that it might be useful to look at men who suffer from benign prostatic hyperplasia, because this causes a frequent urge to urinate around the clock, and all else being equal, it would also disrupt their sleep patterns. So that was the direction we took.’
Monitored for years
Using the National Patient Registry, Mette Nørgaard and her colleagues first of all identified 297,000 men who had been treated with surgery or medication for benign prostatic enlargement in Danish hospitals between 1996 and 2016.
The registry also made it possible to monitor these men in the years after their treatment to see if they came into contact with the health care system later due to developing Alzheimer’s or some other form of dementia, says Mette Nørgaard:
‘On average, using registry studies, we monitored each of the 297,000 men for about seven years after treatment for benign prostatic hyperplasia – and in some cases for as long as 22 years after the treatment was completed. As a basis for comparison, we had gathered health data from the same period for 1.1 million Danish men who had not been treated for benign prostatic hyperplasia – and in both groups, 75 percent of the men were over 60 years of age.’
It was these comparisons, which also included data from the National Prescription Registry and other sources, that finally made it possible to conclude, after a great many very complicated mathematical calculations, that an enlarged prostate of the benign kind statistically increases the risk of developing dementia by 21%. And that this group of night-urinating men, who notoriously struggle with sleep disturbance, also have a 16% statistically increased risk of developing Alzheimer’s – if you focus on this form of dementia alone.
But can we thereby say that there is a causal link between an enlarged prostate and dementia?
‘You can’t conclude that from our study, because it doesn’t say anything about biological links,’ says Professor Nørgaard: ‘But the figures, as I see them, point to the importance of helping these men to get as continuous a night’s sleep as possible – not least to best protect them from developing dementia.’
Now, Mette Nørgaard and her colleagues will begin investigating possible links between dementia and irregular night sleep in women.
As in the case of men, the study will be based on information derived from the National Patient Registry and the National Prescription Registry. The group of women they will be studying are those who have sought treatment for a so-called overactive bladder, which causes a strong urge to urinate around the clock – and forces them to get up frequently at night to visit the toilet.
‘We expect that this group of women may also have an increased risk of dementia,’ says Professor Mette Nørgaard.
- The scientific article – “Sleep disruption and Alzheimer’s disease risk: Inferences from men with benign prostatic hyperplasia” is based on health data from 1.4 million Danish men.
- In the analysis of these data, corrections have been made for a wide range of factors that might otherwise distort the picture, including level of education, heart disease and diabetes.
- Mette Nørgaard, the first author of the article, is a professor at the Department of Clinical Epidemiology at Aarhus University, and is also employed at Aarhus University Hospital.
- The research project was funded by the Lundbeck Foundation, Aarhus University Research Foundation and the National Institutes of Health (NIH), USA.
- Overactive bladder, which causes a strong urge to urinate, can be found in more than 10 percent of the population, and affects both men and women.