It has been long known that drugs that reduce the stickiness of blood help to keep the arteries and heart healthy and decrease the risk of cardiovascular events. Now, there is increasing evidence that these drugs may also help to reduce the incidence of dementia by as much as 48 percent.
Several large-scale studies have investigated the long-term use of blood-thinning drugs for preventing heart attack or stroke in those with atrial fibrillation or other cardiac disorders, but recent research published by the European Heart Journal also indicates that these drugs may reduce the prevalence of dementia.
The relevance of such study cannot be neglected by any means, considering the rising incidence of Alzheimer’s. It is assessed that around 50 million people are affected by Alzheimer’s globally, and this number is expected to rise to 75 million by 2030. According to Alzheimer’s Disease International, the incidence and prevalence of Alzheimer’s would increase more sharply in developing nations like India or China, as compared to western world countries or the US. Countries like India or China are also seeing a rise in metabolic diseases and cardiac ailments1.
The research published in European Heart Journal was the conclusion reached after analyzing the massive amount of data of almost half a million patients with atrial fibrillation, diagnosed in between 2006-14. This is equivalent to a whopping 1.5 million years of follow-up. The data indicated that early initiation of anticoagulation therapy would not only prevent death from complications of atrial fibrillation but would also help to preserve the cognitive function.
One of the reasons why researchers have been slow in finding or studying the preventive measures for dementia is the lack of acuteness of the disease. Everyone, be it a physician or a patient, seems to be worried about the fatal outcomes related to stroke or cardiovascular events and worried about the pain caused by these events. But when it comes to dementia, things are different; no one dies immediately with it. In dementia, a person loses his or her mind only gradually.
Brain cells are very good at compensating small local damages by transferring the functions to healthy cells or even due to regeneration. However, they cannot handle the continuous bombardment by tiny clots for years together. Finally, the brain cells start giving up, grey matter contracts, and a person starts losing their sanity.
Although research could not establish a clear benefit from any particular blood thinning drug or link between atrial fibrillation or dementia, experts believe that atrial fibrillation increases the formation of micro blood clots, which often end up in the brain, thus increasing the risk of dementia.
Further, the research team headed by Dr. Friberg stated that there were many limitations of the present study, as the researchers did not have complete access to medical records of the patients and lack of the knowledge of other comorbidities. Above all, dementia is a disease that evolves slowly over the years and is extremely difficult to diagnose at the early stage, meaning that a number of reported cases could be much lower than in reality.
Dr. Friberg strongly recommends to start the therapy with anticoagulant drugs at the earliest in those suffering from atrial fibrillation, and investigators say that this treatment should not be stopped without severe reasons. Though the researchers do not fully understand the underlying mechanism of such a beneficial effect, but there is no doubt that this benefit exists2.
The most recent study published in the European Heart Journal is by no way the first of its kind. In fact, hundreds or even thousands of large and small-scale studies published during the last few decades have shown the relationship between the prevalence of dementia and changes in blood viscosity.
In a review by Quin et al., investigators screened 7103 titles on the subject, and they selected 485 studies for further analysis. The study aimed to find out the relationship between dementia and seventeen biomarkers of hemostasis. Thus, it was a review that took into consideration the various factors that affect the flow of blood in the vessels.
At the end of the study,Quin et al. concluded that there was moderate and yet clear associations between the prevalence of dementia and high level of various factors in the blood that increases its viscosity and stickiness3.
As researchers are finding more and more links between the various non-communicable diseases, they are continually widening the scope of their investigations. They are working hard to understand how multiple factors that cause dementia and other metabolic disorders are interrelated.
Another excellent example of this interrelationship is between obesity and dementia. Obesity is a well-established risk factor for a whole range of communicable diseases from diabetes to heart disorders. How and why obesity increases the risk of Alzheimer’s is a poorly understood phenomenon, although statistics indicate that such danger exists.
Obesity has been strongly associated with late-onset dementia and Alzheimer’s disease, causing changes in white matter, associated with brain atrophy and disturbances in the blood-brain barrier. In recent times, investigators have started to understand the underlying mechanism. Obesity means an increase in adipose tissues and thus, higher levels of hormones called adipokines. These so-called adipokines are thought to be behind the changes in brain structures. However, the adipokines area's huge group of hormones and exact mechanism is far from understood4.
In conclusion, the blood flow to the brain is a function of both the health of blood vessels and how effortlessly the blood can move through the blood vessels. Experience also shows that controlling the viscosity of blood and ease of its flow through the blood vessels can be done with great success. Drugs that either decrease the blood coagulation or aggregation of thrombocytes are being used in cardiology for a long period of time and have a proven safety and efficacy profile.
- Dementia statistics | Alzheimer’s Disease International. https://www.alz.co.uk/research/statistics. Accessed January 23, 2018.
- Friberg L, Rosenqvist M. Less dementia with oral anticoagulation in atrial fibrillation. Eur Heart J. doi:10.1093/eurheartj/ehx579
- Quinn TJ, Gallacher J, Deary IJ, Lowe GDO, Fenton C, Stott DJ. Association between circulating hemostatic measures and dementia or cognitive impairment: systematic review and meta-analyses. J Thromb Haemost. 2011;9(8):1475-1482. doi:10.1111/j.1538-7836.2011.04403.x
- Kiliaan AJ, Arnoldussen IAC, Gustafson DR. Adipokines: a link between obesity and dementia? Lancet Neurol. 2014;13(9):913-923. doi:10.1016/S1474-4422(14)70085-7