Risk Factors The risk of fatal cerebral hemorrhage is dramatically increased by high blood pressure & smoking

Blood pressure and smoking seem to significantly affect the risk of cerebral hemorrhage

A recent study by German and Dutch researchers provides evidence for an association between the occurrence of aneurysmal cerebral hemorrhage and the risk factors hypertension and smoking.

Risk factors hypertension and smoking

In a recent study by German and Dutch scientists, evidence was found to indicate an association between the occurrence of aneurysmal cerebral hemorrhage and the risk factors hypertension and smoking. The comprehensive meta-analysis was published in the journal "JAMA Neurology" by researchers from the Department of Neurosurgery at the University Medical Center Mannheim (UMM) in collaboration with scientists from the Department of Neurology, University of Utrecht, The Netherlands.

In a recently published meta-analysis, there are clear indications of an association between the occurrence of aneurysmal cerebral hemorrhage and the risk factors hypertension and smoking. (Image: peterschreiber.media/fotolia.com)

Special form of stroke

Aneurysmal subarachnoid hemorrhage (SAB) is a special form of stroke in which blood enters the subarachnoid space filled with cerebral fluid, protecting the brain and spinal cord.

As explained in a statement by UMM, this type of cerebral hemorrhage often occurs when an aneurysm, a saccular extension of an artery, ruptures at the brain base.

Although subarachnoid haemorrhage accounts for only about five percent of all strokes, the consequences are highly threatening:

Half of those affected are younger than 55, one third dies within the first few days to weeks after the onset of bleeding, and about one third of survivors are permanently dependent on help.

The meta-analysis of the German and Dutch scientists now reveals for the first time a worldwide decrease in the incidence of aneurysm-related cerebral hemorrhage parallel to the decrease in hypertension and smoking.

The goal of the researchers was not only to shed some light on the apparently heterogeneous temporal and spatial distribution of the incidence of SAB, but also to identify potential determinants that could be responsible for the decline of this disease.

Number of diseases decreased

The starting point of the project was recently published, sometimes contradictory data from various register-based or regional studies, which document a decrease in the incidence of subarachnoid hemorrhage.

The systematic review included metadata of all global, population-based stroke studies over the past 60 years. On the one hand, the study captures the occurrence of aneurysmal cerebral hemorrhages regionally and their frequency over time.

In addition, the meta-analysis presents for the first time the development of the factors blood pressure and smoking in relation to the SAB incidence.

There are clear indications of a relationship between the occurrence of aneurysmal cerebral hemorrhages and the risk factors hypertension and smoking.

Specifically, analysis of data from 75 studies involving more than 8,000 people from 32 countries shows that the incidence of cerebral hemorrhage has declined significantly in recent decades:

Between 1980 and 2010, the incidence of aneurysmal subarachnoid haemorrhage globally decreased by approximately 40 percent. Here, however, large regional differences were detected:

The incidence in Europe fell by 41 percent, in Asia by 46 percent and in North America by 14 percent. By contrast, the incidence of SAB in Japan has increased 59 percent in the last three decades. The incidence of SAB is also distributed differently according to age and gender.

Decrease in parallel with the decrease in systolic blood pressure and smoking prevalence

It is striking that the development or decrease in SAB incidence worldwide is parallel to the decrease in systolic blood pressure and smoking prevalence over the same period.

"A play of mind: If the decrease in SAB incidence was actually directly related to the reduction in systolic blood pressure, this would mean that the SAB incidence would decrease by 7.1 percent with every 1 mmHg drop in blood pressure," explains the lead author the scientific publication, Professor Nima Etminan.

"And in terms of smoking prevalence, this means that the SAB incidence declines by 2.4 percent per percent decline in smoking prevalence," said the head physician of the Department of Neurosurgery UMM.

Of course, the parallel development of hypotension and smoking prevalence with the incidence of subarachnoid haemorrhages only suggests a causal relationship.

The existing data can not provide proof of this, since quantitative data for these risk factors on a population basis or at the level of individual patients would be necessary.

Nevertheless, the association found in the study supports preventive approaches to control the risk factors of hypertension and smoking to reduce the risk of aneurysmal cerebral hemorrhage.

Reduce risk of aneurysmal cerebral hemorrhages

At the same time, the authors are currently investigating the scientific question as to whether lowering blood pressure in patients with randomly discovered aneurysms, which are not primarily treated but controlled by imaging, has a favorable effect on the development of the aneurysms.

This is part of the prospective phase III study PROTECT-U (www.protect-u-trial.com/) at various neurovascular centers in Germany, the Netherlands and soon also in Canada.

The present work also provides starting points for further studies, the results of which, if they lead to appropriate primary prevention strategies, could actually help further reduce the risk of aneurysmal cerebral hemorrhage:

This would be a closer examination of the regional differences in the incidence of SAB and its reduction, regional differences in age- and gender-related incidences, and their relation to more accurate, quantitative data on smoking behavior. (Ad)