The weather discovered as a new risk factor for strokes
A research team has found that the risk of certain types of stroke increases with dry and warm air masses. The aim of the scientific investigation was to help ensure that both patients and medical care facilities can take appropriate preventive and treatment measures in good time.
Around 270,000 people suffer a stroke in Germany every year. In principle, it can affect everyone - from infants to old people. It is known, however, that the risk of stroke increases with age. Other important risk factors for a stroke include high blood pressure, heart disease, diabetes, smoking, obesity, and excessive alcohol consumption. Researchers have now discovered another factor that increases the risk of stroke: dry, warm air.
Risk increases with dry and warm air masses
According to a joint press release by the University of Augsburg and the University Hospital Augsburg (UKA), their study shows that the risk of certain types of strokes with dry and warm air masses increases based on almost 18,000 cases that have been collected over ten years. According to the information, complex interrelationships with so many cases and subtypes were examined for the first time.
Certain strokes increased over the course of the year
At first it was just a feeling of the neurologists at the University Hospital Augsburg, namely "that certain strokes accumulated on some days during the course of the year", explains Privatdozent Dr. Michael Ertl, one of the two first authors of the study, which was published in the specialist magazine "Cerebrovasc Diseases".
"Many stroke neurologists are familiar with these clustering phenomena, so we suspected that this could also have something to do with weather influences." And in fact the study comes after ten years and 17,989 cases examined - most of them newly diagnosed, but also patients with repeated cases Strokes - for concrete results in connection with certain weather conditions and strokes in the Augsburg region.
For example, the risk for some stroke subtypes increases with dry-warm air masses, whereas dry-cold air masses were associated with a significantly lower occurrence of brain bleeding.
Types of brain attacks that make up over 80 percent of all strokes
The search for the causal relationships turned out to be extremely complex. "The interplay of different meteorological factors - such as air temperature, air pressure and humidity - as well as short-term temperature changes is very complex," explains Privatdozent Dr. Christoph Beck from the Chair of Physical Geography with a focus on climate research at the University of Augsburg, along with Ertl also first author of the study.
If you look at the temperature development in the period of a few days before the stroke event, you will also find differentiated influences on the frequency of stroke or bleeding, which are not yet fully understood pathophysiologically. The interdisciplinary research team was also able to show that weather changes have different effects on the two stroke subtypes of cerebral infarction and cerebral hemorrhage.
Dry, warm air masses pose an increased risk for certain types of cerebral infarction, which make up more than 80 percent of all strokes, but a lower risk for bleeding in the brain. The reverse is true for dry, cool air masses: they promote bleeding in the brain, but cause a less frequent occurrence of brain infarctions. A reduced occurrence of brain infarctions could also be demonstrated with moist air masses.
Never before have complex interdependencies been examined
Ertl emphasizes "that we are not the first to see the climate and the frequency of strokes in context". According to his information, most of the studies examined only a few meteorological parameters such as air pressure and temperature as well as stroke without a specific definition at a certain point in time.
The research team of the UKA and the university's geographic institute goes much further here. "In addition to taking the local meteorological conditions into account, the air mass classifications used also include the large-scale synoptic conditions such as the distribution of soil air pressure across Europe in the assignment to specific weather conditions," explains Beck.
"In addition, we have divided the so-called ischemic stroke, which involves vascular occlusion of the arteries supplying the brain and which accounts for around 85 percent of all strokes, into five further subtypes," says Ertl.
The study also took into account the air mass situation two to five days before the stroke. Classic risk factors of all examined patients such as high blood pressure, overweight, diabetes, cholesterol and lifestyle habits were taken from the doctor's letter and also noted.
Further research needed
“With the help of our study, we would like to contribute to the fact that both affected people and medical care facilities can take appropriate preventive and treatment measures in good time. However, this will require intensive further research in the future. The aim is to confirm and substantiate the retrospectively evaluated data by further prospective studies, ”explains Prof. Dr. Markus Naumann, Director of the Clinic for Neurology and Clinical Neurophysiology at the University Hospital Augsburg. (ad)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
- Press release from the University of Augsburg and the University Hospital Augsburg: Dry, warm air increases the risk of stroke, (accessed: November 13, 2019), University Hospital Augsburg
- Cerebrovasc Diseases: New Insights into Weather and Stroke: Influences of Specific Air Masses and Temperature Changes on Stroke Incidence, (accessed: November 13, 2019), Cerebrovasc Diseases