Asthma sufferers are at an increased risk of heart attacks and strokes, scientists say.
They are twice as likely to have excess plaque buildup in the arteries that carry blood to the brain compared to people who are not asthmatic.
Blockages in the carotid arteries is one of the biggest risk factors for cardiovascular disease, and are behind three-quarters of ischemic strokes.
Asthma leads to plaque build-up because of higher inflammation levels, raising the risk of damage to blood vessels leading to the formation of plaques.
It comes after doctors urged asthma sufferers to keep their inhalers at the ready, because they could suffer an attack while having sex.
In the latest study, researchers at the University of Wisconsin studied around 5,000 adults with an average age of 61 who were at risk of heart disease.
They were given an ultrasound on their carotid arteries — which carry blood from the heart to the head and neck.
Participants were divided into three groups: People with persistent asthma, defined as needing daily medication, intermittent asthma, who had a history of the condition but did not need medication, and no asthma.
Two-thirds of people with the most severe asthma had plaque in their carotid arteries, compared to half of those with moderate asthma and non-asthmatics.
After adjusting for age, sex, race, weight, other health conditions, prescription medication use and smoking, participants with persistent asthma had nearly twice as high odds of having plaque in their carotid arteries than those without asthma.
Researchers at the University of Wisconsin warned asthma raises the risk of suffering from heart disease and
Dr Matthew Tattersall, a cardiovascular expert at the University of Wisconsin who led the study, said: ‘The most important message from our findings is that more significant forms of asthma are associated with more cardiovascular disease and cardiovascular events.
‘Addressing cardiovascular risk factors through lifestyle and behavior adjustments can be a powerful preventive tool for patients with more severe forms of asthma.’
He added: ‘We know that higher levels of inflammation lead to negative effects on the cardiovascular system.’
An increasing number of Americans are diagnosed with asthma every year, with the current number at 25million — up a quarter on two decades ago.
WHAT IS ASTHMA?
Asthma is a common but incurable condition which affects the small tubes inside the lungs.
It can cause them to become inflamed, or swollen, which restricts the airways and makes it harder to breathe.
The condition affects people of all ages and often starts in childhood. Symptoms may improve or even go away as children grow older, but can return in adulthood.
Symptoms include wheezing, breathlessness, a tight chest and coughing, and these may get worse during an asthma attack.
Treatment usually involves medication which is inhaled to calm down the lungs.
Triggers for the condition include allergies, dust, air pollution, exercise and infections such as cold or flu.
If you think you or your child has asthma you should visit a doctor, because it can develop into more serious complications like fatigue or lung infections.
Asthma is a common but incurable condition that affects the small tubes inside the lungs.
When the immune system overreacts to a substance — such as pollen and spores released by mold — airways become inflamed or swollen, restricting them and making it harder to breathe.
Severe sufferers can control the condition by taking regular medication, or use an inhaler to alleviate symptoms.
In the new study, researchers studied 5,029 adults who took part in the Federally-run Multi-Ethnic Study of Atherosclerosis (MESA) study.
Participants were about 60 years old on average, and had been recruited to the study since the year 2000.
Six in ten were from a minority ethnic group, with estimates showing asthma is more common in black and Hispanic communities.
A total of 109 participants had persistent asthma — requiring daily medication — and 388 people had intermittent asthma — where they were diagnosed with the condition previously, but did not need daily medication and it may already be in remission.
A further 4,532 did not have the condition.
Ultrasounds were carried out to determine the number of plaques in the carotid arteries.
Results showed among persistent asthma sufferers 67 per cent had plaques, with about two on average.
For comparison, among those who did not have asthma 50.5 per cent had plaques with about one in blood vessels.
Among those with intermittent asthma, 49.5 per cent had the plaques with an average of one in the vessels — which did not differ significantly from the non-asthma group.
Blood tests for inflammation also showed persistent asthma sufferers had higher levels of inflammation than those who did not have the condition.
Based on the results, scientists warned that persistent asthma sufferers were more at risk from heart disease and stroke.
Scientists undertook the study to determine whether asthma sufferers had more plaques in the carotid arteries.
The study was published today in the Journal of the American Heart Association.