A majority of young adults have high blood pressure and don't know it. What's behind the alarming trend?

Many people view high blood pressure as a potential issue when you get older. But new research shows that many younger adults with uncontrolled high blood pressure were unaware of their health status.

The study, just published in JAMA Network Open, analyzed National Health and Nutrition Examination Survey data from 3,129 American adults with uncontrolled high blood pressure, aka hypertension. The researchers discovered that more than half of the study participants didn’t even know that they had hypertension. Of those who were aware that they had high blood pressure, nearly 71% took medication for the condition, but still had hypertension that was uncontrolled.

Awareness was a particular issue in younger adults. Of those aged 18 to 44 with hypertension, nearly 69% of women didn’t know they had the condition, and 68% of men didn’t know their status. More than 76% of those with uncontrolled hypertension also hadn’t seen a health care provider in the past year.

“These findings have serious implications for the nation’s overall health given the association of hypertension with increased risk for cardiovascular disease,” the study’s authors wrote in the conclusion.

Research has also found that heart disease, including heart attacks, is on the rise in younger people in the U.S. Here’s what cardiologists want you to know about the risks of having high blood pressure — and what to do about it.

What is high blood pressure?

Blood pressure is a measure of the force of circulating blood against the walls of the arteries, which carry blood from your heart to other areas of your body, per the Centers for Disease Control and Prevention.

Your blood pressure reading features two parts: the systolic blood pressure, which is the top number, and the diastolic blood pressure, or the bottom number. Your systolic blood pressure measures the force against your arteries when your heart beats, while the diastolic blood pressure is the tension that remains in your arteries when your heart rests between beats, according to the CDC.

A normal blood pressure reading is less than 120/80 mm Hg, while high blood pressure, or hypertension, is considered 130/80 mm Hg or higher, according to the American College of Cardiology and American Heart Association.

Nearly half of American adults have hypertension, according to the U.S. Department of Health and Human Services.

What is the danger in having hypertension?

Hypertension is linked to a slew of serious health complications. “The risks of uncontrolled hypertension are many, including cardiovascular disease such as heart attack and stroke, as well as diabetes, kidney dysfunction and dementia,” Dr. Christopher Berg, cardiologist at MemorialCare Heart and Vascular Institute at Orange Coast Medical Center in Fountain Valley, Calif., tells Yahoo Life. “There is evidence to suggest that good cardiovascular health, such as having a normal blood pressure, is important in preventing negative cardiovascular outcomes later in life.”

The earlier you develop high blood pressure and the longer it goes untreated can have a “significant impact on quality of life,” along with your mortality, Dr. Thomas Boyden, Corewell Health medical director for preventive cardiology and cardiac rehabilitation, tells Yahoo Life.

In women, uncontrolled hypertension in pregnancy raises the risk of cardiovascular disease and is the leading cause of pregnancy-related deaths, the study’s researchers noted.

Why are rates of hypertension so high in younger adults?

The study didn’t dive into why rates of hypertension are so high in younger adults. Still, cardiologists have some theories.

“Hypertension in young people can be caused by many reasons,” Dr. Saurabh Rajpal, a cardiologist at The Ohio State University Wexner Medical Center, tells Yahoo Life. “There are known risk factors for this like smoking, obesity, family history and excessive alcohol.” But then there are more rare causes of hypertension, such as kidney disease or coarctation, which is a congenital heart disease, he says.

Boyden says that higher rates of overweight and obesity, poor diets and a sedentary lifestyle, all of which are risk factors for hypertension, may also be fueling this. “Additionally, younger people tend to access the health system less frequently, providing fewer opportunities to diagnose and treat the ‘silent killer,’ hypertension,” he says.

Why are so many younger people unaware they have hypertension?

Many people with high blood pressure have no symptoms, Berg points out. “If they never step into a doctor’s office or have their blood pressure checked, hypertension will not be diagnosed,” he says. “Additionally, many health care providers are hesitant to label a young person with hypertension [based on] a single high blood pressure reading.”

Convincing an otherwise healthy young person to return to the office for another blood pressure check to confirm the diagnosis can be “challenging” when they have work and life obligations, Berg adds. As a result, Berg says that doctors “may shrug off the elevated blood pressure as due to ‘rushing and running late’ or ‘getting nervous in the doctor’s office’ and decline further evaluation.”

But doctors may simply not be informing patients that they have hypertension or are at risk for the condition. “This study also shows that even younger people with more frequent exposure to the health care system are still often unaware that they have hypertension,” Berg says.

How to know your status

“Everyone needs to know their numbers,” Boyden says. That can mean getting your blood pressure checked at your local pharmacy chain or asking what your blood pressure reading is the next time you see a doctor, Rajpal says. “If the average is consistently above 130/80, you should discuss with your doctor treatment options, including changes to daily habits such as exercise, diet, sleep, stress and alcohol that impact blood pressure,” Boyden says.

But if your blood pressure is greater than 140/90, “this needs to be treated medically in addition to behavioral changes to lower cardiovascular risk,” Boyden says. Ultimately, doctors say it’s important to be informed and to do what you can to stay healthy based on your blood pressure readings.