Twin study evaluates role of environmental stress in cardiovascular disease

August 27, 2001

Whether environmental stress is a risk factor for cardiovascular disease is the focus of a study at the Medical College of Georgia following more than 500 pairs of twins. "We are looking at the role of environmental stress as a risk factor," said Dr. Frank Treiber, director of MCG's Georgia Prevention Institute and principal investigator on the four-year, $1.4 million continuation grant from the National Institutes of Health.

"Stress, at the moment, is considered a candidate risk factor, not an established one, for cardiovascular disease," he said. "We want to try and clear up its role, to see if indeed those who are under chronic stress show greater elevations in their blood pressure in response to stress and then whether they, over time, show increases in their resting blood pressure as well as deleterious changes in their heart structure and function," Dr. Treiber said

MCG researchers have been following the African-American and European-American identical and fraternal twins for four years to determine how genetics and environment affect the twins' blood pressure at rest and in response to stress. When the twins started the study, their average age was 14; they will be 18, on average, as they start the new study.

Researchers have monitored their blood pressure, heart rate and cardiac function, during stressful situations such as playing virtual reality games and while discussing personal problems and concerns. They already found that among both the African-American and European-American twins, genetics account for about 50 to 60 percent of the differences in blood pressure and reactivity to stress.

"We found very similar heritabilities, very similar influences from the environment," said Dr. Harold Snieder, genetic epidemiologist at the Georgia Prevention Institute and co-investigator on the study. "Now we have to find out what that means."

It may mean that the difficulties lie further along in life for some of these young people who may have chronic exposure to stress without good coping mechanisms. "This study will allow us to follow the twins across a total of eight to 10 years of important psychosocial changes," Dr. Treiber said. "The impact of stressful environments may start showing up as they get older and become young adults."

They also want to determine if the African-American twins - their race tends to have problems with hypertension and other cardiovascular disease much earlier in life and more often, than their European-American counterparts - are the most impacted by environmental stress.

The reasons behind increased cardiovascular disease and related risk factors among African-Americans are still being determined, but one theory is that they encounter more frequent and more intense psychosocial stressors - such as discrimination, violence and poor socioeconomic status - than European-Americans, Dr. Treiber said.

The researchers want to explore that issue as well, looking not only at how the twins react to stress, but if unrelenting environmental stress has a cumulative toll on their blood pressure reactivity and resting blood pressure.

Twins were picked for study because researchers could more easily determine the genetic influence on blood pressure by comparing identical twins who share 100 percent of their genes and fraternal twins who share 50 percent, about the same as any two siblings of the same age. "You would expect, if something is influenced by genetics, that the similarity in identical twins is much higher," Dr. Snieder said.

This phase of the study will follow the twins for four more years, continuing to look at resting blood pressure and reactivity, not only in the controlled setting of the Georgia Prevention Institute, but with 24-hour monitoring as well to measure reactivity to life's routine stressors.

"The other thing we are looking at now is why their blood pressure is going up more during stress," Dr. Treiber said. "Is it because they are retaining more sodium or producing more stress hormones which are contributing to the constriction of blood vessels?" They also are looking at whether blood vessels are becoming less elastic and so less responsive over time in the face of increasing pressures.

In a separate longitudinal study of young African-Americans and European-Americans with a family history of hypertension, the researchers already are finding that the African-Americans are showing telltale signs of blood pressure problems as they move into their late teens and early 20s.

Changes include pressures that are more reactive to stress and increases in the left side of the heart, which pumps blood into the body and, in the face of hypertension, must work against increased resistance.

"We want to see who is going to have the greatest increase in blood pressure over time," Dr. Treiber said. "We already know that if you are overweight, you are more likely to show increases. If you have a family history, you are more likely. If you already have a higher resting blood pressure, you are likely to have it later, too. Factor all that in and then say, 'Does reactivity to stress still help us tell who is going to show the greatest increases over time?''

The researchers suspect that the answer is, 'Yes, it does.' "We think part of it is how much stress they encounter, the other is their coping skills and lifestyle behaviors like physical activity, diet and smoking," Dr. Treiber said. "If we can see what are the environmental contributions that will help us understand what we can do to develop effective primary prevention strategies for people at risk."

Medical College of Georgia at Augusta University

Related Blood Pressure Articles from Brightsurf:

Children who take steroids at increased risk for diabetes, high blood pressure, blood clots
Children who take oral steroids to treat asthma or autoimmune diseases have an increased risk of diabetes, high blood pressure, and blood clots, according to Rutgers researchers.

High blood pressure treatment linked to less risk for drop in blood pressure upon standing
Treatment to lower blood pressure did not increase and may decrease the risk of extreme drops in blood pressure upon standing from a sitting position.

Changes in blood pressure control over 2 decades among US adults with high blood pressure
National survey data were used to examine how blood pressure control changed overall among U.S. adults with high blood pressure between 1999-2000 and 2017-2018 and by age, race, insurance type and access to health care.

Transient increase in blood pressure promotes some blood vessel growth
Blood vessels are the body's transportation system, carrying oxygen and nutrients to cells and whisking away waste.

Effect of reducing blood pressure medications on blood pressure control in older adults
Whether the amount of blood pressure medications taken by older adults could be reduced safely and without a significant change in short-term blood pressure control was the objective of this randomized clinical trial that included 534 adults 80 and older.

Brain blood flow sensor discovery could aid treatments for high blood pressure & dementia
A study led by researchers at UCL has discovered the mechanism that allows the brain to monitor its own blood supply, a finding in rats which may help to find new treatments for human conditions including hypertension (high blood pressure) and dementia.

Here's something that will raise your blood pressure
The apelin receptor (APJ) has been presumed to play an important role in the contraction of blood vessels involved in blood pressure regulation.

New strategy for treating high blood pressure
The key to treating blood pressure might lie in people who are 'resistant' to developing high blood pressure even when they eat high salt diets, shows new research published today in Experimental Physiology.

Arm cuff blood pressure measurements may fall short for predicting heart disease risk in some people with resistant high blood pressure
A measurement of central blood pressure in people with difficult-to-treat high blood pressure could help reduce risk of heart disease better than traditional arm cuff readings for some patients, according to preliminary research presented at the American Heart Association's Hypertension 2019 Scientific Sessions.

Heating pads may lower blood pressure in people with high blood pressure when lying down
In people with supine hypertension due to autonomic failure, a condition that increases blood pressure when lying down, overnight heat therapy significantly decreased systolic blood pressure compared to a placebo.

Read More: Blood Pressure News and Blood Pressure Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to