Mild Stress Can Raise Blood Pressure
By Faith Reidenbach, Reuters Health
NEW YORK (Reuters Health) - It's been clear for some time that
psychological stress is linked to high blood pressure, or hypertension,
but the reason is unknown.
And until recently, investigations of a stress-hypertension link
have been conducted in laboratories, using staged activities such
as public speaking and mental arithmetic to ''stress out'' participants.
Now, in a ``real-world'' setting, a research team in Italy has
confirmed that mild stress can increase blood pressure and impair
the cardiovascular system's ability to regulate itself.
``These changes...might contribute, in susceptible individuals,
to the link between psychological stress and increased cardiovascular
risk of hypertension,'' the team suggests in the January issue
of Hypertension: Journal of the American Heart Association.
The scientists detected the changes using a technique called
autonomic assessment, which measures alterations in the autonomic
nervous system, senior researcher Dr. Massimo Pagani told Reuters
Health. The autonomic nervous system controls blood pressure,
the heart's rhythm and its ability to contract, and other important
Changes in autonomic function can be detected by ''computerized
analysis of beat-by-beat cardiovascular variability'' on an electrocardiogram,
Pagani, an internal medicine specialist at the University of
Milan, and colleagues used electrocardiography and blood pressure
measurements to evaluate 30 medical students on two occasions:
30 to 60 minutes before they took an examination and again 3 months
later while they were on break from classes.
They confirmed that the students were indeed stressed on the
exam day, based on their responses to psychological questionnaires,
their saliva levels of the stress hormone cortisol, and their
saliva levels of cytokines, proteins the immune system releases
when the body is stressed.
The students' blood pressure and heart rate were markedly higher
on the exam day than on the vacation day, the researchers determined.
Other autonomic measures, such as heart rate variability, a measure
of the heart's ability to handle stress, were also elevated on
``Our goal was to find a technique to assess the stress level
acting in any patient,'' Pagani told Reuters Health, so that eventually
therapy for high blood pressure can be ''individually planned
with tailored lifestyle changes.'' In some cases, these would
include non-drug therapies such as ''exercise, food reprogramming
and relaxation,'' he said.
In other cases, medication would be needed, and autonomic assessment
of patients could help physicians choose the drug, Pagani added.
For example, he pointed out, beta-blockers and ACE inhibitors
inhibit an important component of the autonomic nervous system,
called the sympathetic nervous system. Conversely, calcium-channel
blockers, a different class of antihypertensive drugs, boost the
sympathetic nervous system. Autonomic assessment could make it
clear whether a patient's sympathetic nervous system is adequate
or needs to be enhanced or suppressed.
``The main message,'' Pagani said, ``is that autonomic research
might help empower patients, who will be progressively in charge
of their own well-being, and fight against cardiovascular risk.''
SOURCE: Hypertension 2002;139:184-188.
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