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"
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 scientists detected the changes using a technique called autonomic
assessment, which measures alterations in the autonomic nervous
system. 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.
They confirmed that students were stressed on exam days, 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
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 exam
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.