High blood pressure, or hypertension, is a major risk factor for heart
disease and stroke. Hypertension is more prevalent, and leads to worse
outcomes, among African Americans than among whites. Genetic factors apparently
are less at fault than environmental, psychological and social causes such
as diet, income, education or stresses like racism.
The new study, conducted under the direction of Andrew Sherwood, Ph.D.
covers the effects of perceived racism when blood pressure is monitored
over a 24-hour period. It appears in the journal Psychosomatic Medicine.
Sherwood’s team recruited 69 African-American men and women, aged
25 to 44 years. Their blood pressure was measured in the clinic on three
separate visits, each one week apart. The volunteers were then fitted
with an ambulatory blood pressure monitor, a portable device that tracks
and
records blood pressure four times an hour during waking hours and twice
an hour while sleeping.
Participants were asked about demographic information and answered a questionnaire
assessing experiences with racism. Another set of questions measured inhibition
of anger and outward expression of anger.
“Seventeen percent of participants reported experiencing racism
a couple of times a year, 33 percent several times a month, 17 percent
several times a week and 26 percent several times a day,” says
Patrick Steffen, Ph.D., lead author of the study.
Blood pressure during waking hours related to higher levels of perceived
racism. This pattern held true for both systolic blood pressure (the top
number in blood pressure measurement) and diastolic blood pressure (the
bottom number).
People who experience racism might become angry as a result, the researchers
reasoned, and Steffen adds that participants in this study tended to internalize
their anger rather than express it openly.
“Perceived racism was positively correlated with anger inhibition,” says
Steffen, “but was not related to outwardly expressed anger.”
Unlike perceived racism, anger inhibition did not connect to systolic
or diastolic blood pressure when awake. However, higher anger inhibition
was related to increased diastolic blood pressure while sleeping and also
to a smaller drop in diastolic blood pressure as the participants went
from waking to sleeping.
An overnight “dip” in blood pressure is an important indicator,
hypertension researchers say. People whose blood pressure does not dip
during the hours of sleep face an increased risk of heart disease or death.
Because ambulatory monitoring devices measure blood pressure around the
clock, they are especially helpful in learning whether someone’s
blood pressure dips overnight.
“The results demonstrate that perceived racism is related to blood
pressure as measured during daily life, and that although perceived racism
and anger inhibition are correlated with each other, they are independently
related to ambulatory blood pressure,” Steffen says.
He says that perceived racism may play a greater role
during the day, when the participants were more likely to encounter racist
situations.
