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Two New Studies Say -
Heart Disease Rick Factors Begin in Childhood – Or
Before
Oct. 12, 2004 – Lifestyle factors that increase the
risk of heart disease in adults begin to take hold in childhood, and
possibly even before birth, according to two studies reported in
Circulation: Journal of the American Heart Association.
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“Since childhood blood pressure
tracks into adulthood, interventions aimed at early life risk
factors – quitting smoking during pregnancy, breast-feeding,
prevention of obesity in all family members – may be important
for reducing the population distribution of blood pressure, and
thus cardiovascular disease risk.” |
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In one study, Boston researchers found that about
two-thirds of 1,960 adolescents studied had at least one risk factor for
heart disease, and almost 10 percent had a cluster of factors known as
metabolic syndrome.
In the other study, British and Australian
investigators looked at parental and early-life characteristics and
their association with blood pressure in 5-year-old offspring. The
children of women who smoked during pregnancy had higher blood pressure
compared to children of nonsmokers, and parents’ weight also influenced
blood pressure. Breast-feeding was associated with a lower blood
pressure.
Collectively, the findings suggest a need to start
heart disease prevention efforts early in life, rather than after risk
factors have become well established.
“The impact of these data may be far reaching,”
said lead author Sarah de Ferranti, M.D., M.P.H., in the cardiology
division at Children’s Hospital Boston. “[Medical] practitioners should
be aware of the clustering of metabolic abnormalities in children, and
affected children should receive risk-reducing interventions.”
The metabolic syndrome is defined by the presence
of multiple heart disease risk factors: impaired fasting glucose, high
blood pressure, low HDL, elevated trigylcerides, and obesity (measured
by waist circumference). A person who has at least three of the risk
factors meets the criteria for the diagnosis of metabolic syndrome.
The metabolic syndrome has been studied extensively
in adults, but far less in children and adolescents. Researchers
adapted the criteria for adult metabolic syndrome to children, then
applied them to participants aged 12 to 19 years in the third National
Health and Nutrition Examination Survey (NHANES III), conducted between
1988 and 1994.
Overall, 63.4 percent of the children and teenagers
had at least one metabolic abnormality, said senior author Nader Rifai,
Ph.D. Nearly one-third (31.2 percent) of overweight/obese adolescents
had the metabolic syndrome.
The most common risk factor was a low level of HDL
(good) cholesterol, seen in more than 40 percent of boys and girls.
About 30 percent of adolescents had elevated levels of triglycerides,
another type of blood fat, and between 20 percent and 30 percent of
adolescents had a waist circumference that met the definition of
obesity. Additionally, 9.2 percent met the criteria for metabolic
syndrome (three or more risk factors), which occurred almost equally in
boys (9.5 percent) and girls (8.9 percent), and in older (8.3 percent)
and younger (10.3 percent) adolescents.
The distribution of metabolic syndrome by ethnic
group was Mexican-Americans – 12.9 percent, non-Hispanic whites – 10.9
percent, and non-Hispanic blacks – 2.5 percent. These percentages for
adolescents are similar to those reported in adults from the same ethnic
groups.
Because metabolic syndrome is closely related to
diabetes and obesity, the “results are not surprising in view of the
high and rising rates of obesity and type 2 diabetes mellitus in U.S.
children,” de Ferranti said.
In the second study, Debbie A. Lawlor, M.B., Ch.B.,
Ph.D., consultant senior lecturer in epidemiology, department of social
medicine, University of Bristol, United Kingdom, and colleagues,
reviewed parental and early-life factors that influenced blood pressure
in children at age five. Interest in blood pressure at such an early
age comes from the recognition that high blood pressure is a major risk
factor for heart disease, and blood pressure in adults tends to follow
the same pattern seen in childhood. Previous studies of blood pressure
in childhood have tended to involve relatively few children, used
different types of study designs and produced inconsistent results.
The study involved more than 8,500 Australian women
and their offspring enrolled in the Mater-University (Queensland,
Australia) study of pregnancy and outcomes. The investigators evaluated
a variety of variables for their potential influence on childhood blood
pressure. The factors included ethnicity, smoking history, mother’s
height and weight, father’s body mass index, family education, income
and a variety of other factors. At age five, 3,864 offspring were
examined.
Children of women who had smoked throughout
pregnancy had a systolic blood pressure (the first number in a blood
pressure measurement) that was about 1 millimeter of mercury (mm Hg) –or
point – higher at age five, compared to children whose mothers did not
smoke during pregnancy. A comparison of women who quit smoking during
pregnancy with those who continued suggested that quitting during
pregnancy could prevent the adverse effect on offspring blood pressure.
A mother’s age was associated also with higher
blood pressure. A child’s systolic blood pressure was 0.7 mm Hg higher
for every additional five years of age in women at the time they gave
birth, Lawlor said.
Breast-feeding for at least six months was
associated with lower blood pressure. Other factors associated with
blood pressure were the mother’s weight and height, the father’s weight,
and the child’s weight, height, and body mass at age five.
The findings have implications for childhood
prevention strategies that might yield benefits into adulthood, the
investigators concluded.
“Since childhood blood pressure tracks into
adulthood, interventions aimed at early life risk factors – quitting
smoking during pregnancy, breast-feeding, prevention of obesity in all
family members – may be important for reducing the population
distribution of blood pressure, and thus cardiovascular disease risk,”
said Lawlor.
De Ferranti’s and Rifai’s co-authors are Kimberlee
Gauvreau, Sc.D.; David S. Ludwig, M.D.; Ellis J. Neufeld, M.D., Ph.D.;
and Jane W. Newburger, M.D., Ph.D. This study was partly funded by the
National Institute of Diabetes and Digestive and Kidney Diseases.
Lawlor’s co-authors are Jake M. Najman, M.D.;
Jonathan Sterne, Ph.D., B.Sc.; Gail M. Williams, Shah Ebrahim, M.D.; and
George Davey Smith, M.D.
Statements and conclusions of study authors that
are published in the American Heart Association scientific journals are
solely those of the study authors and do not necessarily reflect
association policy or position. The American Heart Association makes no
representation or warranty as to their accuracy or reliability.
Copyright: SeniorJournal.com |
