Cardiovascular Disease

Although cardiovascular disease (CVD) is a disease of adulthood, risk factors for CVD are present in children and persist into adulthood. 

Elevated blood pressure, excess weight, and abnormalities in plasma lipid levels in children and young adults are associated with asymptomatic coronary heart disease and aortic atherosclerosis.^119,120  

Fatty streaks can be found in most children by age 10 and fibrous plaques in adolescents.¹²⁰  While the significance of fatty streaks in the aorta is questionable, their presence along with fibrous plaques in the coronary vessels indicates severe and progressive atherosclerosis.¹²⁰  The presence of three or four risk factors for CVD increased the prevalence of fatty streaks 8.5 fold and the prevalence of fibrous-plaque lesions in the coronary arteries 12 times.¹²⁰  Young blacks had significantly more extensive fatty streaks than whites with a similar extent of raised lesions compared to Whites.¹²¹ 

Two large studies have examined cardiovascular disease risk factors in children.

The Bogalusa Heart Study has examined cardiovascular risk factors longitudinally in African American and White children in Louisiana.  This study conducted seven cross sectional surveys of school children from 1973 to 1994 with a participation rate of greater than 80%. 

The population in Bogalusa, a semi-rural town, was about 43,000, one-third of whom were black.

The Child and Adolescent Trial for Cardiovascular Health (CATCH) is a longitudinal multistate (California, Louisiana, Minnesota, and Texas), school-based intervention promoting healthy eating and activity patterns in elementary school children to reduce and prevent the development of cardiovascular risk factors.¹²¹ 

Almost 5,000 third graders (14% Black, 14% Latino, and 72% White) participated in CATCH.  These studies provide a wealth of information regarding the prevalence of cardiovascular risk factors such as hypertension and dyslipidemia and factors contributing to their development.   

Prevalence of Dyslipidemia

According to the National Cholesterol Education Program Report on Blood Cholesterol Levels in Children and Adolescents, total cholesterol levels < 170 mg/dl are normal, 170-199 mg/dl are borderline and > 200 mg/dl are high.¹²²

CATCH study¹²¹

Percentage of children in the CATCH cohort with serum total cholesterol levels >200 mg/dl by race:

Webber LS, Osganian V, Luepker RV, Feldman HA, Stone EJ, Elder JP, Perry CL, Nader PR, Parcel GS, Broyles SL, & McKinlay SM (1995) Cardiovascular risk factors among third grade children in four regions of the United States. Am J Epidemiol 141: 428-439.

• In Black children the higher cholesterol levels were due to higher HDL cholesterol levels, in Latino children the higher cholesterol levels were due to higher LDL and VLDL cholesterol levels and lower HDL cholesterol levels. 
• A greater portion of Black children than White or Latino youth had cholesterol levels >200 mg/dl.

NHANES III, 1998-1994

Mean Serum Cholesterol Levels in 7,499 children Aged 2-19, from NHANES III

Hickman TB, Briefel RR, Carroll MD, Rifkind BM, Cleeman JI, Maurer KR, & Johnson CL. (1998) Distributions and trends of serum lipid levels among United States children and adolescents ages 4-19 years: data from the Third National Health and Nutrition Examination Survey. Preventive Medicine 27: 879-890.

• Approximately 10% of children have serum total cholesterol considered at or above the recommanded level.¹²¹
• Blacks had a significantly higher mean total cholesterol level than Whites or Mexican Americans.
• Black children had the highest HDL cholesterol levels.
• Black adolescents had the highest LDL cholesterol (101 mg/dl compared to 95 mg/dL for White and 93 mg/dL for Mexican American adolescents) .

Bogalusa and Brooks County Texas Heart Studies.¹²³

• Black children had higher total cholesterol levels than White children.
• Black children had higher HDL cholesterol levels than White and Hispanic children. 
• Hispanic children higher LDL cholesterol levels and triglycerides than White or Black children.

Birmingham, Alabama longitudinal study of childhood obesity

• African American children aged 6.5-13 years did not have a more unfavorable serum lipid profile than their white counterparts.¹²⁴

Elevated Blood Pressure

Reports of ethnic/racial differences in blood pressure values among children and adolescents have been inconsistent

• The Bogalusa Heart Study noted that African-American boys had higher blood pressure throughout childhood and adolescence, even though their White counterparts had a higher body mass index.¹²⁵
• In Brooks County Texas, Hispanic boys had similar blood pressure measurements to black and white boys in the Bogalusa Heart Study but Hispanic girls had lower blood pressure measurements.¹²³
• CATCH found that after adjusting for height and weight, there were no ethnic differences in systolic blood pressure levels.¹²¹ 
• NHANES III reported that black girls 6-17 years of age had higher systolic blood pressure than White girls.¹²⁶

Among adolescents at risk for hypertension, blood pressure was lower in those with higher intakes of a combination of nutrients, including potassium, calcium, magnesium, and select vitamins.¹²⁷

Calcium supplementation lowered blood pressure in African American adolescents with low dietary calcium intakes.¹²⁸ Dietary benefits on blood pressure observed on diets rich in a combination of nutrients derived from fruits, vegetables, and low-fat dairy products could contribute to primary prevention of hypertension when started at an early age.¹²⁷  

Relationships Among Risk Factors

The presence of cardiovascular disease is greater among adults who were overweight as adolescents.  Several studies have shown that excessive weight gain and obesity during childhood and adolescence is related to cardiovascular disease risk in young adulthood.¹²⁹

• Bogalusa Heart Study
  • Over an eight year period increases in weight were accompanied by adverse changes in blood lipid profiles. ¹²⁹
  • Change in BMI was the second best predictor of elevated cholesterol levels at the twelve year follow-up.
  • Most of the individuals with cholesterol levels between 200-239 mg/dl at follow-up had two or more additional risk factors.¹³⁰
  • The prevalence of elevated insulin levels increased from 1% to 27% among 5-17 year olds as the BMI increased from <25^th to >97^th percentile.¹³¹
  • The prevalence of all risk factors increased substantially as BMI increased from the 95^th to 97^th percentile.¹³¹
  • An overweight youth was 2.4 times more likely to have a high total cholesterol level and 7.1 times more likely to have a high triglyceride level than his normal weight counterpart^.131
  • Overweight children were 9.7 times more likely to have 2 risk factors and 43.5 times more likely to have 3 risk factors compared with normal weight children.¹³¹
  • Ninety percent of children with high levels of both insulin and triglycerides were overweight^.131
• The Minneapolis Children's Blood Pressure Study
  • Fasting insulin, triglyceride, HDL cholesterol, and systolic blood pressure, but not total cholesterol or LDL cholesterol, were significantly related to initial BMI. 
  • A follow-up study of 31 participants noted that obesity at age 13 was associated with elevated total cholesterol and LDL cholesterol levels at age 21.¹³²

The coexistence of dyslipidemia, hypertension, hyperinsulinemia and obesity is known as Syndrome X, deadly quartet, insulin resistance syndrome, or multiple metabolic syndrome.¹³³ 

Obesity and the resulting insulin resistance play a significant role in the development of Syndrome X.¹³³  Further support for the link between excessive weight gain during childhood and adolescence and fasting insulin levels is provided by the fact that weight loss improves insulin sensitivity.¹²⁹

Tracking of Risk Factors

• Significant tracking over a 12-year period starting at ages 5-14 years in the Bogalusa Heart Study was observed for blood lipid measurements especially for elevated LDL cholesterol levels.  About 50% of children with total cholesterol or LDL cholesterol levels above the 75^th percentile remained elevated.  When the guidelines of the National Cholesterol Education Program were used to evaluate risk status, 91% of the subjects with very elevated cholesterol at follow-up could have been identified during childhood through cholesterol or obesity measurements.¹³⁰
• "Overall, the data on tracking of cholesterol from childhood to adulthood indicated that children with high cholesterol levels have a substantially greater risk of having elevated cholesterol than the general population, but many of these children will have adult levels that do not require individual intervention."¹²¹