Down Syndrome and the Lipid Heart Clinic at CHOP

The lifespan of individuals with Down syndrome (DS) is certainly increasing. Recent studies show that the median age at death is now almost 60 years, significantly increased from studies from the 1970s and 1980s. There are many reasons for this, including improved treatment of congenital heart defects and leukemias. Therefore, it is surprising that adults with Down syndrome, who now enjoy a longer lifespan, seem to have reduced prevalence of atherosclerosis, the process that causes stroke and heart attack in middle-aged and older adults in the general population. This unusual finding has been known for at least three decades.

Although individuals with DS may not be traditionally susceptible to long-term atherosclerosis, there are a number of findings that raise the possibility that this “protection” from atherosclerosis may disappear over time. Many recent studies of patients with Down syndrome have shown abnormalities of the body’s lipids. These are substances such as cholesterol and triglycerides that normally predispose people to atherosclerosis and heart disease. Most studies show the levels of cholesterol and triglycerides in non-obese individuals with DS are actually normal.

However, there is a great deal of evidence that other systems in the body that facilitate the damage done by cholesterol and triglycerides are abnormally increased in people with DS. The most important of these is called oxidative stress. This is a process in which many things, including exercise, some foods we eat and some natural substances in the body, change cholesterol chemically to make it much more dangerous, theoretically increasing the risk for heart attack and stroke.

Oxidative stress may also cause defects in the way in which insulin is utilized. This may lead to metabolic syndrome, a group of abnormalities that includes diabetes, obesity, high blood pressure and an abnormal pattern of lipids, all predisposing the general population to heart disease. To date, the prevalence of metabolic syndrome in individuals with DS does not seem to be increased, despite the effect of oxidative stress.

Oxidative stress has also been linked to the development of early neurologic impairment. Fortunately, there are natural enzymes and some products in our diet called antioxidants that balance this effect out. It is this beneficial process that seems to be impaired in those with Down syndrome.

Another factor that may be responsible for a changing pattern of atherosclerosis and heart disease in the future is the number of individuals with DS who have undergone successful surgery for their congenital heart defect. Most operations to correct congenital heart disease cause changes in the pattern of blood flow through the heart so that abnormal turbulence is set up within the heart chambers and blood vessels. This turbulence causes damage to the inside lining of chambers and vessels, making it more likely that cholesterol and other lipids will accumulate there and contribute to heart attack and stroke in the future.

A third factor is growing awareness that patients with DS may have an additional genetic abnormality that is associated with early heart attack and stroke in the general population. One of these genetic defects is called familial hypercholesterolemia, a disease in which the mechanism that removes cholesterol from the bloodstream is deficient. As yet, it is not known whether individuals with both Down syndrome and familial hypercholesterolemia will actually develop early heart disease or stroke.

Whether or not the pattern of heart attack and stroke will change in adults with Down syndrome, the Lipid Heart Clinic at The Children’s Hospital of Philadelphia is committed to identifying those risk factors in all children that may predispose them to atherosclerosis in the future. The primary risk factors are abnormal lipid values, obesity, poor diet and family history, but also include other lifestyle issues that may promote lipid abnormalities. Most important of these is reduced physical exercise and the prevalence of sedentary activities such as social networking, playing video games and watching television. All risk factors are assessed at the very first visit to the Lipid Heart Clinic and addressed with appropriate recommendations including referral to the Healthy Weight Program at CHOP, if necessary.

The general procedure is:

1. Obtain a lipid profile (laboratory test for cholesterol and triglycerides), usually through your primary care physician or pediatrician. The test may be obtained at a local laboratory or hospital. Fax the profile — or ask your PCP or pediatrician to fax it — to 215-590-4978.
2. Call 215-590-4040 to register for a Lipid Heart appointment. Our staff will confirm that they have received the lipid profile, review it and return your call to schedule the visit.
3. Download and print the patient questionnaire and three-day dietary history from the Lipid Heart Clinic website and complete them.
4. On the day of your visit, bring the completed patient questionnaire and three-day dietary history with you, along with any other lipid profiles you can obtain from other family members (mother, father, siblings over 2 years of age).

Details regarding appointments in the Lipid Heart Clinic, its staff, questionnaires and necessary laboratory testing can be found on our website. Additional resources are also there. For questions, please call 215-590-1804.