Many people are familiar with the risk factors for vascular disease—high blood pressure, high cholesterol, glucose intolerance and an expansive waistband are but a few. Each alone can increase the risk of heart attack or stroke. But cluster them together, they may pose significantly higher risk. People with three or more vascular risk factors have what is known as metabolic syndrome, also known as Syndrome X; it is estimated that 23% of both men and women live with the syndrome. Studies show that people with a confluence of these risk factors are at particular risk of heart disease, and according to a recent study conducted at New York's Columbia University, metabolic syndrome also puts people at greater risk of stroke.
Below, lead author of the study, Bernadette Boden-Albala, MPH, DrPH, talks about metabolic syndrome and the recent study results.
What is metabolic syndrome?
Metabolic syndrome is a constellation of vascular risk factors, including low HDL, or "good cholesterol," high triglycerides, increased blood pressure and blood sugar levels and obesity as defined by waist circumference. Having three or more of those vascular risk factors constitutes metabolic syndrome.
There is also evidence to suggest that when values are borderline high in people with metabolic syndrome, they are still at risk of disease. So in these people the definitions are actually broader than the normal or conventional medical definitions of, say, hypertension or diabetes. In other words, if you have three or more of these risk factors, borderline or not, we know that your risk for cardiovascular disease is higher. And now we know that the syndrome also puts people at risk of stroke. We also suspect that women and minority populations may be particularly vulnerable to this syndrome.
How many people have metabolic syndrome in the United States on average?
It is estimated that metabolic syndrome is present in about 23% of men and 23% of women in the United States.
Can you describe your research?
The study is called the Northern Manhattan Study, led by Ralph Sacco, MS, MD. We followed 3298 stroke-free people, with an average age of 69, for over four years. Forty-two percent of the study subjects had metabolic syndrome, and within 4.6 years, there were 143 first strokes among our participants.
What did it signify about the relationship between metabolic syndrome and stroke risk?
Basically we found that metabolic syndrome is an important and significant stroke risk factor overall. People are 1.6 times more likely to have a stroke if they have metabolic syndrome than if they don't. And women are at particular risk. Women with metabolic syndrome are 2.2 times more likely to have a stroke than women without metabolic syndrome.
Why is the stroke risk greater in women with metabolic syndrome than in men with the syndrome?
We don't really know. It may be that there are different physiological mechanisms going on among women than among men.
I can tell you that when you look at men and women, that there's not that much difference in terms of the prevalence of risk factors—like the prevalence of diabetes, the prevalence of high triglycerides. So it's not just that women have more of these factors. I suspect that there may be other things going on physiologically that are different between men and women.
Are people who have this syndrome aware that they have it?
I think very few people are aware of it. And I think it's important that primary care physicians be aware that patients are at increased risk of heart attack and stroke when they have this syndrome. They need to encourage people to control each of the risk factors.
What is the purpose of grouping these known risk factors together into a syndrome?
It's controversial, There are scientists and physicians who think we should just be treating each of these risk factors separately and that we gain nothing by giving it a name.
The question remains, however—when you start adding these risk factors together, does something particular change in the body that compounds the effect of these individual risk factors? That's what we really need to investigate further.
Is it possible to treat this syndrome?
The good news is that most of these risk factors, if not all of them, are modifiable. We can decrease weight and increase our physical activity, which will increase our good cholesterol and address the weight risk factor. We can decrease our blood pressure through medication, through diet and through exercise again. The same with diabetes and triglycerides—there are some agents that are supposed to reduce LDL, the bad cholesterol, and they may work in reducing triglycerides.
What advice would you give people who may have these risk factors?
The first thing is to talk to your doctor about it. What is metabolic syndrome? Do I have this? I think I'm a little bit overweight. I think my blood pressure is high and my cholesterol is high, and I've heard this is serious so can I do something about it?
Reducing risk of stroke and cardiovascular disease is both a mission on the part of the patient as well as the physician. Maybe if we talk about the metabolic syndrome, we can create a dialogue between patient and physician and we can really start to work on behavior change and modification.
