The Framingham Heart Study marked its 70th anniversary this week. Major medical findings have come out of the study, in which thousands of Framingham residents have taken part over the decades. Dr. Vasan Ramachandran is the principal investigator and director of the Framingham Heart Study. He spoke with WGBH All Things Considered host Barbara Howard. The following transcript has been edited for clarity.

Barbara Howard: How did the Framingham study come to be?

Ramachandran: The Framingham study began post-World War II, in 1948, when heart disease rates in the United States were very high, and we did not really understand why that was the case. The National Heart Institute decided to put together a study that would help us understand why people were getting heart attacks and strokes at such high rates in the country.

Howard: Why was it started in Framingham, of all places?

Ramachandran: I think there were multiple reasons Framingham was picked. There were other towns also that were competitors, but the fact that it was an average American town which was close to Boston, it was predominantly blue collar, with a few wealthy individuals. And the town had a history of contributing to science. During a tuberculosis study after World War I, everybody in the town was asked to get a chest X-ray, and Framingham was one of the towns where everybody showed up.

Howard: So now you are doing the offspring of the original subjects, and the grandchildren. Is that correct? How many generations out are you?

Ramachandran: We are three generations. Also, I’d like to mention that Framingham is diverse. We also have two minority cohorts that go along with the offspring in the third generation cohort. So in total, we are following about 15,000 participants.

Howard: Tell me some of the findings that have come out of the Framingham Heart Study.

Ramachandran: Ten years into the study, we described the word "risk factor," and these include high blood cholesterol, high blood pressure, high blood sugar, and smoking. We went on to combine these into a summary score called the Framingham Risk Score, and this was the contribution of the initial cohort.

Howard: Back in the early days, you were able to identify diet, exercise, smoking, other contributing factors toward heart disease. But these days, is the focus more on genetics?

Ramachandran: Yes, indeed. I think we're beginning to understand there's a familial predisposition, and we're getting deeper insights into what are the genetic variants that are associated with the risk factors. So we're really able to understand in greater depth the interaction of the genetic makeup and environmental factors, including lifestyle factors.

Howard: And now you're three generations out, and those genetic markers are following generation to generation. So I would imagine it's very helpful to have multiple generations involved in this study over time, over 70 years.

Ramachandran: That is one of our strongest assets. We are a transgenerational study and we are a longitudinal study, so we really can understand familial patterns of disease.

Howard: What do you hear from people who are maybe third generation out? Are they enthusiastic about taking part still in the study, 70 years later?

Ramachandran: Indeed. I think one of the most remarkable stories of Framingham is that of the spirit of contributorship. People are excited to participate in the study, partly because their parents were part of it and their grandparents were part of it. So the altruistic spirit is very much alive across all the generations.

Howard: How much longer will this study go on?

Ramachandran: I see our mission as going on for another couple of decades, and perhaps beyond, especially if we look at another generation, the fourth generation.

Dr. Vasan Ramachandran of Boston University is the principal investigator and director of the Framingham Heart Study.