Lead researcher Dr AlanThomas told BBC News Online the link could not be entirely explained by the fact that cardiovascular disease is a depressing condition from which to suffer.
Associated Press writers Connie Cass, David Espo, Donna Cassata, Henry Jackson, Pauline Jelinek, Richard Lardner, Alan Fram, Ken Thomas, Jim Abrams, Andy Taylor, Seth Borenstein and Eric Tucker contributed to this report.