PAVIA, Italy, Nov. 28 (UPI) -- Italian scientists have determined the brain chemical fired up when a person meets a "true love" doesn't last a lifetime, but rather, just 12 months. When a person falls in love, levels of a protein called Nerve Growth Factor skyrocket, researchers from the University of Pavia found. "We have demonstrated for the first time that circulating levels of NGF are elevated among subjects in love, suggesting an important role for this molecule in the social chemistry of human beings," said Dr. Enzo Emanuele, who led the study. But, after studying a volunteer group of...