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 people between the ages of 18 and 31, researchers found the levels of NGF had fallen to original levels after one year, the Daily Mail reported.
Not to discourage romantics, the team wrote that they believe the same chemical also stimulates companionship, which is essential in any long-term relationship.
The report appears in the current Psychoneuroendocrinology journal.
Copyright 2005 UPI
Explore further: Lethal wounds on skull may indicate 430,000-year-old murder