Ananova:

Men are biologically programmed to fall in love aged 50, according to new research labelled the 'Michael Douglas Syndrome.'

Older men who run off with much younger 'trophy' girlfriends are not having a mid-life crisis - they're biologically programmed to fall in love, for real, for the first time when they reach the half-century.

Researchers at Rome's Institute of Psychology questioned 3,000 men - all in their early 50s - and came up with a decade-by-decade map of the male heart.

American President Bill Clinton, who met Monica Lewinsky shortly after his 49th birthday, is cited as another example.

According to the study, men first fall in love - or think they do - in their teens, BBC Online reports . Yet this is nothing more than "puppy love", a precursor to forming a more serious attachment in their 20s.

The third stage, when men want to "spread their love around", lasts throughout their 30s and 40s.

But once these middle-age Lotharios hit 50, they are biologically disposed to rediscover romance.

Willy Pasini, one of the report's authors, said: "This is not just a question of the odd illicit weekend of passion or a summer fling. These happen, but at least a third of men experience not passing lust, but a genuine resurgence of their emotional life. In other words, they fall in love."

Mr Pasini said: "It's the Michael Douglas phenomenon - when you chuck your partner of several decades and take up with someone much younger."