Stony Brook University researchers looked at the brains of Bernstein and 16 other people who had been married an average of 20 years and claimed to be still intensely in love. They found that their MRIs showed activity in the same regions of the brain as those who had just fallen in love.
...the study found an advantage to the longer-term relationships she studied: The brains of those people showed less anxiety and obsessiveness.
Aron had conducted an earlier MRI study published in 2005 among 17 people who had recently fallen in love. He found that regions of the brain associated generally with reward and motivation - the same regions that light up when cocaine is taken - activated when the subjects were shown pictures of their beloved. These regions, Aron said, are not the same as those associated with sexual arousal.