There's more than a little bit of science about what goes on in a body - and brain - in love.

One study found that intense, passionate feelings of love activate reward systems in the brain that influence pain and reactions to addictive drugs.

Researchers at Stanford University and the State University of New York at Stony Brook did a brain-imaging study of 15 Stanford undergraduates who were in the first nine months of a romantic relationship to see what regions responded when they saw a photo of their significant other while experiencing pain.

When they looked at photos of their beloved and were put in mild pain by a heated device placed in their hand, the pain was reduced and imaging showed the love-induced relief came from regions associated with reward centres.

So romance may indeed be like an addiction, at least early on.

Being shown photos of an acquaintance didn't have the same effect, but being distracted with something like a word-association task (think of sports that don't involve balls) also lowered pain levels, but through a completely different brain pathway using higher, cortical parts of the brain, while the love connections used more primitive parts of the brain.

If affection can stop pain, rejection also exacts a toll.

Stress hormones shoot up after a breakup. Parts of the brain tied to emotion and pain, such as the anterior cingulate cortex, may contribute to aches, stress makes the stomach queasy and the heart rate temporarily drops.

One Dutch study that set up college volunteers for (fake) acceptance or rejection by fictitious students at another university, found that heart rates dropped while awaiting an opinion, and fell even more and stayed that way longer if they were told the other student didn't like them.

The results show that the autonomic, or involuntary, nervous system that regulate the heart and digestive system, fires up when a person is socially rejected.

Marriage also seems to offer the heart some protection. Married men and women have a significantly reduced chance (about 60 per cent less) of dying from a heart attack than their unmarried counterparts, the European Journal of Preventive Cardiology reported last month.

Researchers at Finland's Turku University Hospital studied data on more than 15,000 people who suffered heart attacks between 1993 and 2002, half of whom died within 28 days.

Although reasons behind different survival rates are unclear, married people generally are healthier, are more likely to follow medical advice and have more social support. 

AAP