A medical test to determine the biological evidence for being "in true love" will be available in Britain within a decade, says one of the world's leading neurologists.
The painless, non-invasive procedure will enable doctors to accurately determine whether a patient is truly smitten or "faking it".
It will work by detecting the presence of potent 'love' chemicals in the brain using an MRI-type scanner.
The chemicals, called nonapeptides, are only produced in significant quantities when a person is truly in love, researchers now believe.
At present, the procedure for measuring the volume of nonapeptides in the brain can be done only in living laboratory animals.
But advances in medical technology means a test on the brains of people could become a reality by 2028, Dr Fred Nour, a renowned US doctor, claims.
Unlike lie detectors and other existing devices, such a scanner could not be duped and would boast an accuracy rate of between 97 and 99 per cent.
Dr Nour estimates that at least two-in-three people who undergo the procedure, which would confirm within a few hours whether they are truly in love, will do so for fun or as a romantic gesture.
But the remainder are likely to be the rich and famous who want to protect their fortunes from "fakers and gold diggers" ahead of tying the knot.
A pre-marital scan may even become a necessary - and legally admissible - element of a pre-nuptial agreement.
Speaking yesterday at the Los Angeles launch of his new book, 'True Love: Love Explained by Science' - the first title on the subject written by a neurologist and which hits the UK shelves this week - Dr Nour said: "Nonapeptides are the markers of true love in humans, known to cause the long-term bonding process.
"We can't currently detect the levels of nonapeptides in the living human brain except through invasive procedures, which is why it is only performed on research animals.
"However, there is already a non-invasive test similar to this called DaT scan which measures the levels of dopamine in the living human brain. It takes around two hours to get the results and is virtually painless and harmless to perform.
"As medical scanning technology continues to improve, I think a similar test to measure these love chemicals in the living human brain could be available within a decade.
"In theory, this test could provide a definitive answer to whether someone was truly in love or not. If nonapeptides aren't present in high levels in the brain, then it's a tell-tale sign that a person is not truly in love as it's scientifically impossible to be in true love without them.
"For many couples, the test would be just another novelty, but in some cases a pre-marital scan could help people avoid marrying someone with ulterior motives."True lies
Non-biological love 'tests' are nothing new, with psychological diagnostics, lie detectors and DNA matching services freely available - for a price.
But existing tests are crude, notoriously inexact, and typically administered by 'experts' with little or no real training.
Neither can they examine the 'love centre' of the human body: the brain.In 2005, however, a team of American non-medical researchers claimed to have found the first direct evidence of love-related changes to the brain.
Using functional MRI scanners, they reportedly identified a 'love map' after detecting increased activity in certain areas of the brain linked to reward and motivation in people who were in love.
However, Dr Nour points out that the medical community does not accept the functional MRI as a real test, while neurologists and neurosurgeons worldwide never use it to study or diagnose conditions in the brain.
From his extensive research Dr Nour believes that the only way to scientifically prove that love exists is to measure the volume of nonapeptides in the intermediate-aged limbic part of a patient's brain.
Nonapeptides, which comprise oxytocin and vasopressin, are already known to encourage life-long bonding and monogamy between mates.
Its presence can currently only be detected in living brains following an invasive procedure, where a tiny tube is inserted directly into the brain to extract these chemicals for subsequent analysis at a laboratory.
This is not a practical approach for humans and, to date, they have only been measured in significant quantities in the brains of research animals.
Dr Nour, a global authority on the physical brain science of love, claims that the next generation of brain scanners capable of measuring the love chemicals in the living is only a decade or less away.
"There are so-called love tests available today, but they don't address the actual biological mechanisms," he said.
"The true love test would probably work by injecting a radioactive dye into a patient, which would then bond with the nonapeptide receptors in the brain and show up when the brain is scanned.
"No medical test is 100 per cent accurate, but the love test would be correct 97, 98 or even 99 per cent of the time, and this will only improve with ongoing research."
Love and money
It is unlikely to be made available on the NHS for privacy and ethical reasons, he says, but will instead be developed for private medical practices where scans could cost up to £500.
Whilst most patients will be fun-loving couples seeking a "certification of true love", a third of scans will be carried out for the ultra-wealthy who may require reassurance before getting married.
He said: "A love test brings along with it a big ethical problem as no doctor would be comfortable telling a client that their partner doesn't actually love them. This would be doing harm, which is against medical ethics".
"I've no doubt, however, that those outside of the medical profession will seek to commercialise it as the potential market for such a device would be huge."
"The love test will enable people to confirm that the person they intend to wed really means 'I do' and not, 'I do…want your money'," he added.