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Rosemary essential oil helps improve prospective memory, study says

The Elizabethan belief in the powers of rosemary is borne out in the lab.

A grief-stricken Ophelia hands out flowers and herbs, watched by the King and Queen. Photo/Getty Images
A grief-stricken Ophelia hands out flowers and herbs, watched by the King and Queen. Photo/Getty Images

When Shakespeare wrote Hamlet, he didn’t know that rosemary contains a compound called eucalyptol, which has a similar effect on the brain as the drugs used to treat dementia.

But he and his fellow Elizabethans did associate rosemary with memory. As Ophelia points out to her brother Laertes, “There’s rosemary, that’s for remembrance.”

Four centuries later, research at Britain’s Northumbria University suggests they were right. The research, led by the head of the psychology department, Professor Mark Moss, has found that rosemary essential oil helps improve what’s known as prospective memory. In other words, it helps us to remember to do something in the future, such as post a letter or take medication at a certain time.

A recent experiment found that people aged 65 or older had significantly higher prospective memory scores after spending time in a room in which four drops of rosemary essential oil had been diffused than those who spent time in a non-scented room.

Moss credits some of that effect to eucalyptol, a compound found in rosemary that increases the production of acetylcholine, a neurotransmitter associated with memory. In earlier experiments, he found that people who had been exposed to rosemary essential oil had significantly higher levels of eucalyptol in their blood than those who had not.

But he says it’s likely other compounds in rosemary also affect memory. “There are probably over 250 volatile organic compounds in rosemary essential oil. Of those, about 30 might be considered to be potentially active in terms of affecting human cognition.”

And he says that although rosemary essential oil will never cure dementia, it may help protect against memory loss. “It’s possible that if you use it regularly, you may be able to maintain the health of your brain through this natural stimulation.”

However, getting enough of the right kind of oil for widespread use may be difficult. There are no standards covering the production of rosemary or any other essential oil, and adulteration is common. Even genuine essential oils work differently depending on where the plants used to make them are grown.

“We have done studies with rosemary essential oil where we found they don’t have the same effect. It would appear that some are better than others – it depends on their constituent ingredients.”

And although it might eventually be possible to identify exactly which of those ingredients is needed to get a beneficial effect, Moss doubts they could ever be commercially reproduced in a laboratory. “The combinations you find in nature are so complex it would probably not be possible to get an exact match.”

Moss, who has long been interested in improving mental performance using natural means, has also experimented with lavender essential oil, which contains linalool, a substance associated with relaxation. He’s now testing peppermint essential oil. “Other researchers have found that when you exercise with the aroma of peppermint, you can exercise for longer.”

Moss’ findings don’t surprise Auckland clinical aromatherapist Annie Prince, who is waging something of a one-woman battle to reclaim the word aromatherapy. Prince says the word, first coined by French perfumer and chemist René-Maurice Gattefossé in 1937, has been hijacked by those selling synthetic alternatives to essential oils.

“The word has become debased; it’s associated with airy-fairy nice massages. But I refuse to stop using it just because people have turned it into rubbish.”

Prince is interested only in the real thing – the potent mixture of chemical compounds found in essential oils. She uses a wide range and combination of oils for massages. She’s also interested in their antibacterial properties, pointing to a 2007 experiment in the burns unit of a British hospital that found that airborne bacterial counts dropped by 90% when a vaporiser was used to spray a mix of essential oils into the atmosphere.

She says she has successfully treated persistent urinary tract and thrush infections with pessaries containing several different essential oils – although she warns against trying that at home. “If you’re not using the oils for diffusion or for a simple massage, then you need to consult someone who is properly qualified, just as you would go to the doctor or a physio­therapist.”

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