Attention math students and the math-challenged: Inhaling rosemary oil can make math easier. At least that's what a small study found.

It's well established that odors can have powerful effects on people--that's the basis of the entire perfume industry. And aromatherapy is a form of alternative medicine that claims to use the essential oils of plants to improve physical, emotional and spiritual well-being. But while there's broad agreement that odors affect people, there's been little solid evidence collected about how they affect people.

The more eucalyptol there was in their blood, the better the volunteers performed on the subtraction by threes task, both in their number of correct answers and reaction time.

Researchers from Northumbria University in the UK set out to add to this knowledge by testing the effects of rosemary oil on volunteers' mood and mental abilities.

Four drops of rosemary oil were placed on an absorbent pad and allowed to diffuse throughout the twenty work cubicles of the study subjects. Volunteers were then seated in the cubicles for periods ranging four to ten minutes before being given three computerized tasks to perform. They also filled out mood evaluation questionnaires before and after exposure to the rosemary scent.

The volunteers did not know that this was a test of rosemary oil. The few who commented on the aroma in the cubicle were told that it was left over from a previous study.

The three tasks were serial subtraction of threes (counting backwards by three), serial subtraction of sevens and a rapid visual identification task, where volunteers had to had to indicate if a constantly changing series of digits contained sequences of three consecutive odd or even numbers.

Afterwards, a blood sample was taken and how much rosemary oil had been absorbed into the blood was estimated by measurement of its 1,8-cineole (eucalyptol) content. Rosemary oil generally contains 35-45% eucalyptol. The amount of eucalyptol in their blood was then compared to volunteers' performance at the computerized tasks and to their mood, to see if it had any effect on them.

The more eucalyptol there was in their blood, the better the volunteers performed on the subtraction by threes task, both in their number of correct answers and reaction time. A similar but smaller effect was found for the serial subtraction by sevens task; there, the increase in speed was statistically significant, but the increase in accuracy was not. The amount of eucalyptol in the blood had no effect on the visual performance task.

One interpretation of this is that exposure to rosemary oil improves people's mathematical ability. Another is that it improves performance at tasks that involve memory.

It's not clear if the limited improvement seen in the subtraction by sevens task was because the task was too difficult or if exposure to higher amounts of rosemary oil would have improved performance as much as it did for the subtraction by threes task.

Rosemary oil also appeared to affect the volunteers' mood, with people with the highest blood levels of eucalyptol reporting a decrease in contentment. No effect was found on calmness or alertness.

Since the study was only of 20 people, it's hard to say that everyone would experience these effects. It will take larger studies to confirm that. But considering how little information exists on specific effects of aromas on humans, it's a start. Perhaps one day, rosemary oil will be as common among students taking math exams as calculators are today.

An article on the study was published online by Therapeutic Advances in Psychopharmacology.