March 1, 2012 — The aroma of rosemary may boost cognitive performance, results of a new study suggest.
Investigators found that healthy volunteers performed better on mental arithmetic tasks when exposed to 1,8-cineole, one of the main chemical components of rosemary essential oil. Greater absorption (higher blood concentrations) was associated with greater speed and accuracy on the tests.
"The significant correlations reported in the study suggest that the presence of 1,8-cineole in the blood can potentially enhance some aspects of cognition — in this study, mental arithmetic," first author Mark Moss, PhD, of the Brain, Performance and Nutrition Research Centre at Northumbria University, Newcastle upon Tyne, United Kingdom, told Medscape Medical News.
The study was published online February 24 in the journal Therapeutic Advances in Psychopharmacology.
Dr. Moss said he has been researching aromas on and off for the last 10 years. In the current study, he and coinvestigator Lorraine Oliver, MSc, assessed cognitive performance and mood in 20 healthy volunteers exposed to 1,8-cineole.
The study participants performed serial subtraction and visual information processing tasks in a cubicle diffused with the aroma of rosemary. They did not know that the researchers were testing the effects of rosemary aroma on cognitive performance and mood; those who asked about the aroma were told that it had nothing to do with the testing and that it was left over from a previous study.
To ensure a range of absorption levels, participants were randomly assigned to be exposed to the aroma for 4, 6, 8, or 10 minutes before completing the cognitive tests. Mood assessments were made before and after testing, and venous blood was sampled at the end of the testing session.
Medium to Large Effects
The researchers report that serum levels of 1,8-cineole correlated with performance outcomes (number of correct responses and reaction times) for each task. They saw "medium to large effects by Cohen's definitions" for the serial threes and serial sevens subtraction tasks but not the rapid visual information processing (RVIP) task. The RVIP task provides an assessment of sustained attention and central executive function, whereas the serial subtraction tasks assess continuous working memory, arithmetic processing, and central executive composition, the authors note.
The relationships between 1,8-cineole levels and mood were "less pronounced." There was no strong evidence that exposure to 1,8-cineole improved attention or alertness. However, there was evidence of a significant negative correlation between change in contentment levels and plasma levels of 1,8-cineole.
"Only contentedness possessed a significant relationship with 1,8-cineole levels, and interestingly to some of the cognitive performance outcomes, leading to the intriguing proposal that positive mood can improve performance whereas aroused mood cannot," the authors write.
Summing up, the investigators note that the findings suggest that compounds absorbed from rosemary aroma affect cognition and subjective state independently through different neurochemical pathways.
"The clinical implications are, at this time, unknown," said Dr. Moss, "but there is an ever-increasing interest in the potential for herbal extracts to be used to try and prevent or slow age-related cognitive decline. This avenue of research is going to continue, as this study only had a small sample and needs replicating on a much larger scale," he added.
Implications for Alzheimer's?
Commenting on the study for Medscape Medical News, Ilkay Orhan, PhD, from the Department of Pharmacognosy, Gazi University, Ankara, Turkey, who was not involved in the research, said it has been recognized for some time that essential oils stimulate cognition.
"1,8-Cineole is a simple monoterpene-type of compound [that] exists in many essential oils. The compound has ability to inhibit acetylcholinesterase, which is the key enzyme in the pathogenesis of Alzheimer's disease [AD]," Dr. Orhan explained.
"However, its inhibition capacity is moderate, and it acts with other similar compounds such as alpha-pinene and beta-pinene in a synergistic way, and all of them produce a remarkable cholinesterase inhibition. This is one mechanism that I know for 1,8-cineole for cognitive enhancement," he said.
"Cholinesterase inhibitors are now the most prescribed drug class at the moment for the treatment of AD, and therefore cholinesterase-inhibiting compounds are important in drug design and discovery against this disease," Dr. Orhan added.
The study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. The authors and Dr. Orhan have disclosed no relevant financial relationships.
Ther Adv Psychopharm. Published online February 24, 2012. Abstract
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