This study investigates the cognitive and mood effects of mint essential oils in a group of healthy, human adults. The investigational product will also be tested in vitro to ensure a number of biological mechanisms.
The volatile components of essential oils (e.g. sage, lemon balm and rosemary)are found to exert a number of psychotropic effects and the monoterpenes in particular seem to be responsible for the cognitive and mood effects attributed to them. The current study aims to investigate the cognitive and mood effects of mint essential oil in humans and to ensure the efficacy of the investigational product by conducting in vitro analysis on central nervous system receptor binding properties. This will be achieved by analysing gamma-Aminobutyric acid A (GABAA), neuronal nicotinic and N-methyl-D-aspartate receptor (NMDA) glutamate receptor binding efficacy, acetylcholinesterase (AChE) inhibition, and gas chromatography-mass spectrometry (GC-MS) analysis will quantify % Limonene, % Carvone, % Menthone and % Menthol levels in the investigational treatment. Cognitive and mood assessment will be via a randomised, placebo controlled, crossover design in 24, healthy adults aged between 18-35 yrs which will involve x1 training and x3 testing visits to the lab (placebo, 50 (micro Litre) μL and 100 μL Mentha piperita essential oil).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
TRIPLE
Enrollment
24
Commercially available essential oil suspended in an off-the-shelf vegetable oil.
Inert placebo control in the form of vegetable oil. This matches the vegetable oil in the active intervention condition.
Changes in cognition
Changes in cognitive function as assessed by the following tasks: immediate and delayed word and picture recognition; name to face recall; 'Sternberg' Numeric Working Memory task; Corsi blocks; serial 3 subtractions; serial 7 subtractions; rapid visual information processing; peg and ball and choice reaction time. All tasks provide an outcome measure of accuracy, speed and error.
Time frame: 1, 3 and 6 hrs post-dose
Changes in mood
Changes in mood assessed via the Speilberger State-Trait Anxiety Inventory (STAI) and Bond-Lader visual analogue mood scales. Scores on both measures are calculated at baseline and scores from subsequent completions are subtracted from this to produce change (change from baseline) scores. For both STAI and Bond-Lader these are numerical scores.
Time frame: 1, 3 and 6 hrs post-dose
Neurotransmitter receptor binding efficacy
In Vitro analysis of investigational product for GABAA, neuronal nicotinic and NMDA glutamate receptor binding efficacy utilizing radioligand competition binding assays
Time frame: 0 hrs
Acetylcholinesterase inhibition
In Vitro analysis of investigational product for acetylcholinesterase inhibition as described in Okello, Coleman and Seal (2015)
Time frame: 0 hrs
Quantification of monoterpene levels
In Vitro analysis of investigational product for levels of % Limonene, % Carvone, % Menthone and % Menthol utilizing Gas chromatography-mass spectrometry. The method is described in Abuhamdah et al. (2015).
Time frame: 0 hrs
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