Greek Mountain Tea Extract Improves Cognition, Mood, and Cerebral Blood Flow

by | Jan 21, 2019 | 2018, Brain Health, Polyphenols

Written by Angeline A. De Leon, Staff Writer. Two doses of Sideritis scardica (Greek mountain tea) were capable of improving aspects of cognitive function and mood, specifically increased cerebral blood flow, information processing, memory, and anxiety, in a group of healthy, older adults.

green teaGreek mountain tea is a naturally caffeine-free herbal tea prepared from the leaves and stems of Sidertis scardica. Also known as Shepherd’s Tea, Greek mountain tea is associated with health benefits for the respiratory and digestive systems, as well as general anti-inflammatory effects 1. The active components in Greek mountain tea are primarily phenolic acids, ferulic acid (antioxidant found in the cell walls of plants) and chlorogenic acid (phytochemical found in coffee beans), both of which are associated with vasodilatory effects and increased cerebral blood flow 2. Researchers speculate that, through this mechanism, polyphenols may have the potential to induce beneficial cognitive effects 3. A 2013 study by Camfield and colleagues reported an association between consumption of decaffeinated chlorogenic coffee and enhanced attention and reduced mental fatigue in older adults 4. Convergent evidence from another study (2016) demonstrated that six weeks of supplementation with Sidertis scardica extract could improve cognitive performance during stressful scenarios 5. As a monoamine neurotransmitter reuptake inhibitor, Sidertis scardica is also hypothesized to possess significant mood-boosting properties 6. To confirm the effects of Greek mountain tea extract on mood and cognition, UK researchers at Northumbria University investigated the impact of Sidertis scardica extract on cognitive and mood outcomes in older adults, also looking at acute and chronic effects of supplementation on measures of cerebral blood flow.

A total of 151 healthy subjects (aged 50-75 years) were enrolled in a randomized, double-blind, placebo-controlled, parallel-group trial 7. Participants were randomized to receive two capsules of 475 mg Sidertis scardica extract, 950 mg Sidertis scardica, 240 mg Gingko biloba extract (active control group), or placebo daily for 28 days. On Day 1 and Day 28, participants completed cognitive function tests (using the Computerized Mental Performance Assessment System, one assessment administered pre-treatment and two administered post-treatment for a total of five repetitions) and the Bond Lader mood scales and State Trait Anxiety Inventory. Blood pressure and heart rate readings were also collected, and acute changes in hemodynamic response were monitored before and after consumption of assigned pills during the laboratory visit.

On the Picture Recognition Accuracy test, a significant interaction between repetition x treatment [F(12, 544) = 1.84, p = 0.040] indicated that the 950 mg Sidertis scardica group performed better than the Gingko group on Day 1 and Day 28. A significant interaction between repetition x treatment [F(9, 409) = 2.08, p = 0.030] on the Rapid Visual Information Processing Task also showed that relative to placebo control, individuals in the 950 mg Sidertis scardica group committed significantly fewer false alarms on Day 28. Higher doses of Greek mountain tea also significantly reduced state anxiety after 28 days [F(1, 136) = 4.42, p = 0.005], relative to both placebo control (p = 0.022, d = 0.75) and the active Ginkgo control (p = 0.028, d = 0.77). In regards to cerebral blood flow, both doses of Sidertis scardica, relative to placebo, significantly increased oxygenated hemoglobin [main effect of treatment, F(1, 1589) = 29.0, p ≤ 0.001] and oxygen saturation [main effect of treatment F(1, 1589) = 29.01, p ≤ 0.001] in the prefrontal cortex during cognitive testing on Day 1.

Results of the study revealed that both high and low doses of Greek mountain tea improved measures associated with cerebral blood flow, while only higher doses of the herb showed a favorable effect on both cognitive performance and state anxiety on Day 28. Evidence from the trial suggests that Greek mountain tea, potentially through its modulation of cerebral blood flow, exerts a positive influence on general information processing, memory, and mood. In this respect, Sidertis scardica appeared to outperform Gingko biloba, although its effects on cerebral blood flow were found to be acute (whereas the active control group showed both acute and chronic modulation of hemodynamic response). Future studies should examine whether the effects of Sidertis scardica may strengthen over time. Given that potential sex differences (e.g., effects of menopause on cognitive performance) were not factored into the study design, further studies accounting for sex differences are also warranted.

Source: Wightman EL, Jackson PA, Khan J, et al. The acute and chronic cognitive and cerebral blood flow effects of a Sidertis scardica (Greek mountain tea) extract: a double blind, randomized, placebo controlled, parallel groups study in healthy humans. Nutrients. 2018; 10: 955. DOI: 10.3390/nu10080955.

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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Posted January 21, 2019.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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