By Lisa Offringa, Ph.D.
I am a medical ethnobotanist, which means I study plants that people use for medicine. Most of my work is cross-cultural allowing me the opportunity to work in countries outside of my own. My dissertation research focused on plants of Northern Thailand that are used to enhance memory and prevent cognitive impairment. For my research, I interviewed traditional Thai healers to determine what plants they used to improve cognition, then collected and tested these plants in the laboratory and in animal models. Laboratory testing was used to determine if these plants increased the levels neurotransmitters responsible for memory in the brain. Since my research was in Thailand, only plants endemic to the area were investigated. There was some overlap between plants used in Traditional Chinese Medicine and Ayurvedic Medicine due to the proximity of these countries to Thailand, and the movement of people around South East Asia. Two plants, Ginkgo biloba and Bacopa monnieri, found in Think Gum, are used in Northern Thailand to enhanced memory. Neither of these plants were tested in the laboratory, as they have substantial research to support their traditional uses.
Ginkgo biloba L. (Ginkgoaceae) is used in Traditional Chinese Medicine (TCM) to improve memory loss from abnormal blood circulation. Similar to TCM, Thai Traditional Medicine is based on a system of elements and health is maintained by keeping these elements in balance. In Thai Traditional Medicine, it is used to circulate lom or the element of wind. Lom is the element believed to be responsible for the health of the brain (which is an earth organ) by circulating vital energy around the brain. Research by Krieglstein et al. (1986) found increased blood flow to the brain by subjects using Ginkgo extracts. Increased blood flow to and in the brain can protect it from neurodegenerative disorders as well as illness from hypertension.
Bacopa monnieri (L.) Wettst. (Plantaginaceae) is shown to improve memory and intellect in Ayurvedic Medicine, which originates in India. I discussed this plant with Thai healers, but because its use was already extensively documented in Thailand, no additional laboratory studies were conducted on this plant. It was found to have neuroprotective activity in the form of antioxidant protection against lipid oxidation in the brain (Limpeanchob, 2008).
My research also investigated the role of anti-oxidants on cognitive impairment. Since the brain has high levels of lipids, or fats, lipid oxidation can affect the brain and potentially decrease memory power. Consuming anti-oxidants can help to protect the brain from oxidation and therefore help to improve or maintain memory ability. Many plants have antioxidant protective attributes including blueberries. Increasing intake of fruits like blueberries was found to improve memory function in older adults and potentially prevent the deterioration of brain tissue (Krikorian et al. 2010). A number of other plants found in think gum, like peppermint and rosemary, have shown to have a positive affect on memory, but are found in the western hemisphere.
Krieglstein, J., T. Beck, and A. Seibert. 1986. Influence of an extract of Ginkgo biloba on cerebral blood flow and metabolism. Life Sciences 39(24):2327–2334.
Krikorian, R., M.D. Shidler, T.A. Nash, W. Kalt, M.R. Vinquist-Tymchuk, B. Shukitt-Hale and J.A. Joseph. 2010. Blueberry Supplementation Improves Memory in Older Adults. Journal of Agriculture and Food Chemistry 58: 3996-4000.
Limpeanchob, N., S. Jaipan, S. Rattanakaruna, W. Phrompittayarat, and K. Ingkaninan. 2008. Neuroprotective effect of Bacopa monnieri on beta-amyloid-induced cell death in primary cortical culture. Journal of Ethnopharmacology 120(1):112-117.