A review of Medicinal Plants of Northern Thailand for the Treatment of Cognitive Impairment in the Elderly, by Lisa C. Offringa
An ethnobotanist studies the cultural knowledge, uses and beliefs about plants in any given society and can be trained in a variety of disciplines such as botany, ecology, anthropology, geography or environmental science. An ethnopharmacologist is an ethnobotanist who studies traditionally used plants that have potential to be developed into pharmaceuticals. This dissertation is situated in the language and perspectives of ethnobotany, while its theoretical assumptions are based in the field of biology, which is the awarding department of the author’s doctoral degree. Lisa C. Offringa identifies her work as being ethnopharmacological, as she utilized overlapping methods from anthropology, botany and chemistry for her research (p. 35). Based on seventeen months of fieldwork in the province of Chiang Mai, Thailand, Offringa relied on an anthropological etic perspective of Thai traditional medicine to inform and guide her scientific findings on medicinal plants. She used methods from botany to identify plant medicines that Thai traditional healers use to treat age-related cognitive decline and she used chemistry to test the plants that traditional healers identified for pharmacological value.
The first chapter of the dissertation, the introduction, provides a straightforward project description, bulleted objectives of research, research questions, and hypotheses. Offringa provides the reader with a brief history of Thai traditional medicine, describing the impact of the introduction of Western medicine in urban centres, and the response and efforts of the Thai Ministry of Public Health to restore the Thai traditional medical system. She also delves into existing recorded ethnobotanical accounts of Thai medicine. This project is a complex one in that the western concept of “dementia” does not necessarily exist in the Thai medical view, and so recognized symptoms from one system do not translate into the other. In response to this problem, Offringa chose to study memory specifically, and explains that “mild cognitive impairment falls on a continuum with normal aging on one end and dementia on the other” (p. 21). She explores several of the western medical theories of a not fully understood etiology of dementia and memory loss. She believes that to locate plants from within the traditional Thai medical system that are effective therapies for memory loss could alleviate suffering for people with memory-based neurological disorders. The chapter concludes with a geographical description of the study location.
The second chapter of this dissertation is dedicated to methods. The author gained access to ethnographic information through interviews for plant selection, semi-structured interviews in the form of questionnaires, direct observation, and participant observation. Offringa focused this ethnographic research on Thai traditional healers who have an expertise in medicinal plants. The research was conducted in the northern Thai dialect, kam muang, but it is unclear if Offringa speaks the language or if she used translators, or a combination of both (p. 55). The majority of the research participants she identified were male, some who were former monks, some who learned from their families, and others who had formal education in Thai traditional medicine. Over time, five healers with specialized knowledge became Offringa’s principal research participants. Based on plants that these healers identified, Offringa collected samples from the forest, home-gardens and the local herbal market. She worked with a colleague at the Queen Sirikit Botanic Garden (QSBG) to collect voucher specimens of the plants and deposit them in the QSBG herbarium. Research permits dictated that voucher specimens could not leave the country, so she photographed the specimens and stored this digital information at the New York Botanical Garden. Thailand has an Act that protects and promotes Thai traditional medicine, which governed Offringa’s research and she had permission from the National Research Council of Thailand and ethical clearance from her university to conduct this research. Specific scientific methods for pharmacological analysis are not discussed in this chapter.
Chapter 3 is entitled “Thai Traditional Medicinal Theory and Cognitive Decline” (p. 57) and it provides a detailed literature review of Thai traditional medicine. The chapter explains the intersection of Thai spirituality, environmental harmony, and physical well-being. Thai traditional medicine is based on the need to balance the four elements of earth, water, wind/air, and fire. There are over seven hundred varieties of known medicinal plants used in Thai traditional medicine and each element has a corresponding plant used to strengthen it. There are also specific plant combinations and multi-plant formulas that balance each of the four elements, with corresponding oral traditions. Wind/air disturbance is the origin of cognitive decline (p. 82) and treatment can involve ceremonies, spells, herbal formulas, and specific diets (p. 86). Healers harvest entire plants when flowering and they harvest specific plants on specific days of the week and during certain seasons.
Chapter 4 lists herbal formulas Offringa obtained from her five principal research participants that are used to treat culturally specific Thai diseases related to cognitive decline in the elderly. She looked for plants that occurred in several formulas and then compared these plants to published accounts of plants known for medicinal value to find ones that had not yet been analyzed. She provides lists and tables with detailed information on each plant formula, with five plants formulas and twelve single plants used for cognitive memory decline. In Chapter 5 Offringa describes the methods she and her Thai colleagues used to perform in vitro bioassays on the eleven plants that had not had previous research performed on them, and that her principal Thai healer participants identified as the plants that they would like tested in the laboratory. Offringa and her Thai colleagues screened these eleven plants using four in vitro bioassays to measure the antioxidant activity and acetylcholinesterase inhibition to select one plant for further testing. Cinnamomum bejolghota (Buch.-Ham.) Sweet (Lauraceae) scored the highest in all of these tests and so Offringa selected it for testing on in vivo animals models (rats).
Chapter 6 provides a description of methods Offringa and her Thai colleagues used to perform in vivo testing of Cinnamomum bejolghota on 48 Wistar rats. “The results show the crude extract of Cinnamomum bejolghota to have cognitive enhancing activity in the selected in vivo rat behavioral models and subsequent acetylcholinesterase inhibition of brain tissue” (p. 156). The author then provides a section on the “taxonomic treatment” of Cinnamomum bejolghota. In the final chapter, Offringa concludes with a summary of her key findings (p. 166) and notes that Cinnamomum bejolghota could potentially be used as a memory dysfunction remedy or prophylactic supplement. She expresses hope that studies like hers will help to protect Thai healers’ traditional knowledge.
The strength of this dissertation lies in the interdisciplinary use of methodologies. The author spent seventeen months doing research in Thailand where she worked with traditional healers in close collaboration with Thai colleagues. Beginning with a large number of healers, she narrowed down her research participants to five individuals with specialized knowledge and then worked with them to identify and narrow down plants to be tested in the laboratory for potential pharmacological efficacy in treating age-related cognitive decline. This enabled her to efficiently select plants for laboratory testing and ultimately focus on one plant, Cinnamomum bejolghota to further test for pharmacological potential, which she found.
Janelle Marie Baker
Department of Anthropology
Undetermined number of traditional Thai healers narrowed down to five specialized Thai healers
Dr. Panee Sirisa-ard (Department of Pharmaceutical Sciences, Chiang Mai University)
Wittaya Pongamornkul (Botanist, Queen Sirikit Botanic Garden)
Dr. Jintanaporn Wattanathorn (Khon Kaen University)
City University of New York. 2013. 251 pp. Primary Advisor: Dr. Michael J. Balick
Image: Medical Ethnobotany and Cognitive Impairment – Lisa Offringa