Therapeutic roles of plants for 15 hypothesised causal bases of Alzheimer's disease

Abstract

Alzheimer's disease (AD) is progressive and ultimately fatal, with current drugs failing to reverse and cure it. This study aimed to find plant species which may provide therapeutic bioactivities targeted to causal agents proposed to be driving AD. A novel toolkit methodology was employed, whereby clinical symptoms were translated into categories recognized in ethnomedicine. These categories were applied to find plant species with therapeutic effects, mined from ethnomedical surveys. Survey locations were mapped to assess how this data is at risk. Bioactivities were found of therapeutic relevance to 15 hypothesised causal bases for AD. 107 species with an ethnological report of memory improvement demonstrated therapeutic activity for all these 15 causal bases. The majority of the surveys were found to reside within biodiversity hotspots (centres of high biodiversity under threat), with loss of traditional knowledge the most common threat. Our findings suggest that the documented plants provide a large resource of AD therapeutic potential. In demonstrating bioactivities targeted to these causal bases, such plants may have the capacity to reduce or reverse AD, with promise as drug leads to target multiple AD hallmarks. However, there is a need to preserve ethnomedical knowledge, and the habitats on which this knowledge depends.

Keywords: Alzheimer’s; Causal basis; Ethnomedicine; Medicinal plants; Traditional knowledge.

Fig. 1

Distribution of ethnomedical surveys with potential therapeutic relevance for neurodegenerative diseases. The survey distribution on the map indicates that the surveys were located most commonly in Africa, Asia, Central and South America, suggesting an abundance of studies of ND relevance from those continents. There is also an abundance of surveys for certain countries (e.g., India, Nigeria), with the biggest cluster of surveys [40 in all] in India, Bangladesh and Pakistan combined. 90 out of 157 (57%) of the studies were found to reside within biodiversity hotspots and therefore are under threat. Inset: surveys located in Pacific islands